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  1. #11

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  2. #12

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    Marco, no there isn't, unless the grain focuser projects the image onto a piece of ground glass. Even then you still have to adjust the eyepiece so you see a clear image.

    As you get older, the eye loses it's ability to switch focus points quickly, then you will find the grain focuser becoming more accurate. or depending on your point of view. Years ago, Zeiss made a special focusing telescope so their (mostly younger) technicians could accurately align microscope camera focusing units that used an aerial image in the same way a grain focuser does.
    Bob

  3. #13

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    Sal: page 76 seems mostly to do with using blue filtration, which I'm not doing. I understand the difference between ground glass and an aerial image focuser. I'm not seeing too much else that helps me.

    I just don't understand how four instruments designed to tell me one things provided four different answers. It would be like having four calculators, giving them the equation 2+2, and coming up with the answers 3.75, 3.9, 4.1 and 4.3. You wouldn't say "well, that's close to 4. Good enough."

    I'm not particuarly young, but I was really surprised by how much sharper the prints focused by eyesight were compared to the grain focuser.

    While it's much easier to focus with a grain focuser (everything snaps right into place, doens't it?) it's of no use if it is not accurate.

  4. #14

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    You could also consider switching to swirly, blurry photography with lots of "bokeh" (not found in my dictionary). Then the unsharpness won't make any difference, and you can sell all your grain focusers and use the money to buy film.

  5. #15
    Bill Burk's Avatar
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    Sounds to me like you should focus by eye... Make print and develop to confirm it's still best... then without changing the focus, put the grain focusers down to see which ones confirm the focus... If the direction of error is "up" you could put something significantly thick under the focuser to correct the error. (But if the direction is "down", you're stuck there).

  6. #16
    ic-racer's Avatar
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    Quote Originally Posted by Bill Burk View Post
    Sounds to me like you should focus by eye... Make print and develop to confirm it's still best... then without changing the focus, put the grain focusers down to see which ones confirm the focus... If the direction of error is "up" you could put something significantly thick under the focuser to correct the error. (But if the direction is "down", you're stuck there).
    If they really are off they will need to be lifted or sunken a few millimeters if not centimeters to see any difference.

    I'd suggest just adjusting the eyepiece on all of them. I suspect the issue in the OP is in correctly viewing the aerial image.

  7. #17

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    Again Marco, a grain focuser that isn't set to one of your eyes specific vision, with or without corrective lenses is worse than useless, as you have already demonstrated.

    Assuming the mirrors haven't been replaced, knocked out of position, the crosshair is in the factory aligned position, the frame isn't otherwise bent, spindled or mutilated, the optical adjustment to the user's eye is just plain off unless the user has uncorrected astigmatism when using the grain focuser
    Bob

  8. #18

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    Very frustrating and I can't explain why you have experienced what you have and if it's any consolation to you it would seem that none of us, me included, can give an explanation that resolves the issue. Bob-D659 has really covered all the likely issues but if none of these apply then I am stumped.

    I have two Paterson grain focusers. The micro and the major which is much taller for large prints. It avoids bending down over the print while trying to adjust the focus. There is a very marginal difference between the two so minor differences may not be unusual but not ones that show up on a print that I can see although I should add that my biggest print is 8x10

    However as your best print is the eyeballed one then it may be that your best bet is is to obtain a Kaiser focuser or the Nova Darkroom one called I think a Hocus-Focus or some such comical name. Others here who have got one may know the correct term.

    Both work on the principle of simply magnifying the projected print instead of focussing on the grain. I have the Kaiser as well and I find that it does as good a job as the Paterson if you find a line that demarcates light from dark such as a window frame. Both will also do their jobs into the corners of the projected image

    Before selling all your grain focusers however just make sure there isn't an explanation and solution that you have overlooked. It'd be a pity to sell all your grain focusers only to find that there was a solution.

    Best of luck and I hope someone can suggest an answer


    pentaxuser

  9. #19
    AgX
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    Quote Originally Posted by Bob-D659 View Post
    ..., the optical adjustment to the user's eye is just plain off unless the user has uncorrected astigmatism when using the grain focuser

    Could you explain more? Seems interesting.

  10. #20
    Greg Davis's Avatar
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    Quote Originally Posted by AgX View Post
    Could you explain more? Seems interesting.
    Astigmatism is when the eye is shaped less like a round ball, and more like an ellipse. Or rather, less like a European football and more like an American football. A lot of people have astigmatism and unless the eyeglasses correct for it, it can cause blurred vision at all distances instead of just near of far.
    www.gregorytdavis.com

    Did millions of people suddenly disappear? This may have an answer.

    "No one knows that day or hour, not even the angels in heaven, nor the Son, but only the Father." -Matthew 24:36

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