Lens mounting flanges

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Susie Frith
Posts: 53
Joined: Tue Jul 26, 2011 5:28 pm Etc/GMT-1+01:00

Lens mounting flanges

Post by Susie Frith » Wed Apr 11, 2012 8:04 pm Etc/GMT-1+01:00

I thought some of you might be interested in a lens mounting project that has kept me busy for a couple of days.

Despite having a clearout of cameras, I did recently buy another! This is a whole-plate tailboard camera that I wanted for the impending wet-plate season. It was advertised on ebay, reasonable starting price, and I was the only bidder.

The camera came with three double darkslides, a T-P rollerblind shutter and an un-named 10” f/8 Rapid Rectilinear lens, all in pretty good condition. There are no seperate lens panels, the camera can have only a single flange on it.

As I have two lenses very suitable for wetplate work, I decided to work out how to fit them. One is a 3D Dallmeyer Patent Portrait lens f/6 and the other is a Ross Extra Rapid Symmetrical f/4. Both have their own flanges: neither lens will fit the other’s flange even though it is very close. I also decided that it would be nice to still be able to use the lens that came with the camera.

I happened to chance on the fact in the 1880’s the RPS made a recommendation that lenses with a mounting diameter below three inches should have a thread of 24TPI (turns per inch). On checking with a thread gauge, I found that my two lenses did indeed have the same pitch thread, and that the Ross was only about 1/32” larger. As there was enough brass on the mounting , I decided to re-cut the thread to the same diameter as the Dallmeyer. As the Dallmeyer flange needs a hole 4-1/4” diameter, I decided to make a new flange to screw to the camera that would accept both lenses, and then make a reducing ring to fit the original f/8 lens. The new flange only needs a hole 2-7/8” diameter.

As I only thought of writing this after I had started, the first couple of photos shew the reducing ring being started, but the main flange was done the same way!

A piece of plate brass was set up in the four-jaw chuck in the lathe:

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It was then drilled and bored out to a bit under the finished size:

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The corners were then sawn off and the piece mounted by the hole in the three-jaw self-centering chuck:

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And the outside turned to diameter, including the spigot to fit in the hole in the wooden front of the camera. Here it is supported by the adaptor flange.

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Then, holding it by the outside, the thread was cut. Here is a picture of the flange completed.

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The Ross lens was then dismantled and the mounting thread cut to match the Dallmeyer.

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The adaptor flange was then made:
The brass blank, turned, rough-bored and screw-cut to match the Dallmeyer, was then screwed in to the flange, which acted as a holder for it for boring to size:

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And screw-cutting to the akward pitch of 30 TPI:


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The new flange beith tried for size:

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Susie

Charles Twist
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Re: Lens mounting flanges

Post by Charles Twist » Mon Apr 16, 2012 9:58 am Etc/GMT-1+01:00

Fantastic stuff, Susie. Not the easiest thing to cut internal threads, I am told.
Are you offering to do this for people on the forum?
Keep up the good work.
Charles

Susie Frith
Posts: 53
Joined: Tue Jul 26, 2011 5:28 pm Etc/GMT-1+01:00

Re: Lens mounting flanges

Post by Susie Frith » Mon Apr 16, 2012 7:06 pm Etc/GMT-1+01:00

Hi Charles,

Basically, Yes!

I am quite happy to bore out lens panels and make flanges and all that sort of stuff.

Although I haven't mounted lens elements into shutters, I do have a lens and shutter that I might have a go with. If that is sucessful, and I cannot see why it wouldn't be, and if I can find a reasonable supplier of shutters I could offer that too. The lenses that I have had mounted have always gone to S K Grimes. Although quite expensive, having them do the work, paying shipping and VAT has worked out cheaper than just buying the shutter from Robert White's.

As I mentioned above, when I have a moment I'm making half a dozen lens panels for my Zeiss Jewel, but more pressing is a whole-plate wet-plate holder, which needs to be finished soon.

Best wishes,

Susie

Phil
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Re: Lens mounting flanges

Post by Phil » Sun Dec 02, 2012 2:00 pm Etc/GMT-1+01:00

I've just received my lens flange job back from Susie and I'm very impressed.

From start to finish Susie was involved in the finer points of the design - with her knowledge of old lenses and engineering skills she is a fantastic resource!

I needed a flange making for a Wollensak Vitax No.3 which needed to be front mounted to a panel to allow the use of the variable diffusion control. It is a relatively big and heavy lens which needed a sturdy solution. Not only is it a perfect fit (and the control knob is orientated correctly) but it also matches the black paint and nickel plated aesthetic of the 1920's lens. Neat!

Given the other options usually involve shipping parts abroad and (re-importing them) I'd highly recommend Susie's services here in the UK.

Thank you Susie! :D
Attachments
Sturdy mount needed.....jpg
Sturdy mount needed.....jpg (44.69 KiB) Viewed 5644 times
Problem solved!.jpg
Problem solved!.jpg (46.9 KiB) Viewed 5644 times
Vitax 3 on Sinar panel.jpg
Vitax 3 on Sinar panel.jpg (52.29 KiB) Viewed 5644 times

Andrew Plume
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Re: Lens mounting flanges

Post by Andrew Plume » Sun Dec 02, 2012 2:05 pm Etc/GMT-1+01:00

Phil

a terrific result, not just for the quality of Susie's work but also that YOU ARE USING AN OLD lens and one that has a cultish reputation too. No disrespect to those on here that use modern shuttered optics that are multi-coated and with all of the whistles but it DOES make a decent change

regards

andrew

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