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03-01-2009, 06:59 PM   #31
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QuoteOriginally posted by m8o Quote
Can you or someone explain how this is different than the Magnifying viewfinder? I'm an eyeglass wearer and while the 1.2x helps, manual focus without glasses is very challenging in in-door lighting until I am using ~125mm or more. What does the -3, -2 do differently than a magnifying viewfinder?

thanx
The -3 and +2 refer to actual lens correction factors similar to what your optometrist prescribes for your optician when you get new eyeglasses made. A small frame holding the correction glass fits over the bare frame of the viewfinder - and when you look through the VF it is as if your glasses (for that one eye) are on the camera rather than on your face. The difference is stunning to me.

The Magnifying eyecup simply makes the view 25% larger - but uncorrected is uncorrected, larger or not.

03-01-2009, 07:14 PM   #32
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Ah, thanx very much. I guess in that case folks without my poor vision can't pick-up the camera and use it once the diopter is on. That then begs the question how do I know the correct value for my eyes, but that's for me to research.
03-01-2009, 07:30 PM   #33
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QuoteOriginally posted by m8o Quote
Ah, thanx very much. I guess in that case folks without my poor vision can't pick-up the camera and use it once the diopter is on. That then begs the question how do I know the correct value for my eyes, but that's for me to research.
It is the same as your glasses prescription.

You are correct - other people could not use your camera with a correction lens (diopter) attached any more than they could see with your glasses on.
03-02-2009, 03:10 PM   #34
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KPS Design Model U-13C

I just received the KPS U-13C magnifier and I am impressed with its quality. It came with two different eye cups of soft rubber with integral metal threaded rings for securing to the magnifier. In fact, wherever there is a threaded fastener it is done in metal. It inlcuded two extra screws and a nifty little screwdriver.


I believe it was pointed out in an earlier thread that the U-13C does not "snap" on and off. It is held tightly in place by two screws, so taking in on and off is not as simple as the Pentax version.

Mounted on my K10D I am able to see all the viewfinder information when not wearing eye glasses.

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03-02-2009, 03:34 PM   #35
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Do you need to drill the Pentax body to attach the eyepiece?
03-02-2009, 05:52 PM   #36
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it looks like you slide a thin piece in where the regular eyepiece goes, then screw the magnifier into that
03-02-2009, 11:35 PM   #37
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QuoteOriginally posted by monochrome Quote
Do you need to drill the Pentax body to attach the eyepiece?
There is no drilling or modification to the camera body. The KPS mounts on the same notched flange that the original eyepiece mounts to. The shiny metal piece in this pic is attached to the back of the magnifier with two screws and slides into the notch in the eyepiece flange of the body. The two screws are then tightened to keep the magnifier secure.

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03-03-2009, 04:21 PM   #38
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That's pretty likeable. I am fond of the round type of eyecup like that. If it manages to not obscure any finder info, then, woohoo.
03-03-2009, 07:24 PM   #39
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QuoteOriginally posted by monochrome Quote
It is the same as your glasses prescription.
Hmmm, that I didn't expect (or immediately understand). I know eyeglass prescription to be 20/x based but don't see how it relates to the -m -> +n range of these diopters. But I'll search.
03-03-2009, 09:14 PM   #40
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QuoteOriginally posted by m8o Quote
Hmmm, that I didn't expect (or immediately understand). I know eyeglass prescription to be 20/x based but don't see how it relates to the -m -> +n range of these diopters. But I'll search.
Well, for what it's worth, my contact lens prescription is
-4.5 (left eye) / -3.5 (right eye).
03-03-2009, 09:54 PM   #41
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QuoteOriginally posted by m8o Quote
Hmmm, that I didn't expect (or immediately understand). I know eyeglass prescription to be 20/x based but don't see how it relates to the -m -> +n range of these diopters. But I'll search.
As I understand it, the 20 / n reflects your visual acuity relative to the standard 20/20 vision pattern (you see at 20 feet what the standard sees at n feet). My right eye is 20/50, left eye is 20/30, binocular is 20/30 with my left eye now dominant (the brain is simply amazing the way it adapts to change).

The correction prescription for eyeglass grinding (diopter) is expressed differently as + x or - x in .25 step increments. Since the stock Pentax diopters seem to be in full steps (-5, +3, etc. - see the pdf of the 1984 Lens and Accessories catalog Page 80 linked in Post#1 here Post), a ground glass insert can be more accurate for your vision. It just so happens that my diopter correction prescription for the left eye is +2.

I have a +3 SMC Pentax M-frame diopter that I can sell you if that would work.

Last edited by monochrome; 03-15-2009 at 08:41 PM.
03-03-2009, 11:33 PM   #42
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QuoteQuote:
mattdm: Well, as I said, it's a matter of eyepoint. I don't loose any of the screen, but a) I don't shoot wearing glasses and b) I learned to center my eye more carefully on the eyepiece.
Hey Matt--thanks for trying to help, but my question was for "soccerjoe" and the 1.35 eyepiece. As stated in my post, I already have the Pentax 1.2 and am not happy with that--but am interested in learning more about the 1.35.
03-04-2009, 01:37 PM   #43
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Right, though, Jewel. The magnification is different from a diopter correction, but conceivably, one could add an old, say, +3 diopter onto the built in one, with a range of -3 to +3 and dispense with the need to shoot through thick glasses (say they were +5 by prescription, you could set the built-in to +2ish) altogether. I think they may stack that way, but I'm not sure. (I have certain optometry confusions, as half the reason I was mostly out of photography for some years was that I had labored under the wrong darn eyeglass prescription for my actual problem, so I 'learned' a few things backwards from a bad source. (that didn't make sense, actually) Think I have it clear now. )
03-15-2009, 08:27 PM   #44
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QuoteQuote:
Ratmagiclady
Right, though, Jewel. The magnification is different from a diopter correction, but conceivably, one could add an old, say, +3 diopter onto the built in one, with a range of -3 to +3 and dispense with the need to shoot through thick glasses (say they were +5 by prescription, you could set the built-in to +2ish) altogether. I think they may stack that way, but I'm not sure. (I have certain optometry confusions, as half the reason I was mostly out of photography for some years was that I had labored under the wrong darn eyeglass prescription for my actual problem, so I 'learned' a few things backwards from a bad source. (that didn't make sense, actually) Think I have it clear now. )

I think I am missing something. I do not wear glasses. I am not impressed with the Pentax eyepiece. I saw soccerjoe's mention of a different eyepiece--the 1.35 by a different maker. I was seeking his feelings on this item. That is all.
03-16-2009, 08:03 AM   #45
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QuoteOriginally posted by monochrome Quote
As I understand it, the 20 / n reflects your visual acuity relative to the standard 20/20 vision pattern (you see at 20 feet what the standard sees at n feet). My right eye is 20/50, left eye is 20/30, binocular is 20/30 with my left eye now dominant (the brain is simply amazing the way it adapts to change).

The correction prescription for eyeglass grinding (diopter) is expressed differently as + x or - x in .25 step increments. Since the stock Pentax diopters seem to be in full steps (-5, +3, etc....
Thanx very much for succinctly wrapping it up. I haven't been happy with my eyeglass prescription lately, so I'll have to get my eyes checked and make note of the prescription this time. You'd think in the 30 years of wearing glasses I would have noted that prescriptions are written in the form cited. I guess I didn't pay attention because it was just a couple of numbers I didn't have any frame of reference to. I will only know after that time if I can use a +3.
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