Leica dioptre

[Guest NEIL-D-WILLIAMS]

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All you guys that are using a Leica Diopter..............how are they? Do you find that they make a huge difference, like if you didn't have one you would no longer be able to use your rangefinder??

Sorry to hijack the thread but everyone on here has got a diopter

[jaapv]

Perfect - if you get the right one.

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[satijntje]

I cannot shoot properly without one.

Although I have -4d on my right eye, the -3 will do the job.

Need to get a second one as I have more M's!

John

[satijntje]

On the official leica shop websites I see that the diopters for M are offered from +3 to -3 diopter.

Important to know that the M finder is a -0.5d already.

So if your shooting eye has +2, you need to get a +2.5, with the minus of course just the other ways.

I saw on Ebay that the leicahop in Vienna is offereing diopters up to -7d.

Didn't know that these exist.

Must be a own production as they are not offered by leica.

Right now I'm looking for another -3.0d for my second M!

John

[keithlaban.co.uk]

I wouldn't even think about using an M without one.

[jaapv]

On the official leica shop websites I see that the diopters for M are offered from +3 to -3 diopter.

Important to know that the M finder is a -0.5d already.

So if your shooting eye has +2, you need to get a +2.5, with the minus of course just the other ways.

I saw on Ebay that the leicahop in Vienna is offereing diopters up to -7d.

Didn't know that these exist.

Must be a own production as they are not offered by leica.

Right now I'm looking for another -3.0d for my second M!

John

The viewfinder+diopter must end up @ -0.5, to use it optimally. It is incorrect to compensate for the native diopter value of the viewfinder, which is there for a reason( the virtual distance of the projected framelines and patch) Calculating is not always correct, you must try the value out. Visit your optician and use his try-out lens set.

[ECohen]

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"Perfect - if you get the right one"........."I couldn't even think about using an M without one...."

 

yep I agree with these statements.

 

 I shoot with progressive lenses and you need to hit the right spot......shooting without eye glasses and just the correct diopter slowed me up too much.

Its a very personal decision how you "see" the focus square. For me once I figured out the combination what works best for me ...problem solved.

 

 

Be careful diopters unscrew on there own.....expensive accessory to lose

[Luke_Miller]

Calculating is not always correct, you must try the value out. 

 

Exactly.  My reading glass prescription is +2.5, but I can't focus my M240 while wearing them - much too strong.  The correct diopter in my case is +0.5.  I see pretty well without correction at 2 meters (which is reportedly the distance the rangefinder patch and framelines are calibrated for).  I can actually focus without a diopter, but +0.5 makes the view clearer.  If I add a correction stronger than necessary (say +1.0) I find that I then struggle to focus at longer distances.  jaapv is correct - try before you buy.

[Rick]

The viewfinder+diopter must end up @ -0.5, to use it optimally. It is incorrect to compensate for the native diopter value of the viewfinder, which is there for a reason( the virtual distance of the projected framelines and patch) Calculating is not always correct, you must try the value out. Visit your optician and use his try-out lens set.

 

 

Actually, your distance prescription plus diopter must equal +0.50 D.  For example, your distance Rx is 0.00, then the diopter you will need is +0.50D.

 

If, your distance Rx is -3.50, then you will need a diopter of -3.00D.  Without glasses.

 

If, your distance Rx is -3.50 and you wear glasses with your M, then the correct diopter is +0.50D

 

You need to end up with a total of +0.50 over your correction (not -0.50 as jaapv suggests.  He always gets this wrong and will post a rational why it is -0.50D).

 

Rick

 

 

 

 

 

 

 

Rick

[jaapv]

Because the viewfinder is -0.50 and you must correct your eye to 0 to maintain that. If you add + 0.50 you are overcorrecting. If you read my post you will see that that is what I am saying, not that you must add another -0.5. I'm saying you should not consider the value that Leica put there deliberately.

[Rick]

You simply don't know what you are talking about.  You are wrong.  Please stop posting this.  

 

Rick

[jaapv]

Ok. I fully accept your expertise. Explain please. Leica has a dioptre strength of -0.5 in their viewfinder. I assume they know what they are doing when designing the viewfinder that way. Why would you want to eliminate that when you add a dioptre strength for an eye that needs it?

[Exodies]

The way I think about it is that Leica design the rangefinder for people with perfect eyesight. The fact that this means -0.5d is irrelevant. You need to make your eyesight perfect, so use your spectacles or get a screw-in diopter with the same value as your spectacles. 

 

It's not clear if this matches Jaap's or Rick's calculations.

 

One disadvantage of not using your spectacles is that the other eye gets a blurred view of the scene.

[jaapv]

Well, calculations... My reading strength is +2.25, my distance strength +0.25 (no correction needed). No astigmatism. Using a Leica Dioptre Selector, I found that the dioptre that works best for me is none. All dioptres degrade the view progressively as strength increases. Go figure.

[Rick]

Trust me, I'm right.  Jaapv is a dentist.  I'm an eye doctor.  I know what I'm talking about.  I've had graduate level studies in optics.  And, I do this sort of stuff every day.  

 

If, you are plano (no Rx in the distance) then you need to add a PLUS not minus (as Jaapv states) diopter.  Add a +0.50 for the diopter.  This is for anybody over 50 years old or there about.  But, you must have an accurate Rx from your doctor... which is always questionable.. for this statement to be correct.

 

 

Rick

Edited March 19, 2016 by Rick

[jaapv]

As I posted, Rick, I know you are an eye doctor so I really would appreciate an explanation why one would need to add +0.5. 

 

I never said to add -0.5, as you seem to think - if it appears so to you, I must be guilty of woolly language.  "Ending up at" is really not the same as "including in a calculation".

I only said to disregard the inbuilt strength of the camera , as I assume Leica put it there for a reason. Actually I cannot recall a single post that addressed the rest of the calculation, I am aware of my limitations.

 

Actually the one you are reacting to is a response to this:

 

On the official leica shop websites I see that the diopters for M are offered from +3 to -3 diopter.

Important to know that the M finder is a -0.5d already.

 

And says nothing more than this:

 

 

It is incorrect to compensate for the native diopter value of the viewfinder, which is there for a reason

 

So - why does the viewfinder have a negative diopter value, assuming that it is designed for average good eyesight, and why would one attempt to (over?)correct the eyesight by taking this into consideration  in that case?

 

 

I  am sure that you agree that if people are using their reading glasses prescription to order a diopter for a system that has a virtual distance for the markings at two meters and a telescope reaching to infinity, that the result is bound to be wrong.

 

So in each and every post  I made I encouraged laymen like me to use the trial and error method to determine the strength.

 

Read them.

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What's the apparent distance of the frames? 

[Exodies]

It's not getting any clearer. So we have to trust Rick, because he is an eye doctor but doubt our own eye doctor's prescriptions? 

[pop]

It's not getting any clearer. So we have to trust Rick, because he is an eye doctor but doubt our own eye doctor's prescriptions? 

You can trust your eye doctor's prescription, but only if it's certain the prescription  applies to the situation of looking through the M's finder. That's why I asked about the apparent distance of the frames. If I can tell my iDoctor that I need to see well at arm's length or at a distance of 2m, he can immediately tell me what correction my left or right eye needs. That's how I got the RX for my computer glasses or my piano playing glasses.

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Hallo,

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[Exodies]

You can trust your eye doctor's prescription, but only if it's certain the prescription  applies to the situation of looking through the M's finder. That's why I asked about the apparent distance of the frames. If I can tell my iDoctor that I need to see well at arm's length or at a distance of 2m, he can immediately tell me what correction my left or right eye needs. That's how I got the RX for my computer glasses or my piano playing glasses.

 

 

I suspect you would have to tell the iDoctor about the built in -0.5d in that case.