Spiratone 400mm mod for Visoflex

[rfaspen]

...
My process for shortening the lens tube was rather low tech, but I ensured that it worked well, and very precise.

First, I used a "marking gauge" to mark a line around the lens tube that was about 12mm from the newly flattened end. That's less than the 13.8mm I anticipated I would need to remove: my plan was to sneak up on my final tube length by slowly removing material and checking infinity focus, removing more material (if needed), checking infinity focus, remove material.....until I get what I want.

The marking gauge I used is a common woodworkers tool. Sorry I don't have a ready image of it, but it consists of a fence and post with a sharp "scratch point" held at an adjustable distance from the fence.

I then used my jewelers saw to cut the lens tube at the scratch line around the tube. My jewelers saw is an adjustable version with a 5-inch blade that is actually a diamond-encrusted wire. I am confident that a thin-bladed hacksaw would have worked equally well here.

Once I made my cut, I needed to free the mounting flange that was epoxy glued into the end (the flattened T-mount). I made a short cut and pried the tube off the flange.

You can see where I cleaned the inside surface of the flange to bare metal. Necessary for a good epoxy bond later.

Now, time to shorten the tube.
I used a common technique in the woodworking shop. Sandpaper attached to float glass (plate glass) with a light spray adhesive. I then placed the tube end on the grinding surface and ground away with circular motions.

After some initial grinding to smooth the tube end, I used my caliper micrometer to check the tube length all around the tube. My initial cut with the jewelers saw was remarkably precise and the tube length was almost consistent all around. I marked the "high points" where the lens tube was a little longer with some sharpie and made a few grinds with added pressure at that point. Then checked again with the micrometer. Did that a few times until I had a consistent tube length all around (to about 0.05mm).
Then I just ground with the circular motion with even pressure and the tube remained consistent.

It took a LOT of grinding and checking infinity focus to arrive at my final length. I checked infinity focus by putting the M flange mount in the visoflex, then inserting the flat flange (that I just freed from the lens tube) into the tube, attached the lens tube into the remainder of the lens, and held the whole thing together while looking through the visoflex. I sighted on a ridgeline of trees about a mile away.

 

[rfaspen]

Once I arrived at my final tube length, the hard part was over.

I sanded the inside of the lens tube where the flange would be glued. I sanded just until I could see I was hitting bare metal. The epoxy will not make a strong bond unless we get to metal. I also cleaned the inside of the tube and flange with 91% isopropyl. Then I used a two-part epoxy (JB Weld) to glue the flange in place. Ensured it was seated completely and evenly, allowed to set and dry overnight.

Now its time to attach the M-mount.

I centered the new mount on the flat flange of the lens tube and marked the locations of screw holes. Need to be as precise as possible here...

I have a drill press in the woodworking shop. I think it is important to drill the holes for the mounting screws vertically. I would not have been keen to attempt free-hand drilling those holes, but it might be possible.

I used a #55 (wire gauge) size drill bit for the holes. I then used 0-80 size tap and screws. I didn't check to see if this is the exact same size as Leica uses for their mounting screws, but the diameter is essentially the same. Leica might use a finer thread. 0-80 size screws and tap are available at hobby stores that serve model railroad and/or model airplane enthusiasts.

I attached the M-mount with brass screws. I used some steel screws at first, but one of them protruded just a micro tiny bit and it scratched my visoflex mount. Not bad, but not acceptable. Brass is relatively soft and the risk of this happening again is avoided.

And success!

Now all I need to fully complete the conversion is the raised red dot

 

[Nokton48]

This is very cool. Very well done. I also love to work with my hands and create unusual camera items I can not get any other way. The Visoflex II and III units that I had for a while were just a lot of fun to use and very intuitive to use. Brighter to look through than you would think. I also have had a 400 & 280 Telyt but I know I have a 400mm Spiratone around somewhere.

 

[Livesteamer]

Looks Good!. In the future, a possibility for free machine work is to contact a local community college that has machine shop instruction. For folks in North Carolina, contact me. I have a mill and a lathe and enjoy doing small jobs for friends. Joe

 

[Spavinaw]

It was the Tele-Astranar 400mm lens that was known as the "Girl Watcher" lens, not the Spiratone one. You can see a Stirling-Howard ad that shows the Astranar lens along with the line Girl Watcher by googling: "girl watcher" lens.
By the way, I still have one I bought new.

 

[rfaspen]

Ya know, that's what I've read too. The Tele-Astranar was marketed as the "girl-watcher" lens. The 400mm was the "girl watcher", the 500 was the "big shot" girl watcher.
Hmmmmm
Spiratone pluracoat lenses were apparently different lenses in both marketing and construction. My terse internet research suggests the Spiratone was a better lens.

My personal use of the Spiratone suggests the lens is quite a bit better than expected. I will share some comparisons with other lenses I have. I'm a bit surprised at the comparison of the Spiratone with my other 400mm lens -- a Sigma 400/5.6 APO. I'll share later...

 

[Spavinaw]

The Spiratone and Tele-Astranar are definitely different. I have both. The distnce between the front and rear lens elements is longer on the Astranar, but the Spiratone is longer overall. The lens barrels are also quite different. As I recall (it was about 40 years ago) Modern or Popular Photography did a test on both lenses. The test charts were exactly the same except for one result where the Spiratone was one categoty better. Remember, my 40 year old memory may not be perfect (how's yours?). Anyway, I chose the Astranar because it took a 67mm filter and the Spiratone took a 72mm one. For me the smaller the better.

 

[farlymac]

Now that is a fine looking rig! I take it the rotating tripod collar came with the lens. I've got one of those long 400's, a Lentar if I recall. I've been looking for a Spiratone model, but no luck yet on finding one that is in good shape.

The original owner of Spiratone was particular about how the equipment they wanted to market was made, so quite a bit of it is good quality. I've several Spiratone accessories around here, and tend to snatch them up when I find them on sale. A lot of the early lenses were good performers.

PF

 

[rfaspen]

Ah yes, the tripod collar is part of the lens. The overall build quality of my Spiratone is actually pretty good. I figured part of that was "the times" -- they used to make nearly everything better back then.

One might ask why I would go through the trouble of converting this lens. A good question. I'm hoping to find some time soon to show why...but I can spoil the suspense now. The Spiratone is actually sharper in the central portion of the frame than my 400/5.6 Sigma APO. Its also much sharper with less CA than my Tamron 300, a little better than my Canon 300/4, and challenges my Nikkor 300. In fact, the real motivation for my conversion was my last outing with the Sigma APO -- No matter how good my technique, I could not get images that met my desires. The visoflex system is much slower and tedious than a modern lens on a pro DSLR, but in the end I need images.

We'll see how it goes. If nothing else, its a "fun" lens to keep around.

 

[philslizzy]

I did it with a 300mm. I put the visoflex (it was a PLOOT actually) on the Leica and measured the exact distance between the pressure plate and the front of the PLOOT. Then I took from that the FFD of T mount leaving a figure which measured from the T mount up the lens tube. It stopped just short of the rear element. Around 1cm. This was a while ago so I don't have the measurements but if you do what I did you'll get them.

I marked the distance and drew a ring round the lens with pencil. Carefully I used a hacksaw going all the way round the ring slowly so as to cut it straight. I had a fungussy enlarging lens who's thread I used giving me a male M39 thread. (you could use a metal body cap with a hole cut in it and take into account the flange thickness and cut the lens a little shorter. However I...) I ground round lens tube until it slid into the tube of the 300mm lens.

I then (with the PLOOT on my Sony) adjusted it until I got infinity with paper shims. Then I pulled it out, slathered it with epoxy and put it back. Perfect, infinity focus. I tidied it up with epoxy putty.

Do you know, with a visoflex 2 you can get a T2 to LM and use a 500mm mirror lens on your visoflex and get infinity focus? Both my mirror lenses go way poast infnity.

 

[rfaspen]

Nice conversion!
I can appreciate the LTM / M flexibility of that conversion. I didn't think of that, but so far I only have M mount visoflex units. I'll probably grab an all LTM viso some day. Perhaps a Viso 1 and my Barnacks can play too.

I've found my original conversion (the 400mm Spiratone in OP) is just a bit too soft overall to keep me engaged. I haven't used it in a while. It could just be my copy of the lens. Of course my Sigma APO 400 (Nikon mount) really isn't any better, so who knows....

I have never been a fan of mirror lenses, but if I stumble across one, I'll play 😎 😀