View Full Version : How to Mount the Kong Petzval

11-Oct-2018, 20:30
I'm finally getting around to figuring out what to do with my latest lens, the five pound "Kong Petzval.":cool: It's an 11 inch Voigtlander Petzval c.1863. I mostly bought it because it seemed to be going cheap and is really cool! My biggest camera is a c.1925 Gundlach Korona field camera, 5x7 (plus 4x5 back.) The lens is heavy. I'm thinking of always using it with the rear extension so I can balance it over the tripod head. Also thinking of racking the lens back into the bellows as far as it will go to balance it better on the front of the camera.

Here's what I'm dealing with. The native lens boards are 4.5 in. square. The flange is 5.5 in. diameter. The opening in the front standard is 103mm (call it 4 in. for consistency I guess.) The lens tube diameter is 98mm. It does fit with a little room. The lens board has a 6mm indent to make the light trap.

The lens will have to be bolted, not screwed, using its six holes in the flange. The top of the lens board slips in under a metal strip on top and is locked in place at the bottom with two locking tabs. There is a bevel on the bottom edge of the lens board. I noticed that if I turn a standard wooden lens board backwards, with the indent facing outward, it creates some clearance to mount a larger platform to mount the flange on. I'm not sure if an adapted wooden lens will do the job, or if I should have something machined out of aluminum? Or, have an aluminum based lens board made and then bolt (not screw) a wooden spacer plus larger platform to mount the flange? I do plan on fashioning a "Y" or "H" shaped support to place under the lens to take strain off the front standard and lens board keepers.

I have an alternative idea and that is to buy something like a Kodak 2D 8x10 which has 6 in. lens boards. I've seen some in nice condition (I do want a pretty one) going reasonably from time to time. I don't really want to get into yet another format so would look for a 5x7 back for it. I'm not eager to do this because I really couldn't justify keeping a 2D and my Korona. I love that Korona--beautiful wood, and I don't think it was ever even used! I just put new bellows on it from UK.

So, any advice here is really needed!

Kent in SD

12-Oct-2018, 07:11
I guess it depends on how elegant of a solution you want. You could have a retaining ring machined that would fit on the rear of the lens board, like a traditional lens. Depending on how much room you have to work with, that may require mounting the bare lens board into the camera, and then installing the lens ring from the rear of the camera, which would be a pain, but look nice. For my Petzval on my Anniversary Speed Graphic (with a 4.5" square wooden lens board) I just drilled a hole slightly smaller than the diameter of the threads, lubed the threads, and then threaded the lens right into the lens board. The wood expanded to accept the threads, and it's on there really, really tight. No retaining ring needed. With a lens that large, I'd be afraid you'd destroy the wood (it would be really thin along the edges). However, you could have an aluminum lens board made, and the proper sized thread cut into it, employing the same concept of screwing the lens directly into the lens board.

Then again, if you want something cheap and easy, you could attach the lens to a larger lens board and then bolt that lens board onto the front of an appropriate sized lens board. You'd just need to makes sure there's some clearance between the two lens boards for the lens board retaining clips (and a way to access them). And you'd need to make sure the joint was light tight (which could be done with foam, felt, or a rubber gasket). That's basically employing the same idea as your reversed lens board idea, only doing so in a way that you don't lose the extra light trap of the rear lens board cutout.

12-Oct-2018, 07:21
Id go for the D2 & keep the Korona.

peter brooks
14-Oct-2018, 12:49
Nice to see Annie is still showing an interest in the lens :) I'd suggest something like the second paragraph of jim10219's reply.

I would get a piece of 3/4" (or whatever) ply, cut it to the width and height of the lensboard, rout a rebate all round the back to make the 'indent', then do the same on the top and bottom edges of the front to make a kind of 'outdent' (to give clearance to mount the lensboard).

You can then attach your flange to another piece of ply, and then fix this piece to the first, either by screws, bolts, or bolting through both (if you are lucky with where the holes are on the flange).

Ply is much more likely to survive if you're leaving relatively small sections of wood. Sprayed matt black you'll hardly notice it... This more or less how I made a Canham to Sinar (male to male) adapter - Canham lensboard > square of ply (slightly smaller than Canham lensboard) < Sinar lensboard - the whole bolted through, and with as large a hole as I could get away with based on the smaller board.