I've been trying out a range of different lenses on my NEX-5n, and one of the stranger ones I've come across is a 63mm f/2 Kodak Cine Ektar from the late 1940s or early '50s. It's a Kodak S-mount lens that can, with a proprietary adapter, be used on a standard C-mount.
Mine required a CLA to get working -- the focusing helical was seized with old grease, and it took quite a bit to get it going again. Now that it's clean, it's working perfectly, and it's got that amazing dense heavy feel that only an old hunk of brass and steel can.
I still don't have all the right parts to properly mount it on the NEX, though I've done some tests with an improvised mount. I've got the right parts coming.
What I've discovered so far is that the corner/edge performance is very dependent on extension -- it ranges from terrible to nearly perfect. With the lens at its proper registration distance for infinity focus, anything out beyond 8-10 feet or so degrades quickly, especially wide open. By f/4, illumination is starting to get decent across the frame, but the corners at that focus distance will never be sharp. At closer distances, it's much closer to covering the full APS frame, especially at f/4 or f/5.6. At those stops inside of 5', it's exceptional.
The optical performance of the lens is remarkably good -- super sharp, and a level of saturation and contrast that seems very modern. Out of focus rendering is very nice, though very swirly at the edges. I was stunned when I first opened up the files -- it's excellent in the center wide open, and down a stop two, it's a match for the very best modern lenses, including such benchmarks as the Nikkor 28/2.8 AIS or the 55mm micro. In the center, it's not even a stretch to compare it to the Sigma 150/2.8, which is one of the sharpest lenses ever made. Truly world class performance there -- and this thing is probably sixty years old, and "only" single-coated (or lumenized, as Kodak called it).
I'm still not sure if I'm going to keep it, since its use on NEX is limited to closer distances and/or being cropped. I've got a number of exceptional short teles, so I don't really need it, but nothing draws quite like it does. I might just keep it for fun, and use it for semi-macro and close distance portraits. I shoot a fair amount of live music, and the impressionistic effect at longer distances might be great for that, too. It would be awfully close to perfect on a 4/3 sensor.
What's going on in those shots of the fence though?
Have you considered a Helios 44-3 (or "dash whatever) which would gain you a stop, remove the working distance issue, and still give you the swirly bokeh? Or if you are rich man, in USSR terms, then the 40-2?
The Russian lenses are interesting indeed -- and it does seem like the 44-3 has a similar signature. The 40-2 is quite a hunk of metal -- nice!
I wasn't exactly looking for this lens, and I don't exactly have a hole to fill. I've got a couple of fast 50s, two 85s, and two 100/105s that I can use on the NEX, so I'm reluctant to add another. This was an accidental find, and a great curiosity.
What's really appealing about it, apart from its optical charms, is the gorgeous build. It's a beautiful piece of machinery, and the bare lens is 6.6 ounces and about the size of the Contax 90/2.8 G (ie, slim and compact).
I'll put up a pic soon -- there are many images online, but I didn't want to poach someone else's product shots.
I didn't post more from the shots of the fence since the plane of focus is a little wonky and not really representative. That's because I shot them with a very sophisticated bag bellows system (gaffer's tape and a Canon/NEX adapter), so the lens wasn't exactly perpendicular to the film plane.
;- )
The registration is fairly accurate, though, so that's a fair approximation of what happens to the corners at farther distances. Image sharpness and vignetting really degrade beyond the central 2/3 when focused beyond 8-10'. It's more pronounced at wider stops, but I don't think it ever really goes away. On the up side, central sharpness at f/2 is still excellent.
I've got a working theory that I haven't been able to try out yet. I suspect from my haphazard experiments that with a little bit of extra extension, I might be able to cheat the functional range of the lens out to 15-20'. Once I've got the right adapters, I'll try it (C-mount extension tubes and shims are plentiful and cheap, since many video monitoring systems are made for the CS-mount, which is identical but requires an additional 5mm of extension). The key will be to add enough extension to improve corner performance, while still keeping the ability to focus in the middle distance. 5mm of tube may be too much -- I may try smaller spacers to get something more like 2-3mm.
Dunno.
;- )
It's a fun experiment in any case, and even if I decide to pass this along to someone with a more compatible system (ie, m4/3), it's been informative -- not least for the lesson in mid-century Kodak optics. Somebody was doing something right in Rochester.
Got the right Kodak c-mount adapter, and it works perfectly. I used a couple of small rubber o-rings to make it snug at infinity in a c-mount to NEX adapter, and that works well, too. It turns out that the vignetting is minimized when the lens is mounted for proper infinity focus, so that's another big relief -- there's no reason to mount it at anything other than the proper registration distance.
It still vignettes, of course, and it's most pronounced wide open -- improves a lot by f/4.
There's a small press-fit baffle at the back of the lens that intrudes about 2-3mm. It slips out easily, which reduces the vignetting quite a bit. This has no effect on corner sharpness -- they're at their best down a couple of stops, and at closer focus distances. With the baffle removed, the chrome lens barrel is exposed, which causes flare -- but a carefully trimmed piece of gaffer's tape solves that problem. Nice little improvement, and non-destructive.
It's a bit of a stretch to use this on an NEX, so I'm not sure I'll keep it -- but it's so small and paints so nicely that it's still worth playing with. On m43, it would be pretty darn close to perfect.
I'll post some updated pics soon.
A tip to any tinkerers: it took me multiple rounds of cleaning to get the focusing truly smooth. The helical itself is easy to clean and lube, but the rear-most part of the lens assembly is essentially a bushing that can't be disassembled -- where the focus ring rides against the aperture DOF scale. You can't really get in to clean it, so the best you can do is to flush it liberally with Ronsonol, and then work in a tiny drop of light lubricant. Once that's clean, everything else works much better.
Sharpness is on par with excellent modern lenses. It's very good at f/2, and improves considerably stopping down just a little. By f/2.8 or f/4, it's as sharp in the center as a good modern macro. The central sharp area is pretty large, too -- not just the very center.
I wish it covered the full frame on the NEX. Because it doesn't, I think this one's going to have to find it's way to an m4/3 owner -- but hopefully this info will be of some use to someone.
