[pure-silver] Re: Large Format Tilt
- From: "Nicholas O. Lindan" <nolindan@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Fri, 30 Nov 2007 17:07:11 -0500
"Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
"Nicholas O. Lindan" <nolindan@xxxxxxxxxxxxx>
> At near distances the back-subject distance is set first
> for the desired magnification and then the lens position
> is adjusted for focus.
I'm not sure you meant the above.
How do you set up your enlarger? I move the enlarger
to about the right place, focus, and then iterate as
needed.
I don't start by moving the lens into position first
and holding it there while adjusting the negative and head...
then moving the lens again, holding it and moving the negative
again.
Ditto a view camera. If it's 1:1 I put the film plane 4x the
focal length from the subject and focus, then oooch as needed.
I suppose you can put the lens 2x from the subject --
but then one has to find the place on the lens to
measure the 2x to/from. The resulting 1:1 isn't terribly
accurate.
Hand held with a macro lens I sort-of focus, move the camera
to about the right spot for the desired image size and then
re-focus, so then it is also the lens that is moved for final
focus.
If you are magnifying then things can get weird if you
position the lens first: The lens-subject distance stays
pretty constant and the back zooms in and out for magnification
changes; if you set the lens closer than the f.l. then
you can move the back all you want...
moving the back of the camera changes one variable
while moving the lens changes two variables simultaneously.
On my camera/enlarger moving either the lens or back
(or both) changes focus _and_ size.
==
Nicholas O. Lindan
Cleveland Engineering Design, LLC
Cleveland, Ohio 44121
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