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Correct way to use a Diopter

Guest NEIL-D-WILLIAMS

By Guest NEIL-D-WILLIAMS
in Customer Forum

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Guest NEIL-D-WILLIAMS

Guest NEIL-D-WILLIAMS

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Guys,

I have a +0.25 prescription in my right eye and I was wondering what strength Diopter I should use.

I did try a few Diopters in the Leica shop in KL but he had limited stock, plus his shop is very dark so it was difficult to see if either of these diopter lenses did any good.

but looking at what the Leica manual says the M9 Viewfinder comes with a -0.5 which would mean I would need a +1.0 is that correct

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jaapv

jaapv

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Not neccesarily. This subject has been discussed more than once (:D) Go to your local optician and use his try-out lenses to determine which strength works the best for you. You can then order the nearest equivalent with Leica. Note that the Leica diopters do not provide for astigmatism. You need a Walter RX Eyepiece for that.

There is a Leica M9 FAQ thread that answers well....FAQs...

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Guest NEIL-D-WILLIAMS

Guest NEIL-D-WILLIAMS

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Not neccesarily. This subject has been discussed more than once (:D) Go to your local optician and use his try-out lenses to determine which strength works the best for you. You can then order the nearest equivalent with Leica. Note that the Leica diopters do not provide for astigmatism. You need a Walter RX Eyepiece for that.

There is a Leica M9 FAQ thread that answers well....FAQs...

What astigmatism??
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Guest NEIL-D-WILLIAMS

Guest NEIL-D-WILLIAMS

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Lots of people have astigmatisms in one or both eyes. I am one I them.
What are they.......does it mean long sighted or short sighted .................or what??
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Guest NEIL-D-WILLIAMS

Guest NEIL-D-WILLIAMS

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Isn't it time to have your eyes tested?
Had that done already mate...........if you noticed in the first thread I put my right eye is a +0.25:rolleyes:
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01af

01af

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... if you noticed in the first thread I put my right eye is a +0.25:rolleyes:

So that means, no astigmatism. Good for you. Most likely, the best diopter for you will be the +0.5 dpt ... however if your eyes are young enough to not suffer from presbyopia then you might just as well get away with no diopter at all.

 

To be sure, try and compare: no diopter lens, +0.5 dpt, and +1 dpt. What the best diopter lens is for you depends on many factors ... some of them being of the subjective kind.

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Guest NEIL-D-WILLIAMS

Guest NEIL-D-WILLIAMS

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So that means, no astigmatism. Good for you. Most likely, the best diopter for you will be the +0.5 dpt ... however if your eyes are young enough to not suffer from presbyopia then you might just as well get away with no diopter at all.

 

To be sure, try and compare: no diopter lens, +0.5 dpt, and +1 dpt. What the best diopter lens is for you depends on many factors ... some of them being of the subjective kind.

Thank you sir, I wil try that when I get home
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Guest NEIL-D-WILLIAMS

Guest NEIL-D-WILLIAMS

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Sorry one last question.................at what distance should I try to focus on something when trying out the diopters 1 mtr, 2 mtrs infinity or doesn’t it matter meaning we are just trying to get the small square box in the viewfinder as sharp as possible?

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lars_bergquist

lars_bergquist

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You should try focusing on an object at medium distance – something at about five to ten meters would be appropriate.

 

There is always the temptation to focus at the frame lines, or the hard edges of the rangefinder patch. In both cases, that would mean focusing on the cutouts in the moveable finder mask. This is at an apparent distance of two meters. But you are not interested in seeing that mask more than passably sharply. What matters is that you see the finder image sharply, and that is at a variable distance, optical as well as real – just as when you focus a pair of binoculars for various distances. For you must see the finder image, and the rangefinder image, sharply in order to focus them properly. Hence, a compromise is necessary, and you should make a 'reality test' as suggested, at 5—10 meters (15—30 feet) distance.

 

The old man from the Bifocal Age

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01af

01af

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As I understand the M9 viewfinder is -0.5 dpt. Firstly is that right?

Yes, it is.

 

 

So for someone with perfect vision, does that mean you need a +0.5 dpt to correct it to 0?

No, it doesn't.

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  • 2 weeks later...
}{B

}{B

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It seems that I've reached an age where a diopter correction lens will make focussing much easier. However given the price of a genuine Leica correction lens I'm wondering how securely they screw into the viewfinder. Having to worry about whether it's still in place and not gradually unscrewing itself would take a lot of the pleasure out of being able to focus quickly again.

 

Any comments based on practical experience will be much appreciated.

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dachs

dachs

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G*d I yearn for +0,25........ (+6 right eye + 8,5 left - both wildly off axis, astigmatic, and colour blind on greens too, we are talking Hubble Telescope corrections here)

 

minus by the way (in your prescription) is short sighted (image forms in front of the eyeball receptors), plus is long sight, more common in help the aged (me!).

 

Limitations of the screw in diopter lenses is not just the incredible cost of them but the fine threads and especially they put your eye back a further millimetre, which with these view finders you can barely afford. To enable the ring to grip the glass, the beautiful optically correct perfect glass I may add, the ring has some dimension and further can shade the scene in the v/f. So a 0,72 v/f with a corrector renders the 28mm frames hard work.

 

Nothing in physics is for nothing as Goethe might have said, if he had an MP.

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tobey bilek

tobey bilek

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Actually a dark shop is best to test as your eye opens fully negating depth of field effects.

 

The camera is set to one meter or so, so if you can see one meter sharp and clean without Rx, your eye will accommodate or focus match to the camera.

 

With a +.25 correction, you are far sighted making close vision difficult. This is a minimal correction and I think you will have difficulty at reading distance and then only slightly.

 

Therefore the one meter virtual distance of Leica should be in your range and no correction is necessary. Should you go further far sighted or lose focus accommodation as you age , over 40 generally, you may find it necessary to add +1 to the camera.

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Guest NEIL-D-WILLIAMS

Guest NEIL-D-WILLIAMS

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Actually a dark shop is best to test as your eye opens fully negating depth of field effects.

 

The camera is set to one meter or so, so if you can see one meter sharp and clean without Rx, your eye will accommodate or focus match to the camera.

 

With a +.25 correction, you are far sighted making close vision difficult. This is a minimal correction and I think you will have difficulty at reading distance and then only slightly.

 

Therefore the one meter virtual distance of Leica should be in your range and no correction is necessary. Should you go further far sighted or lose focus accommodation as you age , over 40 generally, you may find it necessary to add +1 to the camera.

I will try again when I get home next week.........hopefully I will be good for a few more years:):)
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mwilliamsphotography

mwilliamsphotography

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Eye exams are essential, and even more essential if one wishes to continue shooting the wonderful M cameras well into a rickety age : -)

 

Of recent, I have experienced more and more difficulty shooting my favorite camera ... the M. I sent for a broad range of diopters to select one and try to restore my acuity. Even the one I had previously chosen went out-dated with-in 6 months, so I sought out my optometrists to determine which correction I might need.

 

Well, he discovered advanced cataracts in both eyes, more advanced in the right shooting eye, and sent me to a well respected eye surgeon ... who also discovered astigmatism in both eyes ... worse in the shooting eye ... of course.

 

In the next month, the cataracts will be removed, and my eye "lenses" replaced with Toric lens implants to also correct the astigmatism. It is not an inexpensive choice of lens because my insurance doesn't cover it, however far less expensive than almost any M lenses ... LOL!

 

With any luck, I will have the eye-sight I had years ago when the M was my dominate choice of camera.

 

My advice:

 

See your optometrist while you still can ... : -)

 

-Marc

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