p.3 #1 · Tuning Contax-Zeiss adapters to Canon lenses
Ok - 'smearing' is simply the focus plane being non parrallel to the sensor. This,as I stated earlier, can be due to other factors but would be exagerated by non accurate alterations to an existing mount. I have adusted my Canon TS-E which has floating elements and it had no effect on infinity focus. Morover there is a seperate adjuster for this and this does seem to shift perfromance from near to far field optimisation. Lastly the focus plane of a lens is rarley flat exept with macro and specialist copy lenses - this means that with traditional film it would somewhat folow the bulge of the film but with flat digital sensors it may well be the case that these lenses are not going to perform as we expect right across the frame.
p.3 #2 · Tuning Contax-Zeiss adapters to Canon lenses
James Allen wrote:
Shirozina, very interesting
Do the CZ lenses have floating elements ?
I guess any with such elements will either be much harder to set up.
My 50mm 1.7 and 28mm 2.8 don't - my 24mm TS-E does but resetting infinity has no effect whatsoever on the adjustment of the floating element setup. Floating elements come in to play when quite large physical movements are made in the lens elements - what I am dong by tweaking the infinity stop has an insignificant effect on this. To put it in perspective the amount of adjustment needed to extend the focus out to infinity is aprox 1/2 the size of the infinity symbol - a few microns of distance - but a few very significant microns at that whan you view samples shot wide open.
p.3 #3 · Tuning Contax-Zeiss adapters to Canon lenses
Thanks. But I suppose I'm thinking that registration (and therefore adapter thickness) could be more critical for lenses with floating elements than for those simpler designs where you can (just) move the infinity stop by a few tens of microns. (I'm worried that the floating element won't do quite the right thing if it is in the wrong place. But my optics is very rusty !)
Do your "adjusted" lenses only sit on a single canon ? It would be very telling if they were "spot on" on Contax film bodies too.
There seem to be at least three and maybe four variables here:
1) flange to imaging (film emulsion) plane (is the adapter the "right" thickness ?)
2) infinity stop on lens (your method helps here, and can adjust for the first error if it is present)
and to get accurate manual focus at distances other than infinity:
3) getting the focus screen ground glass and the film plane the same optical
distance from the flange (there are reports that 5D's have multiple focus screen thicknesses to compensate for poor tolerances in back construction - also, those who have disassembled 300D's report shims in the sensor mounting).
4) maybe mirror stop (as it could also affect the light path to the focus screen)
p.3 #4 · Tuning Contax-Zeiss adapters to Canon lenses
Registration for infinity is more important the wider you go as you have less depth of focus the wider the lens is. If you are say 10 microns too thick on a 50mm you may be 50m instead of infinity but the same error on a 21mm lens and you could be only focusing out to 3m. I used to have the formula to calculate this but it I have lost it. As most lenses with floating elements are wide angle it's more critical but nothing to do with the floating element setup itself. If the lens hits it's infinity stop at the same place as the light rays focus on the film/sensor then OK - even if it over shoots or fails to reach infinity focusing will still be accurate in other distances providing the focusing system is in perfect register with the sensor/film. Cameras can have their screens shimmed or have the mirror angle changed slightly ( there is usualy an adjuster in the mirror box) My 5D is spot on with both the AF and the screen but I have had cameras in the past from various manufacturers where this was not so - manufacturing tollerances!
May 27, 2006 at 11:19 AM
jjlphoto Offline • • • • • [X]
p.3 #5 · Tuning Contax-Zeiss adapters to Canon lenses
p.3 #6 · Tuning Contax-Zeiss adapters to Canon lenses
Found my formula - if the lens adapter is only 0.1mm too thick this will mean a 50mm lens will now only focus out to 25m and a 28mm lens will only focus out to 8m.
p.3 #7 · Tuning Contax-Zeiss adapters to Canon lenses
The depth-of-focus formula on Dante Stella's web site is correct for symmetric lenses only. On retrofocus designs, you must know the exit pupil position and size in addition to the FL: these parameters define the geometry of the light cone before the image plane. In a nutshell, depth of focus is greater for lenses of retrofocus design (versus symmetric WA like CZ Biogon), and is lower for lenses of telephoto design (versus "long lenses" like the classic Leica Telyt).
p.3 #8 · Tuning Contax-Zeiss adapters to Canon lenses
jjlphoto wrote:
If it ain't sharp wide open, it certainly won't be better at f8 than it would be if the lens was properly seated.
I'm talking about hyperfocal focusing. If it doesn't focus quite infinity, thats fine because I hardly ever focus to infinity when I'm shooting landscapes F8-F11, so that I can keep more of the forground in focus as well.
In any case, both my Contax 28mm and 50mm seem to focus to infinity with the fotodiox adapters. Everything far out is in focus at F8 on a 1Ds2 for landscapes, nothing closer to the camera looks sharper, never tried wide open though. I'm quite happy with the results, I can't imagine that it would get any better. Are you offering to grind adapters? I would be interested in seeing if the results are visibly any better at F8 with a ground adapter to match the lens.
p.3 #9 · Tuning Contax-Zeiss adapters to Canon lenses
Ok, I was out shooting landscapes again this evening, and I figured I'd give this little test a shot. Indeed, it's a bit softer when shooting wide open (this is just above the center of the frame, actual pixel size). It looks a bit soft even at F8, but this is looking through a 17mp chip, and from what I gather this isn't the sharpest lens on the block (it doesn't seem to be any sharper than Canon's 1.4, which I never thought of as a sharp lens, compaired to my 135L and 85L)
I'll have to do this same comparison with my Zeiss 28mm 2.8, I know for a fact that for close-up shots shooting wide open (like a portrait, or flowers), that lens is very very sharp, but yet my landscapes don't seem to come out quite as good as I would expect them to in terms of sharpness. Though my copy of the 28mm is old and beat up, when I stop it down a few stops I notice that the aperture blades don't form a perfect shape, it's quite a bit lop-sided. That may be the source of my infinity + f8 landscape softness, or maybe it's this adapter thickness issue. Either way, it's not horrible, Canons 28mm prime certainly didn't do any better
I would love a 50mm that is sharper than the Zeiss 50's, or the Canon 50's. Any suggestions with out breaking out $2000+ for leica? For now a slight bit of sharpening will have to do the trick, and as you can see it snaps right into 'sharp' focus, but I would rather not have to sharpen so much, sometimes I have to blend different levels of sharpening because some areas look bad with to much sharpening.
http://www.danielbuck.net/wip/sharpen_02.jpg
Edited by Daniel Buck on May 30, 2006 at 01:26 AM GMT
p.3 #10 · Tuning Contax-Zeiss adapters to Canon lenses
The Leica 50mm f/2.0 Summicron can be had for around 250 Euro, and is sharper than the Summilux lenses, as far as I know, at least in the corners. You will have similar trouble finding a good adapter for it, but the additional distance between a Leica and EOS body makes it perhaps a bit more forgiving.
p.3 #11 · Tuning Contax-Zeiss adapters to Canon lenses
how does the 2.0 Summicron stand against the Canon 50 1.4? As I remember, my Zeiss 50 1.7 seems to be right on par with the Canon 1.4. If the Summicron is no better than the Canon, then it's not worth the trouble to get another adapter, and try to find one of the suckers.
Though admitably, the results from the 1.4 and 1.7 aren't all that bad, I have easily made 12x18 prints that looked great even up close. I guess I'm just always prying at my work with a fine toothed barbers comb, when everyone else combs with their fingers I probably don't need any more than what I have, I doubt any extra sharpness from another lens would show up in a 12x18 anyway, especially after a touch of sharpening on both files. But for something like, stock photos, more sharpness would be nice, as folks would be viewing the actual file with out any photoshop sharpening.
p.3 #12 · Tuning Contax-Zeiss adapters to Canon lenses
The late-model Summicron is great, very sharp. It is probably my favorite lens (see my profile for the competition). As far as I know, it is one of the very best 50mm lenses ever made. I have only taken a few pictures with a friend's Canon 50/1.4, and from those results I would expect that the Summicron does better. I think that the Summicron also has better bokeh, and perhaps colour, but on the other hand, I doubt the differences are huge. The Canon is a pretty good lens, and does have an extra stop and auto-focus.
p.3 #13 · Tuning Contax-Zeiss adapters to Canon lenses
I can only say that the old F2 Summicron on my Leica M was stunning. My CZ50 1.7 is slightly sharper at the corners and edges than my EF 50 1.4 but indestinguishable in the ccenter. My other good Canon lenses the 85mm 1.8 and 70-200L2.8 are fractionaly less good than either. My CZ 28mm 2.8 is slightly dissapointing - it only narrowly beats my 16-35L and while I can use it as a travel lens it's not good enough or flexible enough to be used commercialy where extra quality can be gained by zooming and framing exactly with the16-35. Maybe I have a good copy of the 16-35?
May 30, 2006 at 03:56 AM
Andi Dietrich Offline [X]
p.3 #14 · Tuning Contax-Zeiss adapters to Canon lenses
Daniel, with raw sharpening you regain the sharpness lost by the Canon AA filter, you can not blame the lens not being sharp in this case. The DMR has no AA filter but Canon and Nikons have. Normaly sharpness is done as last step of post, but you will not be able to regain what you lost without raw sharpening.
shirozina, while the Canon lens is an amazing zoom lens with good sharpness in the center it is far away from the zeiss 2.8/28 and its corner to corner performance.
If your cz 28 is not considerably sharper than the canon wa, you should maybe think about what is wrong with. The difference might be you did not open the canon lens for tuning.
May 30, 2006 at 10:34 AM
jjlphoto Offline • • • • • [X]
p.3 #15 · Tuning Contax-Zeiss adapters to Canon lenses
Even in the center, some Contax lenses need to get to f5.6 for best MTF performance. However, this should not be an excuse for soft infinity, when something noticeably closer is sharper. Many of the Contax lenses need a bit of service. Check the Stickey, page 7 or 8 perhaps, I have a post with service info. The 50/1.4 was the RTS kit lens, and has large samle variation. It seems this was a sore spot between Zeiss and Kyocera, and the production was ramped up pretty fast, too fast perhaps for Zeiss expectation of quality.
The CZ28/2.8 is an amazing lens, and a favorite of many here. If it is not surpasing a similar Canon lens, then yes, it is in need of service.
The 1.7 some say is sharper, but again, it is a victim of large sample variation.
p.3 #16 · Tuning Contax-Zeiss adapters to Canon lenses
bathman wrote:
Daniel, with raw sharpening you regain the sharpness lost by the Canon AA filter, you can not blame the lens not being sharp in this case. The DMR has no AA filter but Canon and Nikons have. Normaly sharpness is done as last step of post, but you will not be able to regain what you lost without raw sharpening.
I guess I'm still used to my old 1D, things just seemed a bit sharper with it I figured maybe it was the 17mp starting to maybe outresolve or something. But it seems to snap back to live with a bit of sharpening. I'm still fairly new to the Mark2
bathman wrote:
If your cz 28 is not considerably sharper than the canon wa, you should maybe think about what is wrong with.
Yes, the 28 definantly seems to be sharper when I'm shooting close and wide open. I'll try and get some samples sometime soon to see what yall think, if it's the aperture blades not forming a perfect hole that causes the stopped-down softness, or if it's maybe the adapter 'issue'. I'm not sure if this lens is worth repairing, I only payed $200 USD for it a few years ago, sounds like the initial repair testing alone will be almost 1/2 that much. Is this lens still in production? I wonder if I could just get a new one.
Edited by Daniel Buck on May 30, 2006 at 09:26 AM GMT
May 30, 2006 at 11:16 AM
jjlphoto Offline • • • • • [X]
p.3 #17 · Tuning Contax-Zeiss adapters to Canon lenses
Contax lenses are only available on the second hand market, mostly right here in fact!
p.3 #18 · Tuning Contax-Zeiss adapters to Canon lenses
hm... maybe I'd better just have it serviced then, who knows I might end up with the same thing again. I'll send them an email and see how much it would cost to have the aperture blades "re-seated" or whatever needs to happen. I wonder if they could put in different blades, ones that are more curved?
p.3 #19 · Tuning Contax-Zeiss adapters to Canon lenses
bathman wrote:
shirozina, while the Canon lens is an amazing zoom lens with good sharpness in the center it is far away from the zeiss 2.8/28 and its corner to corner performance.
If your cz 28 is not considerably sharper than the canon wa, you should maybe think about what is wrong with. The difference might be you did not open the canon lens for tuning.
No my 16-35L is sharp at F11 from center to corner - just a whisker behind the CZ but not IMO significant in real world usage. The CZ is ahead at wider apertures but I shoot mainly F8-F16 for DOF.
May 30, 2006 at 11:48 AM
Andi Dietrich Offline [X]
p.3 #20 · Tuning Contax-Zeiss adapters to Canon lenses
I probably don't need any more than what I have, I doubt any extra sharpness from another lens would show up in a 12x18 anyway, especially after a touch of sharpening on both files. But for something like, stock photos, more sharpness would be nice, as folks would be viewing the actual file with out any photoshop sharpening.