# Playing around with depth of field and I think I finally get it?

Started 4 months ago | Discussions thread
Re: Playing around with depth of field and I think I finally get it?

LillyRoseAvalos wrote:

So according to the calculator I found at a subject distance of 10 centimeters at f9 on a 1.6 crop sensor the total depth of field is 0.46 centimeters. Which is 4.6 millimeters.

Just to complicate matters, this is macro distance and the standard DOF calculations break down here. It doesn't matter because when doing macro it's easier just to see what you get through the viewfinder; but it's worth knowing that the calculations can't always be relied on.

Shooting at F2 at a subject distance of 20 centimeters gives me almost the same depth of field at 0.46. I tried to find some kind of formula for this but its inconsistent. Is there a formula so you can easily calculate the dof by multiplying the magnification? This far and near distance is making my head in though.

Try using more realistic settings. In general it doesn't matter but it's worth considering where subject distance is measured from. When the closest focus distance for a lens is specified it is measured from the sensor. I don't think you'll find a 24mm macro lens; the shortest I know is 35mm with CFD of 145mm and length of 140mm - in other words, the lens is only 5mm from the subject.

Although you can put 10cm into a calculation that puts the subject inside the lens!

Is the difference between the near distance dof and far distance dof a product solely dependent upon how close the thing you focus on is? does the near and far dof always change proportionally?

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Gerry
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I'm happy for anyone to edit any of my photos and display the results
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First camera 1953, first Pentax 1985, first DSLR 2006
http://www.pbase.com/gerrywinterbourne
gerry.winterbourne@ntlworld.com

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