Diopter daze

[JohnP]

Hello,

I have ordered an empty diopter for my M7.

Soon, I'll have my eyes checked; then I'll take the prescription to an optician to get the glass ground for the diopter.

What I don't know is should the optician manufacture glass so that I see clearly WITHIN the viewfinder, that is a matter of millimetres from my eye, or for infinity, that is as far as I can see THROUGH the viewfinder... Or are these (WITHIN and THROUGH) one and the same?

Please help me overcome this confusion.

John

 

[ampguy]

my experience

my experience

which is mild myopia, is the diopter that matches my glasses rx for distance works perfectly, just as if I were wearing my glasses, and using no diopter.

Your needs may vary, depending on astigmatism, bi-focals use, etc. Might want to take your camera in for your eye doc to check out.

Hello,

I have ordered an empty diopter for my M7.

Soon, I'll have my eyes checked; then I'll take the prescription to an optician to get the glass ground for the diopter.

What I don't know is should the optician manufacture glass so that I see clearly WITHIN the viewfinder, that is a matter of millimetres from my eye, or for infinity, that is as far as I can see THROUGH the viewfinder... Or are these (WITHIN and THROUGH) one and the same?

Please help me overcome this confusion.

John

 

[awilder]

It all depends on your age and prescription. The camera's optical system already has a built-in power of -0.5 D, so if you're into middle-age, it should be accounted for. I assume you plan to not were glasses with the camera which complicates matters if the eyes differ significantly from one another in power and astigmatism. If astigmatism is modest (under 1 D), don't worry about it. I'm not sure if you have the special blank diopter holder Leica makes for their camera but a standard eypiece diopter is fairly small and it maybe difficult to get a glass insert thin enough to fit properly so it doesn't scratch the main eyepiece.

 

[waileong]

In SLR, you are looking at an image on the ground glass.

In RF, you look thru the viewfinder at the real thing.

Hence, you need the same correction as you would with your glasses.

 

[john_s]

Having your eyes measured is a start. Ask your optometrist how much accommodation you have. It depends mostly on age. See the wikipedia page on optical prescriptions. If you have only a little accommodation, choosing the right value is critical. As has been pointed out above, you alter your viewing eye's focus for different distances through a rangefinder, but not for an SLR.

Unless you have unusual requirements, I recommend trying several values in a shop (maybe difficult to find one with a good range). Try looking at near and far subjects preferably in not very bright light.

Just as a matter of interest, why have you chosen to order an empty diopter and have a lens specially made?

 

[ChrisN]

Useful article in the Leica FAQ, here.