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Taming The MPE-65

 
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Harold Gough



Joined: 09 Mar 2008
Posts: 5787
Location: Reading, Berkshire, England

PostPosted: Tue Sep 25, 2012 11:30 am    Post subject: Taming The MPE-65 Reply with quote

As I understand it, the lens has manual focus and manual magnification controls. That leaves only the diaphragm to require elecrical/electronic connections.

If that is the case, surely the skills and talents of some members would be able to identiify the contacts involved and the voltage required. This would permit use of this wonderful lens on non-EOS bodies. This would infringe any warranty but some of us would accept that as a small price for removing its limitations.

Harold
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ChrisR
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PostPosted: Tue Sep 25, 2012 12:44 pm    Post subject: Reply with quote

There's only two contacts effectively iirc - clock and data.
Sure, it shouldn't be hard with a PIC or Arduino ( if they're fast enough, otherwise a little digital circuitry), once the protocol was worked out - which an oscilloscope should reveal, with inspiration and perspiration.

The practical difficulty is getting in there, behind the lens, to make the connections. An obvious way would be through a 3rd party "auto" extension tube.
Then you have a couple more issues - one would be reading the information your camera would like to be sending to its own make lens - assuming it hasn't recognised that there's no known lens on the camera.
That would be another bit of detective work, which being newer technology could be much more complex.
Then you just operate the MPE, and maybe have to send a signal back tothe nbody to say "the iris is in the right place".
The other issue for eg Nikon is that you don't have space because of the unfavourable flange distance. I don't know how well an MP-E works if it's on additional exptension. It's probably OK, but...
Oh - and there's no Canon to Nikon adapter which isn't a fudge between Chinese extension tubes.
A 4/3rds body would possibly be easier, to get it all working with.

Another starting point for the Canon end would be to break up a film camera - some of them are worth so little.
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abpho



Joined: 17 Aug 2011
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PostPosted: Tue Sep 25, 2012 2:17 pm    Post subject: Reply with quote

If you have to fabricate an adapter the added length would affect magnification slightly but nothing else. But I hear that the protocol that Canon uses is proprietary. Sigma, Tamron, etc have to reverse engineer the communications protocol. They sometimes get it wrong. That is why some lenses have to go in for "calibration" when a new EOS body comes out.

Why not grab a good prime lens and mount it to an Olympus telescopic tube? It is the closest I have seen to what an MP-E lens is like.

http://www.alanwood.net/photography/olympus/telescopic-auto-tube.html
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Harold Gough



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PostPosted: Tue Sep 25, 2012 2:28 pm    Post subject: Reply with quote

abpho wrote:

Why not grab a good prime lens and mount it to an Olympus telescopic tube? It is the closest I have seen to what an MP-E lens is like.

I do it all the time.

Harold
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Pau
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PostPosted: Tue Sep 25, 2012 2:52 pm    Post subject: Reply with quote

Someone sell it for NEX cameras
http://www.metabones.com/sony/buy-eos-nex-adapter
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Chris S.
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PostPosted: Tue Sep 25, 2012 6:26 pm    Post subject: Reply with quote

I've noodled about adapting an MPE-65 to Nikon myself--not so much for actually needing this lens, but because so many Internet voices have called such an adaptation impossible that it is hard to resist the urge to try. Like Chris R, I'd start by using an oscilloscope to record whatever currents and voltages a Canon DSLR sends to a lens to set the aperture during exposure, and use an Arduino or other microcontroller to mimic that signal, with power supplied by either a small battery of the Nikon's 10-pin remote, if it were to prove sufficient. Based on my limited experience with Arduino, I'd bet that it could handle such a task quite easily.

Redrock Micro seems to have done something like this for the M4/3 mount--but at a rather high price and targeted toward video use through their proprietary control pad: Redrock LiveLens MFT Active Lens Mount. This product does not look very useful for macro still photography, but its existence tends to support the premise that the automatic aperture control can be done.

Mischa, we might note that mounting a prime lens on a bellows or tube usually doesn't usually permit automatically stopping down of the aperture during exposure, while the MPE-65 does. The ability to compose with a bright, wide-open lens, but stopping down for added depth of field during the shot, would be really useful in the field for the 1-5x range.

On looking, I see that this subject has been discussed at least a couple of times--though I hadn't recalled the threads:

http://www.photomacrography.net/forum/viewtopic.php?t=7221&postdays=0&postorder=asc&start=0

http://www.photomacrography.net/forum/viewtopic.php?t=8472&sid=a65cdefe2eafde20d8bd40401466aea1

--Chris
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abpho



Joined: 17 Aug 2011
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PostPosted: Tue Sep 25, 2012 7:48 pm    Post subject: Reply with quote

Chris S. wrote:
Mischa, we might note that mounting a prime lens on a bellows or tube usually doesn't usually permit automatically stopping down of the aperture during exposure, while the MPE-65 does. The ability to compose with a bright, wide-open lens, but stopping down for added depth of field during the shot, would be really useful in the field for the 1-5x range.
I know. I thought I would just throw that out there. But I guess you guys already knew that.

That EOS to Sony NEX adapter looks pretty cool.
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Harold Gough



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PostPosted: Tue Sep 25, 2012 11:17 pm    Post subject: Reply with quote

Let me state my point of view:

I use legacy manual focus lenses on my E-P2. That gives me:

High quality lenses at a (usually) affordable cost. (Having tried it. I don't like AF).

Because the E-P2 body has image stability, those lenses (up to super telephoto) can now be used with that advantage, not available when they were the latest models. The same applies to the MPE-65.

Legacy lenses tend to have optimum sharpness at around f8, a very useful characteristic for macro.

None of the above requires any electrical connection to the body. My camera has no information about the lens in use unless I set the IS for its focal length. Ambient light metering by the camera works perfectly well.

That said, I am more generally intrigued by the lack any fully manual diaphragm control (external battery and switch) for the MPE having surfaced in this forum.

Harold
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rjlittlefield
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PostPosted: Wed Sep 26, 2012 12:16 pm    Post subject: Reply with quote

At johan's request, I have split this thread to form a separate thread regarding his 'almost MP-E' setup. The new thread can be found HERE.

--Rik
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ChrisR
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PostPosted: Wed Sep 26, 2012 7:50 pm    Post subject: Reply with quote

The Canon comms have been cracked, it appears.
There's a lot around the net, including lens (Focus, aperture etc) and flash (ETTL, making an auto flash into a manual one, etc.)

I've found enough to be able to drive a Canon lens I believe, and a company which is in the business of doing it.

The lens interface is a fairly simple Motorola-direction 8 bit 5v serial link with just a few bytes in a packet for each function. When the lens is first connected there's quite a lot of data flowing to and fro, mostly about AF, maximum aperture, lens data and whatnot. Several sites have bits of information. There are still some mysteries it seems, eg exactly how the eprom in the lens is programmed for AF calibration.
Newest lenses have more stuff. It appears there were two lens protocols at significantly differing speeds used. An MP-E is an old one, perhaps.

Info in the link below refers to secret numbers relating to actual apertures, but other have sussed them out and published.

First read this illuminating FAQ page, then go to downloads and look at the pdf file linked near the bottom.
http://www.birger.com/FAQs.aspx
Most is revealed. Smile

I recklessly went ahead and installed the Device Interface 1.1.6, which brings up an intruiging screen:

I have some more links, but it's 3:45am..
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Harold Gough



Joined: 09 Mar 2008
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PostPosted: Wed Sep 26, 2012 11:24 pm    Post subject: Reply with quote

Thanks Chris,

An atmosphere of intrigue is developing!

I suspect that this is not pointing towards use without connections to the camera but the technicalities are something I prefer to leave to those who understand them.

Harold
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