Hyperfocal/Zooms/

[jomar]

To calculate hyperfocal on say a 24-85 zoom, do you base the calculation on the 24mm, or the effective 35mm that applies to digital

Thankks

[Seachicken]

Unfortunately neither :mad:

This thread (http://www.s2pro.com/forums/showthread.php?s=&threadid=306) goes into the complexities of the issue.

Perhaps there is a DOF table out there somewhere... or you could try the quick and dirty trick of someone on this thread of using the hyperfocal distance of the aperture 1 stop wider to compensate.

Andy.

[memobug]

Thom Hogan's e-book is supposed to have a chart in it. I have not seen it.

Regards,

Matt

[Seachicken]

I just found this; f/calc, a freeware program (http://tangentsoft.net/fcalc/) can be used to work out just about anything to do with DOF (including hyperfocal distance).

You will need to use a value for the circle of confusion appropriate for the size of the S2's sensor. For 35mm usually about 0.025mm is used, so a good value for the S2 would be 0.66 x 0.025mm = 0.0166mm

I tried this out for 50mm lens at f/4 on 35mm film; the hyperfocal distance is 25m.

On an S2, a 50mm lens at f/4 has a hyperfocal distance of 37.5m. At f/5.6 this changes to 26.5m .. so the quick fix of 'use the hyperfocal distance of one stop wider' works at least for this case.


Andy.
:)