M6 Dioptre Correction

[mikebidwell]

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Sorry if I've made a mistake but I inadvertently mixed this query in with someone elses thread, so I've removed it to here

 

Like the original poster of the thread I find the matter of Diopter correction a little confusing. I have my M6 but wearing Varifocal spectacles I find its not too easy to focus . I've recently been to my optometrist who tells me that I need for my left eye (my focussing eye) is :-

 

Sph: +3.0 - Cyl :- -0.25 - Axis 1.30. With an additon of +2.75 for reading

 

Perhaps someone with more experience than I can cut through the technical jargon and tell me if I should get a Dioptre Correction Lens and if so what one please. Or any other suggestions would be greatfully received .

 

Best wishes

 

Mike

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[jc_braconi]

I think that a +3 dioptre will let you seing the range focusing screen clearly.

[scsambrook]

Mike, I don't have an M6, I have an M2 and M8 and find focusing both a problem even with an up-to-date prescription for my varifocals. I don't know if the viewfinders have changed over time, but the M2 is fractionally easier to manage than the M8.

 

Mr Braconi's advice might not be entirely safe ... If you want to work without your glasses on, you'll need the -0.25 cyl correction in any correction lens in order to clear up your astigmatism. So that means a custom-made job. Uncorrected astigmatism will smudge the viewfinder image, I fear. And don't forget the viewfinder itself has a -0.5 factor of its own, which the correction lens will need to take care of.

 

My problem, and maybe yours too, is that my eyes no longer have the accommodation to correct for even the relatively small -0.5 diopter factor of the viewfinder system. What I need is simply a +0.5 diopter correction to use with my varifocals. I've tried looking through the middle and close range sectors, but it's just too awkward to manage. I'm shortsighted but I think the principle will apply equally to longsighted people.

 

I'd liaise with your optician - maybe he/she still has the old-style trial frames that take the drop-in lenses; if so you might persuade him/her to let you try different ones at your camera eyepiece. Mine did that for me and actually seemed interested. All I have to do now is shell out the hundred pounds or so to buy Mr Leica's unbelievably expensive eyepiece correction lens !

 

Good luck.

 

Stephen

[jc_braconi]

Mr Braconi's advice might not be entirely safe ... If you want to work without your glasses on,

Stephen

I need a +2 for reading and I use a +2 leica diopter on both M6s & M8s and WHITHOUT wearing glasses

[scsambrook]

I need a +2 for reading and I use a +2 leica diopter on both M6s & M8s and WHITHOUT wearing glasses

 

I think we all have to work round our particular eyesight problems . . . the lack of accommodation is a particular problem for me, hence even with a "correct" prescription I still need the +0.5d to overcome the in-built negative quantity in the viewfinder. For you, that is obviously not a problem - I'm envious ! My optician assures me that I need correction for far distance rather than closer in order to see the rangefinder images clearly - something which trials in his testing room confirm.

 

But my point to Mike was that he might find uncorrected astigmantism to be a problem, hence the caveat that your original advice might not to be safe. I think that before spending a large amount of money on a correction lens that it's better to be absolutely sure all the eventualities have been taken into account.

[jc_braconi]

I think that before spending a large amount of money on a correction lens that it's better to be absolutely sure all the eventualities have been taken into account.

The only way is to go to a Leica dealer and try different diopters on the camera viewfinder.

[wizard]

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The only way is to go to a Leica dealer and try different diopters on the camera viewfinder.

 

 

Exactly that is my recommendation as well. Go to your optician, he will have +1, +2, +3 diopter lenses (and may be even values in between). Just hold each one of these lenses in front of your viewfinder eyepiece, i.e. between your left eye and the eyepiece, look through your viewfinder and decide which one works best.

 

As an aside, what works best may well change over the years. For many years I used a -1 diopter lens, but found out recently that miraculously I am now better off with NO diopter lens at all. Kudos to my ageing eyes .

 

Andy

[lars_bergquist]

I am presbyopic (oversighted) and have long ago lost all ability to focus my eyes. I use varifocals, and I focus anything M without any problem at all. It is just a matter of learning where to place the finder eyepiece against my right spectacle lens. There is a place there -- and on your varifocals too -- where you see objects at 2m sharply. That is the place. With me, this is now a matter of instinct. This worked well with the M2 and it works well with the M9. No need to mess around with correction lenses.

 

Also, using BOTH specs AND correction lenses will place your eye so far from the eyepiece lens that you will probably lose even the 35mm frame.

 

The old man from the Age of Bifocals

[zeitz]

Mike, have to talked to your doctor about contacts? The new silicon contacts are very wearable. Both contracts are set for distance; not monovision. I then use trifocal (not varifocal progressive) reading glasses over them, set to 0, +1.5, and +2.5. I often just wear sunglasses and dispense with the trifocal reading glasses on sunny days.

 

This may seem odd, but my right and left prescriptions are very different and the two lenses in glasses give different size images that are hard to mentally merge, even with "slag-off". I would never go back to just glasses. The contacts with trifocal reading glasses work extremely well for me.

[scsambrook]

I am presbyopic (oversighted) and have long ago lost all ability to focus my eyes. I use varifocals, and I focus anything M without any problem at all. It is just a matter of learning where to place the finder eyepiece against my right spectacle lens. There is a place there -- and on your varifocals too -- where you see objects at 2m sharply. That is the place. With me, this is now a matter of instinct. This worked well with the M2 and it works well with the M9. No need to mess around with correction lenses.

 

Also, using BOTH specs AND correction lenses will place your eye so far from the eyepiece lens that you will probably lose even the 35mm frame.

 

The old man from the Age of Bifocals

 

I regret my own experience has been very different. No doubt this has to do with my eyesight problems and possibly the nature of the varifocal lens make-up in my spectacles, but when I present the viewfinder to my eye no matter which part of thelens I look through, the image is never as clear as when looking directly at the same subject. A +0.5d lens corrects this completely. I totally endorse wizard's observations and urge anyone with similar difficulties to liase with a competent optometrist.

 

Losing the 35mm frame is certainly as nuisance, but probably easier to manage than an unclear rangefinder image. Using a borrowed +0.5 lens with my camera on a tripod, I find that results are consistent whereas without the correction I sometimes have errors significant enough to make me think I have a front/backfocus problem.

 

To each his own, as they say ...

[lars_bergquist]

Yes, I may of course be singularly lucky. But the fact is that I am so presbyopic that I can't see even the horizon sharply without glasses. My eyes are firmly and unalterably focused beyond infinity -- maybe a proper situation for ...

 

The old man from the Age of Bifocals

[scsambrook]

To Lars - who said

 

"But the fact is that I am so presbyopic that I can't see even the horizon sharply without glasses. My eyes are firmly and unalterably focused beyond infinity..."

 

Ahhh, We are at the opposite ends of the scale - my left eye is fixed-focus at about 7cm and my right fixed at around 5 cm. A few years ago when I needed an even stronger negative correction factor than today, I had enough accommodation to be able to focus my left eye about 1.5cm nearer than its 'resting' position and about 1 cm nearer for the right. But now that my eyesight has 'improved' that facility has gone completely.

 

'The not-quite-so-old-man from the era of wire spectacle frames with hooks to go round your ears'

[mikebidwell]

Hi there,

 

I must say a big thank you to all those who showed an interest and gave me advice on my dilemma. After weighing things up I'm going to give it a try, so I've sent for a +3 dioptre. I will keep you updated on the results.

 

Best wishes

 

Mike