SolaresLarrave
My M5s need red dots!
By chance, luck or whatever, I came into possession of a +1 diopter for a Leica M camera. What does a diopter do? Just "fine tune" my eyesight? It doesn't enlarge anything, so I'm wondering what it is for.
Thanks!
Thanks!
clintock
Galleryless Gearhead
If your eyeglasses prescription is +1, you can now take your glasses on and off each time you look through the viewfinder.
SolaresLarrave
My M5s need red dots!
I'm afraid I'd need a lot of diopters, then... My prescription is not +1, but it's not +20 either...
bob cole
Well-known
What does a diopter do
What does a diopter do
The diopter is a special-order item so that if you need a little help to use the viewfinder, you can order the one you need...As Jim Lager explains in his Accessories [vol. III] to his Illustrated History, some Leicas now come with a diopter already installed...
Sorry about the poor quality of my thumbnails...My computer broke down a few weeks ago, erased all my [free] photo software and I am having lots of difficulty rebuilding it -- even after paying a computer tech plenty of money to fix most of the other stuff...
What I badly need is a way to improve contrast...
What does a diopter do
The diopter is a special-order item so that if you need a little help to use the viewfinder, you can order the one you need...As Jim Lager explains in his Accessories [vol. III] to his Illustrated History, some Leicas now come with a diopter already installed...
Sorry about the poor quality of my thumbnails...My computer broke down a few weeks ago, erased all my [free] photo software and I am having lots of difficulty rebuilding it -- even after paying a computer tech plenty of money to fix most of the other stuff...
What I badly need is a way to improve contrast...
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SolaresLarrave
My M5s need red dots!
Thanks a lot, Bob! I guess I'll be returning my +1 diopter... unless anyone here may be interested on it.
Have a nice day!
Have a nice day!
mike goldberg
The Peaceful Pacific
Can you attach photo of the diopter and explain how it works on an M camera?
Thanks, mike
Thanks, mike
Shac
Well-known
This is a useful explanation of diopters on M cameras http://nemeng.com/leica/038b.shtml
David
David
bob cole
Well-known
Pherdinand
the snow must go on
Normally the lens etc in your eye is able to focus the image on the retina precisely and comfortably. If you wear glasses, that is (for most cases) because the above is not true. Simply put, your eye lens focuses a bit in front or a bit behind your retina.
A +1 diopter corrects for the case when your eye lens assembly focuses behind the place where it should focus. The image you see through a viewfinder does not differ in fact froma real object; and therefore it should be formed on the retina with a zero diopter. If your eyelenses focus behind, it cold be translated into stg like the focal length of your eyelens unit is longer than it should be. A positive lens will correct this, make it shorter.
It's exacly like putting two simple positive (convex) lenses like two loupes one after the other - their focal length will be shorter than each separately.
Diopter as unit of measure is equal to the inverse of the focal length, where the f.l. is expresed in meters. The higher the diopter number of a lens, the shorter the focal length, the smaller the image formed, the larger an object seems when you look through it etcetera.
Attaching a lens of diopter x to one of diopter y will result in a lens of diopter x+y. This is why working w diopters is easier than with focal lengths - if you want to express the same "summation" in terms of focal length f, the formula is 1/ffinal = 1/fx + 1/fy. When x=y this means halving of the focal length but when they are different, or, god save us, one of them is negative, it needs a pocket calculator.
With negative diopters all is the same, but the effect is the other way around.
A +1 diopter corrects for the case when your eye lens assembly focuses behind the place where it should focus. The image you see through a viewfinder does not differ in fact froma real object; and therefore it should be formed on the retina with a zero diopter. If your eyelenses focus behind, it cold be translated into stg like the focal length of your eyelens unit is longer than it should be. A positive lens will correct this, make it shorter.
It's exacly like putting two simple positive (convex) lenses like two loupes one after the other - their focal length will be shorter than each separately.
Diopter as unit of measure is equal to the inverse of the focal length, where the f.l. is expresed in meters. The higher the diopter number of a lens, the shorter the focal length, the smaller the image formed, the larger an object seems when you look through it etcetera.
Attaching a lens of diopter x to one of diopter y will result in a lens of diopter x+y. This is why working w diopters is easier than with focal lengths - if you want to express the same "summation" in terms of focal length f, the formula is 1/ffinal = 1/fx + 1/fy. When x=y this means halving of the focal length but when they are different, or, god save us, one of them is negative, it needs a pocket calculator.
With negative diopters all is the same, but the effect is the other way around.