Case study: "Portable" stacking set-up.

A forum to ask questions, post setups, and generally discuss anything having to do with photomacrography and photomicroscopy.

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Planapo
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Post by Planapo »

The "VielzweckGerät" means something like "many-angle-device"..... some German words are magnificent aren't they.
Barry, if I may assist with the "magnificent German words" :wink: : Multi-purpose-device would be the exact translation. BTW, in an English brochure for the USA that I have as pdf it was marketed as "The Versal" back then.

Charlie, Enrico,
Did your solid version come with M42 mounts or was it fitted with the Exakta bayonet mounts? I ask since the black solid one I have has such bayonet mounts and I wonder, if they could be changed against M42 mounts salvaged from one of my lightweight versions, especially as Enrico wrote:
(the mounts of mine will have to go, so not a big loss).
--Betty

enricosavazzi
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Post by enricosavazzi »

Planapo wrote: Charlie, Enrico,
Did your solid version come with M42 mounts or was it fitted with the Exakta bayonet mounts? I ask since the black solid one I have has such bayonet mounts and I wonder, if they could be changed against M42 mounts salvaged from one of my lightweight versions, especially as Enrico wrote:
(the mounts of mine will have to go, so not a big loss).
--Betty
Mine has the Exakta bayonet, albeit not for long :twisted:. The four screws at the front of the lens mount hold this mount in place, but also keep the pleated cloth attached at the rear of the standard. You should remove the four slotted nuts accessible from inside the bellows (through the opening of the rear mount) first, before taking out the screws and lens mount.

The pleated cloth at the rear is also attached with four screws, but accessible only from inside the bellows. This reveals some kind of friction flange that I have not figured out yet. It actually appears that also my bellows originally had a rotating rear mount, but hopelessly blocked by some hard brown gunk (Canada balsam? epoxy?).

This leaves 40 mm holes in both standards, which are too narrow for recessed M42 lens mounts. Filing a wider opening gets the edge of the opening uncomfortably close to the screw holes. You will have to modify a short M42 extension ring to make a lens mount (or if you can turn your own on a lathe, anything can be done). I am planning to cut an old Nikon F extension ring in its middle to make both mounts.
--ES

Planapo
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Post by Planapo »

Enrico,

Thanks for the further information.

That sounds more tricky than I had hoped. But meanwhile I've found suitable adapters on ebay which seem to be an alternative for people without a lathe.

Regarding the rotating rear mount, there should be a knurled screw which is used to fasten the rotating mount, or at least, if this screw is missing, there should be its threaded hole at about 4 o'clock position on the camera standard (when looking onto the bellows from the camera side). Due to little stud bolts which prevent further rotation, the rotating mount only rotates 90°. But I had to use a lot of torque to make it move as I think the old grease has hardened and become very tough over the years.

--Betty

Charles Krebs
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Post by Charles Krebs »

On at least some of the Exakta versions (solid cast, split standard design) there was a rotating back but without a locking knob. Apparently it relied on the tension of the "spring lock ring" that can be seen when the bellows material is removed. The backs mount is limited to 90 degree movement ... vertical through horizontal... by a screw pin that rides in a channel machined into the back of the bayonet mount. If that stop pin is removed then you can have full rotation of the back.

Enrico... it sounds like you may have this type of rotating back. When the bellows material is removed you can see that the rear bayonet mount is inserted through the back standard and "attached" via a screw-on metal locking ring. This ring has several "spring" fingers that provide the tension for the rotating mount. (The grease in here does get very solidified, but even when cleaned out and replaced the movement is still fairly stiff). The metal locking/tensioning ring is prevented from "unscrewing" by an extremely small slot set screw, that seats into small indentation in the back standard. Except for the tiny set screw, it's pretty obvious after you clean out any old grease.

enricosavazzi
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Post by enricosavazzi »

Charles Krebs wrote: Enrico... it sounds like you may have this type of rotating back. When the bellows material is removed you can see that the rear bayonet mount is inserted through the back standard and "attached" via a screw-on metal locking ring. This ring has several "spring" fingers that provide the tension for the rotating mount. (The grease in here does get very solidified, but even when cleaned out and replaced the movement is still fairly stiff). The metal locking/tensioning ring is prevented from "unscrewing" by an extremely small slot set screw, that seats into small indentation in the back standard. Except for the tiny set screw, it's pretty obvious after you clean out any old grease.
Yes, this is it. I only noticed when I disassembled the bellows and started hacking away at the solid gunk. It seems that a previous owner had decided to eliminate the rotation of the mount and poured a large amount of Canada balsam into the works - I don't think it was solidified fat. Even the cloth of the bellows was gunked to the standard. Fortunately, like most mechanical problems, it could be solved by an appropriate combination of tinkering and brute force.

The work is slowly progressing - I should be done with the modification of the front standard today.
--ES

Charles Krebs
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Post by Charles Krebs »

like most mechanical problems, it could be solved by an appropriate combination of tinkering and brute force.

Yes indeed! :wink:

... but I do have a few little plastic bags holding the pieces from the projects where the solution was not what I had intended! :shock: :cry:

enricosavazzi
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Post by enricosavazzi »

Charles Krebs wrote:
like most mechanical problems, it could be solved by an appropriate combination of tinkering and brute force.

Yes indeed! :wink:

... but I do have a few little plastic bags holding the pieces from the projects where the solution was not what I had intended! :shock: :cry:
I prefer to regard it as a way to get spare parts for future projects. :D
--ES

Blame
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Post by Blame »

I may be missing something here.

Can't you solve the problem by using a flash?

Alternately there are camera based vibration reduction solutions. The sony alpha cameras have built in vibration reduction.

I realize that this still leaves you with pictures that are sharp but don't quite stack but can't the software sort it out?

DaveW
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Post by DaveW »

Unless Sony has come up with some new form of Vibration Reduction I understood most of these systems only gave the extra number of stops the makers brag about at infinity focus? As you focus closer camera and lens anti-vibration systems become increasingly less effective giving progressively less stops advantage, until Nikon advises there is no advantage and they are switched off really close up.

If camera anti vibration systems worked in all situations the makers would not provide an off switch? Also anti vibration systems only mitigate camera shake, they have no effect whatsoever on subject movement. Also with high magnification setups on tripods or fixed bases, moving parts around for vibration reduction could itself cause vibration rather than suppress it, just as mirror slap does. To quote from the following link:-

"Most manufacturers suggest that the IS feature of a lens be turned off when the lens is mounted on a tripod as it can cause erratic results and is generally unnecessary. Many modern image stabilization lenses (notably Canon's more recent IS lenses) are able to auto-detect that they are tripod-mounted (as a result of extremely low vibration readings) and disable IS automatically to prevent this and any consequent image quality reduction."

http://en.wikipedia.org/wiki/Image_stabilization

DaveW

ChrisLilley
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Post by ChrisLilley »

Dave, the quotes are correct for in-lens shake reduction (as used by Canon and Nikon, plus lenses for those systems by Tamron, Sigma et. el.) Those systems are using angular displacements of part of the optical system.

Its not clear that the same considerations apply to sensor-shift shake reduction as used by Konica (Konica DiMAGE 7, A1) then Konica-Minolta (DiMAGE A2) when Minolta acquired Konica, then Sony (Alpha) when Sony acquired Minolta.

Provided the stacking software can deal with some x-y misalignment (caused by the sensor shift).

(Previous owner of a DiMAGE A1)

Edit: what you say about subject movement applies to both systems, of course.

Peter M. Macdonald
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Post by Peter M. Macdonald »

The early IS lenses from Canon warned against using the system on tripods. I think that the problem was that the stabilisation mechanism introduced vibrations into the tripod mounted lens.

It is some years since things changed. My 600 mm Canon lens is, if memory serves me correctly, 6 years old now. I have always used the IS when it is tripod mounted, which covers the vast majority of times that it has been used. Never had any problems with the IS system making thinks worse on the tripod. Indeed, my experiece has been quite the opposite.

The IS system on the new 100 mm L macro looks to be quite good, though I have only had the chance to play with one for about 15 minutes. The test shots which I took with it seemed to be quite good, and the resolution was a little better than the nin l non IS 100 macro. Given the difference in the price, it should be better!

ChrisLilley
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Post by ChrisLilley »

The early VR lenses from Nikon had a similar warning. They now have different settings, general VR, 'active' VR (think safari use in a moving landrover) and 'tripod' VR.

Although switching off VR on tripods is often seen as still the best bet.

DaveW
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Post by DaveW »

My point Chris was any in camera or lens mechanical movement before the exposure on a static set up could induce vibration in the system, just like mirror slap, which is why mirror lock-up is recommended. Even the shutter movement itself is undesirable if ever the problems of just turning the sensor on and off for exposure can be overcome.

I cannot see whether if you mechanically move an element in a lens or a sensor in a camera it makes a great deal of difference in a static set up Chris as movement of parts is movement just before an exposure?

Unless you are meaning, unlike the Nikon/Canon systems when hand holding, the Sony system does not reduce in effectiveness the closer you get?

DaveW

ChrisLilley
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Post by ChrisLilley »

DaveW wrote: Unless you are meaning, unlike the Nikon/Canon systems when hand holding, the Sony system does not reduce in effectiveness the closer you get?
That was the specific point I was making, yes. Sorry to not have been clear.

What the overall level of vibration is in the system, and whether the anti-shake/image stabilisation/vibration reduction actually reduces or enlarges it is a separate point.

I think that static mass and good support is better, in fact.

The sensor-shift systems don't seem to have the optics-at-infinity design constraint.

Charles Krebs
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Post by Charles Krebs »

The stacking software handles x/y shift just fine. It would be very surprising if any "sensor based" anti-vibration method (or "lens based" for that matter... but we're using bellows here) could adequately eliminate the "jittery" high frequency, low amplitude type of vibration that is the problem with set-ups like this one. (A pleasant surprise though, if anyone has some positive experience in this regard it would be good to hear).

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