Do lenses need to be made with more precision for Hasselblad's 60MPix camera?

Question

One of Hasselblad's cameras has a Double-Full-Frame sensor.

Does that mean that the lenses needed for it are incredibly more complex to build (to have a sharp, high quality, abberation free image on the borders ?)

Asked by Skippy Fastol

Answer

Back to film camera time, studio enthusiast where used to 6x6 (6cmx6cm) (or even 6x8) camera which have surface about 4 times the 24x36 (24mmx36mm).

If you look (as exemple) at the Zeiss lense for such camera (as exemple for Hasselblad body) you can see that the same optical formula are also used for 24x36 lenses (Zeiss optical formula is indicated by the name Planar, Distagon, Tessar,...)

Theses lenses are bigger and usually build for high-end users but designs are not very different

Answered by floqui

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Lens precision of Hasselblad 60MPix camera

Question

One of Hasselblad's lenses has a Double-Full-Frame sensor.

Does that mean that the lenses needed for it are incredibly more complex to build (to have a sharp, high quality, abberation free image on the borders ?)

Asked by Skippy Fastol

Answer

Back to film camera time, studio enthusiast where used to 6x6 (6cmx6cm) (or even 6x8) camera which have surface about 4 times the 24x36 (24mmx36mm).

If you look (as exemple) at the Zeiss lense for such camera (as exemple for Hasselblad body) you can see that the same optical formula are also used for 24x36 lenses (Zeiss optical formula is indicated by the name Planar, Distagon, Tessar,...)

Theses lenses are bigger and usually build for high-end users but designs are not very different

Answered by floqui

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Which attribute is the most important in a DSLR and lens when shooting objects from a distance?

Question

I need a DSLR & lens that can shoot objects at a long distance with great sharpness when I open the image to view and zoom.

So, what attribute is the most important to do that? Some of my friends say that a DSLR and 200mm to 300mm lens is important but would like to seek advices from experts out in the community.

Asked by Jack

Answer

What are the Most Important Attributes?

1. The Tripod

The most important factor will certainly be the tripod. Telephoto shots taken with a great lens handheld will be inferior to shots taken with a mediocre lens on a middling-to-good tripod.

2. Autofocus

Good autofocus is almost indispensable if your subjects are moving (I'm going to assume they might be). In most camera systems, autofocus is a combined feature of the camera and the lens (that is, both items need to support autofocus).

3. Sensor Area and Pixel Density

If you want to fill the frame with far-away objects, it is financially more efficient (at least in 2012) to buy a crop-sensor camera. Buying a camera with a sensor 2/3 the size of a full frame is much cheaper than buying a lens with a 50% longer focal length.

A high pixel count allows you to crop your original photo and still end up with a reasonable image if the subject didn't fill the frame (as usually will happen for birds, for example).

4. Lens Focal Length

This isn't really the least important of the four attributes, but precisely how important it is depends on things like what you're trying to shoot.

If the object truly is far away, 200mm is probably not enough. Unless you're making images of aeroplanes or buses. A 300mm lens on a 1.5x crop sensor body gives a similar field of view to a 450mm lens on a full-frame body (the difference in sensor size affects the field of view but not the focal length of the lens).

Depending on what you're shooting, 300mm may still not be enough. You can either buy an even longer lens (this rapidly gets expensive) or use a teleconverter. A teleconverter sacrifices some image quality (for the Nikon 1.4 teleconverter this is normally imperceptible) and some light (a 1.4 teleconverter makes your lens exactly one stop slower, and a 2.0 teleconverter two stops slower, and so on). Because the teleconverter loses light and autofocus cameras normally don't autofocus at apertures slower than f/5.6, it's normally a good idea to apply your TC to an f/2.8 lens rather than an f/4 lens. Put another way, a 1.4 TC on an f/4 lens results in a lens which is 50% longer in focal length but it's f/5.6. Autofocus may not be so good on that lens. Better to start with an f/2.8 lens, which will become an f/4 lens with the addition of the teleconverter.

Illustrative Equipment Selection, With Explanation

To fully answer the question, we need to continue to think about budget because one of the things you need to figure out is which bit to spend what fraction of your budget on (and why). This is going to depend on a bunch of things you didn't state (including what size things you want to make photos of, how far away they are, and whether they are moving). I'm going to make a few (explained) assumptions and suggest specific hardware, below. The idea is that this gives you some idea of the trade-offs.

You specified a DSLR so I will ignore odder solutions like Nikon 1 with F-mount converter and 70-200 (total cost probably around $3000 or so).

The idea is to illustrate the ideas I mentioned above, by selecting some specific bits of equipment. There is no reason to choose one manufacturer over another particularly. I happen to have chosen a manufacturer whose gear I'm familiar with, but you could quite happily go with another system and get a good result by applying the same principles.

Camera Body

Assuming Nikon gear for illustration purposes, I will assume you spend $1300 on a Nikon D7000; of the current Nikon crop-sensor cameras it has the highest pixel density and probaby the best autofocus (unless the D300s is better).

Other manufacturers no doubt make cameras of similar features and price (though I don't know offhand which the comparable Canon DSLR is). You could also buy a second-hand D300s from KEH for a slightly more - which might be a good idea if focus speed is important, and focus speed will certainly improve sharpness for moving subjects.

If you really want to save money on this area you could get a D90 second-hand for about half the cost of a new D7000. But there is quite a gap between the two in terms of capability.

Lens

Your original budget was $1000 to $4500. We spent about $1300 so this leaves between $0 and $3200 for the lens. At the bottom end of the budget range you could get the Nikon 300mm f/4.5 AI-S lens, which is manual focus (around $220 at KEH). Bjørn Rørslett rates that lens quite well, though I have never used it. The downside is that if your subject moves it may be difficult to get an in-focus image (unless the objects move through a specific point - like race cars - allowing you to use focus-trap).

Higher up this price range you have autofocus lenses, which will be a better choice for moving subjects. At 300mm focal length we have the autofocus Nikon 300mm f/4 lens (around $1400 new) and the Sigma f/2.8 lens (around $3400 new). If you suspect that low light will be a big problem you will prefer the faster lens. If 300mm may not be long enough, you may need to get a teleconverter, and so again you would need the f/2.8 lens. Spending $3400 on the f/2.8 lens though leaves us no money for a teleconverter (if we need it - but then, if we do, the alternative to a TC is an even longer lens, which is yet more expensive) or a tripod (which we basically can't do without).

There is also a Nikon 300mm f/2.8 lens but it is outside the stated price range.

Supposing for the sake or argument you go for the autofocus Nikon 300mm f/4, that comes to around $2700 for body + lens. This should leave you enough money for support.

Support: Tripod and Head

As I mention above (and as described by Thom Hogan's article on selecting tripods) selecting a good support is important, and the longer/heavier the lens, the more important it is. A Gitzo tripod (around $500) is a great choice.

For long lenses, you can use a ball head but the ideal thing is something that allows the camera/lens to be easily pivoted (to point it at what you're making a photo of). It's also an advantage for the support to allow the centre of pivoting to be the same as the centre of mass of the combined lens/camera system. A Wimberley head ($600) is the classic solution to this problem.

There are circumstances where using a tripod is infeasible, for example on some safaris. For those cases there are a number of other options. They are worse than but also cheaper than a tripod; they range from specialist bar/window clamps to beanbags (much much less effective than a tripod but better than nothing).

Grand Total

All told this comes to $3800 so we're all done with some cash to spare.

Answered by James Youngman

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Why are my photos taken at f/11 less sharp than those taken at a wider aperture?

Question

I am new to photography. I have Fujifilm FinePix HS10 camera. Lately I was trying my hands on landscape photography.

I learnt from different tutorials that setting high aperture value gets most of the scene in focus. Hence proceeding with this notion I set my aperture value to f-11 which is the highest on my camera.

But what I observed is that, f-11 images were very soft and I don't see that background elements well focused.

On the contrary, images taken in range f-4 to f-5.6 were better looking in terms of sharpness of background elements. I have attached sample images for your reference.

Can you please shed some light on this?

Image taken with f-4

Image taken with f-11

Asked by Vaman Kulkarni

Answer

Images with your camera will start showing signs of diffraction around f/4 to f/5.6 due to the size of the sensor. Shooting at a significantly smaller aperture (like f/11) will only increase the diffraction problems. You'll lose resolution.

Here's a good tutorial on diffraction:

http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm

Answered by Eric

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Why doesn't pixel peeping with magnified Live View give the sharpest possible image?

Question

I've seen this comment (most recently in this question), or similar, in several answers here on photo.SE: "Pixel peeped images aren't likely to look sharp".

Why is that? It would seem to me that if you go into Live View, full magnification, and then manually focus on the area of interest, then that is as sharp as it is going to get. Of course, one must assume a stationary subject here, and you have to choose you area of interest carefully, but I keep seeing comments like that one which really imply that I'm missing something here.

So why doesn't pixel peeping with magnified Live View give the sharpest possible image?

Answer

You're misunderstanding the statement. "Pixel-peeping" during focusing is indeed a good way to get a sharp image. The statement "Pixel peeped images aren't likely to look sharp" means that the image won't look that sharp while you're doing the "peeping" because the viewing magnification is so high.

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Does long exposure affect the sharpness of a picture, assuming no camera shake?

Question

Assuming that the camera does not shake during long exposure photography, How does the sharpness of the image get affected? Would it be more sharp, less sharp, or remain the same?

Answer

In a perfect camera with a perfect sensor, sharpness would remain the same. No such thing exists so you have to consider two possibilities with whichever camera you have. The long exposure causes the sensor to heat and increases image noise:

1. Your camera does not like that and therefore applies long shutter noise-reduction to clean things up and you get a less sharp image.

2. Your camera is oblivious to the increase in noise and leaves it there. Speckles caused by noise destroy some fine details but make the image appear sharper sometimes.

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How I could take crisp sharp shots without expensive lens?

Question

Recently I bought my first DSLR camera. It is a beginner's one, a Sony alpha 230 kit. To tell the truth, my shots are not more crisp than those I used to take with my old Point and Shoot Nikon Coolpix.

Is it possible to take really sharp photos not buying expensive lens? What would be your advice for that? (I'm really trying to go beyond automatic mode, though with little success so far)

Answer

There are several factors to getting a sharp image, the lens is only one of them.

Lighting

If you have a well-lit shot it will be much easier to get the crispness you want because you can get higher contrast lines.

Shutter speed

This is actually pretty closely related to a well lit shot, but you want to make sure your shutter speed is fast enough to avoid camera shake, which will cause blurring. A good place to start is with a reciprocal of the lens length (i.e. for a 50mm lens, at least 1/50s).

Camera shake

If you can't get lighting good enough to use a fast shutter speed, then you just have to do your best to avoid camera shake. This means working on you technique, both with holding your camera, and with pressing the shutter, or if your lens has image stabilization (or vibration reduction) then use it. When none of the hand held methods work, then use a tripod.

Aperture

Every lens will have a aperture at which it is the sharpest, a good place to start is in the middle of the range, typically around f/8. This is a bit complicated, because there are 2 opposing elements at play, depth of field, and diffraction. Ken Rockwell has an in depth article about this if you really want to study it.

Lens Quality

Some lenses are just better quality and will have less aberrations, so a shot taken with a kit lens will probably never be as sharp as a correctly-exposed image from a Leica 50mm f/1.4. That is not to say that any shot taken with a superb lens will be better than any shot from a kit lens, because that is certainly false. It does mean that the upper range is higher of some lenses.

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Why does the cheap kit lens seem to be sharper than the expensive L wide-angle?

Question

So recently, I was just browsing through Canon's product lists and found the 17-40 f/4 L to be quite interesting, although I will not buy it anytime in the near future. Still, I decided to make some comparisons, just for fun:

EF 17-40 f/4 L USM vs EF-S 18-55 f/3.5-5.6 IS

These shots were, according to the website, done with the same camera, aperture and almost the same focal length. What struck me is that the L lens seems to be only a little bit sharper in the center, and, even worse, the kit lens seems to beat it in the corner areas!

How can this be? Is the test flawed? Anything I missed out?

Of course, the 17-40 needs to draw a bigger image circle in order to suit FF cameras, and the 18-55 is optimized for an APS-C sensor. But until now I assumed I could still expect clearly better image quality even on an APS-C camera?

Answer

"L" lenses aren't always necessarily sharper than their non-L cousins. In fact, some of them are very much softer, often as a consequence of being two or three stops faster than the cheaper lenses, but sometimes just because they're a decade or two older in design.

What you do get with "L" lenses is professional features and the build quality of a light armoured vehicle. For instance, you might not care so much about a constant aperture while zooming, but I can guarantee that somebody who is using separately-metered studio-type flashes either as main or auxiliary lights would. And the manual focus ring on kit lenses (so far true of both Canon and Nikon) is just a little less than useful.

There have been a couple of "L" lenses that were, frankly, lousy lenses by most objective standards, the most notorious being the now-discontinued 50mm f/1.0. Considering it as a "standard" lens and using it at f/5.6 or f/8, you'd have to be an idiot to spend the extra two grand on that lens (and that was in early-'90s dollars) -- but when TMax P3200 was that fastest thing around, being able to go to f/1.0 for "available darkness" shooting made the difference between being able to get the shot and not being able to get the shot. It didn't matter that the $50 (at the time) f/1.8 version could shoot rings around it at other apertures -- that stop and a half meant everything to the people who needed a lens that fast. Most of the "L" series for the old FD mount were like that -- they filled a niche that pros needed to do their jobs, but were actually worse for general photography than the non-"L" variety. Things got better for the AF EOS era, but there have been a couple of stinkers along the way too. The worst of them have already been replaced by updated designs, but some adequate performers are still in need of an update.

If you want (or need) the build quality, usability and environmental sealing of a pro lens, then the "L" is almost always worth the money. If you're making pictures for your own pleasure and can afford the sometimes fiddly and fragile nature of consumer lenses, then the newer, cheaper optics are often a much better option.

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How can I make a very sharp photograph with a point & shoot camera?

Question

I've taken a picture with my Canon PowerShot SX210 IS and the following settings:

• Aperture: F8 (Maximum I have)
• Shutter speed: 1/400
• ISO: 80
• Focal length: 21.1 mm (118mm 35mm-e)

I did increase the contrast a bit through Gimp later on. What other camera settings and timings should I have considered to make this picture sharp?

Please note: with this camera, I can't shoot in raw, and post-processing is the secondary concern for me.

EDIT: I zoomed it to 100% and then cropped off 600x600.

And I didn't mention previously that I had used manual focus. And also, ALL the broken chairs together are the subject.

Answer

f/8.0 is often the "sweet spot" for lenses on 35mm SLRs however on a small sensor camera like a Canon PowerShot that aperture is probably causing diffraction - there's a good reason the aperture doesn't go any smaller than that!

Light spreads out when passing through a small opening like the aperture on a camera and this results in loss of sharpness. The smaller the hole the more spreading you get, so there comes a point where stopping down a lens results in lower peak* sharpness. Due to compact lenses having (and requiring) shorter focal lengths, f/8 on a compact will result in a smaller opening than f/8 on an SLR, therefore you will get more diffraction.

*I said peak sharpness, as average sharpness can increase after the point where diffraction sets in due to increases in depth of field. However if you don't need the depth of field, try shooting at f/4 instead.

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Can the sharpness of the lens be evaluated with no relation to the DSLR?

Question

When I read lens reviews, they all say that one lens is sharp, another is very sharp, another one is not sharp at all, etc.

For me, it doesn't make sense to just say that a lens is sharp or not, with no information about the sensor used.

For example:

• On a 10MP Nikon D60, Nikkor 50mm f/1.8G and Nikkor 18-200mm 3.5-5.6GII are, visually, equally sharp (both at 50mm with the same aperture).

• On a 16MP Nikon D7000, the first lens is ways sharper than the second one.

Not every reviewer can afford the best full-frame DSLR with the maximum number of megapixels when testing the sharpness of the lenses for the review. On the other hand, rare reviewers who actually have the best camera will write the reviews which may be misleading for most photographers: for example someone who has only Nikon D60 with a Nikkor 18-200mm 3.5-5.6GII and would buy a Nikkor 50mm f/1.8G in order to get sharper images (just for that) will do a mistake.

Can the sharpness of the lens be evaluated with no relation to the DSLR? How the sharpness must be interpreted in the reviews, when the camera model is not mentioned?

Answer

Lenses project a virtual image that has a defined minimum spatial frequency. It does not matter what you use to capture the image the lens is projecting, it can be film, a low res digital sensor, a high res digital sensor, or something that far outresolves the lens itself...that doesn't change how sharp an image the LENS produces, though. This is a bit simplistic, however.

Any real-world system's quality is a factor of its components. A lens has an intrinsic quality in the abstract, as does the sensor, and any other components that may be involved in the process of capturing a photograph (say an extender.) The resolution of the final photograph is a product of ALL the components of the system together, and the lowest common denominator is going to affect the IQ of that image. If the lens outresolves the sensor, the the sensor is probably going to determine the quality of the image. If the sensor outresolves the lens, then the lens is probably going to determine the quality of the image. Of the two are capable of resolving about the same detail, then both factors probably affect quality just as much as the other.

Now, its important to understand the quality of all components individually rather than as a combined whole. Why? Because a single lens may be used on multiple cameras, or a single camera may be used with multiple lenses. The quality of a lens is constant regardless of what camera body it is used on, even if one body has a higher resolution sensor than the other. Similarly, the quality of a camera sensor is the same regardless of what lens its used with. If you only knew the quality of a lens when used on the D7000, you would never know how it might fare when used with a D90, or a D3x. However, knowing the quality of the lens itself without context, you can compute how it might fare on any one of those three cameras.

A key factor in determining the quality of a system is its MTF, or modulation transfer function. An MTF is a way of computing the contrast of a lens or an imaging medium when imaging pairs of white and black lines of a specific thickness, or of progressively finer spacing. The MTF of a lens tells you how much resolution can be resolved starting at its center and progressing through the edge of the lens (most lenses do not resolve perfect detail, and resolve more detail in the center than at the edges.) A useful article that explains resolution, lenses, and sensors can be found at Luminous Landscapes Resolution article. Its rather technical, but explains the situation pretty well. If you are not afraid of math and want to know exactly how MTF describes resolution, you can read Norman Koren's Understanding Image Sharpness (beware, very technical.)

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What is the shutter speed needed to stop motion?

Question

I find that taking pictures where the subject is in motion (people, pets, toy helicopters) I get a blur where there is movement.

On the other hand I see images of a drop of water in free fall in perfect clarity.

How fast does the shutter need to be to capture action in motion with perfect crisp clarity?

For example I want to catch a dog shaking himself dry after a swim and not get a bury mess but to see the hairs flying and water frozen in the air as it flies off the dogs fur and makes a giant mist around the dog.

Answer

While you can get some freezing with speeds around 1/300 (see the first photo below), I would recommend going with faster shutter speeds if you want to take shots of water drops falling or moving away from wet dogs.

One thing to keep in mind is that most flashes have a limit on their sync speed, which means that the use of flash will limit your fastest shutter time available.

• Example 1: 1/320 speed, no flash:

(as you see there's still blur on the water and a flash, even if able to reach the dog, wouldn't make much a difference if it wasn't able to go faster than 1/320)

• Example 2: 1/1300 s, using the internal flash of a Panasonic FZ18 and the ambient kitchen light:

Here a smaller aperture and the ambient light allowed for a slight slower speed, but the shot is sharp enough for me.

• Example 3: 1/1600 s, using the internal flash of a Panasonic FZ18, no ambient light (shot in the dark):

Here the speed was enough to freeze the drop and the flash was set stronger enough to provide the needed reflections on the background (since there was no ambient light).

Finally, if you are into capturing water drops don't miss John Cavan's very good post on the subject - Catching the Elusive Water Drop

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How to shoot sharp “landscapes” with a point and shoot camera?

Question

So, I have been told in a thread here previously that the minimum aperture (F8) on my point and shoot camera can cause diffraction and result in losing details of the subject if too many things are in focus. Fine.

Now, if I have to shoot a far away landscape scene and I choose an aperture of (F5), it won't result in a sharp picture, and I can't use F8! :(

See this:

Now is it possible that I use the aperture as low as possible and increase the shutter speed and thus get the same results as I would be getting from aperture F8 (with a low shutter speed)?

What can be the possible combinations?
I mean with F3, speed 1/500?
Of course one way is to go on trying each and every possible combination, but if I get some starting points, I think it'll make my life easier.

Answer

On your sample photo, fog or smoke in the air seems to be the reason why further landscape is not sharp. Nothing in your camera can help against that. Try coming back at another time to see if the air is more clear. Above a city with polluted air, this might never happen.

A wider aperture with faster shutter time will result in equivalent exposure, but depth of field will be smaller, because it is determined only by the large aperture. Opening up all the way is bad for sharpness because most lenses are getting sharper when aperture is smaller than maximum by a stop or two (unless you hit diffraction limit).

To get maximum depth of field, you should focus to something far away to ensure that you are covering hyperfocal distance. You might also still decide to use f/8, because you might prefer even overall sharpness to better sharpness at smaller range. In technical side of photography, compromises have to be made quite often.

Another thing you could try is sharpening in post processing (e.g. using Unsharp mask).

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Is it worth investing in a used 35 mm Film camera?

Question

I've a Canon 60D and I'm mainly interested in shooting landscapes. I feel very interested in buying a used canon EOS film camera (since my EF lenses are compatible).
I would like to take pictures from my DSLR and then use the same meter reading on the SLR to take a picture. I'm planning on scanning the negatives myself to the maximum resolution and the assumption is that the picture from the film camera would be lot more colorful and sharper.

Would their be a noticeable difference by using a film camera? considering that my 60D comes with 18 Mega Pixels.

Sharpness and resolution matter to me only because I usually end up cropping my pictures.

Also I'm planning on using using films with ISO of 50 or 100.
The used camera I'm interested in cost around $200.

Answer

It certainly is not worth investing in a 35mm film camera for the perceived higher resolution, additional color, or sharpness.

To get results you will likely have to either invest in, or at least have access to a drum scanner that gives you the highest resolution possible right now. Otherwise you will likely be scanning on a flatbed that almost certainly does not produce resolution even near the Canon 60D.

Are you trying to print 24x30inch prints at 360dpi? Sure, grab a 35mm camera, a $20,000 drum scanner, and you may be able to achieve high resolution that would benefit images of this size. You also might not achieve that.

It sounds like the main issue is that you usually end up cropping your images. If this is the case, it sounds like you either need to frame up the subject better before you take the image, or invest in further reaching lenses.

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How to take sharp photos while using maximum optical zoom?

Question

When I shoot with high zoom (above 3X on my point-and-shoot camera), the sharpness of the picture seems to come down. Is it a feature of all cameras or is it due to higher sensitivity to camera shakes during captures in higher optical zoom regions?

Some of the photos in the higher zoom range are pretty good, usually the ones of scenery — so I I feel it can not be a camera problem.

I have a point and shoot camera with 6X optical zoom. Does the same thing happen with other types of cameras with high-zoom telephoto lenses?

Are there any other things to be taken care of when we shoot with higher optical zooms?

Answer

There's two things at issue here.

The first is zoom range, which is the longest focal length a zoom lens has divided by the shortest. That is, a lens which goes between 25mm equivalent focal length and 150mm is a "6x" zoom lens. This terminology is usually reserved for point and shoot cameras; for SLR lenses, one usually gives the actual focal lengths instead. High-zoom-range lenses require more design compromise, and it's likely that that compromise results in relatively weak performance at the extreme ends of the range. So that could be part of it.

Second is the issue of camera movement. Higher focal lengths — "more telephoto", or as you say, in the higher part of the zoom range — show a smaller portion of the scene magnified to the same size, and that means that small movements in the camera translate into larger movements in your photo. This means the effect of camera shake is much more pronounced the more you zoom in.

You can easily demonstrate this to yourself by simply looking at the live-view screen (or viewfinder) as you turn the camera slightly — at short focal lengths you can see a small change, and zoomed-in you can see that the whole scene changes with just a little turn. This same effect magnifies very small movements as well, increasing blur.

There's a particular compromise that most point and shoot cameras and superzoom lenses have which makes camera shake more of an issue when zoomed in. Specifically (as @Itai points out), these lenses usually provide a more-limited aperture at higher zoom. This means less light, which means either boosting the signal (higher ISO), resulting in more noise, or else longer shutter speeds — making it more important to reduce camera movement.

There's not much to be done about the first except to be aware of the strengths and weaknesses of your equipment, and to avoid using the higher focal lengths in situations where the weaknesses are most obvious — like in low-light.

For the second, simply keeping your camera more still will help significantly. You can get better results with improved technique and awareness of your motion as you press the shutter, but a tripod or other support will be even better. You'll also want to make sure that image stabilization is enabled in your camera if available — and make sure it has a chance to activate by half-pressing the shutter and waiting a second before firing.

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How can I achieve well focussed and sharp images at long focal lengths?

Question

Well I guess this is a question every newbie asks. I have a Canon 550D with the 18-135mm kit lens. I was out on a small trip in a nearby town to take some good snaps with my DSLR. I know the lens might not be the best but still when I took my pictures back home and looked at them in the big monitor i have at home I found most of my shots were not well focussed.

Especially, when I take pictures of far away buildings in the high zoom range (100mm and above). Is there anything I can take care of to keep everything in focus and have them sharp?

Answer

It sounds like you might have just had an aperture setting that was too wide, or you have too much camera shake. Either one will cause some degree of softness.

Aperture and Focus
The size of the aperture (the hole in the "middle" of the lens created by the diaphragm) controls more than just the amount of light that can pass through the lens...it also controls the depth of field. The depth of field, or DOF, determines how much depth within your scene, from the point of exact focus, both towards the camera and away from the camera, that is "in focus". A wider aperture (smaller f/#, such as f/2.8 or f/3.5) produces a smaller (or thinner) DOF. A narrower aperture (larger f/#, such as f/8 or f/22) produces a larger DOF. Generally speaking, if you want more of your scene to be "in focus", you need to use a narrower aperture.

Now, beyond the simple basics of DOF and aperture, there are more concerns to be taken into account. Depth of field is a function of aperture, focal length, and subject distance. The closer the subject you are focusing on, the thinner your DOF, while the farther the subject, the deeper your DOF, for a given aperture. A longer focal length will also increase the depth of field for any given aperture, however they also tend to magnify the effect of defocus blurring (along with magnifying everything else), so from a focus standpoint, longer focal lengths won't help much.

Camera Shake and Softness
Another problem that can cause image softness, particularly at longer focal lengths, is camera shake. If you are taking photographs hand-held with a long focal length, without the benefit of IS/VR (image stabilization/vibration reduction) technology, then camera shake can be a real problem. Even on a tripod or monopod, small movements or shakes can still be a problem that softens images. The longer the focal length, the more magnified the scene you are photographing. That magnification affects everything, including the effects of camera movement.

If you are shooting with a longer focal length lens (i.e. 85-100mm and up) under low enough light that your shutter speed is at or lower than the focal length of the lens, even small movements translate into image softening or even outright blurring. A 300mm or longer lens, hand-held, is pretty much unusable without either hands as steady as God's, or the benefit of some kind of image stabilization technology. You can do a few things to solve the problem of camera shake at longer focal lengths. Obviously, one would be to get a lens with image stabilization. Usually, IS is rated in "stops of hand-holdability", and can range from one stops worth to as many as four stops worth. Each stop worth of additional hand-holdability affects how low of a shutter speed you can use below the "reciprocal rule" speed. (The reciprocal rule simply states that a shutter speed of 1/focalLength is as low as you can go without the effects of camera shake affecting sharpness.) If you have a 100mm lens and no IS, you would be limited to shooting at 1/100s shutter speed or higher to get sharp hand-held pictures. A 100mm lens with 4-stop IS, on the other hand, would allow you to get sharp hand-held pictures at about 1/12s shutter speed.

Beyond buying a new lens, there are a couple other things you can do. For one, get a tripod and a cable release, and set up and frame your shots on the tripod, and trigger the shutter with the cable release (or wireless trigger.) That will ensure hands-off operation, keeping the camera as stable as possible. Additionally, you can increase another factor of exposure. If you have the option, a wider aperture will allow more light down the lens, supporting a faster shutter speed. If opening the aperture is not an option, you can also increase the ISO setting of the camera. If you are shooting at ISO 100 with that 100mm lens, but your shutter speed needs to be 1/50s, using ISO 200 should let you get that 1/100s shutter speed. Using ISO 400 will let you use a 1/200s shutter speed, giving you some wiggle room to tweak aperture or cover a small amount of camera shake without affecting sharpness.

Soft Lens
There is one additional possibility that may not be something you can fix without replacing the lens: a soft lens. Before assuming your lens is soft, try other options to see if you can correct sharpness...such as using a tripod or shooting with a tighter aperture. A small percentage of the time, some lenses come improperly calibrated, and that can cause a consistent softness that cannot be corrected by any photographer action. A poorly calibrated lens can probably be fixed by sending it into the manufacturer or taking it to a local camera shop. There are also lenses that are simply not as sharp as others, usually at wider apertures, where uncorrected optical aberrations infringe upon an otherwise sharp picture. Sometimes this is simply a facet lens design...it may be intentional (i.e. purposely uncorrected spherical aberration in a fast portrait lens), or it may be due to the cheaper components of a cheap lens.

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How can I take photographs with a large depth of field?

Question

I was looking at some pictures by TSO Photography, and I was struck by how everything in the image seems to be sharp and in focus.

I do realize that to achieve huge depth of field, you set the aperture to the lowest possible value — but doing so causes diffraction, which reduces the sharpness of the picture. Are their any other methods to get such high depth of field (other than focus stacking)?

The camera used in this case was a Canon 5D Mark II — a full-frame camera, so it's not because the sensor is small.

Answer

Unfortunately, Facebook strips the EXIF data from images, a terrible practice, so I can't get his actual settings. However, a wide angle lens with a reasonable aperture that is focussed to the hyperfocal can put a huge portion of the scene in focus. For example: a 16mm lens at f/8 focussed 3.55 feet away effectively puts from just under two feet away to infinity in focus and f/8 isn't going to wipe your sharpness out.

You can understand the concept, and play with some numbers, using the online depth of field calculator to see what I mean. They make a mobile version for various devices too and that can be handy out in the field.

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How can I get sharp manual focus despite poor eyesight?

Question

I suffer from astigmatism. It's only mild, though I feel it's affecting what I'm seeing when looking through the viewfinder. Frequently, after shooting a photo with my Canon EOS 7D, I'll load it into Lightroom and discover that what looked sharp as an LCD preview is actually not at all in focus when you get down to the 1:1 level.

Normally I let auto-focus do all the work, so I attribute this to back-focusing effects that I'm not picking up on when looking through the viewfinder.

Today, I switched to manual focus while using my tripod to see if I could do a better job than the AF. Rocking the focus ring back and forth, I found it hard to distinguish the point where my subject is in focus (blurry -> slightly blurry -> blurry); indeed, when I got back to Lightroom I still found about a third of my shots came out slightly off-focus.

Is there anything that I can try that could improve my shots, particularly anything that would reduce/nullify the effect of my eyesight while using the camera? The obvious answer to this could be "wear glasses" -- which I do, but not while using the camera, as I feel like they're in my way every time I peer through viewfinder!

Update: I've marked the Katz Eye answer as accepted, as I've used one previously on a Minolta film camera; it really helped when focusing. However, all the answers here are great and have been very helpful.

Answer

Pixel peeped images aren't likely to look sharp unless you're viewing from a distance... Something to bear in mind.

However, for manual focus improvement, you may want to consider a custom focussing screen such as the Katz Eye split prism screen. The basic idea here is much like a rangefinder camera, the prism splits the image when it is out of focus and when it is brought into focus, the image lines up. This can assist quite a bit, especially with poorer eyesight.

On the plus side, it will help confirm if your camera autofocus is iffy.

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Why buy an intentionally soft lens?

Question

While reading some reviews of older lenses, I keep reading "Its soft wide open, but that's not always a problem with portraits." Over my rather short time in photography thus far, I've come to appreciate very sharp portraits and if some softness is needed, its easier to add softness than actual, true clarity.

Am I missing something here? Why would you want to buy a soft lens? (Note, I'm not talking about an adjustable 'soft focus' lens, just an older, not sharp lens).

Answer

Ah, I think what you may be missing is that you're putting two things together that aren't intended to be:

1. A lens that is soft isn't necessarily bad for portraits because people often soften portrait shots anyways and so the lens isn't really a problem.

2. Prefering a soft lens because the softness is a desirable feature.

They seem the same, but they aren't. The first is really a statement that, in the right conditions, the softness of the lens has really no impact. This is not a statement of desire, I think.

Anyways, all that they are really saying is that the soft lens may not be totally useless, so don't just throw it away.

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How to check for sharpness in small LCD screens ?

Question

I have recently bought Macro lens(Tamron 90mm) and been experimenting with it, My camera is Canon EOS 1000D and it has only 2.5" LCD screen.

Immediately after taking the picture, How can one check whether interested area is in sharp focus (especially if you have shallow DOF and photographing bugs eyes, petal edges , pollen etc.?

I have seen people zooming in and check for sharpness, How much zoom-in can approximately tell that particular area is in focus? If we zoom in 100% naturally everything is going to look almost pixellated?

Objective of question is, What usually photographers do to quickly check whether image has come up sharp or not?

Answer

The LCD is great to check for sharpness on-the-field but you need to know your camera's 100% magnification ratio.

When you zoom-in into the LCD view, most cameras display a magnification ratio as X times from the fit-to-fill size of the LCD. So initially, it is one and when you get to say 4X, the image is magnified 4 times in both directions. As you keep increasing magnification, you will reach a point that depends on the sensor AND LCD resolution where the pixels are one-to-one. This ratio is usually between 8X and 11X on a modern DSLR.

If you go beyond that, which you can in models of the last few years (I cannot imagine why someone thought this was a good idea), cameras will interpolate pixels and start blurring the image which works against checking sharpness.

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This doesn't seem very sharp…is this normal?

Question

Body: T2i Lens: Kit, 18-55mm f3.5-5.6

I went to shoot a sunrise this morning at the beach and got some great pictures, but when I uploaded them to some light post-processing, I was slightly surprised by how unsharp it was, and the amount of noise there was when I zoomed in. Is this normal for this camera/lens? My settings for the photo attached were 1/25, f4.0, ISO 100, and focus was set on the chair. My assumption is that it has something to do with the amount of available light, but I've seen plenty of sunrise/sunset pictures that are almost impossibly sharp.

Full-size

Answer

The Canon EF-S 18-55mm Kit lens is not the sharpest lens known, not if you're judging the pic at 100%. But when you're using smaller version of the image, sharpness is acceptable. Your example image looks sharp enough to me in this size, for a kit lens, its a good result.

Now, the noise. Its a very complicated term. It depends on a lot of things, one of them is wavelength of the light, or you can say color of the light. Blue channel is the noisiest channel and green is the least. Your sky is mostly blue and looks like that's the cause of the noise you're seeing.

You did not mention if you shoot raw or jpeg. jpeg images converted from raw provides better sharpness comparing to in camera jpeg. Also, T2i has a very powerful sensor, it's image quality increases a lot more when you use it with a superior lens. So, if you're not happy with it, try getting a lens known for its sharpness (rent for a day or ask a friend), shoot with it and check if it makes you happy or not.

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