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Thread: Could the Image Circle of APO-Ronar 300mm/9, cover 8X10 format ?

  1. #1
    Thalmees's Avatar
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    Could the Image Circle of APO-Ronar 300mm/9, cover 8X10 format ?

    Hi all
    Could the Image Circle of APO-Ronar 300mm/9, cover 8X10 format ?
    My lens is labeled SINAR Rodenstock APO-Ronar 300mm/9 MC on the front cell.
    Rear cell has no engravings at all(but has Rear mount diameter of 37.5mm). Its on Sinar DBM board.
    While the IC is 264mm(@ f/22) as stated by both SINAR and Rodenstock, the lens is capable of much more IC than claimed. The lens(being on f/9 and focused @ infinity) can tolerate up to 6cm (roughly) of lens standard shift sideways with equivalent displacement up or down.
    http://www.prograf.ru/rodenstock/lar...en.html#table1
    When I compare it with Schneider Symmar-S 210/5.6, the later showed full coverage of 8X10 format(actual dimensions of my 8X10 images: 245mmX195mm & 313mm Diagonal) but much less tolerance to displacements(roughly 2.5cm only @ f/5.6). The IC of the Symmar-S is 294mm @ f/22(30mm wider than that of APO-Ronar).
    http://www.schneideroptics.com/info/...5,6-210mm.html
    Is it possible that IC of some kind of lenses(like the APO-Ronar) will not go much wider @ f/22 compared to the IC at maximum lens aperture ? compared to other kind of lenses(like the Symmar-S) ?
    While this can be appreciated ! Why the IC of my APO-Ronar is much much wider than the diagonal of my 8X10 format ???
    Did I forget any thing here ? Can any one describe what’s happening ?
    Appreciate every contribution.
    Thanks so much.

  2. #2

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    Re: Could the Image Circle of APO-Ronar 300mm/9, cover 8X10 format ?

    I have Rodenstock's published MTF curves for Apo Ronars, but not here at work where I can consult them.

    Short answer, there's a difference between coverage and illumination. For some of us "a lens covers x" means "at 1/2x off axis MTF is as low as can be tolerated." For others "a lens covers x" means "at 1/2 x off axis the image is bright enough to use."

    Schneider, Rodenstock, and Sinar are in the first group. You seem to be in the second. The difference between the two groups is irreconcilable.

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    Re: Could the Image Circle of APO-Ronar 300mm/9, cover 8X10 format ?

    No, at infinity at f22 it covers a 264mm circle which gives movements on 5x7 but not on 18x24cm or 8x10".
    The 360mm at f22 covered a 318mm circle which allowed for 4mm of rise and 3mm of shift on 8x10 at infinity. In short, the 300 at infinity doesn't come close to covering 8x10. At 1:1 it would.

    The rated image circle is the circle in which the lens performs as it was designed to. The actual circle may be larger but the added area is far below the manufacturer's accepted tolerances.

    The Apo Ronar is a narrow angle process lens with 48° coverage. General purpose lenses like the Apo Sironar S are 75° coverage lenses and will cover 8x10 with lots of movements at 300mm at f22.

    General purpose lenses are faster and perform optimally over a range of apertures. The Apo Ronar, up to 600mm, was designed to be used at f22 only for optimal performance. Since process lenses were designed for process cameras using lots of light focusing at f9 was no problem. In fact some process cameras used a meter to measure maximum contrast as you focused. When the meter indicated maximum contrast the lens was in focus. Nothing like the way you focus a view camera.

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    Re: Could the Image Circle of APO-Ronar 300mm/9, cover 8X10 format ?

    Thalmees, I looked up the 300 CL. Short answer, at 24 degrees off-axis, the 16 lp/mm MTF is 0% and the 8 lp/mm MTF is around 10%. This at, if I'm reading the document correctly, f/22 and 1:1. Sorry, weak German.

    FWIW, the MTF falls off rapidly starting at around 20 degrees off-axis. So if you're exacting you should treat y'r Apo Ronar as a lens that covers 40, not 48, degrees.

    Why don't you expose some 8x10 film and see how much you can enlarge the corners? Then you'll know whether the low MTFs (in the corners) that Rodenstock claims will hurt you.

    Cheers,

    Dan

  5. #5
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    Re: Could the Image Circle of APO-Ronar 300mm/9, cover 8X10 format ?

    Thanks too much Dan Fromm.
    Great details.
    Quote Originally Posted by Dan Fromm View Post
    I have Rodenstock's published MTF curves for Apo Ronars, but not here at work where I can consult them.
    Short answer, there's a difference between coverage and illumination. For some of us "a lens covers x" means "at 1/2x off axis MTF is as low as can be tolerated." For others "a lens covers x" means "at 1/2 x off axis the image is bright enough to use."
    Schneider, Rodenstock, and Sinar are in the first group. You seem to be in the second. The difference between the two groups is irreconcilable.
    It seems that I'm really there in the 2nd group. Your answers stimulated me to go back to an old Sinar book.
    There are two circles. The full IC of an image that projected by a lens on the rear standard and the usable IC which should be little smaller than the full IC. What’s mentioned in the technical data is the usable IC.
    Beyond the usable IC, the image quality and luminance are inferior to the practical standards.
    That’s what I have understood from the book. The book goes with what you have said, but lacking the very specific information that you kindly added.
    Quote Originally Posted by Dan Fromm View Post
    Thalmees, I looked up the 300 CL. Short answer, at 24 degrees off-axis, the 16 lp/mm MTF is 0% and the 8 lp/mm MTF is around 10%. This at, if I'm reading the document correctly, f/22 and 1:1. Sorry, weak German.
    FWIW, the MTF falls off rapidly starting at around 20 degrees off-axis. So if you're exacting you should treat y'r Apo Ronar as a lens that covers 40, not 48, degrees.
    Why don't you expose some 8x10 film and see how much you can enlarge the corners? Then you'll know whether the low MTFs (in the corners) that Rodenstock claims will hurt you.
    Cheers,
    Dan
    Thanks Dan.
    Once the theoretical resolution approaches 8LP/mm, I think its more cost effective to compare central Vs peripheral resolution visually with focusing loupe on the focusing screen.
    Very hard to find these information at once.
    Thanks so much Dan.

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    Re: Could the Image Circle of APO-Ronar 300mm/9, cover 8X10 format ?

    I used mine not often at 8x10 but used it with success at f 32-45!
    And yes I used one time even 2 cm of shift in it focusing at about 200m not so far away from infinity!
    And yes its covering easely, but the sharpness at the corners is not at best, but at the air on top of the pictures is it not so important!
    The front corners where on the shift one quite okay.

    Cheers Armin

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    Re: Could the Image Circle of APO-Ronar 300mm/9, cover 8X10 format ?

    Quote Originally Posted by Bob Salomon - HP Marketing View Post
    No, at infinity at f22 it covers a 264mm circle which gives movements on 5x7 but not on 18x24cm or 8x10".
    The 360mm at f22 covered a 318mm circle which allowed for 4mm of rise and 3mm of shift on 8x10 at infinity. In short, the 300 at infinity doesn't come close to covering 8x10. At 1:1 it would.
    The rated image circle is the circle in which the lens performs as it was designed to. The actual circle may be larger but the added area is far below the manufacturer's accepted tolerances.
    The Apo Ronar is a narrow angle process lens with 48° coverage. General purpose lenses like the Apo Sironar S are 75° coverage lenses and will cover 8x10 with lots of movements at 300mm at f22.
    Hi Bob,
    Thanks for your input. Yes, you are correct. Great validated details.
    I was wondering why the manufacturer IC(264mm) of Ronar lens is much(really much) smaller than the full IC ?. For the Symmar-S lens the full IC is just little wider than the manufacturer IC(As Expected).
    I’ll add the terminology of Sinar and my observations in another post later.
    Thanks Bob.
    Quote Originally Posted by Bob Salomon - HP Marketing View Post
    General purpose lenses are faster and perform optimally over a range of apertures. The Apo Ronar, up to 600mm, was designed to be used at f22 only for optimal performance. Since process lenses were designed for process cameras using lots of light focusing at f9 was no problem. In fact some process cameras used a meter to measure maximum contrast as you focused. When the meter indicated maximum contrast the lens was in focus. Nothing like the way you focus a view camera.
    Do you mean the designated(engraved) f/no or the effective f/no ? For example: The engraved f/22 is not effectively f/22 @ M= 1:1 compared @ infinity.
    Thanks too much again.

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    Re: Could the Image Circle of APO-Ronar 300mm/9, cover 8X10 format ?

    Quote Originally Posted by Thalmees View Post
    Hi Bob,


    Do you mean the designated(engraved) f/no or the effective f/no ? For example: The engraved f/22 is not effectively f/22 @ M= 1:1 compared @ infinity.
    Thanks too much again.

    I'm not bob, but I'll comment. A lens is "generally" engraved for aperture at infinity focus. Therefore any focus closer would result in less light than indicated f-stop. I doubt the Artars are engraved for effective aperture (f-stop) at 1:1. Most process lenses are used at farther distances than 1:1. So, even though the Artar is a process lens designed for close up work, it probably adheres to the f-stop engraving standards of all other lens...which is to say, f 22 @ infinity, is the "True" f22.

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    Re: Could the Image Circle of APO-Ronar 300mm/9, cover 8X10 format ?

    FWIW, I have a heap of process lenses that I use for landscapes, all mounted in front of a Copal 1 whose speeds are good. I use a LunaPro (= LunaSix III, not the modern one) for advice on setting shutter speed and aperture. I almost always get well-exposed color transparencies with each of my process lenses. From this I conclude that the marked apertures are correct at infinity and that the lenses all transmit light with minimal losses. Either that or my LunaPro (or shutter) is conveniently systematically off calibration.

    Cheers,

    Dan

  10. #10
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    Re: Could the Image Circle of APO-Ronar 300mm/9, cover 8X10 format ?

    Thanks again for every one here.
    As described in the attached image(copy righted), this is my understanding:
    ------------------------------------------------------------
    • Alpha; Full Image Circle = "The Total Angle Of Field".
    Size depends ONLY on lens configuration/Design. A given lens design usually has a constant angle of field, irrespective of the focal length.
    ------------------------------------------------------------
    • Delta; Usable Image Circle = "The Usable Angle Of Field", or what is usually implied by "Angle Of Field". Is Slightly smaller than "Total Angle Of Field". This is the angle listed in technical data sheets of camera lens manufacturers. Within this circle/angle, the image quality is(or should be) acceptable for practical requirements.
    Size depends among other factors, on:
    1- Image quality stipulated.
    2- Aperture size.
    ------------------------------------------------------------
    • Gamma; "The Image Angle". Is the Angle actually utilized by a given format within the Image Circle. This is the angle listed in manufacturers catalogs for miniature reflex camera lenses, and quoted as the “Angle Of View”.
    ------------------------------------------------------------
    For search purposes:
    Full Image Circle
    Total Angle Of Field
    Usable Image Circle
    Usable Angle Of Field
    Angle Of Field
    image quality
    Image Angle
    Angle Of View

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