Sunday, March 4, 2012

Why did my Canon EOS 450D fail to save the entire photo?

Question

After not being used for three months I got this (bottom right corner cropped from processed raw image by Canon's DFP):

enter image description here

(original RAW is available for download here: http://dl.dropbox.com/u/9271284/IMG_9766.CR2)

This was first photo taken that day, all photos taken after were saved ok. Is this a failing SD Card or first sign that my EOS is going bye bye?

Asked by Vnuk

Answer

Looking at the raw file, the JPG preview looks fine, but there is about 1/6th of the RAW image that is blanked out.

It could have been a glitch in the camera, an error on the card, or an error in the transfer to your computer.

If you still have the image on the card, I'd try to transfer again.

Then reformat the card and see if it happens again.

If it does, try other cards, as Rowland suggested.

If other cards have the same issue, then suspect the camera. Until then I'd think a faulty card or transfer is more likely.

Answered by MikeW

Canon EOS 450D failed to save entire photo

Question

After not being used for three months I got this (bottom right corner cropped from processed raw image by Canon's DFP):

enter image description here

(original RAW is available for download here: http://dl.dropbox.com/u/9271284/IMG_9766.CR2)

This was first photo taken that day, all photos taken after were saved ok. Is this a failing SD Card or first sign that my EOS is going bye bye?

Asked by Vnuk

Answer

Looking at the raw file, the JPG preview looks fine, but there is about 1/6th of the RAW image that is blanked out.

It could have been a glitch in the camera, an error on the card, or an error in the transfer to your computer.

If you still have the image on the card, I'd try to transfer again.

Then reformat the card and see if it happens again.

If it does, try other cards, as Rowland suggested.

If other cards have the same issue, then suspect the camera. Until then I'd think a faulty card or transfer is more likely.

Answered by MikeW

Friday, March 2, 2012

Canon 24-70 f/2.8 L mark 1: is the quality really so inconsistent?

Question

I'm considering buying a Canon 24-70 L mk 1.

There is one thing that scares me a bit, though: reading reviews around the intertubes it appears that a fair number of people had to send their copy back to the seller to get another one because of sharpness issues.

Now, I'm always more inclined to blame the photographer before I blame the tools, so I think those reviews are to be taken with the proverbial grain of salt.

Nevertheless, I have to wonder: is it true that the quality of copies of the 24-70 can vary that much? What is the experience of people around here?

And, by the way, how would one go about figuring out if a given copy of a lens is good upon receiving it?

Asked by s.m.

Answer

This is a professional grade lens. People do expect miracles out of something at this cost, and with this "prestige". I am not aware of any particular issues with the Canon 24-70mm f/2.8 L MkI that would cause more copies then the average to have issues. One way of dealing with said "issues" is to send in your camera bodies along with the lenses that you want to match to it to Canon. They actually can perform a series of adjustments to match the lenses that you have to the bodies that you wish. You can do some of this by using the Micro-adjust feature of some of the current Canon DSLR bodies.

I think you would benefit from reading an article from the LensRentals.com CEO - Roger Cicala. He is very experienced in the sense that he gets a very wide perspective into a huge range of lenses. His article "This Lens Is Soft" And Other Myths provides a great deal of information on the topic and really helps to dispel the myths that you commonly can see in internet forums.

While considering all of the above, you can still perform tests on your equipment to make sure they are fairly accurate to begin with. The existing question that I asked goes into great detail on this: How can I test a new lens to make sure it is operating correctly?

This question also gives more information on micro-adjusting: What is the best way to micro-adjust a lens?

Overall, I would just pick up a copy, and give it a few quick tests - if the quality is up to your standards, there is no reason why you should worry about what others have complained about. Canon doesn't produce many lenses that have common issues(but a few do exist), and this isn't one of them.

Answered by dpollitt

Is it practical to shoot portraits by only candlelight?

Question

Is it practical to shoot portraits in candle lights, only, provided there is no flash around? If yes, then for portrait shots, where and how should one place the candles? Are there any specific factors that need to be taken care of? Is it prone to creating a flat light?

Here are some specific details about my gear:

  • Camera: Canon Powershot SX210 IS
  • Min F8, Max F3.1 (but I zoom it gets up to 6, doh)
  • My ISO performs horribly beyond 100, and cannot shoot in raw

Considering these conditions in which way should the candles be placed so that they light up the model's face and do not create a flat light? On the side (left and right) of the person, or in the front of the person? How does the position impact the results?

Asked by Anisha Kaul

Answer

Yes, this can work. I know because I've taken photos of children lit only by their birthday-cake candles and they've come out nicely.

First, some general tips, without regard to your specific camera. These are probably most appropriate for a DSLR or other advanced camera which gives a lot of photographer control:

  • Use manual exposure. The camera's automatic metering will try to make the scene look nicely bright overall, which is probably not what you want. Even if you're trying to create a brightly light room with lots of candles, the metering is likely to be confused.
  • Spot meter on the subject's face. That'll give you a base reading for correct exposure for that area. Metering on the candles themselves will cause the subject to be very dim — which can also work, but tends to make the candle the primary subject.
  • Once you have this base exposure reading, take test shots and see how they look. The histogram will probably be useless here, since it'll be mostly flat with peaks near the edges.
  • Decide on whether you want to have a largely black photograph with a small pool of light, or a tightly-framed portrait with just a candlelit face, or a whole room and scene lit by candles. This will influence your overall exposure decision, and frames your your other artistic choices as well.
  • Decide what you want to use for a shutter speed. A fast speed will reduce the flicker of the flame, and if you're trying to expose so as to show the candle itself clearly, this may be desirable. On the other hand, a little bit of motion blur might be acceptable or even preferred.
  • Decide what you want for aperture. Wide-open to gather the most light is the obvious choice, and will fit with the visual expectation of most viewers. The shallow depth of field can add to the intimate, personal feeling of a candlelit shot. On the other hand, a greater depth of field can help show more context.
  • Choose your ISO to match the factors above, so that the scene is exposed as you want. Again, take test shots here. You may decide you have to compromise on your artistic wishes for depth of field or shutter speed.
  • If you opt for a longer shutter speed, use a tripod. Having to worry about the subject moving is enough trouble; even with image stabilization, keeping the camera still enough will be a challenge.
  • Consider black and white, or perhaps a warm monotone. This will give you more latitude in using very high, noisy ISO settings, because color noise is the most annoying and distracting. A little color is nice for candlelight, though. Choosing a warm monotone similar to that cast by candles may be a good compromise — if you experiment or look at some sample pictures, you can see that color photographs often look monotone orange/yellow in this light anyway.
  • If you do go for color, set white balance manually. Candlelight is very warm — which means low Kelvin temperature. The camera's auto-wb will try to make the lighting neutral, which is probably not what you want. The tungsten/incandescent setting may be a good choice — candle flame is even warmer than that, so you'll still get a pleasant tone. Typically, candlelight is around 1500-1900K, while incandescent lights are 2700-3300K (and flash or sunlight more like 5500-6500K). If you set the camera to incandescent, the candlelight will still have a strong warm cast, which is probably what you want.
  • Manual focus may be required, as autofocus sometimes struggles in low light. Check focus carefully if you're using a wide aperture.
  • If you're using any filters for lens protection, take them off, particularly if the candles are in the frame. This is a perfect opportunity for them to increase glare and ruin your image.
  • Place the lights as close as possible to the subject — light follows the inverse square law, which means it decreases rapidly as you move away from the source. The birthday-cake photos work because the child is leaning in to blow out the candles, providing lots of immediate light.

In general, working with little point sources like this will emphatically not produce flat lighting. You will get pools of bright light and interesting shadows. As for where to put them exactly, experiment! Move the candles around and pay close attention to how these shadows shape the image.

For your specific camera: on the plus side, it offers a lot of manual control, including spot metering, so you can follow most of the suggestions above. But on the downside, the aperture is only f/3.1 at the widest lens setting, 28mm-e, which you probably don't want to use for portraits as it will tend to distort your subject's features unflatteringly. You'll probably want to zoom in to at least 50mm-e, and probably more like 70-100mm-e is ideal. This reduces your light-gathering ability, forcing you to increase the ISO. Additionally, in combination with the tiny sensor, this basically removes the possibility of shallow depth of field as an artistic choice. That doesn't necessarily kill the idea entirely, but it's a constraint you'll have to work around. Likewise, if you really don't want to raise the ISO beyond 100, you may be quite limited.


Here are some examples demonstrating some of the suggestions above. With the exception of a very minor curves adjustment in the last black and white image, these are all JPEG files from the camera, with no post-processing trickery other than choosing different in-camera toning options for the middle example.

A different look and more flexibility could be achieved by shooting RAW and spending more time on post-processing, but I wanted to demonstrate what can easily be done by anyone without special software (or time or knowledge to operate that software.

I spot-metered on on my subject's face, and generally didn't bother with the exposure dials after I was satisfied. I wanted to use settings that you could easily emulate with your point and shoot, so at first, I tried an aperture of f/3.2 and a longer shutter speed, but my model has trouble holding still for more than a fraction of a second. I dropped to f/2.8 and used a 1-second exposure, which almost worked:

f/2.8 / 1 second / ISO 100; two candles ghost effect

But she looked away at the last second.

I should add that this is with my Pentax DA 40mm f/2.8 Limited; I tried the 70mm f/2.4 first, but the fact that I was using fire around a small child meant I really needed to be closer.

As is probably evident, I'm using two standard taper candles. In this image, the white balance is set to tungsten. I discovered that the manual white balance in my camera doesn't go below 2500K, and I didn't bother to take a reading with a gray card. The image is actually a little cool and the candles too white — I don't like at all how the flames are rendered here and would work on that more for a final image. I do like the soft, muted, low-key tones of the "ghost" image — for me, if she hadn't looked away, I'd crop out the candles and this would definitely be a keeper. (Although, while imaging how things could be different, I'd also pose that stuffed animal so it looked somewhat cute rather than being a bedraggled amorphous blob. Don't tell my daughter I said that.)

f/2.8 / 1 second / ISO 100; two candles next try, first rendering

So there's the next try. Pretty much the same as the first but I had her rest her head in her hands in an effort to keep still, which worked relatively well. I also moved one of the candles much closer in order to provide a little more shaping to the shadows on her face. You can see that even that slight change makes a visible difference.

f/2.8 / 1 second / ISO 100; two candles; converted to black and white next try, grayscale

That really looks pretty good. My wife likes the color better; I prefer this one.

Here's the sepia version:

f/2.8 / 1 second / ISO 100; two candles; converted to sepia tone next try, sepia toned

I'm not so keen on how that turned out; I don't think my camera's built-in toning options are flexible enough to make me happy.

Anyway, after that, one second shutter wasn't working — that's a lot to ask of a six-year-old for more than one or two lucky shots. So, I dropped to a third of a second and upped the ISO to 400. I think you might be able to get away with this with your P&S camera too. Or, if you can order up a somewhat more restrained model, you may be able to go with longer exposures and keep the ISO down — even with your more-restrictive aperture in this focal range.

f/2.8 ⅓ second / ISO 400; two candles moving the lights

Here, some experimenting with changing the angle of the lights. You can see that the close candlelight is very much the opposite of flat lighting, and this image feels almost three-dimensional to me.

f/2.8 ⅓ second / ISO 400; two candles, one off-scene with reflector enter image description here

This is the only one I edited out-of-camera, and even then only by adjusting the tone curve so that there's a lot more contrast. The images above could also be subjected to the same treatment: the other B&W image, in particular, is very easy to make more dramatic.

I also did more playing with the light. In particular, there is candle just to the right of the frame next to the foot of the tripod where I had the camera, and right behind that, just far away enough to not catch fire, a 32" silver reflector. I'd planned to post a second version of this with that candle extinguished — the effect was dramatically different — but my model decided she'd had enough at that point.

So yeah. This can be done. You can do it, and you don't need 400 candles, or any such nonsense. Your point and shoot camera might have some limitations, but I'd highly suggest you go ahead and see what you can get out of it. It may pleasantly surprise you.

Answered by mattdm

Thursday, March 1, 2012

How can I take non-blurry extreme sports photos in winter?

Question

I currently have a Canon T3 with the basic EF-S 18-55mm f/3.5-5.6 lens that it came with. I'd like to go out to the local ski hill though, and there is a terrain park there. Most of my photographic experience is simply by messing around, with fairly still objects.

A lot of these skiiers are moving very fast, and the snow is fairly bright. What sort of settings should I be using to get optimal pictures (Ones that aren't just blurs in the air or on a rail)? Are there any good techniques to invoke while trying to capture photos in the winter, or at high speed? What differences will I need to consider between day and night?

Asked by Simon Sheehan

Answer

If you are taking photos of fast-moving subjects, and the subjects are blurry, there are a few potential causes:

  1. Use of a lens that is to slow
    • An f/3.5-5.6 aperture is SLOW
    • An f/2.8 or wider aperture is faster
  2. Use of a lens that does not have IS
    • Image stabilization helps eliminate camera shake blur
  3. Use of a camera that lacks adequate AF capabilities
    • Better AF systems help you nail focus and keep it nailed as you track a moving subject
  4. Use of camera settings that are inadequate
    • Using a shutter speed lower than 1/focalLength is often too low
  5. Use of poor panning technique
    • Panning can be tricky, and poor technique can introduce blur

Gear Recommendations

From a gear recommendation standpoint, I would first look into a better lens. The 18-55mm f/3.5-5.6 kit lens is pretty slow. If you are taking photos of skiers, your probably at 55mm, in which case your aperture is f/5.6. Thats quite slow, and probably forcing you to use a slower shutter speed than necessary to stop motion effectively. The AF system of the Canon T3 is not that great either, and while it is capable of basic subject tracking, your likely to have a low ratio of keepers. With a better/faster lens, you should be able to make more effective use of your camera's AF system, so I would still look into a better lens first.

If I was to recommend a few specific lenses that might help, they would be the EF-S 17-55mm f/2.8 lens, or the EF-S 18-200mm f/3.5-5.6 lens. The former has a nice wide aperture at all focal lengths, and the latter has great IS to make up for the narrower aperture. For shooting action, having a longer focal length up to 200mm can be very useful, and with decent IS, you should still be able to get nice shots at 200/5.6.

Shooting Technique

Shooting technique is another factor that can affect sharpness. Practice your panning as much as you can. Practice it both hand-held, and with a tripod or a monopod, as eliminating vertical shake can help eliminate blur from camera shake. When shooting fast subjects, you want to use fast shutter speeds. As a general rule of thumb, a shutter speed of 1/focalLength is necessary (without IS) to get a sharp shot, although that may change with high speed subjects.

When it comes to technique, properly using an AF system is one of the most important. If you are shooting moving subjects, especially high speed ones, you will not only want to hone your panning skills...you'll want to learn how to use the AF system. The T3 has a 9 point AF system with a single cross-type sensor in the center. Its not the most capable system, but it should do what you need until your skill grows beyond its capabilities (which, depending on how good a learner you are, may be soon, or may take a year or two. If you DO run into the AF systems limitations, the Canon 7D offers an excellent AF system, high frame rate, and a lot of customizability at around $1400 right now.)

First thing you'll want to do when you get out to shoot the action, particularly with the longer focal lengths you will likely find necessary (i.e. 200mm), you will want to switch to AI Servo mode. Single shot mode is inadequate to properly track subjects in motion frame-to-frame. AI Servo mode will continually adjust focus to keep a subject it has locked on to in focus so long as its tracking it. When you press the shutter button half-down, AF will initiate. Once its locked on, you should be able to fully press the shutter button, to take a shot, and release to half-way again to continue AF. Keeping your subject under the center point will improve AF performance.

Camera Settings

When photographing high speed subjects in lateral motion, however, you often need much higher shutter speeds...even with IS. Birds are my favorite in-motion subject, and I often need a shutter speed higher than 1/1000th to capture subjects with minimal motion blur in some areas (i.e. wing tips), and 1/1600th or more to completely freeze motion. I would expect similar needs for photographing high speed skiers and snowboarders. As a general rule for action, ether use Tv mode, auto ISO, and pick a fixed shutter speed, or use Av, set a high ISO setting...such as ISO 800-1600, and let the camera pick the shutter speed for you. With a high enough ISO setting, the camera should pick an appropriate shutter speed to freeze motion most, if not all, of the time.

Getting Artistic

From an artistic standpoint, a bunch of technobable about shutter speeds and ISO settings are not going to help you as much. Some experimentation will be necessary to get the artistic effect you want. If you want to guarantee a certain amount of motion blur in your shots, you will probably want to use Tv mode, wither with auto ISO, or a fixed ISO setting that you know will ensure a proper exposure, and let the camera vary aperture for you. You may only need a shutter speed of 1/500th and an ISO of 400 to get just the right amount of motion blur into each shot.

On the flip side, you may want to keep your DOF as thin as possible. In that case, using Av mode at or near max aperture with a high ISO should ensure the camera selects a high enough shutter speed. Depth of field will be dependent on aperture and subject distance, and unless you have an f/2.8 normal or f/4-5.6 telephoto lens, you might need to get close to your subjects to keep your dof thin...blurring backgrounds.

Don't Fear the Gear!

Finally, you may simply find after some experimentation that a single semi-automatic setting doesn't meet your needs. In that case, don't be afraid to switch to full manual mode, and adjust your settings as the moment demands. And DON'T be afraid to use higher ISO settings...if they are necessary to support a high shutter speed, crank it up!

Answered by jrista

What are the must-have filters for a new photographer?

Question

What filters are good and why?

Asked by CodeToGlory

Answer

To Summarise

This is an attempt to summarise the widely-held opinions of photographers in general.
I believe this is a fair distillation of views.

  • Adding any filter risks adding lens flare and reducing sharpness
  • The effect of most filters can be reproduced in post processing
  • The only filter which cannot be adequately reproduced in post is a polarising filter (particularly when used to remove / reduce reflections / glare).
  • Neutral Density filters are sometimes necessary. For example: when the photographer wants to reduce the amount of light entering the lens to allow a wide apperture and a long exposure (for example, when photographing flowing water).
  • UV Filters:
    • Many photographers feel that it is worthwhile to put a UV filter on the front of every lens, on the basis that this will protect the front lens element - from dust, scratches and catastrophic damage if the lens is dropped. In other words, it is a kind of insurance policy against lens damage. I understand that Scott Kelby takes this position.
    • Many (other) photographers believe that this practice is not worthwhile: they may feel that the reduction in image quality (actual or potential) is not justified by this "insurance policy". I have heard Scott Bourne articulate this belief.

I hope this is a fair and sensitive summary ;)

Answered by AJ Finch

Do I need a filter for my prime lens in order to protect it from dust, splashes, etc?

Question

From here: http://photo.stackexchange.com/a/569/5205

UV Filters:
Many photographers feel that it is worthwhile to put a UV filter on the front of every lens, on the basis that this will protect the front lens element - from dust, scratches and catastrophic damage if the lens is dropped. In other words, it is a kind of insurance policy against lens damage. I understand that Scott Kelby takes this position.

Since prime lenses are not supposed to zoom can dust, water, etc still get inside it if I don't use a filter?

Asked by Anisha Kaul

Answer

The filter doesn't protect against dust getting "into" the lens, it just protects the front element. So the arguments for a filter are equally valid for zooms and primes.

Personally I don't use them, as they have a negative impact on image quality. Always keeping you lens hood on is another way to protect the front element.

Also, I recently damaged my lens (a prime), as I dropped it while changing lenses. Two elements fell out the back, and the focusing system got ruined, but the front element is intact. So the filter is no magical protection for your lens.

Answered by Pete