In short words “this lens is something else”. It’s extremely fast, huge and has a strange focus distance. It was used in Sony CRT Projectors from 1997. I bought it some years ago from a very interesting guy. He had so many more great stuff in his shop and I regret that I did not buy more. It took me some time to find the right opportunity to use that lens. But I think it was worth the waiting. I am glad my friend and former workshop participant Alois Stingl came over with is wonderful ultra large format camera.
Before I could use it, it needed some cleaning, I used a cloth that was soaked with water and just put it on the lens without wiping to avoid more scratches.
I measured the lens at infinity to calculate the F-Stop. I measured 135mm and the front element was 145mm That is about a F0.9 lens. But a document I found on the internet told me its more an F 1.0 lens. Still crazy fast.
When I saw the yellow coating on the front element of the lens, I thought about Mathieu Stern’s video about radioactive lenses. If it really is made of Thorium, it is indeed radioactive, but only for a very small amount. Watch Mathieu’s video to learn more about this Material
Because the lens is very fast it is still dangerous. If it focuses the sun on something, it will start to burn immediately. That’s the reason you should not put the lens near a window and always put a lens cap on it.
I thought it would be interesting to calculate the crop factor of an 40x50cm ultra large format camera. If you use the common formula to calculate crop factors you will see that this plate size has a crop factor of 0.0067 compared to a full frame sensor. With that you also can calculate the comparable depth of field F-Stop. This would also be F 0.067 compared to F 1.0 on a full frame camera. When I tried to focus on the ground glass, I could barley find something in focus. Thats why you see me focusing for a very long time.
But there is more. a 140mm lens is a tele lens on a full frame camera, but it’s a wide angle lens on an ultra large format camera. This is because of the bigger plate size of the ULF camera. listen to my full explanation in the video.
To “connect” the lens to the camera, I designed and printed a basic flange in Tinkercad. It needed some pool line and tape, but eventually it worked out.
The next issue was the fact that my darkroom was not made for 40x50cm plates. only for 30x40cm ones. After some tests with smaller plates, we only had one cup of developer left. Beside that, everything starts to get unpleasantly expensive if you pour on plates with this size. So my goal was to make it work with only one attempt. I did some dry runs to get comfortable with everything. Not only the dark room work was something I had to prepare for, but also the camera. These old beauties all have some quirks. Besides that, Alois made a beautiful plate holder by himself. These holder needed also some special attention. But as explained in the video, I love these challenges. It makes the result at the end even more sweet.
To calculate the strobe power I needed, I used my wet plate strobe calculator that I created for my Patreon supporters. Since I made it, I use it all the time for myself, because it makes life much easier with the wet plate process. If you are a fan of analog photography and the wet plate process, have a look at our wet plate conversation magazine on Flipboard. Besides many great stories about our favourite process, you’ll wind there also work from other wet plate artists.
But this is not the end, because of some kind of funny coincidence, a former workshop participant sent me a very similar lens over. I am thinking to do a still life plate with that one. What do you guys think?
But there is more, I got also a very tiny lens. I guess I need to build a camera for this one
I hope you enjoyed that journey. It took me a long time to finish everything, but I am again glad that I worked through it.
