corners getting soft on 8x10 format

Discussion in 'Large Format Cameras and Accessories' started by aj-images, May 26, 2006.

  1. aj-images

    aj-images Member

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    I just took my 8x10 out for the first time last weekend. B&J with an Imagon soft focus lens. Since I was shooting scenics and wanting max DOF, I didn't use the discs that are usually used with the lens. I stopped down all the way and shot. After developing the film, all four corners were soft. Will a front swing correct this or is there more to it, like not using the discs? Thanks for any help. - Jim
     
  2. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    What's the focal length of your Imagon? It may just not cover the format sharply even when stopped down all the way.

    The disks don't make the image soft per se. The lens is designed to have a fair amount of uncorrected spherical aberration wide open, so the light rays that enter at the edge of the lens focus at a different plane than the rays that enter the center the lens. If you stop down the lens with the normal iris, the image sharpens up, because you are only using the rays at the center, reducing the spherical aberration. The disks are designed to preserve much of the spherical aberration, while reducing the amount of light entering the lens, so you get a longer exposure than you would shooting wide open, but the image stays soft.

    In any case, I just wouldn't use an Imagon if the goal is to make a sharp image. That's just not what it's made for.
     
  3. Petzi

    Petzi Member

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    You should use at least a 420mm Imagon for 8x10".
     
  4. aj-images

    aj-images Member

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    David- It's a 300mm. It's from an Ansco 8x10 studio camera, so I assumed it would work.
     
  5. Petzi

    Petzi Member

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    The 300mm is good for 5x7" at most. They recommended 250mm for 4x5"...
     
  6. Petzi

    Petzi Member

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    The purpose of the lens is to make a sharp but soft image.
     
  7. aj-images

    aj-images Member

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    Thanks for the info Petzi....did some test strips from the center of the negs and they looked beautiful....sharp, but with a soft and smooth look. It's a shame it won't cover. Back to Ebay I guess.
     
  8. Jim Jones

    Jim Jones Subscriber

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    Maybe it did work when focused for head-and-shoulder portraits. Also, the soft corners wouldn't bother some portrait photographers.
     
  9. Petzi

    Petzi Member

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    That's right, but he said he was shooting scenics.