"Mad project" Summaron goggle question

So I got myself the 35 Summaron goggles which - if I'm not mistaken -

have been designed to match the M3 0.91 VF/RF and its particular

optical design. My original idea was to see if they could in some way

be used/adapted to work as an add-on VF/RF combo for the 21mm lens on

a 0.72 M6... Apparently they can't - at least not straight out of the

box.<p>

While the "footprint" seems to be compatible and all parts which are

in the way could suitably be stripped, the optical allignment would

only allow for the RF patch to be spot on at infinity - but when

focussing any closer the patch would drift out of allignment to quite

some extent. Apparently, each of the two separate lens systems

contained in the goggles have been glued into perfect position by the

time of the original assembly, with tiny screws adjusting them into

place while the glue was drying - at least that is what I came up with

at close examination of the goggles' built.

<p>Now, has anybody successfully tried to, hmmm, "unglue" let's say

the RF-side goggle-lens to re-calibrate it for use on a 0.72 VF? I

have read that Reinhold Mueller from Canada used to make 21/goggle

conversions, but I've also heard that he stopped doing so and that

close focus issues have occured with his conversions, but I'm not sure

whether any of these informations are just rumours...

<p>Thanks for adding your thoughts/experiences.

Lutz

 

In the Leica M compendium by Jonathan Eastland, there is a small section about the ABRAHAMSSON 21mm f/3.4 with goggles, with photos, and another picture of one mounted on an M4-P. Pages 98 and 104 respectively. I know that about a year ago, MW Classic Cameras had one [lens + goggles] for GBP1295 and it sold.

 

Maybe Tom is the one to approach?

 

Regards

 

Bruno

Lutz,

 

The goggles will work on any M regardless of magnification but only for the lens they where designed for. Simple explanation, all non goggled lenses work on all Ms.

 

Unglueing the RF end is not difficult, remove the rectagular lens(s) and associated components, there is a plastic bit that will melt during the next phase (I know!).

 

Heat the rest in a domestic oven to about 150C, don't use local heat the glass might crack. When hot (1/2 hour or so) untwist the front cover with a DRY towel. Re-heat and unscrew the second section.

 

In the second bit is the main correcting lens/prism and the cover contains the fine adjustment prism. These can drop out, best to let them and re-glue later.

 

This is conjecture... First step would be to adjust the viewing lens' to frame your 21, (back off ground glass method, if you want to adjust the position of the frame unglue the elements, heat again, and reglue with UV cure glass glue, not conjecture, I have done this). Second step adjust RF end to get near and far correct, this may require a different strength of prism though.

 

I have some 'variable' prisms from an eyetester would you like one (mail me).

Definitely contact Tom. He is in Japan now for the photo Expo, and will be going to the LHSA Spring Shoot right after that, but he will be back April 11.

 

Ed

Lutz

 

Further to what Huw has said, it appears that the ones I mentioned had the 21mmlens's mount adapted to bring up the 28mm frames, and then the drop in magnification from .91 to .72 ,using the goggles, took the view down to about that of a 22mm lens [ near enough !]

 

That is how it is explained in the book.

 

Regards

 

Bruno

<div></div>

Lutz

 

Having read the section again it is clear that Tom Abrahamsson employed Reinhold Mueller to do the work for him.

 

Regards

 

Bruno

Thanks for your detailed how-to, Huw, which instantly reminded me of the good ol' days in the late sixties/early seventies when baking FIMO plastic clay in the oven was *the* hobby of choice! :-)<p>If I got you right, there is a chance to unglue and purposefully misallign the RF prism - but no absolute warranty to actually succeed in getting it to match the 21mm scale's requirements...? Is that why you are suggesting to try the varyable prism instead? Is there a better chance that that one will meet the requirements? If so, let me know how we could handle this offline.<p>My humble understanding at this point is, that very much depending on the angle and position at which the prism is located in front of the RF window, far and close match in respect to the VF are on or off, respectively - and independently from each other. So, a very careful calibration would have to be executed while the glue isn't yet rigid. Correct?<p>Bruno and Ed, thanks for pointing me to Tom - in effect, it's from his site that I originally picked up the idea, years ago. And if memory still serves me correctly, it was him who mentioned Reinhold Mueller to be no longer in business for it. Anyway, I will try to get back to Tom on this.

Lutz, Mueller's method was to graft the entire googles/flange assembly from an RF lens to a 21 S/A, not use the removable googles separately. He had to make changes to the lens' focus cam so it focused correctly (remember if you take the googles off a 35 RF it won't focus right, the cam is calibrated to be used with googles). Last I heard (and this is hearsay) Reinhold was having some health problems and was not working. Perhaps Tom A can be the best source of further info. BTW, there were a few coversions done on 21 Elmarits but the problem there was they encroached on the finder much more than the S/A. The Voitlander 21 would seem a good candidate however.

Lutz,

 

Leica service manuals say to mark the units when adjusted, dismantle, then glue. I was suggesting the variable prism as a 'can it be done' and 'dear optican have you a prism of this strength please'.

 

Huw