Eric Weir <[email protected]> wrote: > >> On Apr 11, 2015, at 9:59 AM, Stanley Halpin <[email protected]> >> wrote: >> >> Assuming you were using 200mm at 20, f/11 the depth of field would be 4. >> 50mm at 20, f/11 would be 59 >> >> The one app I am using to calculate these numbers doesnt want to use an >> aperture smaller than f/11. >> The other app says 211 for 200mm, f/22 at 20 but I am not sure I quite >> trust that. > >I checked out depth of field apps in the Apple App Store. I found several, but >didnt find Peters f/Calc. Ended up purchasing Simple DoF. > >Using it I get different results from those you report above: >For 200mm, f/ll, at 20 I get DOF of 14 versus you 4. >For 50mm, f/11, at 20 i get DOF of 313 versus your 59. >For 200mm, f/22, at 20 we are closer. I get 28 versus your 211" > >I trust you more than the app at this point. But why thefor the most >partwild discrepancies?
There are two settings to examine, Format Size (APS-C vs full frame) and Circle of Confusion. Using a smaller circle of confusion is equivalent to setting yourself tighter standards of what you consider to be "in focus". Changing the Format Size involves changing the Circle of Confusion setting and not everyone agrees on what is considered "sharp enough" to be in focus. -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
