OlyMinCan-28

[Harold Gough]

When I forwarded a link to this thread to a photographer friend he sent me this:

http://www.syncroscopy.com/syncroscopy/news.asp

Harold
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Happiness is having the right adapter.

My manual flash setup for high magnification:

http://www.photomacrography.net/forum/viewtopic.php?p=117843#117843

[rjlittlefield]

[lhhansen]

Dear Chris,
you wrote:

... you almost certainly won't be able to do it "like Charles did ", unless you can figure out a bellows with a rear standard half a millimeter thick. Charles had a total of 3mm or so to play with.

I tend to disagree. If it is possible to move the lens 2.5 mm (difference between the flange-sensor-distance of Canon EOS and Nikon) closer to the camera, all is well. To me, it looks like Charles' infinity stop is protruding at least those 2.5 mm (perhaps even 5mm) out from the front standard. I may need to make a bag bellow (to get enough extension "span" between minimum and maximum - maximum extension requirement will be reduced for a wider lens), but I don't see the need for a slimmer standard.

Best regards,
Lars

[ChrisR]

Lars - I'll dig it out again. It'a a while ago that I tried it!

[Charles Krebs]

Lars, Chris...

Should be possible. I machined off some "depth" of the aperture ring/barrel and there's a little more that could be removed is needed (and still have a nice functional f-stop ring). If needed, a bag bellows would provide even a little more room.

The optical section (once removed from the Olympus lens focus mount) is narrow enough to be moved into the "throat" of the Nikon body. My biggest concern was the mirror clearance at infinity focus, but the reference Lars gave suggests that this will not be a problem.
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http://www.krebsmicro.com

[ChrisR]

The mirror clearance I have tested - on a D700 it does clear at infinity, but it's extremely close. The remaining issues revolve around how much one is prepared to remove from the metalwork of the lens. I Hadn't considered machining it.

[Charles Krebs]

Chris,

This shows the edge that was machined down to give more room.



The lens was purchased for this project (cheap, compared to the 24mm or 21mm), but the Minolta bellows was an old piece laying around in one of my "boxes-o-stuff".

If I were to start from scratch (i.e. no bellows on hand to scavenge) there are other ways to approach this. One that I had mentioned earlier still interests me if I ever get my hands on a wider lens.

[lhhansen]

Dear Charles,

Thank you for your elaboration.
You alternative method with a rail or linear stage under the DSLR sounds interesting and I may investigate it. However, it may not be cheaper if one were to first acquire such a stage rather than an old bellow.

You and others mentioned that not all wide angles would extent nicely. So I would probably test any lens extended first before taking it apart.

Cheers, Lars

[ChrisR]

I found I had a 24 too so I took the monkey wrench to it:
Olympi:

[Charles Krebs]

Chris,

[lhhansen]

ad Charles:
For your "L-plate" method this focusing "rail/plate" may be interesting:
http://reallyrightstuff.com/macro/02.html - and perhaps cheaper than a "linear stage".

ad Chris:
That looks great! Now I wonder what the 21/3.5 looks like and how it fares extended. Have you checked the performance of the 24/2.8 using extension and thereby focusing extra close?

Best regards,
Lars

[ChrisR]

Lars - not recently!
It's supposed to be OK.
I've left it in a box with the 28 in the hope that they have a baby. Maybe a 16?!

That RRS rail says it's $350. Ouch. And you still have to hold the lens somehow.
An idea - the old(?) Cokin filter mount adaptors had a wide flange. which could be used for putting screws through, etc. There was a larger type, called "A" series I think.

I have various old bellows but none of the ones I'm prepared to saw up, are suitable. Something from a Pentacon 6, perhaps!

[JLyle]

Charles,

I am curious to find out how you have the lens affixed in the front standard? Is it a press fit? Did you use a few spots of some kind of releasable cement?

Lyle

[Charles Krebs]

Lyle,

The outside barrel of the front of the lens is a certain diameter at the very end (don't know the exact diameter). This "diameter" continues towards the rear of the lens for a few mm and then the barrel diameter gets larger just before the aperture ring. This provides a nice shoulder. So the hole in the front standard was enlarged so that the narrower diameter at the front would just fit into the hole. The standard was also milled down so that the front edge of the lens came close to, but did not extend out the front. Then I simply used a 52-49mm step ring (the lens has a filter size of 49mm) as a lock ring to "lock" the lens to the front standard. This also then provided 52mm front filter threads.

(Hope that's clear... took more words to describe than I thought )

Chris,

Well, I picked up a 24mm... should be fun on the full frame camera (if I ever find the time to assemble it!)
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http://www.krebsmicro.com

[Charles Krebs]

Lars,