Diopters...how do they work?

[Angular Mo]

I've looked all over the Internet, and have not found an easy source to a question. How do diopters work? I wear eyeglasses when shooting, and would like the option of not wearing them, and switching back to wearing them. It seems that one could see something in the viewfinder as in focus, but the image is really out-of-focus.

Is there typically a "zero adjustment" setting so one knows the picture is in true focus with 20/20 vision ? Admision: I am trying to set it on a Leica R5 (yeah, you could send me to Leica users group, but they don't have much traffic) I don't have the instructions, and the online sources don't quite explain it.

I've been a SLR shooter for three decades, but never had one with this feature before.

If you are going to be critical or condenscending, then just ignore this posting. Only helpful contributions, please.

Angular Mo.

 

[Petteri Sulonen]

I've looked all over the Internet, and have not found an easy
source to a question. How do diopters work? I wear eyeglasses
when shooting, and would like the option of not wearing them, and
switching back to wearing them. It seems that one could see
something in the viewfinder as in focus, but the image is really
out-of-focus.

Is there typically a "zero adjustment" setting so one knows the
picture is in true focus with 20/20 vision ? Admision: I am trying
to set it on a Leica R5 (yeah, you could send me to Leica users
group, but they don't have much traffic) I don't have the
instructions, and the online sources don't quite explain it.

On a good manual-focus screen, like the one on your R5, the diopter setting or any drop-in diopters won't affect the perception of focus. The image is actually focused on the screen, so the diopter only affects the way the image of that screen appears to your eye. So, if you're nearsighted, the screen will appear blurry. If you correct this with a diopter, the screen will be sharp, and the image will be either soft or sharp depending on your focus. If you look at it with your glasses on, it'll still appear sharp, only you'll get more eyestrain -- but the perception of focus will be unchanged.

IOW, just use the diopter as you see fit. It won't affect the perceived focus point at all.

I've been a SLR shooter for three decades, but never had one with
this feature before.

If you are going to be critical or condenscending, then just ignore
this posting. Only helpful contributions, please.

There will always be critical or condescending replies. Instructions like this don't help. They just make you appear bossy, pushy, and thin-skinned and invite criticism and condescension rather than discourage it. (See? Here I am, responding critically and perhaps a tad condescendingly to this part in your post; had you omitted it, I wouldn't have replied in such a way.)

You can't make them ignore you. However, you can ignore them. I suggest that would be a better strategy. You can start with this part of this post.

Petteri
--
My flickr page: [ http://www.flickr.com/photos/primejunta/ ]
Me on photography: [ http://194.100.88.243/petteri/ ]
Me on politics: [ http://p-on-p.blogspot.com/ ]

 

[Deecy]

I've looked all over the Internet, and have not found an easy
source to a question. How do diopters work? I wear eyeglasses
when shooting, and would like the option of not wearing them, and
switching back to wearing them. It seems that one could see
something in the viewfinder as in focus, but the image is really
out-of-focus.

Is there typically a "zero adjustment" setting so one knows the
picture is in true focus with 20/20 vision ? Admision: I am trying
to set it on a Leica R5 (yeah, you could send me to Leica users
group, but they don't have much traffic) I don't have the
instructions, and the online sources don't quite explain it.

I've been a SLR shooter for three decades, but never had one with
this feature before.

If you are going to be critical or condenscending, then just ignore
this posting. Only helpful contributions, please.

Angular Mo.

--Dear Angular Mo (Angular Mo??)

Here's the deal. Without getting into optical physics, if you want to crank some "diopters" into your viewfinder so you don't have to wear your glasses, there are some caveats.

1. Your spectacle prescription cannot be so strong that when you remove your glasses your eyes are more than 1 or 2 diopters myopic or hyperopic (nearsighted or farsighted) because that's usually all the adjustment there is in the camera VF.

2. If you are at the age when you cannot read without readers, (IOW, are presbyopic = losing your ability to focus on near objects. Just to further depress you, "presbyopia" means middle-age sight.), the viewfinder "diopter" adjuster won't help. Viewfinders are set up to provide a clear image using your distance vision, and their adjusters allow for a little fine tuning of that, that's all.

3. Now that you've made the correct diagnosis, you can proceed apace in full possession of everything you need to know about whether you can slip off your glasses and crank their prescription into your camera's viewfinder or will have to wear your specs while making those unmatchable, deathless Leica images.

There's a simple test to determine whether the camera's VF has enough "diopters" in it to work in your (anybody's) specific case: remove your glasses, crank the VF wheel all the way, look through. Not clear? Crank it the other way and look through. Still not clear? Your visual error is greater than the measly couple of "diopters" adjustment provided by Leica, Inc. and you'll need to wear your glasses or contact lenses.

OTOH, if one or another adjustment provides a clear view through the VF, you've got it made in the shade.

Here's hoping!
Tom

Deecy//

http://tomdeecy.blogspot.com/

 

[Deecy]

--Gee, Tom, thanks for the explanation. There's nothing like an expert to set things straight. You really helped a lot.
Angular Mo

Quite welcome, Angular. No trouble at all!

Tom
Deecy//

http://tomdeecy.blogspot.com/

 

[David Hughes124436]

Dioptres don't "work" they are a measurement.

A lens of 1 dioptre has a focal length of a metre and a lens of 2 dioptres has a focal length of half a metre etc. It's the reciprocal of the focal length in metres, IOW.

Leitz used to do correction lenses for the viewfinders. Your optician ought to be able to tell you what you need and Leitz ought to be able to supply it. Can't say for sure as I stopped reading catalogues years ago.

Regaqrds, David

 

[Adrian Harris]

I am a bit puzzled by Deeces comment Re: If you need reading glasses diopters dont work.

Because I use and need really strong reading glasses, yet the diopter adjustment on my Minolta D7i is superb for making everything pin sharp.

 

[Angular Mo]

Not sure if I understand since one would change the position of the lens by refocusing depending upon the value set on the diopter since that is what one percevies to be focus. I would expect to have to do some zero-level calibration.

If there is a link to a technical photo sight that would help.

Thanks for the post.

Mo.

 

[Mark Thornton]

If you need more correction than offered by the viewfinder dioptre correction, then surely you will need glasses/contacts the moment you take your eye away from the viewfinder in order to see much of your surroundings? In which case it would be more convenient to leave them on while using the viewfinder.

I have the usual age related loss of close vision, which is making it a pain to use a digicam as I now need glasses to read small numbers on the LCD. On the other hand I have no problem using my old SLR because my distance vision (everything beyond 1.5m) is still fine.

 

[Petteri Sulonen]

What you're seeing through the diopter is an image projected on the focusing screen. This image, and therefore the position of focus, is only affected by the lens. The diopter affects whether you can see that image sharply or not -- it will not introduce a shift in perceived focus.

Imagine that it's not an image projected through the lens at all, but a slide that someone's shot previously. Will the diopter affect focus on that slide? Of course not. What's so difficult about this to understand?

Petteri
--
My flickr page: [ http://www.flickr.com/photos/primejunta/ ]
Me on photography: [ http://194.100.88.243/petteri/ ]
Me on politics: [ http://p-on-p.blogspot.com/ ]

 

[Deecy]

I am a bit puzzled by Deeces comment Re: If you need reading
glasses diopters dont work.

Because I use and need really strong reading glasses, yet the
diopter adjustment on my Minolta D7i is superb for making
everything pin sharp.

--Okay, Adrian, here's the deal on that. I don't know your age and I don't know if you wear distance correction, but I'll guesstimate that you're anywhere from 45 to 60 Y.O., and while you still don't wear distance glasses you need, as you said, "really strong readers".

This tells me that you are hyperopic (far-sighted). And because you are 55 Y.O you are now also presbyopic(see definition in my other post).

Here's the part that's hard for the layman to understand but I'll lay it on you straight: up to a certain age, hyperopes use the focussing power of their own eye in order to see clearly at both distance and near And they usually have superb uncorrected (no eyeglasses) vision. (Think Chuck Yeager who had "phenomenal" vision. He is far-sighted. In youth, his eye'e focussing power helped him get a really clear view of German fighters no matter their distance, even infinity. His pilot friends always said that he could see the Messerschmits before anybody else. That was the reason.)

As they get older their eye's focussing power diminishes and they start to use what they have left for clear distance vision. This is about when they need readers: they use all they've got for distance and have none left to crank in for reading. Uncorrected distance vision can still be terrific.

Now the doc gives you readers. Fine. Now you put your eye up to the camera VF sans specs and turn the knob to get some help. The little extra dioptric + power that the VF provides helps you with distance AND near visual clarity through the VF.

End of story except for one thing. One of these days I guarantee that you will need distance glasses, and they will be - you ready?- bifocals of one or another variety.

BTW, please forget all the infomation you've been given about the mathematical derivation of a diopter. It's of no help to anybody except doctors and optical physicists (and people who, when you ask them what time it is, tell you how to make a watch).

Cheers!

Tom
Deecy//

http://tomdeecy.blogspot.com/

 

[ChrisD200]

In general diopters are calculated as 1/focal distance. So a 1 diopter is a focal distance of 1m and a 4 diopter is a 25cm distance. Check this against the cheap spectacles available in drug stores.
Chris

 

[john farrar]

Dioptre correction lenses are used to facilitate easier checking of focus; they alter nothing else. If you have really difficult eyes like mine (-9) then, even if I could make up a -9 correction on the v/f it would indeed be impossible to read fine information on the LCD without putting glasses back on. My solution was to get the optician to make a pair of varifocal glasses. Others say contact lenses are the most effective answer.
--
John.
Imagination knows no boundaries...



http://www.pbase.com/johnfr

 

[Hennie de Ruyter]

Since an accident that caused major damage to my eyes (requiring several operations and the removal of the left eye) had to wear corrective glasses of various strengths and suffered severe astigmatism.

I have owned 3 SLRs, the first manual focus only. and I can safely say that even at the times when my glasses were not 'correct' (it never really was) I could still take great pictures. Even with Canon AF, good as it is, I sometimes swap AF for MF and the results are good. Understand that no diopter setting can assist when you have stigmatism, I ignore this setting on my camera.

I have now have no lens in my remaining eye and actually battles more with the EVF and screens of 'smaller' cameras. For my an optical view finder is the easiest.

Believe me when I say that my camera is an extention of my joy to still see, having nearly lost the gift of vision!

Get your camera, get your boots, there must be a mountain somewhere you haven't yet climbed!!!

 

[Mareda]

Not sure if I understand since one would change the position of the
lens by refocusing depending upon the value set on the diopter
since that is what one percevies to be focus. I would expect to
have to do some zero-level calibration.

If there is a link to a technical photo sight that would help.

Thanks for the post.

Mo.

Think of the diopter as someone holding up an eyeglass at the strength you need (unless ones eyes are really bad), up to the viewfinder, thus making it easier to see the image clearly in the viewfinder. Having the eyeglass there or not there doesn't change the image and the cameras ability to capture the image, only how well the viewer can see it, because they don't have 20/20 vision.

Maureen

 

[Adrian Harris]

Hi Deecy thanks for the spot on info.
I am 55 and do wear varifocals.
I am long sited - in fact overlong, cant even focus on infinity anymore!

Hoping eyes wont continue to get worse, as I am really enjoying photography. It is teaching me to enjoy the fine detail in life, that was always to easy to miss whilst rushing throught it!

 

[Mojo151]

Leica offers a + -3 (The web site did not state the number of steps they offer) diopter Eyepiece Corrector viewfinder correction accessory. I use a -2 for my KM 5D. They are a fixed diopter that you clip on the viewfinder. For example my 5D camera viewfinder adjustment is -2.5 to +1 then I added a -2 Eyepiece Corrector and now the adjustment range is -4.5 to -1. That is it will bias the range by whatever diopter adjustment you add on.

Since no camera store has one I had to order on-line and quess at the one I needed. I ordered a -2 and it allowed me to use the viewfinder without glasses when it was cranked all the way to the end of adjustment. I barely guessed correctly.

I've looked all over the Internet, and have not found an easy
source to a question. How do diopters work? I wear eyeglasses
when shooting, and would like the option of not wearing them, and
switching back to wearing them. It seems that one could see
something in the viewfinder as in focus, but the image is really
out-of-focus.

Is there typically a "zero adjustment" setting so one knows the
picture is in true focus with 20/20 vision ? Admision: I am trying
to set it on a Leica R5 (yeah, you could send me to Leica users
group, but they don't have much traffic) I don't have the
instructions, and the online sources don't quite explain it.

I've been a SLR shooter for three decades, but never had one with
this feature before.

If you are going to be critical or condenscending, then just ignore
this posting. Only helpful contributions, please.

Angular Mo.

--
Rick
Maxxum 5D
Sigma 18-50 f/2.8 EX DC
Tamron 28-300mm f/3.5-6.3 XR Di LD

 

[Mojo151]

Order a corrector from a Leica dealer.

A list is below.
http://www.leica-camera.com/markt/adressen/usa/index_e.html

I've looked all over the Internet, and have not found an easy
source to a question. How do diopters work? I wear eyeglasses
when shooting, and would like the option of not wearing them, and
switching back to wearing them. It seems that one could see
something in the viewfinder as in focus, but the image is really
out-of-focus.

Is there typically a "zero adjustment" setting so one knows the
picture is in true focus with 20/20 vision ? Admision: I am trying
to set it on a Leica R5 (yeah, you could send me to Leica users
group, but they don't have much traffic) I don't have the
instructions, and the online sources don't quite explain it.

I've been a SLR shooter for three decades, but never had one with
this feature before.

If you are going to be critical or condenscending, then just ignore
this posting. Only helpful contributions, please.

Angular Mo.

--
Rick
Maxxum 5D
Sigma 18-50 f/2.8 EX DC
Tamron 28-300mm f/3.5-6.3 XR Di LD

 

[Angular Mo]

Thank you to all for replying to this post, I just got home from work and am busy answering my door....we have lots of little witches, goblins, and scary monsters visitng tonight for Halloween.

Lots to read and think about....As a math guy, I like the technical explanations and will study all this carefully.

Angular Mo.

 

[Angular Mo]

Aaaah, that makes sense to me, thank you.

The diopter doesn't make something out-of-focus in-focus. It only allows one to see what being in-focus really looks like. The conclusion then, is that one can get locked in-focus with a sharper photo easier.

ANgular Mo.

 

[Mareda]

Aaaah, that makes sense to me, thank you.

The diopter doesn't make something out-of-focus in-focus. It only
allows one to see what being in-focus really looks like. The
conclusion then, is that one can get locked in-focus with a sharper
photo easier.

ANgular Mo.

You've got it now, Mo!

Maureen