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Re: [OM] OH NO! More Alt dot Moose - Again

Subject: Re: [OM] OH NO! More Alt dot Moose - Again
From: Moose <olymoose@xxxxxxxxx>
Date: Mon, 13 Feb 2017 23:03:51 -0800
On 2/13/2017 4:47 PM, Mike Gordon via olympus wrote:
Easy way Moose writes:
<<What are the requirements? The people at the links below are talking 1:1. Might that be 
a little extreme? In the case at hand, the leaf was maybe 6" in length. To fill almost 90% 
of the frame width would require only 0.1x. The excellent, and expensive, Panny 12/1.4 will do 
<<that. The Oly 12/2 would fill 70%.

Appreciate your thinking about how to accomplish these macro landscapes. I do 
like the single lens solution.  I suppose if the higher mag subject is not to 
close and the lens doesn't close focus  by use of a helicoid so much that the
the entrance pupil to subject distance doesn't change by a substantial 
percentage, then it should work.

I was thinking more about IF prime lenses. I know they often change FL to focus, but if image size is maintained, it might work The A710 example suggests that.

The Oly M.Z 9-18 might look like a good candidate, but dpreview notes 'focus 
breathing':

"One immediately obvious feature of the 9-18mm is that the angle of view changes very markedly on focusing, becoming wider as you focus closer." That's not going to work. A quick look through the 25/1.8 shows no such obvious in the VF effect.

I thought I might have a line on a cheap 12/2.0, with messed up front ring, but the owner has opted to repair/refurb. Probably the smart thing . . .

I have no clue if those conditions are met for the lenses you mentioned.  A CU 
diopter might make the fov too different and ball up the stacking w/o some 
fancy PP footwork.

I was not thinking of using the C-U lens only for the close slices, but for all exposures. Elsewhere, as you suggest, lies madness. :-)

Thus the need to limit the added mag and rely on DoF to cover less than perfect infinity focus. Where's Dr. DoF, with his hyperfocal calculations? Maybe I'm better off without them (but not without Chuck!), as they'd probably show it wouldn't work, and I'd have to try it anyway.

I would bet there would be substantial artifacts to clean up no matter 
technique is used.   Perhaps even the G9 would work but perhaps they shorten 
the FL to allow for higher mag which might muck up the works.

Then, once you spend ages mucking about - you end up with a G9 image file. I don't have the option , as I sold off my G11, but don't think I want it, anyway.

What I'm curious about is if it's possible to get first class results using the focus bracketing mode of an E-M5 II. If I can find a good subject, the distant background part, I may experiment using the Panny 14/2.5. Not as wide as one might like, but already in hand. And, as a pancake design, the depth of the whole lens optical assembly is so shallow that the unmoving front aperture requirement shouldn't be a problem. Should provide proof of concept - or that it won't likely work.

Imagine, instead of all the fussing of set-up and the tedium of manually setting the slices, if one could just focus on the closest point, push the button and wait a few seconds. That's my kind of solution. I've tried manual slicing, and find that I suffer from some form of attention deficit syndrome - or - just plain boredom, and tend to lose my place. Did I just shoot at this mm setting, or just move to it?

Any way that works, Mike

Only If It's Easy Moose

Well, OK, there is a possible elegant manual solution, using/modifying an Oly Bellows (and possibly leaving it so it can be restored.)

Subtract the E-M register distance of 18 mm from the OM of 46, and we have 28 mm to work with for a focusing mechanism that reaches infinity. The minimum flange to flange distance of the Oly Bellows is 35 mm

The actual rear mount is screwed on to the tube that mounts in the bellows assembly very simply. The diameters of the male E-Mount, both bayonet and overall, are very similar to the OM mount. I believe a mount taken from a cheap extension tube could be attached by drilling some new holes in the bellows piece and attaching the E-Mount. As the locking mechanism of the E-Mount is on the camera body, not the lens, it would work without modification - and save about 2 mm occupied by the locking mechanism on the bellows. That would give a total mounting flange to flange depth of about 33 mm.

That leaves about 5 mm of excess length. About 5+ mm could be gained by unscrewing the front of the bellows from the fabric and gluing the fabric to the front mount. Or, more solidly, and reversibly, by screwing the interior fabric mounting plate to new little holes drilled in the front standard. My measurements aren't exact, but it looks like it would be very close, maybe even a tiny bit past, infinity focus. If not quite there, a pleat of the bellows could be cut off.

Everything but any bellows shortening would be reversible. There may be replacement fabric portions available. Or one could just put up with a small limitation to the 7+" of extension it allows.

That would do the job of allowing focusing by moving camera body relative to a fixed lens with excellent, smooth control. And yes, the A7 will clear everything on the bellows. Looking on Camreasize, is appears the II and RII would also work.

The Hard Way Moose

--
What if the Hokey Pokey *IS* what it's all about?
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