Canon EOS EF mount pin readout!
Ever wondered if there are any ways to use the marvelous 85mm at f1.2? I mean not in the lowest of lights but outdoors etc.
As many of you already know twisting method will disable any focusing with many ring type USM lenses and using ND's seemed to be the only option and still valid for getting normal shutter speeds. I've been wondering that with just placing a small transparent piece of tape on the last 3 pins of the lens will discard/disable aperture data but the focusing power will remain. The tape should be placed on the right hand side of the lens when looking at it, if I'm not mistaken. At least so you can lock the aperture but use focusing motor on those fly-by-wire "L" series like the magical 85mm f1.2. So, the Canon EOS EF mount pin readout at the camera body is: (Left to right, looking at the front of the body) 1. VBAT 2. P-GND 3. P-GND (pins 2 & 3 are common on the lens) 4. VDD 5. DCL 6. DLC 7. LCLK 8. D_GND Pin Functions explained: VBAT - Motor power P_GND - Motor power ground VDD - Logic circuitry power D_GND - Logic circuitry ground DCL - Data from body to lens DLC - Data from lens to body LCLK - Clock Data protocol: Motorola SPI; 8 bit serial; Such as the protocol used with the 68HC05 chip. (hint hint for FF makers) I assume the few RED EF mount makers use the same chip. Experiment on a cheap lens first, as this so far is only in theory! Cheers, T |
Thank you for the info. Maybe you can post a small photo of the tape as you've applied it? We will make this into a real cinema camera! :)
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I tried some tape on a cheap lens. And then it disappeared. I hope it's not in the camera.
I won't be applying any more tape, unless there's a way to ensure that it stays put. |
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I would seriously be tearing apart my camera looking for that piece of tape. Things like that bug me. I lost a lens cap once in my bag and after 5 minutes of tearing the thing apart I found it. |
Jon: Sux .. most likely, when you mount the lens there is a friction point and the tape probably dislodged. Most likely, it's in your camera body.
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I tried it every way and it didn't work with 85mm 1.2L, no focusing power.
:( |
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that is if the tape stays on... sorry John.... Oh, and a note to the wise... if you come across the old 85mm1.2 L going cheap, it had power assisted manual focus, so taping/twisting, means no focus on that baby... |
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T |
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Canon Australia - EF 85mm f/1.2L II USM that mention full time mechanical focusing. Shame.. looks like it will be the nikkor... |
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