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Thread: loupe for GG and loupe for viewing 4x5 transparencies?

  1. #1
    David J. Heinrich
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    Oct 2008
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    loupe for GG and loupe for viewing 4x5 transparencies?

    Loupe for GG?

    I have a large Promaster 3.5x loupe; it was actually designed for 35mm slides, and can cover them completely; I use that for my 4x5 loupe right now when focusing on GG. It is nice in the sense that it has no distortion when looking straight-on and can look at a lot of GG. However, I can't view corners with it, and I'd like more magnification.

    I have very finely ground GG, hand ground by Steven A. Hopf (Ultra Fine). He sells on eBay.

    Given that, what would be the largest magnification for loupes I could reasonably use?

    Loupe for viewing transparencies?

    For viewing transparencies and negatives, I figure that my sharpest lens can deliver 100 lines/mm to Pan 25 B&W film. Assuming that I want to look at the film at 5 lines/mm (the lowest resolution I'd consider printing at, according to studies of what human eyes can discern), that means I'd need a 20x loupe. Any suggestions for a good one?

    Basically, I want to use this loupe to (a) enjoy my transparencies / negatives; (b) Figure out how sharp they are, thus how much resolution to scan them in at. (would it then make sense to get an intermediate loupe between 5x and 20x, say 10x)?

    Any suggestions on loupes for this purpose?

    Worth considering this loupe for examining transparencies? 40x multifunction macro scope from eBay

  2. #2

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    Re: loupe for GG and loupe for viewing 4x5 transparencies?

    I can't help with the transparency part of your question, I almost never use slide film. But for gg use the largest magnification you can reasonably use is a matter of personal preference. I've used 3.5x, 4x and 8x. I didn't like 8x but that was with a Fresnel viewing screen and 8x magnified the Fresnel lines too much, which actually made it harder to focus than a smaller magnification. With your plain ground glass 8x might be fine. I've heard of using a 10x loupe but that's about the biggest I've ever heard of anyone using for gg viewing though I'm sure somebody somewhere has used something larger. I think 8x is about the largest commonly used mag factor for gg viewing.

    For gg viewing you don't need an expensive loupe. You're only using it as a magnifier so the loupe doesn't need to be color corrected or have any of the other optical qualities that add to the expense of a loupe used to view slides on a light table. So you can buy a couple at different mag factors and see which you like without breaking your bank account.

    I assume you can't view the corners because your loupe has a round base. I never liked that kind of loupe for the same reason. I prefer the Peak loupes that have a square base which allow you to go right up into the corners. Of course if your ground glass is cut out at the corners you won't be able to view the corners with a loupe no matter what you use.
    Brian Ellis
    Before you criticize someone, walk a mile in their shoes. That way when you do criticize them you'll be
    a mile away and you'll have their shoes.

  3. #3

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    Re: loupe for GG and loupe for viewing 4x5 transparencies?

    Just turn the loupe around for the corners. A bit more work to hold it at the right distance, but you can also use it at an angle to get a brighter image.

  4. #4

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    Re: loupe for GG and loupe for viewing 4x5 transparencies?

    I use the Silvestri 6x Tilting Loupe and quite like it; especially good for corners.

    Edit: That is for GG, of course, For trannies, I use a large-ish round Pentax, but I think and good loupe will do there.

  5. #5
    Glenn Mellen
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    Re: loupe for GG and loupe for viewing 4x5 transparencies?

    I too use a Silvertri 6x Tilting loupe for ground glass... it's the best one I've used, allowing one to get right into the corners easily.

    For viewing transparencies on a light table, I have a Mamiya 3x (6x7 size), but works very well for 4"x5". Also a very clear and fine loupe.

  6. #6
    David J. Heinrich
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    Re: loupe for GG and loupe for viewing 4x5 transparencies?

    Quote Originally Posted by Larry Gebhardt View Post
    Just turn the loupe around for the corners. A bit more work to hold it at the right distance, but you can also use it at an angle to get a brighter image.
    Thanks for the suggestion. A good idea, although I fear I didn't properly convey the enormous size of my "loupe". The part that I put my eye agains (including the metal edges) is 2.25" in diameter. The base of it that goes against the GG is 3.25" in diameter. So that would help a little for this sized loupe, but not totally eliminate the problem.

  7. #7
    David J. Heinrich
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    Re: loupe for GG and loupe for viewing 4x5 transparencies?

    Another idea is that James Phillips has suggested that with a cheap old 35mm-format lens, you can make a loupe better than professional loupes sold to you. He uses a Minolta lens to make his loupe, and I'm particularly fond of Minolta lenses for the 35mm-format. I use a 58/1.2 and 50/1.4 Minolta on my Oly E3, and they produce sharp images even on the 4/3rds sensor.

    Brian,

    Thanks, maybe I will try getting the 5x, 7x, 9x, 20x Bausch & Lomb Eye Glass Loupes, so I can try a variety of different magnifications.

    The Belomo brand seems to be even better than Bausch & Lomb from what I've read, and cheaper too.

    Paul, Glen,

    Thanks for suggesting the Silvestri. I'd heard good things about it before, and will consider it highly if I end up thinking that 5x-7x is the magnification I want to work with with that Bausch & Lomb multi-loupe.

  8. #8

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    Re: loupe for GG and loupe for viewing 4x5 transparencies?

    I too have Hopf ground glass on my 4x5 cameras as I abhor Fresnel rings and grid marks. I use only an 8x Rodenstock, having discarded a 3.5 Toyo and relegated my 4x Rodenstock to the light table.
    Duncan Dwelle

  9. #9
    David J. Heinrich
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    Re: loupe for GG and loupe for viewing 4x5 transparencies?

    Quote Originally Posted by DuncanD View Post
    I too have Hopf ground glass on my 4x5 cameras as I abhor Fresnel rings and grid marks.
    It's a great GG, I think I heard about it here. I got it because I wanted brightness but also resolution, and I'd read that Fresnels basically sacrificed resolution for brightness, aside from being very expensive. My only wish is that he'd drill holes in it, so you can put thin wire on the GG side and use that for aerial-image focusing with a loupe (then you can focus with max brightness & resolution).

    Or maybe I can get a fine circular grinder and eliminate the "ground" part at a few spots to make the glass clear there, then put a thin wire there. I know that if you put water on the ground side, it becomes see-through. Better ask Steve Hopf first before grinding.

    Quote Originally Posted by DuncanD View Post
    I use only an 8x Rodenstock, having discarded a 3.5 Toyo and relegated my 4x Rodenstock to the light table.
    Just a quick Q, why do you only use the 8x Rodenstock for focusing on GG, but use a lower-power one for looking at on a light-table. I'd think you'd want to criticall examine print-sharpness on the light-table.

  10. #10

    Re: loupe for GG and loupe for viewing 4x5 transparencies?

    Here's my amateur take on loupes...

    I use a Horseman 7x for my GG with fresnel, and yes, at times the high magnification ups the fresnel rings a bit much. I'm still experimenting with different powers (when I have time which is very little these days). Even though the Horseman loupe is outstandingly clear and crisp, I experience the same problem with ultra wide lenses and dark corners. The tilting tip helps.

    As for viewing and examining trans on a lightbox for publishing and production, my previous experience helping Art Directors was that (personally) one doesn't want a very high magnification, but the best clarity one could get. I used to use a jeweller's loupe (15x or 20 IIRC, as well as my standard 'go to' 10x) and struggled with it happily till one day I peeked through a 4x Rodenstock loupe and let's just say, I SAW the light!

    The contrast and clarity that the 4x Rodenstock offered was astounding, and actually revealed a lot more information from the trans than the various high magnification loupes I was using at the time. I understand that the Schneider loupes are also among the very best around, but I'm not sure I am comfortable with the current ones made of plastic (or at least that was what I was told, or was that Carl Zeiss loupes?).

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