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Thread: Rodenstock Imagon Tiefenbildner 250mm h=5.8, some questions.

  1. #21

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    Re: Rodenstock Imagon Tiefenbildner 250mm h=5.8, some questions.

    And another idea regarding the h-number.

    To me it could be defined like this:
    #1 Take a picture of a gray card, properly focused, with the Imagon fitted with the special iris. Focus with the outer array of perforations closed, then re-open. Measure the illumination in the image plane.
    #2 Substitute to the special iris a simple circular hole centered on the optical axis, located in front of the glass at the same place, do not re-focus in order to keep exactly the same distance between the glass and the image.

    When both experiments yield the same illumination, the h-number in #1 experiment is equal to the regular f-number in #2.

  2. #22
    Peter De Smidt's Avatar
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    Re: Rodenstock Imagon Tiefenbildner 250mm h=5.8, some questions.

    I dislike the funky aperture artifacts that appear on specular highlights in the background. I would avoid such highlights if I used the lens disk with the holes open. Note that using a regular iris in front of the lens would get rid of that behavior, and if you made the diameter of the disks smaller, you'd get sharper results, but with less of a glow. I prefer some sharpness + a glow, but that's subjective, of course.
    "Why can't we all just get along?" President Dale, Mars Attacks

  3. #23

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    Re: Rodenstock Imagon Tiefenbildner 250mm h=5.8, some questions.

    Quote Originally Posted by Emmanuel BIGLER View Post

    However the when the shapes of this perforated disk are projected in out-of focus highlights, the visible shape is definitely non-natural and somewhat disturbing, I agree.

    So with the Imagon, you should only take pictures of flat subjects with no depth, focused with the outer holes closed and then re-opened, if you want to see the added fuzziness but do not want to see the disturbing shapes in the background
    Sorry, Emmanuel, but again I don't agree with the out-of focus-theme.
    The main thing for creating disturbing shapes is direct light - of course in the out-of-focus-areas.
    But it's not the out-of-focus area herself.
    Again I read the manual of the Imagon, written by Michael Neumüller in his great book "the praxis of softfocus" from around 1950.
    He describes " a special case is direct light, which requires closing the disk to avoid spreading highlights" (bedbucks).

    He also describes the effect of increasing and decreasing the sharpness AND the glow by playing with the bellows distance but doesn't give a warning concerning spreading shapes in this situation.

    I have learned to work with my Imagon exclusively from this book, so unfortunately I haven't more to say by own observations than this :-)


    Concerning the iris of a shutter, let me throw in that Neumüller describes why it is best to put the iris in front of a meniscus (the Imagon is a kind of meniscus).

    If the iris is behind the lens, this may give an effect which I can't translate exactly by word, but this may give problems at the edge between shadow and light.

    I didn't use a meniscus with a shutter iris, but the resulting effect is described as a similary effect like burning a print in a bad way.

    This effect seems to be more little, so I have problems to follow his examples given by pictures, but I want to spread the old news :-)

    I didn't found the formula for the distance lens/front iris at this moment, but I remember nearly 10 percent of the focal length was given as the best distance.
    I try to refind this formula.


    Best,
    Ritchie

  4. #24
    Drew Saunders drew.saunders's Avatar
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    Re: Rodenstock Imagon Tiefenbildner 250mm h=5.8, some questions.

    Cameraeccentric has two scans of old Imagon documents: http://www.cameraeccentric.com/html/info/imagon_1.html and http://www.cameraeccentric.com/html/info/imagon_2.html

    Your shutter most likely needs to be serviced, or at least test it to see what speeds you actually get at each setting. Yes, you use the same H-stops value as F-stop when determining exposure, but if your shutter is a stop or more off, you're going to have problems. If you're not familiar with compound shutters, you can easily break one if you try to cock the shutter in "B" or "T" mode ("T" might be labeled "Z" on your shutter). Here's a video of the Imagon 300 in box, and Eddie shows you how NOT to break your shutter: https://youtu.be/AsL1ZNqUspM

    I have a recent (post 1980 I guess) 250 Imagon in Copal shutter with all the disks and the 4-stop ND filter (more useful these days than the 2-stop green filter) and mostly use the 7.7/9.5 disk, at either setting. You'll get different results using the 5.8/7.7 disk at 7.7 than you will using the 7.7/9.5 at 7.7, so you'll want to experiment to see which one you like. As others have said, you're welcome to use the aperture either with or without the disks. I sometimes stop the aperture down w/o any disks to help focus, choose a disk, re-confirm focus, choose a disk setting, and then shoot.
    Flickriver (to avoid Flickr's annoying new format): http://www.flickriver.com/photos/drew_saunders/

  5. #25
    Marco Gilardetti's Avatar
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    Re: Rodenstock Imagon Tiefenbildner 250mm h=5.8, some questions.

    Quick update.

    I've had the shutter checked professionally and it worked absolutely perfectly. The technician said it was even a little bit faster than its nominal values (like 1/98th of second instead of 1/100). Not bad for a Compound of that age!

    He also checked the f: value of the lens at full aperture and said it is 5,6. I have later grossly confirmed this value by comparison with another lens and a groundglass light meter. At the same time I have marked the standard apertures on the blank scale, and have later had the values engraved by a lady who engraves keyholders etc. with a pantograph (she did only a so-and-so work, but it's functional anyway).

    With the help of a sir who owns a very big lathe, I managed to make the mounting flange. It was very interesting as I never used a lathe before, but man how much does it take to work with these machines! We spent the whole day at the lathe! Had I only knew, I wouldn't have asked him to do me this favour. In the end it turned out he didn't own the proper pair of gears to make the thread and we had to carry our piece to a friend of his who owned the appropriate gearing. Much more complicated than I thought, but interesting and stimulating nonetheless.

    Finally, this weekend I took the lens out for shooting. I have had the hardest time of my life in focusing this lens. I could just inspect the developed film sheets so far, but it's obvious that some photographs are quite all right, while in others I managed to slip up the focus somehow. I bought a different loupe and will come back and repeat the wrong photographs as soon as possible.

  6. #26

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    Re: Rodenstock Imagon Tiefenbildner 250mm h=5.8, some questions.

    Quote Originally Posted by Marco Gilardetti View Post
    Quick update.

    I've had the shutter checked professionally and it worked absolutely perfectly. The technician said it was even a little bit faster than its nominal values (like 1/98th of second instead of 1/100). Not bad for a Compound of that age!

    He also checked the f: value of the lens at full aperture and said it is 5,6. I have later grossly confirmed this value by comparison with another lens and a groundglass light meter. At the same time I have marked the standard apertures on the blank scale, and have later had the values engraved by a lady who engraves keyholders etc. with a pantograph (she did only a so-and-so work, but it's functional anyway).

    With the help of a sir who owns a very big lathe, I managed to make the mounting flange. It was very interesting as I never used a lathe before, but man how much does it take to work with these machines! We spent the whole day at the lathe! Had I only knew, I wouldn't have asked him to do me this favour. In the end it turned out he didn't own the proper pair of gears to make the thread and we had to carry our piece to a friend of his who owned the appropriate gearing. Much more complicated than I thought, but interesting and stimulating nonetheless.

    Finally, this weekend I took the lens out for shooting. I have had the hardest time of my life in focusing this lens. I could just inspect the developed film sheets so far, but it's obvious that some photographs are quite all right, while in others I managed to slip up the focus somehow. I bought a different loupe and will come back and repeat the wrong photographs as soon as possible.
    1; the Imaginq changes sharpness with each change of the disk or the aperture ring.
    2; the Imaginq does not have a point of exact focus at any aperture or distance.
    3; wide open your lens is a 5.8, not a 5.6.
    4; focusing must be done a shooting aperature, not wide open.
    5; the shutter’s aperture ring should never be used as that will block off the peripheral rays which are the one# that create the Imaginq effect! Only use the disks. The small holes in the disks that surround the large center hole are there to allow the peripheral rays to hit the film or digital sensor.
    6; the Imaginq requires a strong 5:1 lighting ratio from a strong light source, not an umbrella, to get the proper haloing.

  7. #27

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    Re: Rodenstock Imagon Tiefenbildner 250mm h=5.8, some questions.

    I prefer using the Compound shutter's conventional iris, which makes the Imagon similar to the Kodak Portrait Lens and other early achromatic meniscus lenses.
    Me to most of the time but in my case is it a Copal shutter! The lens without any Imagon discs in front its about f4,5 in my case if the Copal is also fully open! For the 250mm Imagon!
    Mine 250mm covers 8x10 in near distances, but I do not recommend this for near Portraits!

  8. #28

    Re: Rodenstock Imagon Tiefenbildner 250mm h=5.8, some questions.

    Plaubel Makiflex 9x9cm SLR, 250mm Rodenstock H5.8 barrel mount lens, Legacy Mic-X dev, Foma 200

    Makiflex Std 250 Imagon Foma 200 2 by Nokton48, on Flickr

    250 Imagon Makiflex Foma by Nokton48, on Flickr




    200mm Rodenstock Imagon barrel mounted, on Plaubel Makiflex board;

    001 by Nokton48, on Flickr




    300mm barrel mounted Rodenstock Imagon mounted on Plaubel Makiflex lens board. I have owned Imagons from 120mm to 420, all are in barrel mounts (no shutters). This unit is cumbersome, but NOT heavy. Works well. The screw together tubes come from China.

    001 by Nokton48, on Flickr
    Last edited by Daniel Unkefer; 30-Nov-2017 at 04:42.
    - Sinar Norma User

  9. #29

    Re: Rodenstock Imagon Tiefenbildner 250mm h=5.8, some questions.

    My 120mm and 150 Imagons I sold to "Mr. Pentacon Six". I had a special Rodenstock helical custom modified to fit my P6 and EX66 cameras.

    See his extensive article on these unique lenses here:

    http://www.pentaconsix.com/imagon.htm
    Last edited by Daniel Unkefer; 30-Nov-2017 at 04:44.
    - Sinar Norma User

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