View Full Version : 790mm F:5.4 LF & ULF Lens Data

Reinhold Schable
14-Jun-2013, 17:48
I needed a way to evaluate the bellows draw and image circle for a ULF lens I've been concocting.

By commandeering my wife's sewing room, I blacked out the windows, cut a hole in a blackout that looked out over my back yard, and ...presto... a camera obscura. I rigged up a 4'x6' white sheet of plywood on a tripod to focus the image and measure bellows draw and image circle.

Here 's a data sheet covering the image circle, bellows draw, and effective apertures at various focusing distances. Notice that it projects a 1425mm (56") diameter circle at infinity, and a circle well over 1830mm (72") !!! when focused at 3 meters (10'). The folks shooting huge wet plate and paper negative portraits should have fun with this lens.

More later...


Tin Can
14-Jun-2013, 18:02
You are a big tease! Now I want to make my van into a camera, or maybe make one for the roof rack.

When will "Cet obscur objet du désir" be available?

Dan Fromm
14-Jun-2013, 18:34
Um, Reinhold, aren't you acquainted with arithmetic? The theory's well-known and well-validated, you don't have to measure (if the focal length is what you think it is), you can calculate extension.

Jim Fitzgerald
14-Jun-2013, 18:38
Reinhold, congratulations! Can't wait. Let me know about it as my 14x17 and 8x20 lens boards await!

Reinhold Schable
14-Jun-2013, 19:39
Dan... Shhhhhh, you'll blow my cover. Besides, I find it comforting to verify things with physical involvement

Jim... Just a few small details to work out. Maybe the unveiling will be this weekend.
So that you can prepare your lensboards, here's a drawing...


Craig Tuffin
15-Jun-2013, 03:28
Happy to test one on my 20x24 for you Reinhold...or in the van and shoot a 24x32 :)

Steven Tribe
15-Jun-2013, 05:00
Reinhold - when you get round to making more complex lenses, get in touch.
I can supply spherometer measurements etc. for the Darlot (et alia.) Objectif d'Artist - 3 +ve lenses and the -ve lens. All simple lenses.

Tin Can
15-Jun-2013, 05:26
No sleep. All night designing new camera!

Reinhold Schable
20-Jun-2013, 09:56
Ta Dahhh...
I've just posted the lens details and pricing in the For Sale section.
Thanks for your interest and patience.

Tin Can
20-Jun-2013, 09:58
going there now

Ta Dahhh...
I've just posted the lens details and pricing in the For Sale section.
Thanks for your interest and patience.

Reinhold Schable
29-Jun-2013, 17:28
It's been 9 days since the 790mm f:5.4 Wollastom Meniscus lens was introduced.
Since then I've been quite busy.
There's a bit more involved than hacksawing off a piece of plastic pipe and hot-glue mounting a lens...


Tin Can
29-Jun-2013, 17:50
I am not resting (I bought one) either. I needed to make many mods to my Levy Process camea to handle this lens. Extension box lens board is complete. I did some initial sharpness testing at all apertures, by shooting my GG with digital.

I could shoot 11X14 right now, but my DIY 11X14 back is slow to use.

Tonight I am finishing a 8x10 reducing back, using a Calumet C1 back, actually I will be able to mount any C1 back. Test with Fujiroid.

In between hacking, sanding, gluing and painting, I have been working out a sort of ring flash set up with 3 SB 800's. I have no shutter and will focus with string and use the lens cap and hand fire the the strobes. Tested all that with digital, works great.

Also converted an old Sachtler & Wolf wood tripod to mount a Saltzman tripod head. It should be HD enough to hold the big Levy in the field, if I ever do try that.

Next I need to make a 14x17 extension back.

I should be shooting 8x10 tomorrow, baring Hell or high water. We have been flooding, Chicago area.