Is this too much to ask from the 7D (or Sigma 17-50)

Started Jan 4, 2013 | Discussions thread
Topaz Contributing Member • Posts: 588
Re: Is this too much to ask from the 7D (or Sigma 17-50)

sabdalla wrote:

My question is: was this just a recipe for blurred images, or was the lens the culprit here and would a canon (say the 24-70L) lens have been any better (assuming that the sigma focusing motor had a hard time keeping up with the camera...or was this simply too much to ask from the 7D (I hope not because I love mine)

I will agree with what other posters said here; I don't think you need to worry about focus and sharpness depending on the output size you're looking for.  I viewed your landscape-oriented shots on my monitor at about 8-9" width, and they didn't look soft or out of focus at all.  Pretty sharp.

If you are concerned about larger output, though, I would say your equipment should be capable - in the right situation - of getting sharper photos than you got.  When I do some pixel peeping and look at your original image, it's definitely far less sharp than I see many of my images shot using AI servo, when I look at 100% size.  So for the discussion below I assume you're bothered by the sharpness when you view at 100% on your monitor.

I doubt it's the equipment's fault, though.  Too many variables.  While even something like 60ms should be fast enough to stop motion at reasonable print sizes for a running kid, the required shutter speed scales with output size.  So when we're pixel peeking at 100% you need a faster shutter speed to avoid motion blur.  250-500ms might be fast enough, but I'm not sure.

It's still a wild guess, but I would suppose another big consideration is actually camera shake.  We all know the "rule of thumb".. e.g. if you're shooting at 20mm focal length, then on an APS-C sensor you should shoot at 1/36" or faster.  You're shooting way faster than that.  So far, so good.  But again the "rule of thumb" has always been a bit meaningless to me, because you can't predict blur without a discussion of output size and viewing distance.  But I'm sure that at 100% viewing, compared to say a 4x6 print, you need a proportionally faster shutter to avoid blur from camera shake.  And furthermore, that rule of thumb was written with a stationary photographer in mind!  As you are actually walking with your camera, I have a hunch you're jiggling the camera around a lot more than a photographer standing in place.

So overall if you're looking for sharp results at very large output sizes, or if you just like doing pixel peeping, I think you might try an even faster shutter speed for this scenario.

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