DOF Calculations

Started Feb 13, 2013 | Discussions thread
jkjond
Veteran MemberPosts: 6,661
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Re: Here you go: formula
In reply to Big Bang, Feb 13, 2013

Big Bang wrote:

David Lal wrote:

http://forums.dpreview.com/forums/post/27188903

David

David, thanks for the post! I tried searching DPReview but couldn't get the right key words. Though I would have figured "DOF calculation" should have brought that link up for me!
Of course now that I have it, I have to admit the formula is sufficiently complicated that I don't see myself solving it in my head on the fly. I suppose an iPhone app is probably how I'll go for that purpose. That said, I think I'll study the equation before bed for the simple sake of expanding my understanding of optics. I was reading the following website earlier and found it quite enlightening.

http://www.cambridgeincolour.com/tutorials/depth-of-field.htm

I printed out a dof chart to fit in my ND filter case (the 9 indicates is the box for my ND6, but its upside down!). This shows me the hyperfocal point and nearest sharp focus for a number of focal lengths and apertures on DX, specifically for landscapes - didn't bother with macro.

The plus side is that its always with me and takes up no space and is quick and easy to reference - far faster than a phone app, though not as flexible.

The minus side is that lenses aren't marked out accurately enough for it to be any practical use, so I tried it once then ignored it. But its always there...

In practice, I find dof is easiest to assess using the LCD, zooming in to check focus. Far better than dof preview which is far too dark and small for small apertures.

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