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DOF/fstop/lens

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Hi -

 

this may be a "duh" question but I thought I'd ask the members anyway.. Given the same f-stop but different lens (60mm vs 105mm) would the DOF be different for each lens? It seems that my 60mm photos when compared to my 105mm have more of the subject and negative space in focus compared to the 105mm... Is it my imagination? Thanks in advance for any replies.

 

Mike.

 

ps.. assume shooting 1:1 with both lenses...so working distance will be different but object on sensor (both sensors same size d70 and d2x) will be same size..

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Given the same f-stop but different lens (60mm vs 105mm) would the DOF be different for each lens?  It seems that my 60mm photos when compared to my 105mm have more of the subject and negative space in focus compared to the  105mm...

 

I'll go with a simple 'yes, the DOF can be different' and let Herb elaborate :) Of course, sometimes the DOF can be the same for a given f-stop, if the distance is different.

 

You ask this question without providing more specifics. It's hard to quantify beyond that.

 

Here are a few semi-in-depth articles on what you're asking about: http://www.waynesthisandthat.com/dof.html , http://www.luminous-landscape.com/tutorial...eries/dof.shtml , and http://www.naturescapes.net/102004/ps1004.htm . Hope this helps.

 

~Matt Segal

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Thanks Matt - that was a good read..

 

So, I think what I am asking is answered in statement 4....

 

4. DOF is constant if the aperture is constant and the focal length and distance are changed in such a way so that the size of the image of the object projected on the sensor is constant.

 

If Im shooting 1:1 with both lenses the working distance will be different but the object on sensor would be constant size.

 

It makes sense but maybe my f-stops I'm shooting with (30 +) are so small that diffraction and blurring becomes the problem......

 

Let me read more.

 

M.

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