[pure-silver] Re: correction for bellows extension
- From: Myron Gochnauer <goch@xxxxxx>
- To: Pure Silver group <pure-silver@xxxxxxxxxxxxx>
- Date: Thu, 5 Mar 2015 02:47:24 +0000
Lets say I have an 8 inch lens. That squared is 64. With 10 inches of
extension, squared is 100. 100/64 = about 1.5 so probably about a half a stop.
Again, probably not earth shaking and probably plenty close enough.
My favourite 4x5 lens was/is a 210mm, which is a bit over 8 inches. If the
distance between the lens board and film plane got to 11 inches, I would add
a stop. If it got to 16 inches (it never did!) I figure I should add another
stop. No muss, no fuss, no embarrassing arithmetical errors. I've known the
standard f-stop sequence since I was a teenager, and always have a little
3-foot tape measure attached to my car keys. When I’m “being visual” in the
field, my ability to think technically pretty well shuts down, so this approach
fits my abilities, or lack thereof.
Myron
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