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Photo Forum / General Photo Topics / General Topics / September 2006Bad eyes, diopter? (and Vuescan)
I have diabetic neuropathy in my optic nerves, which is sugar crystals in there and that messes-up eyesight. But glasses do work fine to correct my vision. I seem to notice that my images (35 slides) look sharp under a loupe, then I scan them and they come up fuzzy! My older 6x7 positives are alright, but not my recent 35s, and I take time focusing. Maybe I am getting pixel bloom in scanning from overdone settings in Vuescan? Overworking the CCD? Settings too intense? Or maybe I am focusing the lens to the wrong length, using the lens as like my eye glasses, or in another term; focusing to the same prescription of my glasses, and therefore the images are a bit fuzzy? Is that exactly what diopters are for? If so I need a -1.25 for my Pentax K2 and I don't know where to find one. I would appreciate any positive advise, please. TIA,  Signature}<)))*> Giant_Alex cravdraa_at-yahoo_dot-com not my site: http://www.e-sword.net/ > I have diabetic neuropathy in my optic nerves, which is sugar crystals in there > and that messes-up eyesight. But glasses do work fine to correct my vision. [quoted text clipped - 20 lines] > cravdraa_at-yahoo_dot-com > not my site: http://www.e-sword.net/ I don't know where to get dioptors, but many cameras have diopter adjustments built into the viewfinder. You might want to check out something like that. see this article - http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=009hUG&tag= search for "diopter" THere are correction clip on lenses for the K series. regards, >>I have diabetic neuropathy in my optic nerves, which is sugar crystals in there >>and that messes-up eyesight. But glasses do work fine to correct my vision. [quoted text clipped - 24 lines] > adjustments built into the viewfinder. You might want to check out > something like that. > I have diabetic neuropathy in my optic nerves, which is sugar > crystals in there and that messes-up eyesight. But glasses do work > fine to correct my vision. I'm not an expert, but that seems odd. Glasses just correct for focus aberrations. > I seem to notice that my images (35 slides) look sharp under a > loupe, How much magnification? > then I scan them and they come up fuzzy! My older 6x7 positives are > alright, but not my recent 35s, and I take time focusing. Seems to indicate an issue with your 35s, maybe you use different ppi settings between 6x7cm and 35mm? > Maybe I am getting pixel bloom in scanning from overdone settings in > Vuescan? Overworking the CCD? Settings too intense? The histogram will reveal scanner blooming, because it is related to highlight clipping. > Or maybe I am focusing the lens to the wrong length, using the lens > as like my eye glasses, or in another term; focusing to the same > prescription of my glasses, and therefore the images are a bit > fuzzy? > Is that exactly what diopters are for? The camera diopters allow the eye to focus without glasses. > If so I need a -1.25 for my Pentax K2 and I don't know where to > find one. I would appreciate any positive advise, please. A camera shop? SignatureBart Bart sorry for being late here... >> I have diabetic neuropathy in my optic nerves, which is sugar >> crystals in there and that messes-up eyesight. But glasses do work >> fine to correct my vision. > > I'm not an expert, but that seems odd. Glasses just correct for focus > aberrations. Eye glasses? >> I seem to notice that my images (35 slides) look sharp under a >> loupe, > > How much magnification? 4x coated glass optic. >> then I scan them and they come up fuzzy! My older 6x7 positives are >> alright, but not my recent 35s, and I take time focusing. > > Seems to indicate an issue with your 35s, maybe you use different ppi > settings between 6x7cm and 35mm? Nope, whatever gives me a final 300 ppi in Vuescan, larger dimensions for the 6x7cm films. >> Maybe I am getting pixel bloom in scanning from overdone settings in >> Vuescan? Overworking the CCD? Settings too intense? > > The histogram will reveal scanner blooming, because it is related to > highlight clipping. Thanks for that, I don't quite know how to read a histogram, much less pick out the bloom from it. >> Or maybe I am focusing the lens to the wrong length, using the lens >> as like my eye glasses, or in another term; focusing to the same [quoted text clipped - 3 lines] > > The camera diopters allow the eye to focus without glasses. Makes sense! >> If so I need a -1.25 for my Pentax K2 and I don't know where to >> find one. I would appreciate any positive advise, please. > > A camera shop? Yep, the local cam shop can order me a genuine SMC one for $24, as I found out. But not to my exact perscription. I can get a -1.00, my eye is -1.25, will that matter? Signature}<)))*> Giant_Alex cravdraa_at-yahoo_dot-com not my site: http://www.e-sword.net/ > Yep, the local cam shop can order me a genuine SMC one for $24, as I > found out. But not to my exact perscription. I can get a -1.00, my eye > is -1.25, will that matter? Look for a variable diopter. I see them going to -2. Google "variable diopter". LD > Look for a variable diopter. I see them going to -2. Google "variable > diopter". > > LD Okay I searched, impossible for my camera. Go back to your woodworking. AAvK >> Look for a variable diopter. I see them going to -2. Google "variable >> diopter". [quoted text clipped - 3 lines] > Okay I searched, impossible for my camera. Go back to your > woodworking. AAvK Looking for a diopter for my biscuit joiner. <G> > Bart sorry for being late here... >> [quoted text clipped - 6 lines] > > Eye glasses? Yes. They correct for focal distance limitations caused by the shape of the eye ball or the inability of the eye lens to change shape enough. >>> I seem to notice that my images (35 slides) look sharp under a >>> loupe, >> >> How much magnification? > > 4x coated glass optic. You'll need something like an 8x magnification to judge critical sharpness of 35mm film. A 4x magnification is good for a full image view, but not good enough to check for defocus and such. SNIP >> The histogram will reveal scanner blooming, because it is related >> to highlight clipping. > > Thanks for that, I don't quite know how to read a histogram, much > less pick out the bloom from it. If there is an abundance of signal counts in the highest bin, there is an increased chance of charge spilling over to adjacent sensels, thus causing blooming. >I can get a -1.00, my eye is -1.25, will that matter? Well, it won't be perfect. Wearing glasses is a bit of a compromise, it can correct for most focal deficiencies, but it will be physically in the way when trying to look through the viewfinder. SignatureBart > "AAvK" <Idondodat@wahoo.com> wrote in message SNIP >>> The histogram will reveal scanner blooming, because it is related to [quoted text clipped - 6 lines] > an increased chance of charge spilling over to adjacent sensels, thus > causing blooming. That's much clearer now ;-) >>> If so I need a -1.25 for my Pentax K2 and I don't know where to >>> find one. I would appreciate any positive advise, please. [quoted text clipped - 4 lines] > found out. But not to my exact perscription. I can get a -1.00, my eye > is -1.25, will that matter? FYI, if your eyeglasses have anything beyond basic adjustment, the diopter may not help. E.g., it won't correct for astigmatism (which has a specific axis). The difference between -1.00 and -1.25 would keep you from seeing sharp vs. tack-sharp focus. Depending on how much you want to sink into this project, you could find an eyepiece adapter and have a prescription lens ground to shape and inserted. But if you have astigmatism or other axis-specific correction, you won't be able to rotate the camera from landscape to portrait and still see through it. :-) (An easy test for this is to rotate your eyeglasses 90 degrees and look through them.) Cheers, Richard > Depending on how much you want to sink into this project, you could find > an eyepiece adapter and have a prescription lens ground to shape and > inserted. But if you have astigmatism or other axis-specific > correction, you won't be able to rotate the camera from landscape to > portrait and still see through it. :-) (An easy test for this is to > rotate your eyeglasses 90 degrees and look through them.) Oh dear... Why does the world not do that when I take mine off and rotate my head? Signaturehttp://www.petezilla.co.uk Some Pentax cameras, came with a -1.00 (ME Super) and -0.50 (MX) diopter lens in the viewfinder. You may want to check the K2 specifications in your user manual before you order. Jim >snip< >>> If so I need a -1.25 for my Pentax K2 and I don't know where to >>> find one. I would appreciate any positive advise, please. [quoted text clipped - 4 lines] > found out. But not to my exact perscription. I can get a -1.00, my eye > is -1.25, will that matter? > I have diabetic neuropathy in my optic nerves, which is sugar crystals in there > and that messes-up eyesight. But glasses do work fine to correct my vision. > > I seem to notice that my images (35 slides) look sharp under a loupe, then I > scan them and they come up fuzzy! My older 6x7 positives are alright, but not > my recent 35s, and I take time focusing. When you say "recent" do you mean that at some time in the past you were getting acceptable results and now you're not? If this is the case then possibly there's a problem with the scanner or a software setting. You might try changing the unsharp mask setting. <snip> > Or maybe I am focusing the lens to the wrong length, using the lens as like my > eye glasses, or in another term; focusing to the same prescription of my [quoted text clipped - 3 lines] > If so I need a -1.25 for my Pentax K2 and I don't know where to find one. > I would appreciate any positive advise, please. There are viewfinders that offer continously variable diopter settings in the range you need but they don't fit your camera. Here's one for the Pentax LX: http://www.bhphotovideo.com/bnh/controller/home?O=productlist&A=details&Q=&sku=4 1085&is=USA&addedTroughType=search I don't know if you can use contacts but if so that might be a useful aid to focussing. I don't think focussing is the problem with your scans not unless you only shoot wide open and never stop down your lens. DOF latitude provided by stopping down should compensate for minor errors in focus. Good Luck, photog > TIA, |
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