Asselblad loupe (6X)

Discussion in 'Medium Format' started by diegobuono, Feb 13, 2012.

  1. Hi Everyone,
    I would like to buy a used Hasselblad loupe to use it as a loupe for viewing the slide on the lightable; I think that 6X is a good magnification (and for more magnification I can use a mor powerful loupe) if you consider that you have the whole picture view (does it let you see all the picture I suppose). And they are quite cheap compared to new professional loupe.
    The questions are:
    1) does it have a good image quality?
    2) Due to the fact that is designed to sit in a Hasselblad body, in wich the focusing screen is recessed compared to where the loupe rest, I need to build something with the proper thikness to stick to the base plate of the loupe. Do you know the exact thikness I need?
    I hope you can help me, above all with the second (more technical) question.
    Thank you.
    Diego
     
  2. Loupe! Do you mean a waist-level finder?
    The WLF has a simple lens, which necessarily suffers from chromatic aberation, curvature of field and linear distortion. You might get better service, though less magnification, from a chimney finder, which has a compound lens which can be focused.
    For the same cost, you could get a loupe designed to examine slides and negatives. The better ones (e.g., Schneider or Mamiya) are highly corrected for chromatic aberation and distortion, easily focused, and have interchangeable skirts for slides (opaque) and prints (translucent). Unlike the Hasselblad finders, there are no metal parts to scratch the film. 4x is a good power for editing 35 mm, and 2.5x for medium format.
    For magnification greater than 6x (e.g., 7x - 20x), get a Hastings Triplet magnifier. The image quality is superb, but you will only be able to examine a small part of the film. Hold the magnifier against your eye, not at arm's length like Sherlock Holmes. Nothing looks sharp at 10x, but you can see the grain clearly. The working distance is inversely proportional to the magnification. At 10x it is about 1", 1/2" at 20x.
     
  3. No matter what the advertisement text says, that finder does definitely not produce a 6x magnification, Diego.<br>Only 2.5x - less than the folding focussing hood.
     
  4. The highest magnification among the various Hasselblad finders is 4x, found on one of the 90° finders.
    - Leigh
     
  5. The Russian-made Horizon 4X MF loupe is quite good and fairly inexpensive. I don't think they're made any more, but , with some patience, you could probably find a used one.
     
  6. "The highest magnification among the various Hasselblad finders is 4x, found on one of the 90° finders."

    Not so, Leigh.
    The highest magnification - 4.5x - is provided by the loupe in the 'collapsing' style folding focussing hood.
    A thing many Hasselblad users already have. I suspect you have (at least) one of those too, Diego.
     
  7. OK. I was quoting from Nordin by memory and mis-spoke myself. I should have said:
    "At 4x it's the highest manification available in any prism finder." (ref: Nordin 2nd p183)
    Interestingly, he says absolutely nothing about the magnifier in the folding hood. (p179)
    I expect there's some information in Wildi, but I didn't bother to check.
    - Leigh
     
  8. I wish I knew how to calculate the magnification. I swear I get better magnification with my chimney finder than I do with my WLF.
     
  9. Depends on what folding hood you compare it to, Michael.
     
  10. Ok, thank very much. I will continue to use my spare (old style) collapsible focusing hood.
    My second question still remain though, someone do knows the answer?
    Ciao.
    Diego
     
  11. For a simple lens, or compound lens which acts like a single element, magnification is approximately equal to 10 inches divided by the distance from the lens to the subject. Telescopes, which magnify virtual images internally, have much higher magnification than this simple formula would suggest. Inspection microscopes, which have a long working distance and wide field, are actually close-focusing telescopes.
     
  12. The old style only offers 2.5x magnification, Diego
     
  13. I have a Pentax 5.5X and a Rodenstock 3X and both are just fine. The Pentax has an extra skirt which you can buy to convert it from reflective (clear sides) to transmission (black skirt) use. The Rodenstock has a reversible skirt that accomplishes the same thing.
    The last time I looked Gil Ghitelman has some Rodenstocks that were NIB, old stock for a very reasonable price. The last link that I have is http://www.gilghitelman.com/lenses.html .
     
  14. Remember, Diego, that though a good loupe may make viewing the slides a bit more pleasant than viewing them through a really bad one, the loupe only has to be good enough to allow you to judge what's on the slide well enough.<br>Other than the quality of a taking lens, you do not get to see the quality of the loupe in whatever you do with the image. ;-)<br>So no need, i'd say, to spend megabucks on the indeed expensive ones that are available, when, i'm sure, you can find many cheaper ones that do the job just as well.<br>(I use an inexpensive Russian 10x hand loupe myself. Bought it whenthe iron curtain came down and Polish traders started bringing lots of cheap Russian stuff to fairs and markets in the west.<br>It's too small to view an entire image at once, but good enough to focus in on the bits i'm interested in, both for negs and transparencies and prints.)
     
  15. I wish I knew how to calculate the magnification. I swear I get better magnification with my chimney finder than I do with my WLF.​
    Magnification is a bit arbitrary, since it depends on what you compare it to. The usual method is to compare it to what the eye sees at the distance of ten inches. The magnification is then computed as 10 inches divided by the focal length of the lens in inches. Inches over inches cancels out, resulting in a dimensionless ratio that is the magnification. Example: a lens of two inch focal length has a magnification of 5, as follows: 10"/2" = 5.
    Here's another one: a lens of 4" focal length: 10"/4" = 2.5.
    So. the shorter the focal length, the higher is the magnification.
    Will it work in millimeters? Yup. Just use 254mm in place of 10 inches. Let's try a 35mm lens: 254mm/35mm=7.26. So your 35mm lens can be used as a 7 power magnifier? Yup. And a well-corrected one, too! What if we want a 5-power magnifier? Figure it this way: 254mm/5=50.8mm. So we can use a normal 50mm lens as a 5-power magnifier. And if we need a 10-power, we can use a 25mm lens.
    So if you have lenses in these focal lengths, and don't want to buy anything, you don't really have to.
     

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