> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of
> [EMAIL PROTECTED]
> Sent: Monday, 22 January 2001 6:29 AM
> To: [EMAIL PROTECTED]
> Subject: EOS Canon DOF tables causes confusion
>
>
> Hello All,
>
> I had problems figuring out the Depth of Field data for EF lenses
> at the Canon Camera Museum:
> http://www.canon.com/camera%2Dmuseum/
>
> But Canon's numbers do not seem to agree with several online DOF
> calculators. E.g. Java DOF at Photozone:
> http://www.photozone.de/depth.htm
> or the Javascript ones: http://members.home.net/gillettm/DOF.html
> http://javascript.internet.com/calculators/field%2Ddepth.html
>
> Which one(s) are correct?
> On what planet do Canon's number apply?
> What sharpness criteria does Canon use? 3"x5" prints viewed at 5"?
>
> Cheers
> Julian Loke
Hi Julian
I have only had time to check out the Canon Museum. The formula was not
provided on the pages that I opened, but it is likely that Canon uses a
formula incorporating the circle of confusion (COF) as the limiting factor
that defines the depth of field.
Depth of field calculations will vary depending upon the COF value used in
the formulae.
Traditionally, a value of 0.035 mm was used, but with the increasingly high
resolution of today's films, values of 0.025 mm and less are now commonly
used.
I don't have a URL reference handy for a further explanation of COF; if I
happen across one I will post on the list.
I have a MS Excel spreadsheet that I created some years ago that calculates
depth of field and hyperfocal distances (it prints as handy pocket-sized
charts). I will email it to you separately (and anyone else who wants one)
for you to compare to your findings thus far.
Regards
Chris H
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