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Thread: Flat Field Focus on LF Lenses?

  1. #11

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    Re: Flat Field Focus on LF Lenses?

    Quote Originally Posted by Dan Fromm View Post
    Yeah, yeah, yeah, but what sensible person would use an Apo Rodagon D as a general purpose taking lens? Now that I've posted this, I expect that a few creatures will come out of the woodwork to announce that their Apo Rodagon Ds are the best general purpose taking lenses they've ever used.
    Not quite. I have a 150mm Componon in a Compur shutter that I bought because it was cheap and looked like it had never been used. The lens works well at close distances, but is weaker at infinity where the Plasmats do better.
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  2. #12
    Greg Davis's Avatar
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    Re: Flat Field Focus on LF Lenses?

    I tried using my 240mm APO Symmar for a flat subject fairly close and saw a donut shape in the focus, so fuzzy corners fuzzy center and sharp middle area. I took the Symmar out of the shutter and replaced it with my 240mm Componon-S and got a sharp image across the whole thing. The Symmar is fine for regular stuff, but for flat and close the Componon-S worked better.

  3. #13
    Drew Bedo's Avatar
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    Re: Flat Field Focus on LF Lenses?

    Just spit-balling on this but:

    Pick a sunny day. Go somewhere where there is a flat lawn.. .a golf course, soccar field or similar. Set up you camera and lens and focus at various distances wide open. Maybe you will be able to see the thin DOF in the grass by looking on the Ground Glass. Perhaps a football field with straight lines will help. You might have to expose a few sheets of film to see if the zone of focus is curved or flat.

    Am I way off on this or will it work?
    Drew Bedo
    www.quietlightphoto.com
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  4. #14
    Drew Bedo's Avatar
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    Re: Flat Field Focus on LF Lenses?

    Quote Originally Posted by Dan Fromm View Post
    Yeah, yeah, yeah, but what sensible person would use an Apo Rodagon D as a general purpose taking lens? Now that I've posted this, I expect that a few creatures will come out of the woodwork to announce that their Apo Rodagon Ds are the best general purpose taking lenses they've ever used.
    You are probably right: Other lenses may very well be more suitable for general photography.

    I may be overly defensive, but I'd point out that when I broke into LF photography, it was on a shoe-string . . .a frayed one at that. At that point in my life, the best general photography lens was the uncoated 135mm something in a dial-set Compure shutter marked in German . . . .from the 1930s I think. It was the best lens for me because it had come on the Pre-Anniversary Speed Graphic beater I'd been able to snap up at the Houston Camera Show for what I had in my pocket that Saturday.

    The best lens to use for a shot is the lens you have. If you have more than one lens . . .great . . . figure out which one is better for the shot you have in mind.

    Now, there is a guy I know who has two stand-up roll-around Snap-On tool chests that hold much of his small camera gear. There are drawers and drawers of lenses that if sold off could probably pay for my grandson's first year of non-Ivy League college. He can pick and choose the "best" lens for about shot.
    Drew Bedo
    www.quietlightphoto.com
    http://www.artsyhome.com/author/drew-bedo




    There are only three types of mounting flanges; too big, too small and wrong thread!

  5. #15
    Alan Klein's Avatar
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    Re: Flat Field Focus on LF Lenses?

    Quote Originally Posted by Drew Bedo View Post
    Just spit-balling on this but:

    Pick a sunny day. Go somewhere where there is a flat lawn.. .a golf course, soccar field or similar. Set up you camera and lens and focus at various distances wide open. Maybe you will be able to see the thin DOF in the grass by looking on the Ground Glass. Perhaps a football field with straight lines will help. You might have to expose a few sheets of film to see if the zone of focus is curved or flat.

    Am I way off on this or will it work?
    Sounds great. PLus the lines with have the yards marked on the ground for reference.

    On a separate issue, I'm thinking about wide-angle lenses like the 90mm. Ordinarily, you want a center filter to account for the fall-off towards the edges. Does that falloff have any effect on the OP's project?

  6. #16
    Drew Wiley
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    Re: Flat Field Focus on LF Lenses?

    Dan - I actually knew someone like that. Jewelry maker by trade, miniaturist photographer as hobbyist. Prints were displayed with a gooseneck magnifying glass in front of them. I sometimes do macro shots of natural subject, but rely on versatile lenses not only specially close corrected, but good clear out to infinity too, like G-Clarons and Fuji A's. Those can be hypothetically used on enlargers too (I've tested em), but aren't quite as well corrected as real deal apo process lenses for critical applications.

  7. #17

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    Re: Flat Field Focus on LF Lenses?

    Quote Originally Posted by Dan Fromm View Post
    Big front, small behind .
    I'm ok with that.

  8. #18

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    Re: Flat Field Focus on LF Lenses?

    Tape a page of newsprint to a wall, focus camera to it full frame, and examine image on GG and neg with good magnification to see how even focus is...

    Steve K

  9. #19

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    Re: Flat Field Focus on LF Lenses?

    Years ago was involved in a long term project for a Historical house that was turned into a walk through Museum. Project was to shoot 4x5 Chromes of many original documents. Chromes were archivally stored, but before that they were scanned. From the digital files. 1:1 double sided prints made on thin archival paper. Ragged edges and holes in the paper very carefully cut with a Xacto knife. Then the paper was "beat up" on a stiff rug. The resulting prints could be easily mistaken for the original documents. They were left on desks and tables in the Museum. If they were stolen the Museum was only out a few bucks, and the perpetrator would have been in for a rude surprise. Camera used was a 4x5 Sinar Norma. After testing out several lenses, we used a 210mm Repro-Claron (not a G) at f/16 or f/22 I seem to remember. Flat field focus was exceptional. Had to leave my photo equipment in a separate new modern "workshop" building on the grounds for several weeks. At first I was skeptical of doing that, but then I was shown their elaborate alarm system.

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