Sigma lens & close focusing - how picky should one be?

Hi everyone! Long time since I posted. Searched existing threads already so please forgive me if I'm redundant.

I just received my Sigma 18-50 EX DC Macro for my 40D and am a little curious about the autofocus accuracy. Playing with distances of less than 2ft, I experience about ½ inch close focusing on about 75% of shots (the other 25% are dead on or close enough).

My question is, would you care about this if it were your purchase? Am I crazy for noticing this or should we be that picky? I plan on using the 1:3 magnification capability quite a lot. I don’t mind manual focusing for macro shots, but the trouble is I can’t tell that’s it’s off until I’m reviewing the shot and zooming in. LiveView is a non-issue here since I don’t really want to use that as a Band-Aid if it’s the lens’ fault. And I don’t think the 40D has focus bracketing.

½ in. is small, and certainly won’t be an issue for anything other than close-ups at large apertures. And part of me wonders if all my information scouring and reading of Sigma’s close-focusing issues has made this a self-fulfilling prophecy in a way, since I may very well have not noticed this so quickly without prior knowledge of it. On the other hand, my Canon lenses are much more dead on in their AF.

It’s a great handling and feeling lens that’s super sharp at it’s focus point, so it would be a treat to have a higher good focus hit rate. Just wondering if I should accept this or buy another one and hope that one’s better.

Thanks for any help!

The lens is focusing 1/2" in front of or behind the subject at close range? I want to be sure I have this right.

Are you shooting from a tripod and using manual focus (using whatever focusing aid the camera has, I'm not a Canon guy)? To me, if you're not doing both of these there is a certain amount of luck involved. Try manual focus and a tripod and see if your results improve.

Thanks for the reply. It's front focusing (between the subject and lens) by about 1cm or less some of the time. With more playing with it, I decided I was being too picky and probably demanding more than modern AF could offer. The results were similar with my Canon lenses.

I think I simply found too much information on the internet and set up a bad test! I shall just enjoy my new equipment now.

Best,
Andy

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Originally Posted by Phil Flash

Hi everyone! Long time since I posted. Searched existing threads already so please forgive me if I'm redundant.

I just received my Sigma 18-50 EX DC Macro for my 40D and am a little curious about the autofocus accuracy. Playing with distances of less than 2ft, I experience about ½ inch close focusing on about 75% of shots (the other 25% are dead on or close enough).

My question is, would you care about this if it were your purchase? Am I crazy for noticing this or should we be that picky? I plan on using the 1:3 magnification capability quite a lot. I don’t mind manual focusing for macro shots, but the trouble is I can’t tell that’s it’s off until I’m reviewing the shot and zooming in. LiveView is a non-issue here since I don’t really want to use that as a Band-Aid if it’s the lens’ fault. And I don’t think the 40D has focus bracketing.

½ in. is small, and certainly won’t be an issue for anything other than close-ups at large apertures. And part of me wonders if all my information scouring and reading of Sigma’s close-focusing issues has made this a self-fulfilling prophecy in a way, since I may very well have not noticed this so quickly without prior knowledge of it. On the other hand, my Canon lenses are much more dead on in their AF.

It’s a great handling and feeling lens that’s super sharp at it’s focus point, so it would be a treat to have a higher good focus hit rate. Just wondering if I should accept this or buy another one and hope that one’s better.

Thanks for any help!

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If you are talking about taking macro shots, the easy way to up your macro keeper rate is very simple. Turn off the auto focus. Most macro shoots manually focus for macro. With a depth of field that narrow it is more accurate that auto focus. Depending on what I am shooting, I select my focus distance, turn it to manual and move the camera back and forth until my subject is in focus. I tend to be a bug guy with some flowers thrown in.

Quote:

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Originally Posted by Phil Flash

I shall just enjoy my new equipment now.

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Excellent idea! :) Be sure to share some of your results in Viewfinder or Critique.

For Micro Photography I found that the auto focus is useless. Use manual focus.