Linhof Back Mystery

[jjstafford]

See this link, please: http://elearning.winona.edu/jjs/linques/

Any ideas?

 

[Jeff Dyck]

I would have to assume it is for a fresnel screen.

i.e. Here

 

[jjstafford]

That was my take, too but the US national distributor, Bob Solomon, jumped down my throat when I suggested it, saying the fresnel has been mounted on the other side of the GG for three decades. Dunno, but it is a good mystery. If the ledge is not to be used, I wonder why they machine it, unless it's too hard to make a new setup once every thirty years.

 

[David A. Goldfarb]

If it's really a Tech V back, indeed there should be a post with an adjustable rest for the groundglass in each corner (that is how the back is "zeroed" so that you can interchange cammed lenses between cameras), and the groundglass does go on the outside. My guess is that you have something other than a Tech V back (like maybe a Tech III back) on your Tech V.

 

[MichaelBriggs]

In another forum Bob Salomon stated that the Tech V and Technikardan use the same back. Your photos show a different back from the Technikardan. It is missing the adjustable screws and adds the extra machined ledge. I agree with a David -- you don't seem to have a Tech V back.

Did the back come with a Fresnel lens? Perhaps it is supposed to have one. If the back doesn't have the original Fresnel / ground glass configuration, the focus may be off. I suggest testing to be sure of the focus. One way is to photograph a ruler or a fence at an angle, and compare the best focus in the negative with the intended focus point.

 

[jjstafford]

Bummer, but thank you for the help, David. Guess I had best look for a V back.

 

[MikeS]

If it's really a Tech V back, indeed there should be a post with an adjustable rest for the groundglass in each corner (that is how the back is "zeroed" so that you can interchange cammed lenses between cameras), and the groundglass does go on the outside. My guess is that you have something other than a Tech V back (like maybe a Tech III back) on your Tech V.

Looks a lot like the back on my Tech IV. On it, the fresnel is mounted in front of the GG, and would rest on the lower machined portion. Of course my Tech IV is from 1959 or maybe 1960 which is lots older than just a few decades!

On a different note, there's something I can't figure out. If moving the GG alone will 'zero' the back to make the cams interchangable, am I missing something, or wouldn't the settings of the inf. stops have more to do with it? I mean, if my GG is 1/32" further back than one on another camera, when setting up both cameras, just setting the inf. stops 1/32" further back on the track should make it so that one cam would work with either camera, right?

-Mike

 

[David A. Goldfarb]

One would think that adjusting the infinity stops should work, and sometimes people do it, but apparently it's not as accurate as the zeroed back system, though I'm not exactly sure why. I would guess that the accuracy of the rangefinder system is dependent not only the distance from the lens to the groundglass, but also the position of the feeler wheel on the cam with respect to the groundglass, so if you just adjusted the infinity stops without having a zeroed groundglass, the start point of the curve could be slightly off, which might produce good enough results for many purposes, but if you really want to focus at close distances with the lens wide open, it might not.

For a Tech IV or III, cams have to be ground for the camera and the back together, so the serial number of the camera is on one side of the cam and the serial number for the lens is on the other side. For a Tech V or MT, cammed lenses are interchangeable, so there should be a serial number only on one side of the cam.

 

[jjstafford]

David's explanation of the the RF's mechanical algorithm seems correct.

One last query, please; my "V" has serial number 79217 and came with a "IV" 135mm Planar and cam. The cam has the correct matching body and lens numbers, and it does focus accurately throughout the range. The front rise is a plastic lever. I removed the accessory shoe to see if there was a different number beneath and there is no number underneath. Given that the body and cam match numbers, could I have a transition model V?

 

[David A. Goldfarb]

That's a possibility. Bob Salomon would know. I know the plastic lever was earlier than the metal lever. I think there was such a transition model IV/V on eBay recently (maybe not US eBay).

 

[MikeS]

One thing that still doesn't make sense, If the GG can be 'zeroed' by what sounds like a relatively simple modification to the back, why doesn't Marflex offer zeroing service, so that a IV could from then on use V cams? I wonder if this isn't a case of German perfectionism? I mean with a Speed Graphic, they made stock cams, and granted they made a couple of different cams for each focal length, once you got the right one, it was good to go.

I have a 210mm Rodenstock Geronar that I just bought a few weeks ago, and I also had a 'stock' 210 Linhof cam, and with a bit of filing, and sanding, and a bend on the end part, I now have a cam that I can use perfectly. Is it as perfect as a cam I might have gotten from Marflex? I doubt it, and chances are if I was going to use the lens wide open I might notice it being slightly off, but I usually use the lens at f16 or smaller, and so far have never noticed the focus being off, and it didn't cost me $250.00 to get the cam!

-Mike

 

[David A. Goldfarb]

One thing that still doesn't make sense, If the GG can be 'zeroed' by what sounds like a relatively simple modification to the back, why doesn't Marflex offer zeroing service, so that a IV could from then on use V cams?

Good question. I suspect they could do that, but it would only make sense if you had a IV with no cammed lenses. If you already had cammed lenses for the IV, recalibrating the back would mean having to have the lenses re-cammed. I suppose one could have two backs for two different calibrations, but that seems like a hassle.

 

[jjstafford]

GOOD GRIEF, the mystery deepens!

My "V" (as evinced by serial number and white plastic rise/fall crank lever which, BTW, doesn't rotate to change direction, but pulls in/out) has an early rangefinder body, too.

It has this one: http://elearning.winona.edu/jjs/linques/huh1.jpg which with the right attachment can do this: http://elearning.winona.edu/jjs/linques/huh2.jpg

Yes, the RF body itself is not flush with the top of the camera as the late model is (unless you count the screw that protects the option's hole) however the flash attachment is located further down.

 

[MikeS]

Another thing that doesn't make sense with the idea that moving the GG on the back 'zero's' it... If you're moving the GG in relation to the spring back frame, you're changing the distance of the GG from where the film will sit when inserting a film holder! Their term of a zeroed back must be something different.

-Mike

 

[David A. Goldfarb]

Well, it just so happens that I had to repair the guide plate for one of the Graflok slides on my Tech V a couple of days ago, so I had a look under there. I think there are two sets of adjustments actually--one to zero the back and one to adjust the groundglass.

Regarding my repair, if you're curious, the plate cracked--it's plastic--so I super glued it, but eventually it will have to be replaced. The camera is so overbuilt, you would think this part would be metal, since it can flex a bit from the pressure of the slide holding in a rollfilm holder.

 

[MikeS]

David:

That makes more sense. I assume the adjustment to zero the back was on the back itself (would move the back itself forward & backward, not just the spring back portion)?

-Mike

 

[David A. Goldfarb]

It seems that way, yes. There are some screws in there which I'm guessing adjust the position of the back, and then the spring back has four screws for adjusting the position of the groundglass with respect to the back.