rob_w Posted January 27, 2009 Share #1 Posted January 27, 2009 Advertisement (gone after registration) I have the Leica 1.25 magnifier and both the 75mm and 90mm Summicron ASPHs, yet I find I get better focus results WITHOUT using the magnifier. Consequently it stays in my bag. The image seems less clear when I use the magnifier -- a little darker, perhaps, and not as sharp. I wondered if using the magnifier changed the effective focal distance of the viewfinder? I need reading glasses for close work, so if the focal distance is closer it may not be as clear using my regular distance glasses. The thought was prompted by reading the quote below on another thread on this forum: I used the Leica 1.25x with my 75 Summicron and 50 Sonnar, but recently got the Japanese 1.35x with built-in adjustable diopter - it's great. You adjust the diopter by turning the eyepiece. It's as slim as the Leica 1.25x and much cheaper of course. I also find I can now keep my left eye open which aids focus. I am no optical specialist. Could one of the more technically gifted members of the forum explain whether a dioptre adjustment would help? Thanks Robert Link to post Share on other sites More sharing options...
Advertisement Posted January 27, 2009 Posted January 27, 2009 Hi rob_w, Take a look here Does 1.25 magnifier need a dioptre adjustment? . I'm sure you'll find what you were looking for!
Shootist Posted January 27, 2009 Share #2 Posted January 27, 2009 Yes it does IF you need it. With younger and good eyes probably not but if you already use a diopter lens on the normal eyepiece of the camera to correct for your vision then you need at least the same strength diopter lens or one step stronger. I use a +1 diopter on all my M camera eyepieces and if I do use the magnifier I jump that up to a +1.5. The magnifier brings the view through the viewfinder closer to the eye and for me the closer things get to my eyes the stronger diopter lens I need to see it clearly. The M viewfinder is set at a distance of 2 meters (7 feet). That is even things far away appear to the eye to be at a distance of 2 meters when looking through the M viewfinder. The magnifier brings that distance closer to the eye. Link to post Share on other sites More sharing options...
aj55 Posted January 27, 2009 Share #3 Posted January 27, 2009 Same here. +1.00 for my regular M8, +1.50 with the magnifier! Age I think. Arnold Link to post Share on other sites More sharing options...
gravastar Posted January 27, 2009 Share #4 Posted January 27, 2009 I've found when choosing a diopter correction lens for the camera or magnifier it pays to check that you can focus OK with both near and distant objects. Because the Leica is a direct vision viewfinder the apparent distance of the object in the viewfinder changes with the object distance, unlike an SLR with a fixed focus screen. In my case with eyes that have limited accommodation there isn't one diopter that suites all distances. For that reason I use a magnifier which has adjustable correction. Bob. Link to post Share on other sites More sharing options...
Aerospace Posted January 27, 2009 Share #5 Posted January 27, 2009 1.25 magnifier works with 50 mm and up,OK. But, is it work with 28 mm or 35 mm ?( for M8 of course) Link to post Share on other sites More sharing options...
Paul_S Posted January 27, 2009 Share #6 Posted January 27, 2009 Yes it does. I use M8 without 1.25x magnifier without diopter adjustment or with magnifier AND +1.0 Link to post Share on other sites More sharing options...
jaapv Posted January 27, 2009 Share #7 Posted January 27, 2009 Advertisement (gone after registration) I've found when choosing a diopter correction lens for the camera or magnifier it pays to check that you can focus OK with both near and distant objects. Because the Leica is a direct vision viewfinder the apparent distance of the object in the viewfinder changes with the object distance, unlike an SLR with a fixed focus screen. In my case with eyes that have limited accommodation there isn't one diopter that suites all distances. For that reason I use a magnifier which has adjustable correction. Bob. But the rangefinder and framelines are projected at a virtual distance of 2 m., so that is the distance you must focus on in all situations, irrespective of the image in the viewfinder. Link to post Share on other sites More sharing options...
Rick Posted January 27, 2009 Share #8 Posted January 27, 2009 Robert... post your glasses Rx and age and I'll give you a diagnosis that relates to your magnifier. Also, does the magnifier you have allow you to change the focus of the magnifier? Link to post Share on other sites More sharing options...
Shootist Posted January 27, 2009 Share #9 Posted January 27, 2009 I've found when choosing a diopter correction lens for the camera or magnifier it pays to check that you can focus OK with both near and distant objects. Because the Leica is a direct vision viewfinder the apparent distance of the object in the viewfinder changes with the object distance, unlike an SLR with a fixed focus screen. In my case with eyes that have limited accommodation there isn't one diopter that suites all distances. For that reason I use a magnifier which has adjustable correction. Bob. But the rangefinder and framelines are projected at a virtual distance of 2 m., so that is the distance you must focus on in all situations, irrespective of the image in the viewfinder. I agree with jaapv here, just like I stated above. You get a diopter that you would normally use at a distance of about 2 meters. The M viewfinder is not a straight through system. Light come in the front and goes through mirrors/prisms/lenses, the rangefinder patch and frame lines are combined/projected somewhere in those mirrors/prisms/lenses and projected to the eyepiece. Link to post Share on other sites More sharing options...
Rick Posted January 27, 2009 Share #10 Posted January 27, 2009 Also, let me know if you use your glasses or if you take them off. Link to post Share on other sites More sharing options...
rob_w Posted January 27, 2009 Author Share #11 Posted January 27, 2009 Robert... post your glasses Rx and age and I'll give you a diagnosis that relates to your magnifier. Also, does the magnifier you have allow you to change the focus of the magnifier? Rick, I have +5 glasses with +0.75 for reading. I am 60 years old and I changed to vari-focal lenses about 10 years ago. I leave my glasses on when using the viewfinder. Any advice gratefully appreciated! I have been following the posts through the day and the first, and most critical, piece of information is that the magnifier DOES change the focusing distance -- confirming my experience that it seems to make the image less clear. It is strange to me that this point is not emphasized more, and that the Leica 1.25 does not include some adjustment by way of assistance. For heaven's sake, it costs enough! I gather there is an alternative product available from Japan Exposures which includes diopter adjustment, so I may investigate using that instead. Thanks Rick, and thanks to everyone for their replies. It really has been very helpful. Robert Link to post Share on other sites More sharing options...
ChrisC Posted January 27, 2009 Share #12 Posted January 27, 2009 I have the Leica 1.25 magnifier .... Robert - The variable dioptre version is : http://www.japanexposures.com/shop/product_info.php?osCsid=bf55d96ca766be9b821ee67d8228b519¤cy=GBP&products_id=109&osCsid=bf55d96ca766be9b821ee67d8228b519 It's a 1.35 magnification though. Sort your own currency conversion [i'm in GB]. They may have some 1.15 versions left. .................. Chris Link to post Share on other sites More sharing options...
Rick Posted January 27, 2009 Share #13 Posted January 27, 2009 Robert, Ok, this is an area that has been asked over the years and sometimes it is difficult to come up with just a single answer for all cases. In your case you have given the specific data needed to explain what you are experiencing. I'll try and explain why this magnifier isn't working for you and I'll suggest some alliterative solutions for you. First, I'd like to make sure you are with me on the optics of your specific prescription and the optics of the range finder and magnifier. First, let's start with you. You have given that you are a 5.00 diopter hyperopic person that is 60 years old and wears a +0.75 power reading glass, over your distance prescription, I assume. Next, let's take a look at your range finder's optical system, without the magnifier. I want you to look through the range finder with your glasses on and you use the top(distance portion) of your glasses and you look at a distant object. That object should require your eyes to do no focusing (accommodation). It doesn't matter where you focus the lens. The accommodative demand on your eye should be zero. Some on this forum believe that because the range finder presents an image at 2 meter that there exists some extra accommodative demand by the visual system when using the Leica range finders. I haven't been able to demonstrate this to myself. And, I'm not sure why Leica would want the viewer to fatigue their accommodative system when using M cameras. So, for this explanation I am going to assume there is no accommodative demand when viewing distance or near objects that is imposed by the range finder, (believe it or not, this will be the contested point in this whole post). Back to you Robert. The Beattles said, "when you were young, so much younger than today" you could accommodate a lot. And, Donder, a Dutch Physiologist in the 18 hundreds, described and measured your accommodation. He came up with a table, Donder's Table (imagine that) that describes how much your eyes can focus at any given age. If we look you up in the table, it shows you have 0.75 diopters of accommodation left. To understand what that means we need to visit another guy named Prentice. He came up with the lens equation that describes how much you need to focus at a given distance. The equation is; P=1/f , Prentice's Law (imagine that). Where "P" is power needed to accommodate and "f" is the distance to the object you want to see measured in meters. So, for example, if you want to see something 2 meters away, you need to focus 0.50 diopters or P=1/2. If, you need to focus 1 meter away, you need to accommodate 1 diopter. If you are still with me I'll get back to your eyes and your M8. When you look at something through the range finder using the top of your glasses (and assuming that you are fully corrected, a lot of hyperopes are not) at an object that is 1 meter away, you need to focus your eyes 1 diopter. But, Donder is telling us that you are only able to accommodate 0.75 diopters. Well, luckily you are not a statistic and 0.25 diopters won't be noticed. So, you are still just fine when you use your camera and your glasses and no magnifier as long as you do not try to focus closer than about 1m. Actually, most people can focus closer and they don't notice a problem but, its there. By the way, Donder tells us that at age 65 you have 0.25 diopters of accommodation and at age 70... none. So, these people have an entirely different situation. And, there is help for them too. Now, let's add the magnifier. The optics of the magnifier seem to change the exit vergence of the finder and place an accommodative demand on the visual system. So, although the image is larger, it is harder to view. I know this because you say it isn't as easy to use (focus) and you state that the image is darker. That is your accommodation interacting with the vergence of the magnifier and causing you to see a darker image. You are percisely at the age where all of this is very critical, so you notice it. A younger person wouldn't notice this small disturbance to the exit vergence at all. The solution is to get the 1.35 magnifier that imploys a system to move the two lenses of the magnifier in order to change the exit vergence of the magnifier. In other words, you can focus it! The big advantage comes in when you look at something close up (even several feet away). You can let the magnifier do the focusing for you and you won't believe how wonderful it is to see things in your finder so clearly. I know you think you see clearly now, but wait until you get this little jewel, you'll change your mind. And, you need no additional diopter lens, just the 1.35 type magnifier. Another solution is to use the lower portion of your progressive lens and find the spot in the glasses that clear up the image through the magnifier. You stated your reading power was only +0.75. That seams low for a progressive. A typical number for someone your age would be around +2.50. That is more like the power needed to use the finder on the Leica. I know that I have read other forum members who do quite well, thank you, with their progressive lenses. They need no diopter lens. They just find the power they need for a given distance by using their progressive glasses. This example varies somewhat for everyone. It depends on your age and the type of refractive error you have and if you use your glasses or not. There are quite a few variables hidden in most everyone's individual case. Just remember, the range finder produces an accommodative demand on your eyes dependant on the distance the object is away from your eyes, irrespective how you have the lens focussed. If, you are over 60 or if you have individual circumstances, you need to accommodate when using the range finder at objects that are near. The Magnifiers make the demand worse. If you are young, none of this applies... yet. So, get the Pearl 1.35 that has the ability to focus and I'm sure you will like it. Hope this helps. Link to post Share on other sites More sharing options...
akiralx Posted January 27, 2009 Share #14 Posted January 27, 2009 One thing about the 1.35x with diopter is that I find I can't use it with glasses as I did with the 1.25x Leica. Link to post Share on other sites More sharing options...
GMB Posted January 27, 2009 Share #15 Posted January 27, 2009 Robert, Ok, this is an area that has been asked over the years and sometimes it is difficult to come up with just a single answer for all cases. ........ If you are young, none of this applies... yet. So, get the Pearl 1.35 that has the ability to focus and I'm sure you will like it. Hope this helps. Rick Leica, Very interesting answer you gave although I must admit that I lost you somewhere after the third paragraph. I also do not expect you to give a solution for every case -- but I still dare to describe my situation because I am also struggling with the rangefinder. And while I have the 1.25 Leica magnifier, I am not 100% as happy with it, in particular as it darkens the picture you see. And I wonder whether I would need a correction lense as well, and if yes what. Basic data: 48 years old; miop since I am 6 years of; about -10 on left eye (+ astigmatism of -1.5) and about -6.0 or right eye (wish astigmatism of -0.5). I wear hard contacts which full correct the view (including the astigmatism) (I achieve 10 out of 10 when tested by my doctor). Not surprisingly, I need reading glasses (about +1.75 left and +1.25 right). it would be great if you could spare some time to share your thoughts but I would fully understand if that's not possible. Cheers, Georg Link to post Share on other sites More sharing options...
Rick Posted January 28, 2009 Share #16 Posted January 28, 2009 Hello Georg, I don't mind a answering your question at all. This forum has given me so many answers over the years, it is my pleasure. Sorry I lost you in paragraph 3. I just know that there are a lot of very technically competent people on this forum. I actually was hoping that someone could challenge me on the often stated opinion that the range finder is somehow focused at 2 meters and therefore people need to get a diopter lens to focus the range finder better once they get to a certain age. I believe the answer has to do with other things. This paragraph has nothing to do with my answer for you, I'd just be curious for the other point of view from one of the technical people here. I might change my mind about this if it could be explained to me. Back to you. When you have your gas perm contacts on and assuming you are not over-corrected (you could easily be) you should be able to look through the rangefinder and see at distance clearly (be sure to clean the front glass in the finder and patch). Your eyes do not need to focus at all, just like looking in the distance without the camera. When you add the magnifier, several things happen. First off you have to move your eye away from the range finder and this makes the finder a little more difficult to use. Next, the magnifier does indeed cause a loss of light to your eye and the image of course is darker and harder to see. Remember, this all adds up to making it harder to use. But, the big problem is that the magnifier makes it harder for your eye to focus through the finder. If you were younger you would not have as much problem with this because you would have a much greater ability to focus your eyes. Add all of this up and you are having problems, like many, with the finder when you add the magnifier. The magnifier just puts you over the edge of what your eyes can do to focus throught the range finder. I'd have to do a ray tracing diagram to figure this all out I suppose. But, I wonder if you are someone could tell me if backing the magnifier out from its threads a little makes it easier or harder to focus? That might help me explain it better. Anyway, you also need the Pearl type of magnifier and I don't think you will find its increase in magnification from what you have much of a problem (it is 1.35X and you have 1.25X). The key with this magnifier is that you can focus it. And, you need to focus it for each distance you are taking a picture at. One thing that bothers me about your prescription is the unequal reading adds. this is possible but, it is somewhat uncommon. Do your eyes really focus differently? Try this. Take a piece of paper with small print on it and use poor illumination. As you bring the paper from your nose out, does the print become just readable at the same point in front of your nose (say 40cm for example) in each eye or are do your eyes have different points that they become just clear? Most would have the points ABOUT the same in each eye (not the time to be an engeneer about this, nothing is exact). If not, you may be over corrected in your contact in the left eye for distance or you truly do have eyes that have different abilities to focus. And, I assume you use your right eye for the camera, correct? Unless I've uncovered something about your vision, you would be happy with the Pearl type of magnifier. But, it still takes a bit of skill. Hope this helps you... Link to post Share on other sites More sharing options...
Rick Posted January 28, 2009 Share #17 Posted January 28, 2009 I gave some thought to the magnifier and although I don't have one, I realize that it must be a double lens system. Is that true (someone who has one)? That would explain why it is difficult to use for presbyopic people. Leica chose a distant focal point for the fixed lenses in the magnifier. The magnifier actually increases the demand on the eye's accommodation as objects get nearer. More so than with no magnification (magnifier) in the optical path. That explains why it is more difficult to use. If, that is true, it should suck if you are "older"... Link to post Share on other sites More sharing options...
gravastar Posted January 28, 2009 Share #18 Posted January 28, 2009 I gave some thought to the magnifier and although I don't have one, I realize that it must be a double lens system. Is that true (someone who has one)? That would explain why it is difficult to use for presbyopic people. Leica chose a distant focal point for the fixed lenses in the magnifier. The magnifier actually increases the demand on the eye's accommodation as objects get nearer. More so than with no magnification (magnifier) in the optical path. That explains why it is more difficult to use. If, that is true, it should suck if you are "older"... Yes, the magnifiers have two lenses and since the magnifier is "non inverting" there's only one optical construction it can have, a Galilean Telescope formed from a negative eye lens and a positive objective lens. I'm older and it sucks . Bob. Link to post Share on other sites More sharing options...
Rick Posted January 28, 2009 Share #19 Posted January 28, 2009 Gravastar... thank you for that. Yes, the Pearl is also a two lens Galilean telescope design except the two lenses can be moved and thus alter the exit vergence. That is why it works so well for "us" and why it doesn't suck. I think it can be adjusted from +2.50 to -3.50. I'm away from my notes but, I think this is right. Link to post Share on other sites More sharing options...
rob_w Posted January 28, 2009 Author Share #20 Posted January 28, 2009 Rick, Chris, everyone, ... thanks for the comprehensive feedback. Rick, think I follow your comprehensive explanation, 'though I might read it through once or twice more to be sure! I am a little concerned about the post that said the Megaperls 1.35 does not work well with glasses on, which is how I would use it. I think I will experiment first using my varifocals to understand the explanation in practice. All being well the Megaperls looks like the answer! Cheers Robert Link to post Share on other sites More sharing options...
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