p.1 #1 · 5D mirror collision with Mamiya 21mm f/4 M42 lens - is it harmful?
Hi,
I am new to Canon. Just played around with my 5D. Fitted a modified Mamiya Sekor 21mm f4 SX lens with a M42 to EOS adapter (I have two - a heavy brass and a black lighter adapter). At infinity the camera takes a shot correctly, but then the mirror hits the lens and I will have to refocus to ~30m mark to release the mirror. The mirror goes up no problem during the shot at infinity and it takes a proper picture, but when the mirror returns back down it is stuck.
How much harm am I doing to the camera, especially if I do this repeatedly over time?
p.1 #5 · 5D mirror collision with Mamiya 21mm f/4 M42 lens - is it harmful?
Decide if the lens you want to adapt to the Canon full frame system is worthy. If it is then you have no choice but to shave the mirror. By shaving the mirror, it will open the door for you to use so many other different lens such as the Leica wide angle lens and etc.
p.1 #8 · 5D mirror collision with Mamiya 21mm f/4 M42 lens - is it harmful?
I prefer to modify the lens and leave the camera alone; regardless of lens value (so far). It opens the door to use the lens with all of the future cameras that I will own. After all, if I'm going to keep the lens for a long time, then it reduces the number of "operations" that I have to perform - right ?
p.1 #9 · 5D mirror collision with Mamiya 21mm f/4 M42 lens - is it harmful?
If you have a lot of lenses that do this, modify the mirror. If you have only one or two, consider modifying the lens. I did the latter with my Leica 28mm f/2.8. That's a relatively expensive lens (though not when compared to other Leicas that sell well over $2K and more). I sanded down the rear shroud till the mirror cleared. By chance, the mirror cleared before I ran out of metal to sand, so that is not going to work for all lenses clearly. I repainted the bare metal on the end, and it looks and functions fine. Personally, I believe this lens is now worth more than I paid for it, because it is now functional on the 5DII, which is definitely not typical.
On whether you do damage when the mirror hits. Since there have been reports of mirrors coming unglued on some 5D's, I suppose the cumulative stress on that glue joint could displace the mirror off its mount eventually. But of more immediate concern is what I believe to be the short term tendency for the mirror to become misaligned. After a whack or two of that mirror, what appears to be in focus in the viewfinder may not prove to be in focus on the sensor and the file. I think this does happen, making images subtly out of focus. On the 5DII, it's possible to check the discrepancy between the manual, viewfinder focus and the sensor focus by alternating between the viewfinder and live view. If they are not in agreement, either you need to microadjust the lens, or if that was previously done, the whack of the mirror on the back of the lens has probably misaligned the mirror temporarily. My guess is that to the degree the mirror mechanism has some flex, that mechanism probably eventually rebounds to its original positioning over some indefinite period of time (like less than a day, maybe less than an hour, just depends). This is my hypothesis, as I have not seen anyone writing about this, and I suggest this because it seemed to fit the facts for me prior to shaving the Leica. There would be a brief time period where all my lenses appeared to need more microadjustment, and it subsequently dawned on me that the Leica had likely been the culprit. In reality, they did not need any readjustment, as I came to realize over time.
p.1 #10 · 5D mirror collision with Mamiya 21mm f/4 M42 lens - is it harmful?
The down stroke sounds so soft that I don't worry about it. I can't trim the Takumar 50 1.4 nor the CZ 60 2.8 1:1. Another 42mm lens hits but I'm not going to worry about it.
p.1 #11 · 5D mirror collision with Mamiya 21mm f/4 M42 lens - is it harmful?
Yes, what I think is happening is that the power and speed occurs on the upswing, which powers the mirror across what on the return trip proves to be an obstacle. In order to power through, something has to give, and I think it's a flex backward on the mirror supports. I'm guessing the return trip for the mirror is powered only by fairly weak springs, as the speed is not critical at this point, and this is why the mirror doesn't quite make it this time 'round. So in my mind, the damage/risk is done on the move up due to high impact and implicit mechanism flex.
The mirror trim is not for the faint of heart, IMHO, having done it once.
p.1 #12 · 5D mirror collision with Mamiya 21mm f/4 M42 lens - is it harmful?
Simon,
I just picked up a Mamiya SX 21mm f/4 myself. Mine is completely stock, so right now I can only focus within a few feet, but what I'm seeing looks very good. Much nicer than the Yaschica I bought & sold.
Do you have any follow-up on your lens? Did you shave your mirror, or try further grinding of the lens? I see there's a small silver aperture pin on the back. Did yours have this ground down, or removed?
p.1 #13 · 5D mirror collision with Mamiya 21mm f/4 M42 lens - is it harmful?
mudsill wrote:
The down stroke sounds so soft that I don't worry about it. I can't trim the Takumar 50 1.4 nor the CZ 60 2.8 1:1. Another 42mm lens hits but I'm not going to worry about it.
But surely if its catching on the way up (but not sticking) then the mech is being stressed beyond what it should be. wouldn't this probably lead to an early fail of the mirror mech?
p.1 #14 · 5D mirror collision with Mamiya 21mm f/4 M42 lens - is it harmful?
siriusdogstar wrote:
Hi,
Same thing happening here 5d & s-m-c takumar 50/1.4
I think the mirror "up" mechanism is stronger than mirror "down"; mirror also hits going up, but catches only going down.
I have decided not to continue using the lens at infinity, because maybe scratch lens or damage mirror, over time.
sds
I had the same issue with this very lens. A little careful filing of the rear lens shroud took care of the problem completely. My guess is that I removed about 1mm or so of material from the shroud.
p.1 #15 · 5D mirror collision with Mamiya 21mm f/4 M42 lens - is it harmful?
Here's my experience:
I first filed the back lip (and the little electronics pin) dead-flat with the main part of the lens's housing. You would expect this to be what is needed.
With a "know to be correct thickness" EOS adapter mounted, if I turn the focus ring all the way towards "infinity" my 5D mirror hangs. However, the lens is also focusing PAST infinity. When I pull it back to good infinity focus, the mirror JUST clears. I wonder if the OP really had infinity set, or was being fooled by the large amount of DOF & actually going past, like me?
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Mike, I assume you are taiking about the inner shroud, directly around the element, yes? I think I'll try filing that, just to be safe. -Also, I kind of like being able to go slightly past infinity. Some lenses are designed that way, and for good reason.
p.1 #16 · 5D mirror collision with Mamiya 21mm f/4 M42 lens - is it harmful?
Cableaddict wrote:
Here's my experience:
I first filed the back lip (and the little electronics pin) dead-flat with the main part of the lens's housing. You would expect this to be what is needed.
With a "know to be correct thickness" EOS adapter mounted, if I turn the focus ring all the way towards "infinity" my 5D mirror hangs. However, the lens is also focusing PAST infinity. When I pull it back to good infinity focus, the mirror JUST clears. I wonder if the OP really had infinity set, or was being fooled by the large amount of DOF & actually going past, like me?
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Mike, I assume you are taiking about the inner shroud, directly around the element, yes? I think I'll try filing that, just to be safe. -Also, I kind of like being able to go slightly past infinity. Some lenses are designed that way, and for good reason....Show more →
Exactly right. IIRC, I either posted a thread about it quite a while back, or had it buried in a thread about shimming the screen. A search should turn it up. Basically, I went heavy on the blue painter's tape and made sure to have everything on the rear of the lens good and protected, putting a second layer on the rear element to offer a bit more protection just in case the file slipped. Took less than five minutes of filing...actually took more to apply the tape.
