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| p.1 #1 · How to (not) fix your Rokkor 58/1.2 for infinity on EOS (5D2). |
Rokkor 58/1.2 is a magic lens by all standards. It offers medium format look (or better) on FF. Now I've had mine for a year, but due to a Zeiss coma I have used it too little. I wanted the oldest version, radioactive and yellow and finally found a copy for 300€. Mount was converted to EOS/EF but I soon find out it did not reach infinity on my 5D2. Mirror hung and while evaluating what was wrong I also found out that the mirror box stopped the rear element from going back-enough to enable infinity. I may have bought it for short distances and stitches, but it was disappointing still. Mine reached perhaps 5 meters or so.
While smoking Zeiss I sometimes stumbled across images at infinity on FF. Almost always a wow. Cant remember all names but I believe Paul Yi here at FM is one of them. Apart from PP skill and composition taste and all that I realized that the lens I got was severely crippled.
I'm no lens surgeon by any standard but finally I did this. Hopefully someone else will find this thread and realize that you can do this better than me. If I did it a 2nd time the "(not)" would not be in the title.
So here's the lens. If you look carefully you'll see where my 5D2 mirror have hit a number of times. Look to the left on the retainer ring, you'll see two small light marks on each side. This is the upper side of the lens when mounted. The chip is at the bottom (to the right).
And here's the problem. A 5D2 in all it's glory but not capable of using this glass to all what it is capable of. It's as much lens-porn as a CY 85/1.4, just a shell and then glass. Dont mind the dust, for this lens I am using a semi-productive filter as lens protection, I never shoot with it on.
This is what you'll need. A dremel or similar. This is a 40€ probably Chinese made and for those living in Scandinavia this is from Clas Ohlson. Now, I was not sure what kind of grinder/front to use and I started with the pink stonish variants. That is bad, dont use those (!). What's mounted here is a more standard grinding/sand paper cylinder and that really eats through the soft metal nicely.
This is how the set up looks like. The lying radio to the left sole purpose was to lift/hold a flash-light to clearly see where you grind. The cloth here is real Cashmere scarf from Italy, but you can do with something simpler :-)
As you see in the previous image you want to cover cavities with tape carefully. I had a strong vacuum cleaner and each and every 2-3 minutes I used it close to what has been grinded. VERY close. It's like copper or a similar soft yellow metal that turns into golden dust. When paused you may wanna use a black marker when you see where you want to grind the most next time, you want it even of course. The mirror-box is flat, and if you e.g. use Liveview, the mirror will lock up and extend the lower part of the mirror box with 2-3mm.
Now, here's the final result. It took three iterations (grinding-vacuum-test) before the mirror got clear. Now it's clear for infinity both in Liveview and normal shooting. The retaining ring is still very secure although it's only parts of mm's left. It's not very visible on this image but now there's a clear 1 mm slope now to the right - which in this image is the upper part of the lens when mounted. The grinding should of course be centered at the top of the distance/DOF scale of the lens.
Now, I made a mistake. A single second I grinded carelessly so I got a scratch in the back element. It's a small scratch and I am sure it does not affect image quality. But the value was cut in half that second while the lens usability was doubled. A bit contradictory of course. Regardless, here's the first ever infinity shot by this lens on a 5D2 and I will surely explore this lens further now. This is a 5 sec tripod shot through the window with reflections and all an hour ago. From my apartment on the 5th floor down to the street. Two cars came and went away if you wonder about the lights. Shot is very sharp.