p.1 #1 · Canon SH 30/1.7 -- Demi 17 half frame lens on NEX
Got a wild hair to inflict harm on a poor defenseless rangefinder, and I've cobbled together something that will, I think, be useful on my NEX. It began as a little guy that had seen better days, and I quickly turned it into a pile of chaos.
I've still got some work to do. I've now done a basic mount in a lens cap, which has the benefit of me being able to use some of the camera hardware as a locking flange -- but it's not as stable as a true adapter-based mount, and I still have some fussing to do to get it to infinity focus. I also need to rig up an aperture control -- the donor lens had a focus-linked aperture system (for flash), and it doesn't readily adapt to purely manual use. Still, it's a lot closer to usable than it was 24 hours ago.
A couple of shots. First, down a stop or so from wide open, followed by a 100% crop, then two wide open crops.
Wide open, it's a bit bloomy, but still usable. Overall, contrast and color saturation are low, but sharpness is good. Any guesses as to what it is? It's a moderate wide, faster than f/2, and approximately 45 years old....
p.1 #3 · Canon SH 30/1.7 -- Demi 17 half frame lens on NEX
Thanks!
Here's another 100% crop -- from the above image, at the top edge. It shows both the edge sharpness (probably between f/2.8 and f/4) and offers another clue about its pedigree. No one will mistake this for uhoh7's new 28/2 cron, of course -- but they do have some characteristics in common.
p.1 #4 · Canon SH 30/1.7 -- Demi 17 half frame lens on NEX
is it a lens from one of the canon ~50mm f0.95 canonettes ... I seem to remember seeing one years ago. Anyway, total shot in the dark, but that's my guess... nice conversion job !
p.1 #7 · Canon SH 30/1.7 -- Demi 17 half frame lens on NEX
A little more alt than that -- it's from a non-interchangeable lens viewfinder camera (I said a rangefinder earlier, but that's not really correct -- though it is from a manufacturer that has made some nice rangefinders).
Here's another hint: This lens is so cute, one might almost say it's half-size....
p.1 #9 · Canon SH 30/1.7 -- Demi 17 half frame lens on NEX
Yup -- Demi EE17. The Demi S has the same lens.
Not perfect, but decent, and kind of fun as a salvage project. The four-bladed aperture doesn't make for the cleanest backgrounds, but it's perfectly round wide open (and still fairly round by around f/2). It's most pronounced at f/4, then diminishes.
I didn't think infinity focus would be as much of a hassle as it is, but I think I can figure something out.
The controls and optical quality on the compact full frame rangefinders (like the QL17) are a little better, but the shortest lenses on any of them is 35mm, and most are 40mm+.
p.1 #11 · Canon SH 30/1.7 -- Demi 17 half frame lens on NEX
Thanks. I've still got a ways to go -- I think I've figured out that the only real way to get this working properly with a working focus helical and infinity focus is to build up from a c-mount adapter. To do so, I'm going to have to find a good drill press or a machine shop, so that I can enlarge the c-mount hole just enough for a snug fit with the lens mounting flange. I'm pretty sure it will work, though I might end up shaving down the end of the helical a bit for piece of mind -- the registration distance is very short.
I should have taken some pics in process, though I think I can reverse-engineer them pretty easily. In trying to figure out how to build a mount, I've had the lens apart a dozen times. The only thing I haven't touched/disassembled/pillaged/destroyed is the sanctum sanctorum of the aperture and shutter blades -- haven't had to get in there, and don't want to.
I've got the aperture control working more reliably now, which has allowed me to figure out that image quality improves dramatically from f/1.7 to f/2. These are some quick shots in my office. There's some vignetting at wider stops, but it's not as pronounced as these images look, since this is the spill light from a lamp, which falls off quickly to the right. There's a lot of bloom in the f/1.7 shot, though the sharpness isn't actually too bad. By f/2, the bloom is gone, and sharpness and contrast are both considerably improved. Stopping down beyond f/2 extends the depth of field, but it also complicates the bokeh. Heck -- Might just lock this thing in at f/2, and leave it there. If I want to shoot stopped down, I'll use a different lens.
I think this thing will be usable. A sharp 30mm f/2 that weighs 5 ounces and is no deeper mounted than the 16/2.8? Fuggedaboutit.
p.1 #13 · Canon SH 30/1.7 -- Demi 17 half frame lens on NEX
Very interesting!
My broken EE17 is in the mail, I hope to make the same conversion later this month.
Just by curiosity, how did you get the shutter open? Did you have to take the lens assembly apart?
p.1 #14 · Canon SH 30/1.7 -- Demi 17 half frame lens on NEX
Michel, I'll take some pics in a few days when I've finished solving the mount problems. The shutter was not a problem. I didn't open it up completely -- I just took off all of the easily accessible parts, and there was a small space in the control mechanism where I wedged a piece of foam to keep it open.
This thread should show enough information to help you disassemble the camera. The important steps:
-- Peel back the leatherette to take out the four screws on the front of the body -- these hold the top and bottom plates on.
-- Remove the rewind crank. To do this, you wedge a small screwdriver in the fork that engages a film canister, and then rotate the crank to unscrew it.
-- remove the viewfinder apparatus to be able to get to the lens mounting plate.
-- detach the lens plate from the body. This is a black steel plate that all of the lens hardware is mounted on. Three of the screws are readily visible, and the fourth is under the viewfinder assembly.
-- you'll need to remove the lens assembly from the black mounting plate. There are a couple of stop posts that you can simply remove, since they are of no use in reusing the lens. Once they're off, you can unscrew the lens from the brass threaded fitting that is attached to the plate. It's important to keep the brass fitting -- this is the best way to build a mount for the lens. The brass fitting is very firmly attached, and I ended up having to grind off two of the screws in order to free it from the plate. There are also two black tabs on the plate that engage slots in the focus helical -- these keep the lens from rotating, so that the focus will work properly.
-- remove the front lens assembly. The first step to removing this is the threaded retaining ring -- if you don't have a spanner to engage it, you should be able to use a small screwdriver. Once this is done, you can lift off the aperture control ring, and the front lens set will unscrew, as will the small retaining ring that is underneath it.
-- remove the shutter hardware. I was able to keep the shutter open by simply wedging a piece of foam in the mechanism. That should be plenty.
-- the aperture control is a little unusual -- it is linked to the focus mechanism, in order to provide a crude variable flash control (it stops down as you focus closer). This is a hassle, so I wedged this control system wide open with foam, just like I did the shutter. I also clipped off two posts that are connected to the aperture control mechanism, since they interfere with the focus mechanism. There's a secondary aperture control that is essentially a small arm that passes through the front of the lens, where it's controlled by the front ring. The mechanism is a bit crude and stiff, but it works just fine. Don't remove this -- this will be your aperture control.
If the aperture is working correctly, you shouldn't have to open the lens further. If the aperture is stiff, you can clean it from the front with lighter fluid on a swab -- hopefully this will be enough. I was reluctant to go any further into the mechanism.
-- In building my mount, I'm using the brass fitting that was attached to the black plate as a flange. I will have a c-mount adapter drilled out by a machinist to match the brass fitting very closely, so I can tighten the lens onto it.
-- I couldn't figure out a way to use the focusing mechanism the way it's designed, since I would have to create a mechanism with tabs on the mount to fit into the slots on the helical to keep it from rotating. That seems too complicated, so instead I'll focus by rotating the front of the lens. Not quite as nice, but it's simple, and it will work. It also helps me avoid the problem of trying to engineer a mechanism at the back of the lens mount, where there's very little room to work because of the shallow registration distance.
I'm sure this is hard to visualize now, but it should make more sense once you've got the camera in front of you. I'll also post some pics of my completed mount once it's done.
p.1 #15 · Canon SH 30/1.7 -- Demi 17 half frame lens on NEX
Another update:
After some brilliant advice from robertro on the dpreview NEX forum, I've successfully figured out a mounting system for this lens. Rather than build up something with a c-mount adapter, I used a Leica thread mount adapter. What makes that adapter unique is that the threaded insert is attached with grub screws from the side -- if you loosen them and remove the threads, you can fit in a lens and then use the screws to lock it into place. Remarkably, the Demi lens fits perfectly. No need to use a dremel to reshape the lens body, it slides into place and reaches infinity focus perfectly.
Pics to follow.
Performance is ok, but not great. Sharpness is good, but color and contrast are very flat, and it flares a lot. Unfortunately, this is not a lens that will be a general purpose substitute for a modern lens. Right now I've got an empty 34mm filter mounted to give it a bit of a hood, but I'll probably try to rig up something better.
I think this might be best dedicated to black and white, where the vintage-y look of the lens can be part of its charm.
p.1 #16 · Canon SH 30/1.7 -- Demi 17 half frame lens on NEX
Bouncing this back up, with more details. First, an optical report, then will follow with updated pics of the mount.
This is a curious lens. It's capable of excellent sharpness (even close to wide open), but contrast is nearly always a little flat. Worse, it is very prone to veiling flare. All it takes to turn a shot into mush is a little glare -- a hazy or overcast sky, bright light just out of the field of view, etc. I've tried some improvised hoods, and will experiment further, but so far that hasn't helped much. It looks like it's coated, but it's almost certainly only single-coated. If I had to choose a lens to reproduce the look of uncoated WWII-era lenses but didn't have Steven Spielberg's budget, this would be my first choice. It's probably best suited to black and white, and I'll continue to experiment with it -- but a foolproof general purpose lens it's not.
Some examples, this time on the 24mp NEX-7. It's pretty amazing that this old lens looks as good as it does when the light is agreeable and you're stopped down.
Full frame at f/8, followed by 100% center, edge, and corner crops:
That's not so bad, though, since I wouldn't expect a whole lot from this lens at/near wide open.
The problems are when there's veiling flare, which is pretty fierce. Same shot as the first, more or less, but with a harsh, bright overcast sky in the background. First at f/2, then at f/8.
Blech. The flare robs it of all contrast and a lot of sharpness, which is not recoverable.
So -- a finicky lens, and something of a historic relic. Obviously something that is capable of nice results, but which also takes some care. I'll keep playing with it, and I expect in some circumstances it will be great. Not something I would want to rely on, though.
p.1 #17 · Canon SH 30/1.7 -- Demi 17 half frame lens on NEX
Very nice! I'm impressed by the sharpness. The short flange NEX really has brought new life to a lot of once forgotten lenses.
I also wonder why both Sony and 3rd party lens makers like Sigma & Tamron are not making affordable small fast primes for this mount (esp, wider angler ones). The fastest from sigma is f/2.8 and Tamron only makes a slow super-zoom.
It was pretty easy to mount once I got the tip about the LTM adapter. Unlike any of the others I've seen, the threads are in a removable sleeve, held in place with grub screws through the side. If you can make the lens fit, this is an ideal way to build a mount. Remarkably, the 30/1.7 fit into the adapter perfectly, with no milling required -- I just set it into place, and tightened it down.
It was fortunate that it worked. Because of how shallow the registration distance is on the lens, it would have a challenge to build a mount that would hold it firmly. The one sacrifice is that it doesn't focus using the lever (which was removed to make it fit the adapter). Instead, the rear of the lens is locked in place, and the front just rides in and out on the helical. That was far simpler, because otherwise I'd have had to work out a retaining tab to fit into the notch on the inner helical, which would have held the front optical unit in place and rotated the rear assembly around it (thus pushing it in/out). Hard to explain, but not too hard to visualize.
