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Viewfinder magnifiers - do they help with focussing?


The Kevster

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I got the 1.25 Leica magnifier some years ago, in fact somehow I ended up with 2 of them. I find that the advantage it adds through magnification, it more than subtracts through loss of brightness and contrast. I'm not sure if that's true of the higher magnification version as I've never tried it. The other downside of the magnifiers is the need to remove and reinstall them when switching to-from wider lenses, because you can't see the frame lines. I found that a real chore, unless using 2 bodies.

 

One thing I should mention in passing, is that fingerprints and smudges on either or both rangefinder/viewfinder windows can have a surprisingly strong detraction on focusing, so it pays to keep an eye on them. I don't ever recall touching them with my fingers and yet they always seem to be smudged. I keep a microfiber cloth nearby when I'm shooting, and give the windows a breath-fog and a wipe now and then between shots.

Edited by bocaburger
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Theoretically a magnifier does not add any accuracy to a 50 mm lens. The measuring base of the M9 is ample for that focal length...

 

Again, rangefinder accuracy has nothing to do with the lens or focal length. It varies with base, distance, vision, and magnification. The accuracy is the difference between the plane of focus, and where you intended it. What you are talking about--just getting the focus somewhere in the depth of field--is another matter.

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I said nothing of the kind Dof was never mentioned. The baseline needed to focus a lens of a given focal length is determined by the ability of the eye to resolve two points (see G.O.) That baseline is ample for any 50 mm lens. So magnifying the baseline will not add any meaningful accuracy. However that is theory. If one finds a magnifier comfortable it is perfectly all right to use it. It is doubtful it will add to accuracy in that case, but may well add to ease.

Edited by jaapv
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HI Jeff

I also have an astigmatism, (not serious) - but the contact lens solution is still excellent - they are also UV filters.

 

Of course, I agree about trial and error, but it seems odd not to try something which is such a complete solution if it suits.

 

Thanks, Jono, but I still like sunglasses (which are very protective and easy to remove indoors), and I'm really bad with sticking things in my eyes.:(

 

Jeff

Edited by Jeff S
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I can add one bit of information to this discussion for the benefit of the crowd at large.

 

I am farsighted, so I wear glasses for close-up work. I asked my optometrist whether the act of focusing on a Leica M9 or other rangefinder is a close-up task or a distance task. He said it was a distance task -- even though the viewfinder is close to the eye, the ability to align the images in the center is relying on information in front of the camera. Therefore, assuming one's distance vision is okay, one wouldn't benefit by changing the diopter that ships with the camera.

 

Best,

Jeff

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I said nothing of the kind Dof was never mentioned. The baseline needed to focus a lens of a given focal length is determined by the ability of the eye to resolve two points...

 

"The baselength needed to focus a lens of a given focal length" comes from equating the d.o.f. to the accuracy. I don't have Osterloh, and it has been quite a while since I looked at that book. If I remember, there is a diagram and a chart, but no derivation of anything. You need a book with a derivation.

 

The rangefinder accuracy is plus or minus ru^2/(mb), where r is the factor for vision you are talking about, m is the magnification, etc. So the bigger the magnifier, the better the accuracy, in theory.

 

You are trying to get the focus within the d.o.f. and concluding you don't need a magnifier with a 50mm lens. That is one way of looking at focus; another way is that there is only one place to put the plane of focus. From that viewpoint you would use a magnifier.

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Well, it is time you looked at Osterloh again It is explained in detail. If you don't have it, Erwin Puts' new compendium can be helpful for you as well. I am saying nothing about DOF. Stop misinterpreting my words.

Edited by jaapv
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Well, it is time you looked at Osterloh again It is explained in detail. If you don't have it, Erwin Puts' new compendium can be helpful for you as well. I am saying nothing about DOF. Stop misinterpreting my words.

 

...well corrections are always welcome, but I'm sure the "baseline [sic] needed to focus a lens of a given focal length" comes from the depth of field.

 

As in:

 

"...the focussing error [accuracy] is E=+- U^2 R/L where ... L = physical baselength X magnification. Relating this to the formula for depth of field, we can find the effective baselength required for any focal length and f-stop ..."

 

(from a well-known book)

 

And here again, the accuracy of the rangefinder is proportional to the magnification.

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I found the shade I purchased from Lutz Konerman - LeicaGoodies really helps in bright light situations. Bought one for my M6 years ago and because of postage decided to get a spare which I forgot I had until a few months ago. (had it for 10 years) So I tried it on the M9 and yes, can report remarkable improvement. I also use 1.25 x magnifier. My dealer told me years ago that a square of yellow cellophane does the trick too.

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It might also be worth mentioning that you can get a perfectly adequate 1.25x magnifier on eBay for £25, instead of a Leica adapter for £250. What's the point of a Leica-brand magnifier on your eyepiece if the price makes your eyes water so much you can't focus anyway? :D

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Thanks, Jono, but I still like sunglasses (which are very protective and easy to remove indoors), and I'm really bad with sticking things in my eyes.:(

 

Jeff

 

Well, that's simply practice - something you can get used to pretty easily - and the normal contact lenses are 100% protective with respect to UV - and of course there's no need to take them off indoors because they don't reduce the light.

 

I actually visited my optometrist today for my 6 month check up - he says there are now special disposable contacts for long sighted people with significant astigmatism (apparently mine's not bad enough to warrant them). He was saying that lots of his older customers were doing the same thing (going to contacts with one stronger than the other). It doesn't affect your 3d vision,

 

It's just a joy not to have to wear glasses after 10 years of it, and to be able to focus really easily on the M9 - 5 years into this, and on the rare occasions I run out of lenses going back to the old varifocals is a real pain in the backside!

 

all the best

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I got a 1.25x magnifier today and pretty much went “aaaaaah” after putting it on. What a joy to focus and just look through the viewfinder! I’m with bocaburger on this one; the magnification far outweights the magnifiers potential problems for me. I tried it in a dim room / interior situation; I didn’t find the diminished contrast or brightness to have any impact – in fact I had to unscrew the magnifier to notice the difference in these respects.

 

Unfortunately, it would have taken the 1.4x magnifier to go back to both-eyes-open focussing à la M3, at least after first comparison. But as the 1.25x makes it possible for me to use 28mm, 50mm, and 90mm this was the better option for me. I don’t go wider.

 

I, too, have been a wearer of glasses for two decades. I gave contacts a try occasionally, was never satisfied so I stopped trying them until I thought “well, there certainly have been advances here, too?” last year. I seem to have been right; the contacts I now wear per default are far better than the uncomfortable things I tried on ten years ago. In fact, they are nicer to wear than the Dailies I used 15 years ago for sports.

 

Cheerio,

-Sascha

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I have both the 1.25 and the 1.40, and rarely use either. I find that, for me, the small reduction in brightness and contrast hurts my ability to focus accurately more than the increased magnification helps.

 

One thing I've noticed is that keeping the two finder windows clean -- as clean as you'd want the lens to be -- makes a HUGE difference. My thumb has a tendency to smudge the main window when I cradle the camera, which degrades the finder contrast and sharpness ever so slightly. After I noticed I was doing this, I developed a healthy obsessive compulsive disorder by getting into the habit of cleaning the windows every time I pick up the camera. My focusing ability went way up as a result.

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I found the shade I purchased from Lutz Konerman - LeicaGoodies really helps in bright light situations.

 

It really does work, and I was pleasantly surprised. Got 'em on both early M7s.

 

OT: At one time I think they sold a rubber-bumper for the eyepiece. You can see it in the pictures of the Leicas on leicagoodies.com

 

No longer advertised.

 

But these work almost as well and are pennies each.

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Comment Jaap? The passage quoted (Goldberg) suggests you are mistaken.

 

The depth of field theory leads to an inequality that, depending on how it's rearranged, gives you the maximum usable focal length, maximum usable aperture, or minimum usable baselength. This is where the charts come from. Same as I have seen it in other books, Cameraquest website, etc.

 

So I don't think you can crusade against d.o.f. formulas one week, and use them for something else another.

 

(But I'm sure you are right, that it really comes down to how the magnifier works, or doesn't work, in experience.)

 

"...the focussing error [accuracy] is E=+- U^2 R/L where ... L = physical baselength X magnification. Relating this to the formula for depth of field, we can find the effective baselength required for any focal length and f-stop ..."

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What you are saying is nonsense...Enlarging it [measuring base] by a magnifier will only push the accuracy even further beyond the resolving power of the eye, so it won't solve underlying problems.

Before you ask: Gunther Osterloh, Advanced Photoschool pp 40 ff.

 

...The baseline needed to focus a lens of a given focal length is determined by the ability of the eye to resolve two points (see G.O.)...

 

well I bought this book just to follow up. The point of the diagram (fig. 31 right, p.47 in the current printing) is that accuracy varies with magnification. The error a or a' is calculated from the geometry and compared to the depth of field. He skips the details, but your clue is on one of the next pages, "...when this focusing error is smaller than the depth of field of the lens, it will not be recognizable in the picture."

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Without getting into an argument about optical theory, I have to say that I own the 1.4, 1.25 and also a diopter for my m9 (-2) I find them all useful, and have found that since my diopter correction is mild, I don't have to use the diopter with the magnifiers, though it does help when shooting wides.

 

I have found my focusing accuracy to be improved, and especially enjoy using the 90 with a tighter window view.

 

And I enjoy the 2 eyes open trick with the 1.4.

 

Expensive game, but not compared to what you spent on your camera and lenses.

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I now use a mag on both of my M9s. A 1.25X on one M9 dedicated to the 21/1.4, 28/2 and 35/1.4. A 1.40X dedicated to the 50/0.95, 75/1.4 and 90/2.8 on the other M9.

 

My in-focus hit ratio went way up after installing them, so they never come off. The difference was immediate and dramatic with the 50/0.95 and 75/1.4.

 

Theory aside, use it if it works, don't use it if it doesn't.

 

I shoot a lot in quite dim ambient and do not detect any significant loss of brightness, but I do clean them before each assignment.

 

-Marc

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