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  1. #1
    paulie's Avatar
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    Home made hobo 10x8 camera + componon

    here is a link to a shot i made today on my hobo camera, i seem to have a hotspot under the light in the picture

    the light was on in the daytime so i was hoping to get your opinions on what this hotspot might be

    is it a lens issue or perhaps flare

    the lens is a componon 210mm f5.6 in a compur shutter.

    Click image for larger version. 

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    Last edited by paulie; 12-15-2009 at 06:05 PM. Click to view previous post history.

  2. #2
    Ian Grant's Avatar
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    and the link is ?

    Ian

  3. #3
    paulie's Avatar
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    here it is

  4. #4
    Ian Grant's Avatar
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    looks like flare from an uncoated lens, you certainly don't need a centre filter

    My Componon 210 won't quite cover 10x8 on my enlarger so would be worse at Infinity, so you must be lucky.

    Ian

  5. #5
    ic-racer's Avatar
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    Light leak? though a little unnusual for it to hit right in the center like that. How is the lens attached? Do you have a ground glass back? If it is flare you can see it on the ground glass.

    If it is flare, you can also consider a modern multicoated Symmar-S 210. They are way-cheap and would have a similar coverage suited to that type of camera.

  6. #6
    paulie's Avatar
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    yeah i was most surprised when it actually covered 10x8 at infinity, i will post a picture of my camera at some point for you to look at.

    no ground glass just exterior site lines, calumet lens board was used with compur and elements screwed directly to shutter

    the lens board is press fit in a rebated opening in the camera and then black tape sealed, the camera has been light tested with paper for 4 hours with no noticable fogging

    flare could be a factor , i had a u.v filter on the lens with no hood , naughty me, but it was a shady shot

  7. #7
    paulie's Avatar
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    Click image for larger version. 

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    Click image for larger version. 

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    Click image for larger version. 

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    the box is a kinda fair weather tripod, going to be used for ALT process

  8. #8
    Greg Davis's Avatar
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    I had this problem with a 12 inch Dagor lens. I never solved it, but it would overexpose the center of the image. It may have been flare, but it happened a lot on overcast days or with close focussed items. It didn't seem consistent.
    www.gregorytdavis.com

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  9. #9
    vdoak's Avatar
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    Does a blade on the shutter hang open? On one of mine the lubicant turned to thick paste that stopped the shutter form closing completly and in sync. One blade "hung open" a slpit second longer than the others. This left an over exposed area dead center when it happened but it did not happen all the time.

  10. #10
    Marco B's Avatar
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    Quote Originally Posted by vdoak View Post
    Does a blade on the shutter hang open? On one of mine the lubicant turned to thick paste that stopped the shutter form closing completly and in sync. One blade "hung open" a slpit second longer than the others. This left an over exposed area dead center when it happened but it did not happen all the time.
    Funny, I have never experienced this, but I was starting to think along the same lines, because looking at the image, is flare likely? It seems to have been an overcast day in Amsterdam when this picture was taken. There are hardly any shadows.
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