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Thread: Easy Testing Used LF Lenses?

  1. #11

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    Re: Easy Testing Used LF Lenses?

    When I was sorting through a box of junk optics and wanted a quick idea of how sharp/contrasty/and color correction, I would sit about 6' away from a TV, a good loupe in one hand, and test lens in the other... I would hold up the lens towards the TV, and with the loupe would find the aerial image point where the raster on the screen would focus...

    I would clearly see how sharp the edges of the pixels were, or if there was a bleed over on the edges, if the color blobbed over those edges, and look at the overall color contrast... Then tilt the lens a little off axis and look again to see if the image degrades...

    This quik test help me scan a # of lenses quickly, and gave me ideas of which lenses should be mounted for further film testing... (One old projection Petzval seem to have a unusual "signature" and ended up with machined mounts, and beautiful special effects!!!)

    It takes a little practice to learn what to look for, but a useful first test...

    Steve K

  2. #12
    Tin Can's Avatar
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    Dec 2011
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    Re: Easy Testing Used LF Lenses?

    Thanks everybody, all is helpful.

    I am changing camera, lenses, and film to FP4+ or HP5+ and shooting a few tests today, process tonight, scan and light table tomorrow.

    Right now I need a working set for Sunday event, 1890 Christmas more or less...full Sun

    I will get the Premo SR working later, it is such a nice box, very lightweight, yet strong and totally closes up securing lens, bellows and GG from damage.

    A camera design that should make a comeback...
    sin eater

  3. #13

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    Re: Easy Testing Used LF Lenses?

    My testing method is pretty simple, I machined an adapter for my digital camera to fit into one of the copal 3 lens boards for my monorail. I mount the lens board to the rear standard, attach the camera and focus using the lcd, and then use shift+rise to check corners. It only works well with 135mm or longer lenses though, a mirrorless camera would allow the testing of shorter lenses.

  4. #14

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    Re: Easy Testing Used LF Lenses?

    Quote Originally Posted by aphcl84 View Post
    My testing method is pretty simple, I machined an adapter for my digital camera to fit into one of the copal 3 lens boards for my monorail. I mount the lens board to the rear standard, attach the camera and focus using the lcd, and then use shift+rise to check corners. It only works well with 135mm or longer lenses though, a mirrorless camera would allow the testing of shorter lenses.
    Had done the same recently with my Nikon Z6 on my Sinar 4x5. Problem I encountered was that I couldn't shift the lens to one side and the back to the other side enough to determine the maximum coverage of the lens. Though it worked great for judging the center sharpness of the lens. Viewed the image in live time on my MacBook, was amazed to see how diffraction all of a sudden just kicked in as I stopped down the lens.

  5. #15
    Tin Can's Avatar
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    Re: Easy Testing Used LF Lenses?

    Greg, your diffraction comment may lead me to try the DSLR trick

    There are adapters...

    More news, shot another camera and lens which looked sharp to me on GG, but very poor on light table and scans. No need to post the failures

    I am getting worried my eyes are deceiving me

    Today I will try a Nikon lens
    sin eater

  6. #16

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    Re: Easy Testing Used LF Lenses?

    I test lenses not only for sharpness,but how they render round objects such as a tree, or a part thereof.
    I set up a scene large enough to not require a bellows length adjustment which includes large foliage, a tree branch or weed resembling one, and a variety of objects of various shapes, sizes and colors.
    I photograph these in daylight, some in sun, other parts in shade using 8x10 single sided x-ray film.
    I know this seems like a lot of work,but it also gives me an abundance of information.

  7. #17

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    Oct 2015
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    Re: Easy Testing Used LF Lenses?

    Like others have already commented, I've always followed Fred Picker's advice in that if the lens can render bare tree branches against clear sky, it's sharp enough. I'd be willing to bet that any modern lens we all use is sharper than most of the optics that Ansel Adams, Edward Weston, et al used.

  8. #18
    Tin Can's Avatar
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    Re: Easy Testing Used LF Lenses?

    Thanks Jim and Alan,

    Yesterday I shot my backyard at 50 ft to shed and 200 ft at power lines with trees between that. Full sun to heavy shade. 5X7 B&L Tessar in Volute focused and shot at f11. Really out of focus neg, never used that lens before.

    Just loaded 4x5 and 2X3 holders with FP4 and will shoot more modern lenses. Soon...
    sin eater

  9. #19

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    Aug 2018
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    Re: Easy Testing Used LF Lenses?

    I test side-by-side lenses of same focal length. This way, my 300mm Apo-Ronar MC got a rest while waiting for a new back cell, while the single coated Copy-Claron with some scratches would come with me in my 5x7" bag. To do the test, I used a Sony 5100 with Nikon adapter, Pentax 67 adapter and a Copal #0 adapter + Pentax 67 focus adapter. Identical photos of a tree showed the Copy-Claron was good and sharp, while the Apo-Ronar was bad and unsharp.

    Sent fra min SM-G975F via Tapatalk

  10. #20

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    Jul 2008
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    Re: Easy Testing Used LF Lenses?

    Some examples of how film_color balance_color correction filter_color densitometry and ... was done back in the day circa 1996.
    Took some digging to find these OLD color transparencies, then scan them.

    Camera:
    8x10 Sinar P with Sinar Shutter.

    Film:
    Agfa Chrome RS100. film used MUST be from the same lot number & box preferred.

    Lighting:
    Bronocolor light box, Elinchrome lamp head with 404 power pack.

    Subject:
    Macbeth color chart, white board, some newspaper clippings pasted on. Subject to camera-lens distance similar to to be photographed subject on product table.

    Exposure:
    MUST be within and less than 1/3 f-stop or the 18% gray density and color rendition of the film/lens/lighting/subject/processing will have more errors. Calibrate your light meter as needed (Minolta Flash 4, from that time).

    E6 processing was at The New Lab in San Francisco. They held their E6 line tight and consistent day to day.. majority of the time. Common practice was to expose several sheets of color transparency film identical. Have TNL process one sheet, hold the rest. Once the processed sheet was done. examine the color transparency the very best loupe available (Schneider 4x, later Schneider 6x Aspheric_fave to this day). Push-pull as needed. If you got it all good, it would be process normal. If wrong, you got a problem to serious problem if push-pull was more than 2/3 stop.


    Two lenses tested were 14" Goerz Red Dot Artar in Ilex shutter set to T (Sinar shutter... using strobe, shutter speed is far less a factor) and 14" Goerz LD Artar in barrel. Taking aperture is f16, which is what Goerz optimized these lenses for as noted in their sales brochure.

    Resolution was narry-A-factors as they were BOTH more than good enough regarding resolution. Contrast was nearly identical (favored over the Rodenstock Sironar used at that time).

    Note the difference in CC filter correction between the Red Dot Artar and LD Artar.. difference comes up on the color densitometer, as noted on the New Lab gray card test notes... Now, can anyone via the web measure-tell the difference using the 18% gray square on the Macbeth color chart?


    14" Red Dot Artar @ f16.
    Density numbers:
    Red: 84
    Green: 88
    Blue: 89
    Suggested CC filter: 025 green.

    Click image for larger version. 

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    14" LD Artar @ f16.
    Density numbers:
    Red: 84
    Green: 94
    Blue: 90
    Suggested CC filters: 025 green & 025 cyan.

    Click image for larger version. 

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    This was only the beginning of how any lens to be used was considered for ownership. Once this was done, the lens to be considered for ownership was used LOTS in a variety of image making conditions for about a month or more to learn the personality of the lens. If it was acceptable, lens found a good home.

    ~Could lens testing like this be done today?~
    *No such thing as "easy" lens test.*


    Bernice

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