Checking Rangefinder

[Ed_Ingold]

<p>I have experienced considerable difficulty obtaining sharp focus with a new (to me) M9, especially with longer lenses. I conducted a series of tests with a target about 5' away alongside an inclined yard stick (0.9144 meters), in which produced a short focus by about 2". This occurred with 35mm, 50mm and 90mm lenses. I did not have similar problems with my old M3, but that's a different viewfinder, and using film takes a lot longer to get feedback.</p>

<p>In the 15 years or so since I last used a Leica with regularity, my eyes have gone south, and I wear bifocals full time with astigmatism correction. Part of the problem was difficulty seeing the overlap converge due to slight double vision. In part, this is due to the thickness of my glases, but mostly due to astigmatism. I had much better luck once I installed a +1.5 diopter corrective lens in the eyepiece, which is much clearer than my prescription glasses, and lets me get close enough to see the frame markers clearly, even the 28mm frame. While my success with 50mm and shorter lenses improved greatly, I still had problems with a Summicron 90mm, a recent acquisition. I suspected an actual problem with the lens, and/or a calibration issue with the rangefinder. I was prepared to do without the camera for several weeks (and $500 or more in CLA fees), then had a brainstorm.</p>

<p>With the camera on a tripod, I tried shining a laser pointer through the eyepiece. After some fumbling, I was able to shine the beam through the focusing spot and the rangefinder window. This produces a double dot on the target, which converges when the rangefinder is focused. It is very difficult to hold the laser straight and centered, but I made a little rubber fixture to aid in alignment. Bingo! The problem is with my eyes, not the camera or lenses. I obtained sharp focus every time. Some oldtimers may remember the Graflex Focospot rangefinder, which used a lamp to do essentially the same thing as my laser. (I still have my Graflex with rangefinder, sans the lamp attachment.)</p>

<p>Stage two, what if I simply shine the laser on the target outside the camera, and use the rangefinder by eye on the reflected spot? It turns out focusing is very precise using the spot alone, since it has high contrast and reflects exactly from the plane at which it is directed. It's a lot easier to point the laser like a flashlight and focus by eye than to try to maintain perfect alignment with the eyepiece. As far as I can tell, its just as accurate as using the laser to collimate the rangefinder directly.</p>

<p>This method would probably work in the field, at least for immobile objects. You can see a low power green laser at 50 yards in broad daylight. However, a jiggling laser spot on people would be, um, intimidating to anyone who has seen CSI Miami, not to mention impractical on any moving object. Nonetheless, it is a simple, inexpensive way to validate the operation of a camera at home before committing it to Mr. Goodwrench.</p>

<p>Stage three is to purchase a 1.4x magnifier for the M9, which will bring the M9 viewfinder up to M3 standards for 50mm and longer lenses. It's not cheap, and may be a PITA in practice, but they're not taking trade-ins on old eyes.</p>

<p>I have attached a center crop from a test shot with a 90mm Summicron at f/2, approximately 5' from the subject. A laser pointed at the object while manually focusing the lens. The knife is aligned with the 20" marking, but looks a little off due to parallax.<br /> <br /> <img src="http://d6d2h4gfvy8t8.cloudfront.net/17876072-lg.jpg" alt="" width="700" height="467" /></p>

[Ed_Ingold]

<p>I'm having trouble linking the image.</p>

[astral]

<p>I like the idea of using a laser pointer to give a high contrast spot to focus on. This would be useful kit for my Leica SL and a couple of other old cameras with plain matte or fine microprism screens, as well as M and Barnack Leicas. Usually I skirt around near-range focusing with rangefinder cameras by exploiting depth of field, or by using an SLR. In particular, I find that using any lens longer than 50mm on a rangefinder is rather hit-and-miss due to quirky or squinty cameras and eyesight. Thanks for the tips.</p>

[rgerraty]

Great science here. Well done. I occasionally now have difficulty focussing with the M9, especially when I'm tired. I

remember once my M5 RF vertical alignment was out just a little. While technically that needn't matter for focussing it did

slow me down and was very distracting. Hope your x 1.25 proves satisfactory.

[Brian1664876441]

Very clever idea! I will be doing this for shimming lenses.

 

I use a 1.25x magnifier, have a Leica magnifier and a less expensive "Chinese" version. The latter runs ~$100 and I find it as good as the Leica. I use the two interchangeable on my cameras. I can nail the focus with the 135/2.8 Tele-Elmarit on the M8 using the 1.25x. I also wear very thick glasses that have to be special ordered.

[Ed_Ingold]

<p>With astigmatism, the vertical alignment looks off even when it isn't. Fortunately, my left eye is much better, but results in nose prints on the LCD :). So far my glasses aren't all that thick (+1.5), but keep my eye too far from the finder to see the 28mm frame lines. There seems to be an internal reflection that causes some doubling too.</p>

<p>Without the laser as an aiming guide, my sharpest focus would often fall on the 16" to 17" mark, even with a shorter lens. That's not quantitative, but using a similar setup each time. Why I would consistently err on the short side is a mystery. The photo I posted was the first try out of five or six using the laser, and all were right on mark.</p>

<p>I should be able to jury-rig an adapter that would hold the pointer in the flash shoe. James Bond would be right at home with that setup.</p>

[SCL]

<p>Hi Edward - I remember seeing somebody recommending something similar about 10 years ago, they were using the setup to actually align the horiz./vert. components of rf cameras. Like you, I've gone down the path of thinking my gear is out of alignment only to discover it was me, not the cameras (usually). Although I don't have any digital RF cameras, I have a number of film ones, and generally check them once or twice/year for proper alignment, as some of them seem to lose the fine edge when they get lightly knocked about in my car or when I'm out hiking with them. Thanks for sharing the results of your investigation.</p>

[christopher_junker1]

<p>Edward, Thanks for your post. Your comments really helped as I've just had eye surgery and everything vision wise has changed for camera use. My laser pointer will be getting new batteries and going into my camera bag.</p>

[Gus Lazzari]

<blockquote>

<p>"RF vertical alignment was out just a little. While technically that needn't matter for focussing it" <em><strong>Richard G.</strong></em></p>

</blockquote>

<p>Just to "clarify", if the "vertical cal" is off even slightly, in addition to labored focusing, the "snap-too" <strong>wow effect</strong> of the wonderful Leica rangefinders <strong>is lost</strong>.</p>

 

 

<blockquote>

<p>"a Leica magnifier" <em><strong>Brian S.</strong></em></p>

</blockquote>

<p>The magnifier is a very good workaround for the issue of low magnification"wide-angle" rangefinder views... </p>

 

 

[Ed_Ingold]

<p>That "snap" or "wow" effect of perfect alignment in the rangefinder is what I remember from the early days when my eyes were still flight grade and viewfinders (i.e., the M3) had 0.95x magnification. The manual talks about lining up the partial images, but that's not quite how it works. The M2 wasn't quite as good, but a lot better than the "let it do everything" M9.</p>

[Ed_Ingold]

<p>Having assured myself that the rangefinder was properly calibrated, I ordered a 1.4x magnifier for use with lenses 50mm and longer. It arrived a couple of days ago, and works well enough I can use a 90mm and 135mm lens at maximum aperture. It is inconvenient to remove the diopter lens from the camera each time, so for the moment I will leave it attached to the magnifier. There's less need for assistance with 28mm and 35mm lenses.</p>

<p>There are cheaper magnifiers than ones branded by Leica, but this one works well, and is much smaller than others I've seen. It is a small Galilean telescope with two elements - a positive objective and negative eyepiece - with a case that attaches to the neck strap and a short tether.</p>

<p>In the meantime, I've experimented with the laser and an Hasselblad. You can't point it through the viewfinder, but the laser makes a distinct spot on the subject (inanimate subject) for focusing on a plain ground glass screen. Focusing is usually difficult unless you have an edge or bold feature in the subject with good contrast. Done right, the camera resolves textures far too indistinct to see while focusing, like concrete or wood grain.</p>

[james_elwing]

<p>'The Japan Exposures magnifiers are quite popular as they're much cheaper alternatives to the Leica Camera ones. The optical quality is good, but there is some dimming. One of the best features perhaps is the built-in diopter correction (-3.0 ~ +1.0), which allows you to dial in the correction to your exact eyesight needs. They come in 1.15x, 1.25x and 1.35x strengths. The 1.15x magnifier is quite popular as it magnifies the view just the slightest bit while still allowing you to see all but the widest framelines - but perhaps more importantly, allows for a variable diopter adjustment. These magnifiers do not come with a leash or a pouch - so storing it when removed is left up to you. These are a great combination of price, performance and options.'<br>

from 'La Vida Leica' website. The 1.35 is great on the M9, but it's best to set the dioptric correction & tape up with aluminium tape, as the 2 parts come unscrewed & eyepiece ends up on the ground </p>

[nathancraver]

That's a good idea using a laser. What would be really nice is to make a laser that mounts to the flash shoe and has a

remote (wired) button that is pressed to turn the laser on and off. The button could be stuck to the front of the camera, or

the top using a double sided adhesive. Maybe something like a tactical laser used on rifles, but with a hot shoe mount instead of a picatinny rail mount. Many of those come with a remote switch. I'm going to have to research this further.

 

One thing that I do is to not directly focus with the image in the patch, but to use the top or bottom edge of the patch and

align the image in the patch with what's above or below the patch. My new Zeiss Ikon's patch is so bright that sometimes

it's hard to see the normal image, so this method helps a lot. It's pretty much the same method as using a split image

screen on an SLR. Obviously this only really works with a camera that has a well defined patch, it won't work on a Canonet or Olympus.