This is topic Out of focus images with new spectacles in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.
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Posted by James Robertson (Member # 888) on 01-14-2002, 05:53 PM:
A friend has just got a new pair of photochromatics with super duper new technology lenses from Germany. The lenses as well as being photochromatic have a Teflon coating and a prismatic arrangement to align the eyes properly.His problem is that when he watches a movie he gets an out of focus image. In all other respects the lenses are first rate. Even t.v. images are fine.
His optician tells him that he's imagining the problem and they're having "interesting" discussions about replacement.
Incidentally my friend's local cinema is the Ritz,Randwick one of the best cinemas in Sydney so the problem is not with the cinema presentation.
Anyone have any thoughts on this.
JIm
Posted by Gerard S. Cohen (Member # 994) on 01-14-2002, 06:25 PM:
The formula of the corrective lens needed varies with the distance
from the eye to the screen. My reading glasses are set for 14",
my computer glasses for 25", and for watching TV from about 10ft,
I have still another pair. (My bifocals aren't any help with viewing
these screens, since I'd get a stiff neck trying to look through
top or bottom; besides neither has the right correction for movies.)
Your friend might try sitting at different distances from the screen
to see if it appears in better focus. Also, he might try an outgrown
pair of his old glasses for the distance needed at the movies.
Since there's no such thing as "one pair fits all distances", the best
solution seems to be to measure his normal viewing distance from the movie screen, and have the optometrist make a pair of corrective lenses to give him sharp focus at that distance, not the 20ft distance of the old Snellen eyechart.
Posted by Jerry Chase (Member # 660) on 01-14-2002, 09:46 PM:
Gerard is in the same boat I'm in. I had to measure exactly how far I sit away from the computer screen to get a pair of glasses that I could comfortably use while programming. Fortunately my bifocals seem to work fine so far for tv and other distance viewing. Eventually they won't and I'll have more pairs of glasses.I wonder if Jim's friend isn't having problems with beginning cataracts that milk up images when there is high contrast and a low light level in the room. The contrast range of TVs is much less and room lighting is usually higher.
I wouldn't take the word of an optician, but would find a referral to a good optometrist. Most large cities have one or two that take all the hard cases no one else can properly figure out or fit.
Posted by Ray Derrick (Member # 1001) on 01-14-2002, 10:05 PM:
Also, maybe it has something to do with the reduced light level in a cinema and that the new fangled lens coatings may have some effect in reducing light transmission through the glasses.When the light level drops, the iris of the eye must open up to compensate and by the laws of optics, the depth of field is reduced. When your friend is outdoors or watching television or otherwise in a normally illuminated room, the light level is quite high. But in a cinema, the room is in darkness and the screen may not be all that bright (even at the superb Ritz). So maybe it's the reduction in his eye's depth of field that is causing this problem. (Of course, as I am not an optician, this should be taken purely as conjecture).
------------------
Ray Derrick
President/Chief Engineer
Panalogic Corporation Sydney, Australia
Phone: 61 (0)2 9894 6655 Fax: 61 (0)2 9894 6935
Posted by Bill Enos (Member # 440) on 01-14-2002, 10:06 PM:
I had a pair of those multi focal distance continuously variable specs a couple years ago. What they don't tell you is that these lenses don't work if you have a lot of astigmatism. If you do, these lenses make everything past a few feet appear to be on a deeply curved field. With a lot of discussion the shop replaced them with conventional bi-focals. They would not however refund the extra $80 the worthless (to me) lenses cost.
Posted by Ray Derrick (Member # 1001) on 01-15-2002, 09:48 PM:
Interesting question: Why would you need a Teflon coating on a pair of spectacles? Maybe if you're a really messy eater, or work as a chef in Japanese Teppan-yaki restaurant?? 
------------------
Ray Derrick
President/Chief Engineer
Panalogic Corporation Sydney, Australia
Phone: 61 (0)2 9894 6655 Fax: 61 (0)2 9894 6935
Posted by James Robertson (Member # 888) on 01-16-2002, 06:53 PM:
Thanks for info.I have passed it on and my friend is digesting same, and will discuss further with optician.
Jim
Posted by Will Kutler (Member # 770) on 01-16-2002, 07:35 PM:
From a person who was legally blind w/o Coke bottle bottom glasses and geek straps to hold them on--prior to Lasik, that is! 
Keep in mind that when you go to the optromotist for an exam, the machine is right up to your eyes. When you actually get your glasses, they are farther away from from your eyes than the machine, and will cause a noticable corrective difference--been there done that! But a good optromotist should be able to somewhat comp for this.
When lenses are made, the ideal focal point is through the center of the lense. Depending on frame style/design, this could affect the perifry vision around the outer portion of your lenses.
I have been a patient of some very reknown eye physicians, and yes, they were really able to do a great job of correcting my vision in the office, but once I got my glasses, it was never as good as the office visit.
Also, say you have a constant prescription, but opt to change lense styles, possibly affecting lense shape--your eyes will have to adjust to the new lenses--been there...done that!
Also, speak with your physician about exercises that can strengthen the eye muscles. Be sure to keep your eyes well lubed w/drops and good solid uv protection!