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Depth of field of extension tube vs dedicated macro

Started 7 months ago | Questions thread
Joseph S Wisniewski Forum Pro • Posts: 35,461
Cropping and enlarging alters f stop...
1

JamesMorgan wrote:

However, my understanding of post-processing cropping is that whilst this does reduce DoF, it does so in a linear manner rather than according to a square rule if increasing lens focal length. So, for example, if I increase focal length from 150mm to 300mm, DoF reduces to a quarter, however, if I crop the 150mm image to achieve the same field of view DoF only reduces by around a half. This can be useful to extract the maximum possible DoF if you don't mind losing a few pixels.

What you're seeing is the crop factor affecting effective f stop along with effective focal length. You gain more DOF, but you burn resolution. Open up to get the resolution back, and you've lost the DOF advantage.

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The term "mirrorless" is totally obsolete. It's time we call out EVIL for what it is. (Or, if you can't handle "Electronic Viewfinder Interchangeable Lens" then Frenchify it and call it "LIVE" for "Lens Interchangeable, Viewfinder Electronic" or "Viseur électronique").
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Stanley Joseph Wisniewski 1932-2019.
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Christine Fleischer 1947-2014.
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Rahon Klavanian 1912-2008.
Armenian genocide survivor, amazing cook, scrabble master, and loving grandmother. You will be missed.
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Ciao! Joseph
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