Visoflex III needs focus adjustment -- how?

[rfaspen]

So I have started playing with my Micro-Visoflex III. BTW, the Micro-Visoflex III is just a regular Viso III that has interchangeable screen capability. Sadly, Leica only made 2 screens and one of them is useless for most application.

Anyway, I have been using the Viso with a Bellows-II and doing some closeup work without any noticeable problems (except for one that I will describe in another thread).....

... But the other day, I attempted to use the Viso with my Tele-Elmar 135 (in the OTZFO focusing mount) just as you would for normal shooting. I was taking photos of some friends and their farm animals. At this point I was using the Viso on an M9, and I only glanced quickly at the screen on the back of the camera and assumed all was good.

However, looking the images on the computer back home I could see that I had a severe focusing problem. The actual point of focus was always behind the point that I was focusing on (with the viso ground glass screen). The amount of back focus (?) varied with the distance to my target subject. If I focused on a goat about 15 feet away, the actual sharp focus would be about 3 feet further away. If I focused on something about 4 feet away, the actual focus would be about 10-12 inches further back.

So, something's wrong. I did some confirmation testing. I took the Viso and M9 in the back yard and did some careful focusing and shooting. Back focus (I think that's the right term) is still there. I then put the Viso on an M240 and did the same careful focusing and shooting. Exact same behavior.

There's something amiss with the viso. I could only find extremely little information about what could be wrong, and how to adjust it, and that was mostly on another Leica oriented forum. Those threads were unfortunately too ambiguous for me to get a grasp on the situation.

I read some mentions of mirror adjustment and shimming (but where?). I'd love to learn more explicitly about these things....

I know there's visoflex experts here 😀 Any help or hints would be much appreciated!

 

[JMQ]

Just to rule out variables, have you tried another lens? I too have the micro-viso III, though it's been rarely used lately.

 

[Ronald M]

Move the focus screen up or down. If back focusing, the screen is too high.

On a regular Viso 3, 4 screws hold the screen in place. I do not recall any simple adjustments.

The mirror may not be going back as far as designed .

The is supposed to be 1 mm between arm screw and shutter just before the mirror starts going up. The very last Viso 3 were made with a shorter screw because digital had higher deck. It looks as long as regular, but the last 1/4" can be removed. Mine was very difficult the first time. now it works on high deck cameras perfectly. It has a red Leica logo rather than blue. Some reshape the the arm get same effect, cut and weld.

 

[rfaspen]

Thanks for the replies so far folks!

I tried another lens (a Hektor 135 this time) and the focus issue remained.

I'm not entirely sure how to go about moving the screen up or down. Or what the best practice would be to go about determining up or down. And of course, how I make such an adjustment permanent. Of course it would be good to determine first if I need the screen to move up, or down.

I read about shims, but I'm not entirely sure where to place them, what shape to make them, etc. I'm also unsure about adjusting the mirror (which would affect focusing). I noticed two small posts that the mirror rests on when in the down position. I'm assuming those can be adjusted....but how?

Luckily, my micro-viso fits nicely on all my M bodies. Only minor adjustment to the length of the screw at the end of the release arm is necessary between them. I would like to use my visoflex a bit more often. I hope I can find a solution to the focusing problem...

 

[Beemermark]

As far as I know the screen isn't designed to adjust up or down. I only have the regular III so I might be wrong. There are no "focus" adjustable parts. The screen could be installed incorrectly but that seems unlikely, especially since the focus is correct for close up work. The DOF is shallow for close up work and that would you show as incorrect focus if something was wrong with the Visoflex. Are you sure you have the right adapter for the 135mm lens?

 

[JMQ]

If all else fails, send it to DAG for correction.

 

[rfaspen]

OK.
I'm stunned there aren't more responses here. I just know there are Leica experts here at RFF who know a little something about visoflex (and beyond).

Working off of some threads over at l-forum, I have deduced that there are two small mirror posts (the mirror rests on these posts in down postion) with eccentric surfaces that provide adjustment. I have noticed that my GG (ground glass) image is just a little shifted up, so I'll try to remedy that. This adjustment is unlikely to solve my primary focus issue though. I read that the mirror adjustment posts are either 5/32" or 4mm and difficult to access. Of course they are.

The focus screen position is adjusted by shims below the focus screen frame, which is the part the viewfinder attaches to. From the l-forum threads, I gather its best to simply loosen this frame and slip shims into the gap, as opposed to fully removing the frame. There's some little bits in there that can go missing.

I have confirmed that my focus issue is not related to lens or lens mounting configuration. It is not surprising that the amount of back focusing increases as focus subject increases. Its a ratio. That would explain why my very close-up images (3-8 inches) were sufficiently in focus that I would not notice the problem. The amount of back focus for those images would have been much less than an inch (perhaps 0.2") and covered by depth of field, even at the relatively high magnification.

So, shim adjustmet of the focus screen seems the necessary path right now. I'm a little surprised that my viso would be so far out of adjustment. It has never been opened since leaving the factory, so Leica sent it out this way. Because this kind of adjustment is not one that typically happens over years of use and handling, I am a little concerned by the fact I'm experiencing this focus issue.

Has anyone fiddled with their visoflex? Tips, warnings, suggestions, all welcome before I start messing around.

 

[rfaspen]

BTW, I was asked why bother with visoflex in 2018?

The viso system is still relevant. I mostly use it with the bellows II for close-up work. I can use my stunning, massively underappreciated, tele-elmar 135/4 with great results. I can use the visoflex system on any of my M cameras, including the M240. This is important because I have a slim hotshoe connector that allows me to use flash as well. I can't do that if I opt for the electronic viewfinder instead of the old viso setup.

For true telephoto (long focal length) uses, the visoflex is terrible. But I still do this on occasion, just for the challenge and quirky fun of it. But don't weep for me. I have a Nikon system (D/SLR) when I need to be efficient.