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Why are some of my photos tack sharp while others in the same series are out of focus?

AO
Contributor

My camera is a Canon Rebel XS (dSLR) and I primarily use the 50mm f/1.8 lens. 

 

I shoot in Manual Mode with Autofocus ON.

 

I am having difficulty with my photos coming out incositant - some are out of focus, while others in the same series (taken a moment apart) are tack sharp.

 

I've attached two examples - one of the out-of-focus image, the other sharp images (both have been blown up).

 

It is not camera shake and my settings are identical for both photos. (ISO 200 | f/4.5 | 1/100sec in this instance.)

 

This has become such a problem that I find myself needing to take 10x more photos of the same subject/pose in order to hopefully get one sharp image from the series.

 

I have asked multiple people about this problem (though I have yet to take my camera and lens to a shop due to lack of funds) and no one has any idea of either what I'm talking about or what the problem could be.

 

I would appreciate your thoughts and help!

 

Thank you! 

 

Fuzzy/Out of Focus:

1- Fuzzy.png

 

Sharp:

2 - Sharp.png

 

13 REPLIES 13

bmac
Apprentice

I would check your focus with live view to determine if it's lens or camera body. Live view and viewfinder use different systems for autofocus, Canon has had a huge problem with viewfinder autofocus consistency with the 7D and now the 70D.

 

Good luck, I'm wrestling with the save viewfinder autofocus incosistency on my 70D.

 

BMac

I also think it is camera motion or shake.  As nothing seems in focus. With a 50mm lens at f4.5 one would think something would be in focus.  I am not a fan of ths Canon lens.  I have never been but lots of folks are and they like it.

I agree the lens may be faulty and you must confirm it is OK

EB
EOS 1DX and 1D Mk IV and less lenses then before!

If it's tack sharp in live view and not in viewfinder thens it's not the lens.

 

 

BMac

TCampbell
Elite
Elite
Look carefully at the ear of the gentleman on the right.

I suspect in this particular image, the problem may actually be camera movement after all. It looks to me as if there's some movement along the lower-left to upper-right direction of the frame.

When focus accuracy is in doubt, I always suggest isolating all variables and using a focus chart (you can download and print these from the internet or buy a commercially produced test target.) Camera should be on a solid tripod and the target should also be mounted on a stationary surface (or another tripod) to guarantee that movement can't be part of the issue.

You may have a lens focus issue after all... but as I look at the particular example you've posted, I think it looks more like motion blur. Of course I cannot see the exposure settings you used when you took this -- I'm drawing this conclusion by carefully inspecting edges oriented in particular directions to determine if some directions appear sharper than others -- and I think they do.
Tim Campbell
5D III, 5D IV, 60Da
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