My viewfinder is too small!

Question

I own a 450D, and I am very satisfied with the image quality, features, a.s.o. The only thing that disturbs me is the viewfinder. I can barely see the whole image when looking through it (black blends in near the edges as my eyes focus the image) and as soon as I look through it slightly from the side, e.g. when I'm shooting near the floor, the whole thing gets to be controlled by luck. Manual focus is almost impossible to get right - especially with the crappy focus ring on the kit lense (it's slightly better with the 60mm/2.8). Later, when I view the photos on my PC, I can see details that I haven't noticed at all while using the viewfinder and therefore did not have control of.

My question is: Am I the only one having these problems? Is there any possibility to improve my viewfinder's image without buying a new camera? And last but not least - which cameras do have good/big viewfinders? Does it have something to do with the size of the sensor?

Asked by eWolf

Answer

There are a few things conspiring against you. First is the fact that your camera uses a pentamirror rather than a pentaprism to orient the viewfinder image so up is up and left is left. Mirrors are nowhere near as efficient as total internal reflection within a prism, but they are a whole lot cheaper. And unlike a prism, they get worse rather than better the further away from the normal angle you get. (The 60D, 7D, 5D, 1D and 1Ds all use a pentaprism.)

The focusing screen makes a difference as well. I don't know enough about the actual construction of the screens in the various Canon models to say for sure whether that's a contributing factor in your case, but I do know that back in the day the Minolta Acute Matte screen was brighter than other designs by a significant enough margin (nearly a full stop of apparent brightness compared to the screens Nikon and Canon were using) that Hasselblad licensed the technology for their medium format cameras.

The reflex mirror is only partially silvered these days as well (it used to be just an ordinary front-silvered mirror in the Dark Ages). Again, I don't know if there is a significant difference in transmissivity between the various models of camera, but it wouldn't surprise me if there were.

The image erector, the screen and the reflex mirror (not to mention the optics used at the eyepiece) are all places where a camera maker can save a buck or two when making an entry-level camera.

Answered by Stan Rogers

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Do full frame camera require more power than a crop sensor camera?

Question

I had a Canon 60D and used to get around 800 to 1000 shots on full battery charge. I've now traded my 60D to a 5D Mark II and it looks like it requires a lot more power.
Is this normal for a full frame camera? The 5DMII and 60D use the same battery.

Asked by Vivek

Answer

All else being equal, yes.

A bigger sensor requires more power. Advancement in power-saving technologies can sometimes improve that but with higher pixel counts being the norm, we do not see much of that. Each pixel requires circuitry so higher megapixels require more power than making the sensor bigger.

Luckily bigger cameras have room for bigger batteries which compensates nicely until you get to the huge DSLRs with integrated grips which are rated upwards of 4000 shots per charge! Otherwise, most DSLRs are given batteries to last them between 500 and 1000 shots per charge.

Keep in mind the shots you get are highly dependent on usable. Using the flash is the most power hungry thing to do, followed by using the LCD, including Live-View and Video capture.

The stats for the 60D vs 5D are misleading because the CIPA standard requires 50% flash use if there is one, which the 5D does not have.

Answered by Itai

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Why Shave A Cropped-Frame Fisheye Lens Instead of Buying A Full-Frame One?

Question

Recently I found people shaving the lens hood off their Nikkor 10.5mm Fisheye which is a DX lens to use it on a full-frame Nikon DSLR. The result is a wider field-of-view but not even completely circular, more like a wheel-barrel.

What are the advantages of this? Why not just buy a Nikon-mount Sigma 8mm Circular fisheye instead? Or just get a rectangular full-frame fisheye? Has anyone seen how panorama software angle these types of images?

The lens warranty goes void and the damaging is permanent.

Asked by Itai

Answer

Apparently Nikon currently only offers a 16mm fisheye for the FX cameras. I suppose "gaining" 5.5mm and "saving" $150 by modifying the DX is more than enough justification for some people.

Answered by Andrew Heath

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What does “angle of view equivalent to that of some lens in 35mm format” mean?

Question

Does "angle of view equivalent to that of 22.5-585 mm lens in 35mm [135] format" for a digital camera mean that the lens is equivalent to a 22.5-585 mm lens for a DSLR camera?

Asked by Jack

Answer

The answers at What is "angle of view" in photography? should help. In short, the "equivalent" gives you a way to compare the angle of view of these lenses, by putting them all in the terms of a common format.

The format usually used as the standard is that of normal 35mm film — called "135" because that's the standard film cartridge format of that size. This format is also used by "full-frame" DSLRs. However, that's (currently and for the forseeable future) the realm of high-end cameras, usually well above $2000 for the body with no lens. Most DSLRs use a smaller format called "APS-C", which is about half the area. There's actually a number of slightly different sizes that go by this name.

For these smaller formats, you can get the "equivalent" field of view by multiplying by the "crop factor". For Sony, Nikon, and Pentax, the value is 1.5x. For Canon, it's 1.6x.

To put that in concrete terms, with the Nikon D5000, a 15-390mm lens would have that same 22.5-585 equivalent angle of view as your example. (Because 15 x 1.5 = 22.5, and 390 x 1.5 = 585.)

The lenses in compact cameras are often specified only in terms of their equivalents, because a) bigger numbers are more impressive and b) there's a dizzying array of sensor sizes in compact cameras, so using some standard makes sense. A typical sensor size is called 1/2.3", and that has a crop factor of about 5.6 — so a compact camera advertising a 22.5-585mm lens may really have a 4-105mm lens.

But don't be too swayed by the impressiveness of that gigantic zoom range. It comes at a cost — one of course being that it's easier to do with the smaller sensor coverage, and those pinky-finger-nail-sized sensors are at a disadvantage, especially in low light. But that's not all, and the lens will certainly also have significant compromises in sharpness, chromatic aberration, distortion, bokeh, and every other aspect of image quality. It still may be very capable of good results, but you should be aware of where the gear you are using makes compromises. See What does 'how much zoom' mean? for more on this.

Finally, remember that zooming is functionally equivalent to cropping — that's why the term is "crop factor" and why this equivalence works out in the first place. That means that if you have an image shot at a "300mm equivalent" focal length (for example, with a 200mm lens on a typical DSLR), and you take 25% off each edge, the resulting cropped image has a field of view like a 600mm lens. Because of the larger sensor and potentially better lens, this cropped image probably will look even better than the "full" image from the point-and-shoot with the 585mm-equivalent lens. (A decade ago, pixelation might have been a concern, but now even entry-level DSLRs have more megapixels than needed for reasonably-sized prints even after such a crop.)

Answered by mattdm

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What is the difference between the newly launched Nikon D800 and D800E?

Question

These two cameras have been announced by Nikon just this month, and they appear to be quite the same. However, getting the D800E instead of the D800 costs around $300 more. I don't know why that is since they appear to be exactly the same. I read this could be related to anti-aliasing but I don't understand what that is. Anyway, these two are now the highest resolution full frame-sensor cameras, at 36+ MP. Does anybody know why there's that price difference between these two?

Asked by the.midget

Answer

Whenever you digitize something, there is going to be some amount of information lost. When the original is reconstructed, that loss of information may lead to results that have little to do with the original signal. That applies to sound, electronic signals and to light patterns projected onto an imaging sensor.

As long as the things we digitize are larger (have a lower frequency) than the resulting digital signal, then the original can be reconstructed with at least decent fidelity. (The maximum frequency that can be faithfully digitized must be less than half of the sampling frequency. It might help to look at the Wikipedia entry for Nyquist frequency.)

When we try to take digital samples of objects with fine patterns, like regularly-spaced lines, the sensor might not be able to keep up, and when the picture is reconstructed we wind up with a moiré pattern, which generally shows up as an area of false colours in a digital image. Instead of the fine pattern, you'll get a splotch of colour that isn't in the original, or lines running at opposite angles to the lines in the original pattern.

To get around the moiré problem, most small-format (full-frame 35mm and smaller) digital cameras incorporate an optical low-pass filter into the sensor assembly. Essentially, its a filter that blurs the image somewhat so that there are no harsh transitions at a finer level of detail than the camera can accurately reconstruct from the sensor recording. The "ordinary" D800 works in exactly that way.

With the sensor resolution now sitting at over 36MP, though, there are a lot fewer instances where the detail you are trying to record cannot be resolved and reconstructed accurately -- especially if you are working in a studio situation and can change things if you bump into the Nyquist limit and create moiré (changing the magnification to make the pattern larger so that it can be resolved properly, smaller so that it doesn't really resolve optically due to limits of the lens, or changing depth of field are all ways of attacking the problem). In order to get the maximum image resolution, then, it might be worthwhile foregoing the low-pass filter, as medium-format DSLRs (and a few high-end cameras, like the Leica M9) do.

Now, you might think that taking something out of the camera should cost less than putting it in, and you'd be right. The D800E doesn't exactly leave out the low-pass filter; it has a sandwich of filters instead. There is still a thin low-pass filter, but it's backed up by another thin filter that largely undoes the effect. That allows the cameras to be produced with the same basic tooling and tolerances. Leaving the low-pass filter out of the equation would make the sensor thinner, and require different mounting and alignment to keep the focal plane in the same position relative to the lens mount flange and the reflex mirror. The extra $200-300 for the modified sensor is probably a lot cheaper than a whole different tooling setup for the body castings.

The upshot is that the D800E should be able to take sharper and more detailed images, but it does that at the risk of creating moiré patterns in areas of fine detail. Both cameras may have the same number of pixels, but the D800's pixels will be "mushy" when compared to those from the D800E.

Answered by Stan Rogers

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When do the differences between APS-C and full frame sensors matter, and why?

Question

I'm trying to decide on a higher-end digital SLR, and I'm down to choosing between an APS-C model and a full-frame model.

I understand that the sensors are of different sizes, and as such have an effect on the perceived magnification of the lens, with the smaller APS-C sensor having an effective focal length greater than what it otherwise would be with a full frame sensor. But why does this matter?

• What things should drive my choice between one or the other?
• In which situations is one better than the other, and why?

Asked by Winston Smith

Answer

• One major difference is that a FF camera produces a depth of field that's around 1.3 stops shallower than an APS-C camera for the same subject & framing. This is most important when you have the aperture as wide as possible, e.g. for portraiture. To replicate the look of a 50 f/1.4 lens you'd have to use something like a 31 f/0.9 lens, which doesn't as far as I know exist!

Quick and dirty comparison image, APS-C Canon 30D left, FF Canon 5D right, same lens (FF image was zoomed in, however to give the same field of view), same composition, both f/2.8

• Another difference is that if you're using a lens designed for a full frame camera (like all Canon EF lenses) you are making full use of the image circle, which is less demanding of the optics and so you can expect a sharper image for the same number of megapixels. It's true that some lenses get softer toward the edge of the image, but you will still get higher average sharpness with most lenses, and telephotos will be sharper right across the frame. The crop factor of APS-C cameras takes the middle out of the lens and blows it up, losing sharpness in the process in a similar manner to a teleconverter.

• Larger formats allow for sharper optics. One of the driving forces for larger formats (other than the relatively constant resolving power per unit area of film) has been that it allows lenses to be produced which resolve a greater number of line pairs per picture height. Going full frame on a DSLR benefits from this to an extend - see: With all other things equal, in a DSLR, will a larger sensor produce a sharper image?

• A bigger sensor means bigger pixels, which in turn means you capture more light usually achieving lower noise levels in the process. Greater dynamic range goes hand in hand with this.

• You get a larger, brighter viewfinder on a full frame camera, which can be helpful composing shots. Having said that, I personally find the 5D viewfinder too large, I've not used a 7D but it has a very high spec 'finder.

• You have more mirror to move on a full frame camera. The larger mirror used to mean shooting speed is limited (the mirror on my 5D moves so slowly I can actually see the world slide sideways/up for an instant) however high speed full frame models are now available.

• Likewise the mirror box, focussing screen and pentaprism are larger, meaning the camera is larger and heavier.

• Lens hoods are designed for FF image circle and are therefore slightly more effective on FF cameras. This mostly applies to prime lenses, as zoom lens hoods are designed cut to accommodate the widest zoom setting, so everything else is already non optimal. If you're using an EF lens on a crop camera you ideally want the hood tighter (since the extra shading will lie outside the smaller sensor a tighter hood wont vignette.

I have nothing against APS-C cameras but for any format it makes sense to use lenses designed for your sensor size. The range of EF-S lenses is smaller than the range of EF lenses. However for some uses (sports etc.) the smaller sensor size is helpful for the extra reach and speed it allows. Also the better noise characteristics of a FF sensor don't quite make up for the higher ISO you need to use get the same exposure when stopping down to match the DOF as a crop. So if you have to maximise DOF crop has a slight edge.

If there are EF-S lenses available for what you want to shoot then it wont be noticeably worse choosing this camera. However I feel full frame gives you more flexibility (speed aside) - as you can get the same deep DOF as a crop, but go narrower if you need to.

Answered by Matt Grum

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Fancy technology cropped vs old technology full frame - Which will give better images?

Question

After selling my 1Dmk2 last year the time has come to get myself a new body, all along I'd decided that I wanted to do more "wow" pictures, big landscapes and do some more portait photography (up until now I had been doing mainly motorsport photography).

My budget is such that I can't afford a 5Dmk2, so the obvious candidate would be a 5Dmk1, its been around for a while and is famous for producing stunning images.

However, the thought has crept into my head that a 7D might be a better option, it's had the benefit of 3 or 4 years extra development and the Dual Digic4 processors, but has this allowed the image quality to catch up with the 5D?

(I'm trying to keep the question generic, but if you want to tailor your answer I use 17-40L, 50mm and 70-200f2.8L and I'm not bothered about shooting video)

Asked by LC1983

Answer

As a former 5D owner I can tell you that using full frame, even on a camera as 'old' as that one, is a joy. The colours and image quality on that 12MP sensor are amazing. You will notice the benefits particularly with your 17-40mm lens.

If I were in your position, I wouldn't hesitate to pick up a second hand 5D.

Answered by Nick Miners

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Main differences between the newly launched Nikon D800 and D800E?

Question

These two cameras have been announced by Nikon just this month, and they appear to be quite the same. However, getting the D800E instead of the D800 costs around $300 more. I don't know why that is since they appear to be exactly the same. I read this could be related to anti-aliasing but I don't understand what that is. Anyway, these two are now the highest resolution full frame-sensor cameras, at 36+ MP. Does anybody know why there's that price difference between these two?

Asked by the.midget

Answer

Whenever you digitize something, there is going to be some amount of information lost. When the original is reconstructed, that loss of information may lead to results that have little to do with the original signal. That applies to sound, electronic signals and to light patterns projected onto an imaging sensor.

As long as the things we digitize are larger (have a lower frequency) than the resulting digital signal, then the original can be reconstructed with at least decent fidelity. (The maximum frequency that can be faithfully digitized must be less than half of the sampling frequency. It might help to look at the Wikipedia entry for Nyquist frequency.)

When we try to take digital samples of objects with fine patterns, like regularly-spaced lines, the sensor might not be able to keep up, and when the picture is reconstructed we wind up with a moiré pattern, which generally shows up as an area of false colours in a digital image. Instead of the fine pattern, you'll get a splotch of colour that isn't in the original, or lines running at opposite angles to the lines in the original pattern.

To get around the moiré problem, most small-format (full-frame 35mm and smaller) digital cameras incorporate an optical low-pass filter into the sensor assembly. Essentially, its a filter that blurs the image somewhat so that there are no harsh transitions at a finer level of detail than the camera can accurately reconstruct from the sensor recording. The "ordinary" D800 works in exactly that way.

With the sensor resolution now sitting at over 36MP, though, there are a lot fewer instances where the detail you are trying to record cannot be resolved and reconstructed accurately -- especially if you are working in a studio situation and can change things if you bump into the Nyquist limit and create moiré (changing the magnification to make the pattern larger so that it can be resolved properly, smaller so that it doesn't really resolve optically due to limits of the lens, or changing depth of field are all ways of attacking the problem). In order to get the maximum image resolution, then, it might be worthwhile foregoing the low-pass filter, as medium-format DSLRs (and a few high-end cameras, like the Leica M9) do.

Now, you might think that taking something out of the camera should cost less than putting it in, and you'd be right. The D800E doesn't exactly leave out the low-pass filter; it has a sandwich of filters instead. There is still a thin low-pass filter, but it's backed up by another thin filter that largely undoes the effect. That allows the cameras to be produced with the same basic tooling and tolerances. Leaving the low-pass filter out of the equation would make the sensor thinner, and require different mounting and alignment to keep the focal plane in the same position relative to the lens mount flange and the reflex mirror. The extra $200-300 for the modified sensor is probably a lot cheaper than a whole different tooling setup for the body castings.

The upshot is that the D800E should be able to take sharper and more detailed images, but it does that at the risk of creating moiré patterns in areas of fine detail. Both cameras may have the same number of pixels, but the D800's pixels will be "mushy" when compared to those from the D800E.

Answered by Stan Rogers

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Does shooting at lower RAW resolution using crop sensor camera mimics qualities of full frame cameras?

Question

I'm not talking about changes to the focal length.

I've read many post that say in full frame camera the pixel density is lower compared to crop sensor camera's and so it captures more light and has thus has better ISO performance and greater dynamic range. So if I change by crop sensor camera to shoot at a lower resolution, will that equate to a better pixel density and mimic the performance of a full frame (or medium format) or will it always shoot at maximum resolution and the reduce the size?

--EDIT: 1--
I've a Canon 60D and I've 3 options for RAW image sizes (RAW, M-RAW amd S-RAW). If RAW is just a dump from the Camera sensors, How can their be 3 different sizes? Does the camera also scale down RAW images as well?

Answer

Given that you have a Canon, the lower RAW modes, mRAW and sRAW, DO INDEED UTILIZE ALL of the available sensor pixels to produce a richer result without the need for bayer interpolation. The actual output format, while it is still contained within a .cr2 Canon RAW image file, is encoded in a Y'CbCr format, similar to many video pulldown formats. It stores luminance information for each FULL pixel (2x2 quad of 1 red, 1 blue, and 2 green pixels), and each chrominance channel is derived from half pixel data (1x2 pair of 1 red+1 green or 1 blue+1 green).

I am not exactly certain what the specific low-level hardware read and encoding differences between mRAW and sRAW are, however generally speaking the smaller the output format, the more sensor pixel input information you can use for each output pixel. The small amount of interpolation present in m/sRAW is moot, as both formats interpolate far less than native RAW. It should also be noted that neither mRAW nor sRAW are actual "RAW" formats in the normal sense...sensor data IS processed and converted into something else before it is saved to a .cr2 file.

For more details about YUV derived formats and Canon sRAW, see my answer here: Why isn't the xvYCC color space seeing uptake for still photography?

From "Understanding What is stored in a Canon RAW .CR2 file":

The sRaw format (for "small RAW") was introduced with the 1D Mark III in 2007. It is a smaller version of the RAW picture.

For the 1D Mark III, then the 1Ds Mark III and the 40D (all with the Digic III), the sRaw size is exactly 1/4 (one fourth) of the RAW size. We can thus suppose than each group of 4 "sensor pixels" is summarized into 1 "pixel" for the sRaw.

With the 50D and the 5D Mark II (with the Digic IV chip), the 1/4th size RAW is still there (sRaw2), and a half size RAW is also appearing : sRaw1. With the 7D, the half size raw is called mraw (same encoding as sraw1), 1/4th raw is called sraw (like the sraw2).

the sRaw lossless Jpeg is always encoded with 3 colors component (nb_comp) and 15 bits.

Jpeg code of Dcraw was first modified (8.79) to handle sRaw because of the h=2 value of the first component (grey background in the table). Normal RAW have always h=1. Starting with the 50D, we have v=2 instead of v=1 (orange in the table). Dcraw 8.89 is the first version to handle this and the sraw1 from 50d and 5D Mark II.

"h" is the horizontal sampling factor and "v" the vertical sampling factor. It specifies how many horizontal/vertical data unit are encoded in each MCU (minimum coded unit). See T-81, page 36.

3.2.1 sRaw and sRaw2 format

h=2 means that the decompressed data will contain 2 values for the first component, 1 for column n and 1 for column n+1. With the 2 other components, decompressed sraw and sraw2 (which all have h=2 & v=1), always have 4 elementary values

[ y1 y2 x z ] [ y1 y2 x z ] [ y1 y2 x z ] ...
(y1 and y2 for first component)

Every "pixel" in sRAW and mRAW images contain four components...a split Y' component (y1 and y2), as well as an x (Chrominance Blue) and z (Chrominance Red). All four components (from a 1/2 image perspective, sRAW1/mRAW) have a column height of 2 (h) and a width of 1 (v). This indicates that the Luminance value (Y') is comprised of a FULL 2x2 pixel quad...or two 2x1 pixel columns stored in y1 and y2.

The references below do not seem to specifically state this, so I am speculating a bit here, however with the sRAW2 (1/4 raw) I believe Luminance information would be derived from a 4x4 pixel block where h=4 and v=2. Encoding chrominance would get more complex at a 1/4 size image, as the bayer color filter array on the sensor is not arranged in neat red and blue columns. I am unsure whether alternating 2x1 height columns are processed for each Cr and Cb component, or if some other form of interpolation is performed. One thing is certain...the interpolation of source data is always larger than the output data, and no overlapping (as in normal bayer interpolation) occurs as far as I can tell.

Finally, sRAW1/mRAW and sRAW/sRAW2 are compressed using a lossless compression algorithm. This is a critical distinction between these formats and JPEG, which also uses a ycc type encoding. JPEG performs lossy compression, making it impossible to restore pixels back to their exact original representation. Canon's s/mRAW formats are indeed able to be restored back to original full precision 15-bit image data.

References:

• Understanding What is stored in a Canon RAW .CR2 file, How and Why
  • For pulldown details, see text just before section 3.2.1
• DIGITAL COMPRESSION AND CODING OF CONTINUOUS-TONE STILL IMAGES – REQUIREMENTS AND GUIDELINES

Check more discussion of this question.

Does shooting at lower RAW resolution using crop sensor camera mimics qualities of full frame cameras?

Question

I'm not talking about changes to the focal length.

I've read many post that say in full frame camera the pixel density is lower compared to crop sensor camera's and so it captures more light and has thus has better ISO performance and greater dynamic range. So if I change by crop sensor camera to shoot at a lower resolution, will that equate to a better pixel density and mimic the performance of a full frame (or medium format) or will it always shoot at maximum resolution and the reduce the size?

--EDIT: 1--
I've a Canon 60D and I've 3 options for RAW image sizes (RAW, M-RAW amd S-RAW). If RAW is just a dump from the Camera sensors, How can their be 3 different sizes? Does the camera also scale down RAW images as well?

Answer

Given that you have a Canon, the lower RAW modes, mRAW and sRAW, DO INDEED UTILIZE ALL of the available sensor pixels to produce a richer result without the need for bayer interpolation. The actual output format, while it is still contained within a .cr2 Canon RAW image file, is encoded in a Y'CbCr format, similar to many video pulldown formats. It stores luminance information for each FULL pixel (2x2 quad of 1 red, 1 blue, and 2 green pixels), and each chrominance channel is derived from half pixel data (1x2 pair of 1 red+1 green or 1 blue+1 green).

I am not exactly certain what the specific low-level hardware read and encoding differences between mRAW and sRAW are, however generally speaking the smaller the output format, the more sensor pixel input information you can use for each output pixel. The small amount of interpolation present in m/sRAW is moot, as both formats interpolate far less than native RAW. It should also be noted that neither mRAW nor sRAW are actual "RAW" formats in the normal sense...sensor data IS processed and converted into something else before it is saved to a .cr2 file.

For more details about YUV derived formats and Canon sRAW, see my answer here: Why isn't the xvYCC color space seeing uptake for still photography?

From "Understanding What is stored in a Canon RAW .CR2 file":

The sRaw format (for "small RAW") was introduced with the 1D Mark III in 2007. It is a smaller version of the RAW picture.

For the 1D Mark III, then the 1Ds Mark III and the 40D (all with the Digic III), the sRaw size is exactly 1/4 (one fourth) of the RAW size. We can thus suppose than each group of 4 "sensor pixels" is summarized into 1 "pixel" for the sRaw.

With the 50D and the 5D Mark II (with the Digic IV chip), the 1/4th size RAW is still there (sRaw2), and a half size RAW is also appearing : sRaw1. With the 7D, the half size raw is called mraw (same encoding as sraw1), 1/4th raw is called sraw (like the sraw2).

the sRaw lossless Jpeg is always encoded with 3 colors component (nb_comp) and 15 bits.

Jpeg code of Dcraw was first modified (8.79) to handle sRaw because of the h=2 value of the first component (grey background in the table). Normal RAW have always h=1. Starting with the 50D, we have v=2 instead of v=1 (orange in the table). Dcraw 8.89 is the first version to handle this and the sraw1 from 50d and 5D Mark II.

"h" is the horizontal sampling factor and "v" the vertical sampling factor. It specifies how many horizontal/vertical data unit are encoded in each MCU (minimum coded unit). See T-81, page 36.

3.2.1 sRaw and sRaw2 format

h=2 means that the decompressed data will contain 2 values for the first component, 1 for column n and 1 for column n+1. With the 2 other components, decompressed sraw and sraw2 (which all have h=2 & v=1), always have 4 elementary values

[ y1 y2 x z ] [ y1 y2 x z ] [ y1 y2 x z ] ...
(y1 and y2 for first component)

Every "pixel" in sRAW and mRAW images contain four components...a split Y' component (y1 and y2), as well as an x (Chrominance Blue) and z (Chrominance Red). All four components (from a 1/2 image perspective, sRAW1/mRAW) have a column height of 2 (h) and a width of 1 (v). This indicates that the Luminance value (Y') is comprised of a FULL 2x2 pixel quad...or two 2x1 pixel columns stored in y1 and y2.

The references below do not seem to specifically state this, so I am speculating a bit here, however with the sRAW2 (1/4 raw) I believe Luminance information would be derived from a 4x4 pixel block where h=4 and v=2. Encoding chrominance would get more complex at a 1/4 size image, as the bayer color filter array on the sensor is not arranged in neat red and blue columns. I am unsure whether alternating 2x1 height columns are processed for each Cr and Cb component, or if some other form of interpolation is performed. One thing is certain...the interpolation of source data is always larger than the output data, and no overlapping (as in normal bayer interpolation) occurs as far as I can tell.

Finally, sRAW1/mRAW and sRAW/sRAW2 are compressed using a lossless compression algorithm. This is a critical distinction between these formats and JPEG, which also uses a ycc type encoding. JPEG performs lossy compression, making it impossible to restore pixels back to their exact original representation. Canon's s/mRAW formats are indeed able to be restored back to original full precision 15-bit image data.

References:

• Understanding What is stored in a Canon RAW .CR2 file, How and Why
  • For pulldown details, see text just before section 3.2.1
• DIGITAL COMPRESSION AND CODING OF CONTINUOUS-TONE STILL IMAGES – REQUIREMENTS AND GUIDELINES

Check more discussion of this question.

Is it possible to make a 35mm digital camera with the same size / weight / price as a 35mm film camera?

Question

Why are full-frame digital cameras huge, heavy, $6000 beasts when 35mm film cameras fit in a pocket and cost $6?

Are full-frame cameras getting smaller, lighter and/or cheaper? If not, why?

If there are the technological or physical limitations, what are they?

Answer

When comparing film to digital cameras, you need to compare apples to apples. I searched for the EOS 1, EOS 1Ds and EOS 1DsMk3 and found a surprising fact: the EOS 1, when equipped with the battery and motor drive extender (grip) which brings it to about the same physical size as the EOS 1Ds/1DsMk3, becomes almost the same weight and even heavier!

• EOS 1: 1450g
• EOS 1Ds: 1585g
• EOS 1DsMk3: 1385g

More modern materials enable the built of lighter bodies. OTOH, more bells-and-whistles add somewhat to the weight. I assume the greatest contributor is the introduction of BIG LCD backs.

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How do Micro 4/3s cameras compare with DSLR cameras?

Question

What are the major (and perhaps more subtle) differences between the newer Micro 4/3s format in comparison to the well-established DSLR cameras? What are the pros and cons of the Micro 4/3s format, the camera body and lens capabilities and offerings, size/weight, etc.

Answer

The first technical difference is the fact that the sensor is smaller to the most common DSLR sensor sizes (APS-C and larger), whilst it's going to be less optimal than an APS-C, full frame or medium format (very expensive) sensor, it's still going to be far better than compact sensors. Noise will be comparable to APS-C (1.6x), though probably not quite as good, but this is also dependent on the sensor technology.

The second technical difference is that almost all Micro 4/3rds cameras currently use an electronic viewfinder, not SLR viewfinder. This means there is no phase detect auto-focus which is much quicker than contrast based auto focus. Phase detect AF can take less than a second in good light, whereas contrast AF can typically take 3-4 seconds and most often takes this long in any conditions.

Another difference is that on a lot of Micro 4/3rds cameras, the manual controls for aperture, shutter speed and ISO aren't as accessible as an SLR camera. If you plan on shooting manual with a Micro 4/3rds camera you may have to look around for the one that won't hinder you. For example, Sony's NEX-5 (not Micro 4/3rds but similar) apparently are very fiddly and it's better to just use them in an automated mode like Program mode.

A major physical difference is the size. The camera body itself is typically no larger than a large compact. The problem with this though is that the lenses are still fairly large when it comes to portability. You probably wouldn't try putting one in your pocket unless you have both a large pocket and a very short lens attached.

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How do Micro 4/3s cameras compare with DSLR cameras? Pros/Cons?

Question

What are the major (and perhaps more subtle) differences between the newer Micro 4/3s format in comparison to the well-established DSLR cameras? What are the pros and cons of the Micro 4/3s format, the camera body and lens capabilities and offerings, size/weight, etc.

Answer

The first technical difference is the fact that the sensor is smaller to the most common DSLR sensor sizes (APS-C and larger), whilst it's going to be less optimal than an APS-C, full frame or medium format (very expensive) sensor, it's still going to be far better than compact sensors. Noise will be comparable to APS-C (1.6x), though probably not quite as good, but this is also dependent on the sensor technology.

The second technical difference is that almost all Micro 4/3rds cameras currently use an electronic viewfinder, not SLR viewfinder. This means there is no phase detect auto-focus which is much quicker than contrast based auto focus. Phase detect AF can take less than a second in good light, whereas contrast AF can typically take 3-4 seconds and most often takes this long in any conditions.

Another difference is that on a lot of Micro 4/3rds cameras, the manual controls for aperture, shutter speed and ISO aren't as accessible as an SLR camera. If you plan on shooting manual with a Micro 4/3rds camera you may have to look around for the one that won't hinder you. For example, Sony's NEX-5 (not Micro 4/3rds but similar) apparently are very fiddly and it's better to just use them in an automated mode like Program mode.

A major physical difference is the size. The camera body itself is typically no larger than a large compact. The problem with this though is that the lenses are still fairly large when it comes to portability. You probably wouldn't try putting one in your pocket unless you have both a large pocket and a very short lens attached.

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Is crop-factor a bad thing?

Question

It seems to me that there is a preference for full-frame sensors rather than cropped sensors, and I'm curious as to why. It seems to me, that the cropped sensor means that I get more bang for my buck with zoom lenses. True, I suppose it means I would need to a shorter lens to get the same wide-angle effect on the short end, but it seems like wide-angle lenses are (generally) cheaper than telephoto lenses. Am I missing something?

Answer

No, it is not a bad thing. It is not really "good" or "bad" in any sense. Its simply a different format than full-frame, which is different than medium format, etc. There are pros and cons to each. The smaller APS-C style "cropped" sensors do have some effects on lens focal length due to their field of view, and that can be beneficial or detrimental, depending on how you choose to see it. Here are some facts about sensors:

1. Cropped Sensor Formats (APS-C)
   • These are smaller sensors
     • They have higher manufacturing "yield" than larger sensors
     • As such, they are generally much cheaper
   • Photosites are generally smaller and more densely packed
     • This generally results in lower signal-to-noise ratio, more noisy pictures
     • This also means the maximum dynamic range (contrast ratio) of cropped senors is lower (less light gathering power per photosite)
   • They have a narrower field of view compared to larger sensors
   • Their narrower FOV has the effect of multiplying the focal length of any lens
     • This may be beneficial if you need super telephoto lengths (i.e. 400mm on FF ~= 640mm on APS-C, effectively)
     • This may be detrimental if you need ultra wide angle lengths (i.e. 16mm on FF ~= 26mm on APS-C, effectively)
   • The additional "effective magnification" offered by a cropped sensor is only illusory, and is not actual magnification
     • Given a large enough sensor with enough megapixels, and the same exact "crop" provided by a cropped senor can be achieved with a full-frame or medium format (however, the larger sensor would need some SERIOUS megapixels to achieve this.)
       • The 1.6x crop sensor of a Canon 450D would require a full-Frame sensor with 31mp to achieve the same crop
       • The 1.6x crop sensor of a Canon 550D would require a full-frame sensor with 46mp to achieve the same crop
2. Full-Frame Sensor Formats
   • These sensors provide the same "usable" pixel area as 35mm film
   • These sensors are larger, and have lower manufacturing yield
     • This generally means they are more expensive
   • The photosites are larger and often less densely packed
     • This results in better signal-to-noise ratio, less noisy pictures
     • Dynamic range is generally higher with larger photosites.
       • (The new Canon 1Ds IV with a 30mp+ sensor is touted as having full 16bit RAW capability, which offers much greater dynamic range than the general 12bit RAW of cropped sensors)
   • Their field of view is "normal" from the perspective of the bulk of the photography community and equipment
   • A lenses focal length is as stated when used on a full frame
3. Medium Format Sensors
   • These sensors are often much larger than full-frame (up to 57mm or larger)
     • They have extremely low yield, and thus their cost is extremely high
   • They have high density, but large photosites
     • This results in some of the best dynamic range possible in a digital sensor
     • Leica and Hasselblad's latest medium-format sensors tout 24bit RAW
   • They may have a much wider field of view than normal 35mm for a given focal length
     • A lens of a normal 35mm focal length would be shorter on medium format, providing even greater field of view
     • As with cropped sensors, the effect is illusory, and only useful when describing things at a technical level

(Note that the effect of sensor size on focal length or the apparent magnification assumes a common lens system. Medium format cameras tend to be rather specialized, so a direct comparison here is likely impossible. For the sake of discussion, the effect given similar lens system and focal lengths would thread throughout the range of sensor sizes.)

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What are the different sensor sizes used in DSLRs?

Question

What do the different sensor size names used by Canon mean? There's APS-C, APS-H and full format? What are the standards used by Nikon, Pentax, Sony, Olympus, Panasonic, and others?

What are the effects of these different sensor sizes (and the corresponding "crop factor") on lenses?

Answer

These are the different sensor sizes:

• Full frame sensor (Nikon's FX, Canon does not use special term): 36 x 24mm, no crop (actual size might differ slightly between brands and cameras)
• Canon's APS-H: 27.9 x 18.6mm, crop factor 1.3
• Canon's APS-C: 22.3 x 14.9mm, crop factor 1.6
• Nikon's DX: 23.6 x 15.8mm, crop factor 1.5 (23.1 x 15.4mm, crop factor 1.55 for Nikon 3100)

The effects of crop factor to the lenses is that the smaller sizes lessen the angle of view, but as the focal length is universally adapted to represent the field of view, you can multiply the focal lengths by the crop factor to get the indication for angle of view.

In example if you take 18-55mm zoom, it's effective angle of view on APS-C is equivalent to 18x1.6-55x1.6 ~ 28-90mm lens on a fullframe camera.

You might find this discussion about focal lengths and their equivalents useful.

When shopping for lenses, one should keep in mind that when you have camera with cropped sensor, both fullframe (Canon's EF, Nikon's lenses without DX marking) and cropped sensor (Canon's EF-S, Nikon's DX) lenses are usable on your camera, but lenses made for cameras with cropped sensor are not usable on fullframe cameras.

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Why do the differences between APS-C and full frame sensors matter?

Question

I'm trying to decide on a model in the Canon DSLR range, and I guess it's a choice between the 7D and the 5D MkII.

I understand that the sensors are of different sizes, and as such have an effect on the perceived magnification of the lens, with the smaller APS-C sensor having an effective focal length greater than what it otherwise would be with a full frame sensor. But why does this matter?

• What things should drive my choice between one or the other?
• In which situations is one better than the other, and why?

Answer

• One major difference is that a FF camera produces a depth of field that's around 1.3 stops shallower than an APS-C camera for the same subject & framing. This is most important when you have the aperture as wide as possible, e.g. for portraiture. To replicate the look of a 50 f/1.4 lens you'd have to use something like a 31 f/0.9 lens, which doesn't as far as I know exist!

Quick and dirty comparison image, APS-C Canon 30D left, FF Canon 5D right, same lens, same composition, both f/2.8

• Another difference is that if you're using a lens designed for a full frame camera (like all Canon EF lenses) you are making full use of the image circle, which is less demanding of the optics and so you can expect a sharper image for the same number of megapixels. It's true that some lenses get softer toward the edge of the image, but you will still get higher average sharpness with most lenses, and telephotos will be sharper right across the frame. The crop factor of APS-C cameras takes the middle out of the lens and blows it up, losing sharpness in the process in a similar manner to a teleconverter. See this related question:

• With all other things equal, in a DSLR, will a larger sensor produce a sharper image?

• A bigger sensor means bigger pixels, which in turn means you capture more light usually achieving lower noise levels in the process. Greater dynamic range goes hand in hand with this.

• You get a larger, brighter viewfinder on a full frame camera, which can be helpful composing shots. Having said that, I personally find the 5D viewfinder too large, I've not used a 7D but it has a very high spec 'finder.

• You have more mirror to move on a full frame camera. The larger heavier mirror usually means shooting speed is limited. The mirror on my 5D moves so slowly I can actually see the world slide sideways/up for an instant!

• Likewise the mirror box, focussing screen and pentaprism are larger, meaning the camera is larger and heavier.

• Lens hoods are designed for FF image circle and are therefore slightly more effective on FF cameras. This mostly applies to prime lenses, as zoom lens hoods are designed cut to accommodate the widest zoom setting, so everything else is already non optimal. If you're using an EF lens on a crop camera you ideally want the hood tighter (since the extra shading will lie outside the smaller sensor a tighter hood wont vignette.

I have nothing against APS-C cameras but for any format it makes sense to use lenses designed for your sensor size. The range of EF-s lenses is smaller than the range of EF lenses. However for some uses (sports etc.) the smaller sensor size is helpful for the extra reach and speed it allows. Also the better noise characteristics of a FF sensor don't quite make up for the higher ISO you need to use get the same exposure when stopping down to match the DOF as a crop. So if you have to maximise DOF crop has a slight edge.

If there are EF-s lenses available for what you want to shoot then it wont be noticeably worse choosing this camera. However I feel full frame gives you more flexibility (speed aside) - as you can get the same deep DOF as a crop, but go narrower if you need to.

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APS-C vs Full Frame - why should I care?

Question

I'm trying to decide on a model in the Canon DSLR range, and I guess it's a choice between the 7D and the 5D MkII.

I understand that the sensors are of different sizes, and as such have an effect on the perceived magnification of the lens, with the smaller APS-C sensor having an effective focal length greater than what it otherwise would be with a full frame sensor. But why does this matter?

• What things should drive my choice between one or the other?
• In which situations is one better than the other, and why?

Answer

• One major difference is that a FF camera produces a depth of field that's around 1.3 stops shallower than an APS-C camera for the same subject & framing. This is most important when you have the aperture as wide as possible, e.g. for portraiture. To replicate the look of a 50 f/1.4 lens you'd have to use something like a 31 f/0.9 lens, which doesn't as far as I know exist!

Quick and dirty comparison image, APS-C Canon 30D left, FF Canon 5D right, same lens, same composition, both f/2.8

• Another difference is that if you're using a lens designed for a full frame camera (like all Canon EF lenses) you are making full use of the image circle, which is less demanding of the optics and so you can expect a sharper image for the same number of megapixels. It's true that some lenses get softer toward the edge of the image, but you will still get higher average sharpness with most lenses, and telephotos will be sharper right across the frame. The crop factor of APS-C cameras takes the middle out of the lens and blows it up, losing sharpness in the process in a similar manner to a teleconverter. See this related question:

• With all other things equal, in a DSLR, will a larger sensor produce a sharper image?

• A bigger sensor means bigger pixels, which in turn means you capture more light usually achieving lower noise levels in the process. Greater dynamic range goes hand in hand with this.

• You get a larger, brighter viewfinder on a full frame camera, which can be helpful composing shots. Having said that, I personally find the 5D viewfinder too large, I've not used a 7D but it has a very high spec 'finder.

• You have more mirror to move on a full frame camera. The larger heavier mirror usually means shooting speed is limited. The mirror on my 5D moves so slowly I can actually see the world slide sideways/up for an instant!

• Likewise the mirror box, focussing screen and pentaprism are larger, meaning the camera is larger and heavier.

• Lens hoods are designed for FF image circle and are therefore slightly more effective on FF cameras. This mostly applies to prime lenses, as zoom lens hoods are designed cut to accommodate the widest zoom setting, so everything else is already non optimal. If you're using an EF lens on a crop camera you ideally want the hood tighter (since the extra shading will lie outside the smaller sensor a tighter hood wont vignette.

I have nothing against APS-C cameras but for any format it makes sense to use lenses designed for your sensor size. The range of EF-s lenses is smaller than the range of EF lenses. However for some uses (sports etc.) the smaller sensor size is helpful for the extra reach and speed it allows. Also the better noise characteristics of a FF sensor don't quite make up for the higher ISO you need to use get the same exposure when stopping down to match the DOF as a crop. So if you have to maximise DOF crop has a slight edge.

If there are EF-s lenses available for what you want to shoot then it wont be noticeably worse choosing this camera. However I feel full frame gives you more flexibility (speed aside) - as you can get the same deep DOF as a crop, but go narrower if you need to.

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Are full-frame cameras bad for sports photography?

Question

I was reading about crop factor from various places on the internet, and the general idea that kept building in my mind was that full-frame cameras are good for wide-angle shots but not that good for tele-photo. In Wikipedia it's written:

[...] a 200 mm lens on a camera with a crop factor of 1.5 has the same angle of view as a 300 mm lens on a full-frame camera. The extra "reach", for a given number of pixels, can be helpful in specific areas of photography such as wildlife or sports.⁶

It makes sense, but how high would the level of detail be on a full-frame with 300mm compared to the other example?

Answer

One aspect of this comparison that has not been mentioned is the fact that crop-sensor cameras are generally faster for a given price point.

• The 7D shoots at up to 8 Frames/Sec, the 5D manages 3.9 Frames/Sec
• The 1Ds III manages 5 Frames/Sec, while the 1D III/IV manages 10 Frames/Sec

In sports photography, where continuous drive is often used, those extra frames could mean the difference between capturing a player right before hie hits/kicks a ball, and actually at the moment of contact.

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Regarding using telephoto lenses on a crop-sensor body, the critical measurement here is the pixel pitch, which is the thing that actually determines how much detail you will get from a lens.

Basically, if you have two different sensors with the same pixel pitch, the larger one effectively takes the exact same image, with some cropping.

As an example, I have a 30D and a 5D2. Both have 6.4µm pixels. Therefore, every exposure on the 5D2 effectively includes the entire area that a 30D exposure would capture, with the same resolution.

However, the 7D has 4.3µm pixels, so for a given focal length, the 7D will resolve 1.5X (1.488 to be exact) the detail.

This is all assuming an ideal lens. If your lens cannot resolve fine details, either camera will produce a blurry result. Also, small pixel sizes will be less forgiving of lens defects than larger pixels, since the smaller pixels require a larger lpm from the lens. A lens that is at the edge of it's resolving capabilities on a 5D2 may not see any improvement on a 7D, since the extra pixel resolution has no effect on the lens sharpness.

There is a nice breakdown of the Canon series camera pixel pitches on the-digital-picture.com. It's about 2/3 of the way down the page.

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There are other considerations - larger pixels generally give less ISO noise, though modern image processing is advancing faster then sensors are shrinking, so it is not as much of an issue as it could be.

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Note: I am writing about canon bodies because I am a canon user, and know them far better. However, most of the arguments are much more broadly applicable, basically to anything that uses a CCD/CMOS image sensor:

• The two critical factors in a camera's FPS are Number of pixels, and ADC speed.
• The critical factor in how much detail you get from a lens is pixel pitch (Smaller pixels gets more detail, until you reach the limitations of the lens).
• The largest influence in ISO performance is pixel size (larger pixels are less noisy). The readout electronics have much more influence here, though, so it is not an absolute determining factor as the two above are.

This is true across all brands.

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