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Old Aug 30, 2006, 9:46 AM   #1
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Hi All,

Do you know where I can find a DOF table (DOF based on aperture and focusing distance) for Pentax-A 50/F1.7 ?

Sigma for example puts .PDF files with DOF tables for their lenses to download on Sigma's website - what about Pentax ?

Thank you all in advance.


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Old Aug 30, 2006, 9:49 AM   #2
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isn't it on the lens???

roy
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Old Aug 30, 2006, 9:59 AM   #3
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yes - but I'd like to find specifically a table.
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Old Aug 30, 2006, 2:08 PM   #4
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try google -- dof chart--
HERE
first 2 hits
http://www.photocritique.net/dof.html
http://johnhendry.com/gadget/dof.php

roy
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Old Aug 30, 2006, 2:21 PM   #5
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well, you are saying that regardless of the lenses any generic DOF calculator will work (based on generic parameters like focal length) w/o errors, right ? even for short distances like one ft away @ F1.7 for example ?
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Old Aug 30, 2006, 4:10 PM   #6
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yes, optics is a science. 50mm=50mm
roy
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Old Aug 30, 2006, 5:24 PM   #7
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deejjjaaaa wrote:
Quote:
well, you are saying that regardless of the lenses any generic DOF calculator will work (based on generic parameters like focal length) w/o errors, right ? even for short distances like one ft away @ F1.7 for example ?
I guess the fact that we keep talking about crop factors and equivalent focal lengths has clouded the basic fact that all calculations of f number and DOF are based on the actual focal length of the lens, regardless of the digital or film format it covers. The shorter the focal length, the greater the DOF, at the same f number. That is why small sensor digicams have such huge DOF. My Optio 33L has a 1/2.5" sensor (read very tiny) and its lens is a 5.8mm to 17.4mm zoom. result, massive DOF. There are some interesting implications for minimum aperture as well but that is not part of this discussion.

Ira
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