Today I disassembled my rokkor (for the n't time :P ) beacause i got something fun in the mail! focus lubricant (for the focus mechanism). I cleaned every mechanical part for residue and old (black) oil and relubed it all. Now the focus is perfectly (almost :P ) damped and smooth! Good going!
Just to be clear... the 5D mirror will hit this lens no matter how much is filed down at the rear, correct? From what I've read thus far, it seems that the only way to avoid hitting the mirror on a 5D is to either 1. Not focus to infinity, 2. File the rear AND shave the 5D mirror, or 3. Somehow Steal Dim.ka's camera.
Am I missing something, or is this pretty accurate with most of you who are using it on the FF?
Also, anyone manually file the shim of the adapters? What is the best (and hopefully the easiest) method for it, and about how much really needs to be filed?
Sahid Limon wrote:
Just to be clear... the 5D mirror will hit this lens no matter how much is filed down at the rear, correct? From what I've read thus far, it seems that the only way to avoid hitting the mirror on a 5D is to either 1. Not focus to infinity, 2. File the rear AND shave the 5D mirror, or 3. Somehow Steal Dim.ka's camera.
Am I missing something, or is this pretty accurate with most of you who are using it on the FF?
That's how I see it.
Also, anyone manually file the shim of the adapters? What is the best (and hopefully the easiest) method for it, and about how much really needs to be filed?
There is nothing approximate about how much the shim needs to be reduced, so "about" is irrelevant. Each lens is calibrated (collimated) differently, so one person's measurement could way overshoot infinity on your copy. You can file or power grind to your heart's content, but the most accurate and reliable way (without buying a lathe) is the method I describe.
So if you get the lens to focus to infinity on one camera and then try to mount it on another camera will it also focus to infinity on the other camera. I was hoping that once I do the modification on the shim I can use it on any canon camera I buy in the future (planning to upgrade my 20D to new 5D).
ziyadj wrote:
So if you get the lens to focus to infinity on one camera and then try to mount it on another camera will it also focus to infinity on the other camera. I was hoping that once I do the modification on the shim I can use it on any canon camera I buy in the future (planning to upgrade my 20D to new 5D).
Once the lens it tuned to infinity, it should be able to hit infinity on any body (or at least extremely damned close = close enough). If not, a minute or two of sanding will fix it right up.
The thing about moving to a 5D is that you are very likely to have a mirror issue.
Thanks Cogitech for the clarification. I haven't had my mirror hit any lenses so far (didn't bother "testing" the takumar 50 f/1.4), so I don't even know what may happen, or if it will permanently damage the camera. But I guess after a good filing, it would be safe to say that as long as you don't focus from 15ft - infinity, it shouldn't be a problem on the 5D?
cogitech wrote:
There is nothing approximate about how much the shim needs to be reduced, so "about" is irrelevant. Each lens is calibrated (collimated) differently, so one person's measurement could way overshoot infinity on your copy. You can file or power grind to your heart's content, but the most accurate and reliable way (without buying a lathe) is the method I describe.
I think you misunderstood my question here, I was referring to the m42 adapters that has the shim, and not the lens. Or maybe I'm misunderstanding your response. I was just trying to understand the best way to file down the shim portion of the actual adapter. Unfortunately, I wasn't able to get the adapters like you have in your guide. I read earlier about there are no approximate thickness for filing down, so I guess I have to just experiment and hope I get lucky.
The part you are calling the shim on the adapter, I usually refer to as a flange. It is added to some M42 adapters as a feature, to push the lens's aperture pin in, to engage the aperture and stop it down to the aperture selected. The Taks don't need it, because they have the switch on the side.
Anyway, yes, I just took a file and filed it off. In fact, the black adapter used in my howto was filed in this manner. If you look closely, you can see the evidence of this. It is a chore to do all that filing.
I don't have any shots taken with it yet since I only shoot film. It gets to about 50ft @ 1.2, so not *true* infinity, but if I am shooting something that far away, I'll stop down and infinity will be no problem. This is on a full-frame camera of course (tested on an A2 but also will give it a go on the 1vhs), with no mirror shave and no mirror clearance issues at least on the A2.
I used a belt sander (carefully!) to plane down the adapter. It's not that hard if you are handy with tools and have a belt sander that can be mounted upside down (belt up). I checked flatness with a digital caliper good to 5/10000ths and it wasn't off by a measurable amount, fortunately.
I used all 8 holes, since the mount/ring sandwich needs all the strength it can get, IMO. They all lined up fine, no problems. I drilled with a hand drill (ashamedly I don't have a drill press available @ the moment), not a cordless though. I used a 1/16" bit since 5/64" seemed way too large vs. the screw shank size. I ended up having deburring them with a carbide dremel bit, which cleaned the holes right up. 2 other carbide dremel mill bits helped mill out the flange area where the holes poked through (on the mount side), and a ball shaped mill in the dremel took care of counter sinking the screw holes. I had clamped/taped the two pieces (ring and mount) together for the drilling process, so they didn't move relative to each other while drilling.
I used the dremel with a 1/2" or so grinding wheel to hog out the flange area on the M42-EOS adapter, so the rear element would clear it. I didn't remove it completely, just enough to get the lens element through.
The dremel also made quick work of the apeture ring tab, in less than a minute with a fine cutoff wheel. I didn't bother to remove the apeture ring or fool with the ball bearing/spring, I just masked the whole back of the lens with masking tape.
I also used the dremel with grinding wheel to mill down the rear element retaining ring, rather than a file. I used masking tape to mask off the glass itself so there was minimal risk of dinging that with the dremel. I unscrewed the rear element set from the lens, and masked it all with tape to do this part. (cleaned the surfaces while apart of course).
All in all, not a bad job, I did it in about 4 hours. I have another 2 to convert, one is a 200163* very early version, basically identical physically to this one. Although this one has the 256xxxx serial number, it's got the early(?) long-type focusing ring...? The third one is a late model rubber-ring one. It will be interesting to compare the three. The 2 metal ring lenses came from the original owners, they are in quite fine condition, one in particular is near new (the 200xxxx one). Both metal ring ones show yellowing so they will get the UV treatment soon. The rubber one I have yet to receive but it likely has no yellowing hopefully.
I don't have any shots taken with it yet since I only shoot film.
-Ed
Ed,
Nice handiwork on the mount, but I hope you eventually plan on using it for digitial. Otherwise, why wouldn't you just go with a Minolta film body?
I may have to try one of those carbide Dremel bits. I'm also considering just using an old EF mount or perhaps K mount (if my other Rokkor pans out) and drilling the holes there which seems like it would be a little easier than dealing with the thick flanges on the M42 adapters.
Well, one of these came with a minolta film body, (srt-101) but it's a bit old-school for serious shooting, though it is satisfying to work with, from a mechanical standpoint. still, I have a pair of Fuji 6x7 and 6x9 cameras for the times when the all-manual mood strikes. thus the conversion of this lens to EOS mount. Someday I may go digital but for now I prefer film.
I havent' seen a Kmount so not sure how those stack up to the M42 types. An old EF mount would be nice, no doubt, esp. in stainless.
The carbide dremel bits work great, easy to eat right through the brass/bronze no problem. A bit tricky to control at times but more precise and way less grabby than using a drill. The comparison would be like a router vs. a drill with spade bit, when making holes in wood, as an example.
I just came across the guy on Pbase however that has machined up adapters so this whole sanding/drilling thing can be avoided. Checked with him to see if those are available... if so it would make this a lot faster/easier and also reversible to original mount if desired. Will post what I hear here.
Um... Does anyone who converted these (or in the process) have any of those microscopic balls they are not using? I seem to have lost all 4 of them in my room, and it's almost impossible to find them... trust me, I've looked for hours now. For some reason, the spring in my lens is very powerful, and shot all the balls out. I will gladly send a self addressed stamped envelope to someone if they can send me a few of their extra ones. I will be very greatful for anyone that can help.
I guess I have to grease them up before trying to adjust the aperture ring on it. Wonder if normal vasoline would work.
If not, I have another Rokkor on the way which I can certainly grab one from.
The trick is to hold the ball bearing depressed into the hole with a flat-head micro screwdriver (held at an angle) and then slide the aperture ring in place as you are still holding the ball. The edge of the screwdriver stays in place, holding it, until the aperture ring is basically right on top of the flat edge of the screw driver. Then, all at once slide the screwdriver out and push the aperture ring into place fully.
The trick is; the aperture engage arm on the aperture ring needs to stay engaged in the inner aperture mechanism throughout this process. I've done it so many times now that it only takes one try, but I do remember the first lens taking several tries (and ball bearings).
Interesting story concerning my conversion, but more about the 5D than the lense. My mirror hung several times while sanding the shim, before I filed the ring that holds the rear element. The adapter I used has a focus confirmation chip and I believe the camera made a mental note that with this lens the mirror hangs. After the full conversion, in about 1 of 10-15 shots the mirror would not fall in variuos focus ranges. I remeber seeing on one of the threads here that 5D would remember things about lenses, so I placed some tape over the focus confirtmation chip and the problem has seemed to go away. I need to do further testing to verify this to be true, but for now unless I pass infinity ( I sanded a bit more than I should have) I have not had the mirror hang once in about 30 shots.
I have some of the ball bearings, feel free to email and I can send you some.
The real trick is to not even bother taking the apeture ring off, there's no need- use a dremel to cut off the tab with the ring in place.
Good to hear re: 5D mirror issue, tootalew. I shot a couple rolls (KM 25 hell yeah!) today with the 1VHS and had no mirror clearance on mine either. Mine goes out to about 30-50ft @ 1.2, so not quite infinity per se.
Hey, thanks guys for the help. I somehow miraculously found one on the carpet (got really lucky), so I was able to put that one back in. Paul, I did put it in the way you mentioned it, but the problem I had was that after I would push the aperture ring in all the way, it would stay stuck and wouldn't turn. I figured the ball bearing was just dry and needed some grease, so I put some vasoline in the area, and it solved the problem. My aperture ring is somewhat loose, so the way I lost the last 2 balls was after taking off the shim to sand for infinity, it would losen the aperture ring... and shoot out the ball. I still don't have infinity yet. I'm not gonna bother taking it apart for a while now, and even if I do, I'll have to tape down the aperture ring first. However, it may be good for you guys (esp. you Paul) to just keep those around somewhere incase any other members (a clutz like me in the future) may need it.
Everything is finally installed, will try to take some pics tomorrow! Hopefully I didn't screw anything up.
Ok, my conversion is finally complete and successful. I have to sincerely thank Paul (Cogitech) with all his assistance throughout the process, as well as khidir for helping me solve another issue. I couldn't have done it without their kindness and generosity.
Now, on to some samples. I am still a bit worried about testing it on my 5D, so these are all from the 20D. I didn't really have much time, so I just snapped a few things last night, and spent about 15 minutes at a rose garden getting some sample. These are definitely not the best samples, and definitely not the sharpest (didn't have a tripod on me). I know I broke the cardinal rule of photography and put the subject in dead center for most of the shots... but again, this was simply for test purposes.
All shots are hand-held and wide open (unless noted).
There are absolutely NO post processing of any sort done to the following images.
1.
This was the assembling desk. This shot was taken with the Takumar 50 1.4.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
100% crop (center)
12.
f/5.6
13.
100% crop (center)
14.
Again, sorry for the inconsistency, but I had no tripod.
I am very very impressed so far with this quick test. The bokeh of this lens is incredible... I would even say slightly better than the 85L! I love how it almost has a painter like feel like in image 9. As everyone else stated, it's pretty sharp wide open as well (though my copy may be slightly less sharp than some of you). At f/5.6 and beyond, it's as sharp as it needs to be for any lens. Overall, I am loving this lens already.
Edited by Sahid Limon on Sep 13, 2008 at 09:36 AM GMT
