I started collecting parts for a summer project with my son. I’ve been wanting to build a Goodman 3D printed medium format camera for a while and finally took the plunge on ordering a Mamiya Sekor 65mm f6.3 Press lens. It’s the recommended lens for one of the kits and only costs about £50 on ebay.
When it arrived I tested the leaf shutter fired and the focus ring turned but I had no way of knowing whether the shutter was actually working. BUT maybe I could somehow test the lens on my Sony A7Rii and this little side project was born.
Firstly flange distance, I had no idea what it needed to be, so while setting the lens shutter at B and locking it open I held the lens in front of my A7Rii body and using the rear monitor moved the lens back and for until something came in to focus at infinity. That gave me a rough starting point. No tape measure was harmed in the execution of this experiment, because I didn’t use one (maybe I should have)
I had quite a distance to fill between the lens and sensor so first I attached my Sigma MC11 adaptor, this covered more than half the distance and also gave me a flat base to add my modification.
Next task was to find a tube that could be trimmed to the correct length to fit between the MC-11 and the lens. I’ve just finished renovating my kitchen so I have lots of silicone sealer tubes half used and they just happened to be a good fit. But they were white, so I had to line them with matt electrical tape to avoid the mother of all lens flair. After cutting, testing the focus and cutting again….repeatedly, I found the size that gave me clear infinity focus. Then all I had to do was wrap about two metres of electrical tape around the lens and camera to hold it together and stop any light leaking in.
I began by testing the lens indoors in my new kitchen, because I haven’t spammed the world with enough kitchen pictures already. The image at f8 was pretty damn sharp and the colours looked good too. These test images have not been adjusted in any way, they were shot RAW on the ‘standard’ Sony colour profile with auto white balance and haven’t been altered or sharpened in lightroom. The Mamiya optical viewfinder will be used in the final project but is only mounted on the Sony because…well I wanted too (such a geek) on a full frame 35mm sensor the lens is cropped more than the optical viewfinder shows.
The complication for testing was that although setting the lens shutter to B allowed me to focus accurately, I wanted to test the lens shutter itself. So once focussed I set the camera to a 3 second exposure and cocked the leaf shutter. Fired the camera shutter and while the Sony was exposing darkness I fired the leaf shutter. 1/125 for the indoor shot and 1/250th for the outdoor shot.
(above shots were taken on a Sony A9 and Sony 55mm f1.8)
An interesting observation which I cannot explain is that the first image below was taken using B on the lens and 1/250th on the Sony shutter but the second image below was the 3 second exposure on the Sony and the leaf shutter firing at 1/250th so basically the exposure of each image is the same but the second one using the leaf shutter has slightly less contrast and is a tiny bit softer. No idea why.
Overall I am really impressed I managed to get clear sharp images via a plastic tube and about two metres of electrical tape and I’m really looking forward to building a 6×7 medium format film camera with this lens.
Thanks to Hamish for encouraging me to share this little bit of fun.
A note from Hamish:
This post is one of the first of a new series here on 35mmc called “That time I shot a…” I’m looking for stories from a time you have shot something or somehow that is a little less than ordinary. This might be some sort of film shot in an odd way, a lens mounted on a camera it has no right to be mounted on, a camera that was broken or bodged to work in a way it wasn’t supposed to, or something else out of the ordinary. You might have discovered something wonderful, or it might have been a complete failure. As long as you have some sort of results, you can tell me what you did and why and how you did it, then please get in touch and let’s share some weird and wonderful photographic experiments with the world!