[Laci.4400]

Hi dear all,

I’m curious if there’s a trick of how to change the aperture when using a m42 Takumar on a bellows unit.
If I can’t and it’ll be wide open then I’m questioning its usefulness because of the so shallow depth of field.
I don’t have the bellows at the moment as I’m waiting for the post so it could happen that I just have to wait and try it because it’s easy.
But it’s hard to wait hence I needed to compose this thread!
=)

[photoptimist]

It's not hard.

Set the Takumar lens to "M", open the aperture all the way, focus, close the aperture to the desired setting (the scene will darken), meter the scene, and fire.

[Not a Number]

Focus with the lens wide open. Manually stop the lens down to meter and take the exposure. If the lens has an auto/manual switch, set it to auto to focus and manual to stop the lens down. With the A/M switch you can preset the f-stop and not have to turn the ring to open and close the iris.

If you have an auto lens (with A/M switch) and the Asahi Pentax Auto Bellows for M42, even better. Set the f-stop on the lens, set the lens to auto and stop the lens down by pressing the DOF button the bellows. Even better attach a standard mechanical cable release to to DOF preview and you can stop down and lock with the release. Normally this is for the dual cable release which would stop down the lens and release the shutter. Using the cable release has the advantage of there being less chance of inadvertently moving the lens and rig.

Late K-mount auto-bellows have a lock on the DOF button but you still risk moving something.

What camera bodies, lenses and bellows are in question here?

[Laci.4400]

It's not hard.

Set the Takumar lens to "M", open the aperture all the way, focus, close the aperture to the desired setting (the scene will darken), meter the scene, and fire.

Awesome! Thanks!

---------- Post added 07-12-20 at 01:35 PM ----------

Focus with the lens wide open. Manually stop the lens down to meter and take the exposure. If the lens has an auto/manual switch, set it to auto to focus and manual to stop the lens down. With the A/M switch you can preset the f-stop and not have to turn the ring to open and close the iris.

If you have an auto lens (with A/M switch) and the Asahi Pentax Auto Bellows for M42, even better. Set the f-stop on the lens, set the lens to auto and stop the lens down by pressing the DOF button the bellows. Even better attach a standard mechanical cable release to to DOF preview and you can stop down and lock with the release. Normally this is for the dual cable release which would stop down the lens and release the shutter. Using the cable release has the advantage of there being less chance of inadvertently moving the lens and rig.

Late K-mount auto-bellows have a lock on the DOF button but you still risk moving something.

What camera bodies, lenses and bellows are in question here?

Thanks for your response!
A Spotmatic sp2(light meter works and accurate), a SMC Takumar 55mm f1.8 and a Vorsatz m42 bellows.
So that’s what I assumed also that the pin on the lens will be pushed after mounting on the bellows like when it’s mounted on the camera.

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Last edited by Laci.4400; 07-12-2020 at 01:46 PM.

[Not a Number]

Is this the bellows you are looking at?

Vorsatz (Helios) Macro Extender Bellows reviews - Pentax Camera Accessory Review Database

[Laci.4400]

Is this the bellows you are looking at?

Vorsatz (Helios) Macro Extender Bellows reviews - Pentax Camera Accessory Review Database

Yes, this is the one.

[WPRESTO]

That bellows appears to have a standard threaded cable release socket at the top. so the best way to stop the lens down would be to use such a release.
Sequence:
1) adjust magnification by moving lens fore-aft on belows
2) focus by moving entire camera + bellows + lens fore-aft
3) stop lens down using a cable release that has either a thumb-screw lock or automatic lock to keep the lens at the taking aperture
4) meter

5) Lock up mirror

6. Make exposure

Threaded cable releases should still be available at modest cost, but if you have trouble finding one, send me a PM.

[Not a Number]

That bellows appears to have a standard threaded cable release socket at the top. so the best way to stop the lens down would be to use such a release.

If that is the case a double release cable can be used. They can be found on eBay.

As long as the cables have the "standard" tapered thread on them any brand should work.

Looking more closely at the photos it looks like that "horn" on lens mount has a tapered thread. I don't see the typical crescent shaped "flipper" that Asahi used for the aperture pin but there seems to be some sort of mechanism connected to the horn.

Good spot!

[WPRESTO]

If that is the case a double release cable can be used. They can be found on eBay.

As long as the cables have the "standard" tapered thread on them any brand should work.

Looking more closely at the photos it looks like that "horn" on lens mount has a tapered thread. I don't see the typical crescent shaped "flipper" that Asahi used for the aperture pin but there seems to be some sort of mechanism connected to the horn.

Good spot!

I think that the "flipper" that presses the aperture actuating pin is at the top, directly below the cable release "horn." The edge of it is just visible at the top of the lens mount opening in the front view of the bellows. Because of its position, when a lens is threaded into place the aperture index will be off to about the four or five o'clock position as viewed from the front.

[Laci.4400]

That bellows appears to have a standard threaded cable release socket at the top. so the best way to stop the lens down would be to use such a release.
Sequence:
1) adjust magnification by moving lens fore-aft on belows
2) focus by moving entire camera + bellows + lens fore-aft
3) stop lens down using a cable release that has either a thumb-screw lock or automatic lock to keep the lens at the taking aperture
4) meter

5) Lock up mirror

6. Make exposure

Threaded cable releases should still be available at modest cost, but if you have trouble finding one, send me a PM.

This Vorsatz bellows is really simple. There’s no cable release socket or anything. Just the bellows, the mount and the rail. But I mounted the lens and I can focus by opening the aperture and then stop it down in manual mode. No big issue. I won’t be able to determine the dof and haven’t tried it with ttl yet so I can comment on this, but I’ll need a dedicated macro lens or a enlarging lens as the Takumar 55mm f1.8 failed at this extreme close up. The edges were blurred of course.

[WPRESTO]

This Vorsatz bellows is really simple. There’s no cable release socket or anything. Just the bellows, the mount and the rail. But I mounted the lens and I can focus by opening the aperture and then stop it down in manual mode. No big issue. I won’t be able to determine the dof and haven’t tried it with ttl yet so I can comment on this, but I’ll need a dedicated macro lens or a enlarging lens as the Takumar 55mm f1.8 failed at this extreme close up. The edges were blurred of course.

The images of a Vosatz bellows that I was looking at, recommended above by Laci.4400, must be a different model from yours. Almost all lenses not specifically designed to operate in the deep-macro range (1:1 and greater magnification) function better (=give better IQ) when reverse mounted. This is because typical lenses are designed for a lens-to-subject distance that is greater than the lens-to-film/sensor distance. On a bellows, the lens-to-subject distance is typically less than the lens-to-film/sensor distance. (the crossover for distances takes place at 1:1 reproduction ratio where the two distances are equal). Reversing rings for M42 to filter thread are inexpensive. You might try such a ring with your 55mm f1.8 before purchasing a new lens. If you cannot locate one with the correct filter thread for a lens you want to use, there are always stepping rings. For bellows use only, an enlarger lens is commonly better than a typical camera lens, I use a 50mm f2.8 Componon in reversed position for some deep macro imaging. A much less expensive enlarging lens that works well is the 50mm f2.8 Nikkor, generally available on EBAY. The 50mm f4 Nikkor DOES NOT WORK WELL. A caveat: not all enlarging lenses have filter threads, and on those that do, the thread size is small which means using a stepping ring to attach to a reversing ring (that's what I do with the Componon). Even used in non-reversed position, a good enlarging lens will outperform most normal FL camera lenses used in normal or reversed position (as always, there are exceptions - the 28mm f3.5 Takumar apparently works extremely well in reversed orientation on a bellows). If you use an enlarging lens in normal orientation on the bellows, you will need an M42 to M39 ("Leica thread") adapter. Most short FL enlarging lenses (= 100mm or less) have an M39 thread.

more and more information
1) enlarging lenses are near "perfect" = their best IQ is either wide open or at most one stop down. IQ degradation from diffraction becomes visible @ f5.6 on almost any/all enlarging lenses.
2) In deep macro range, DOF is extremely shallow and gains in DOF by stopping down are also very small. Even at a nominal (as marked on the lens) f16 DOF is painfully small for photographing something like the head of an insect, and that incremental gain in DOF will come with considerable loss of IQ caused by diffraction.

3) because of the DOF problem. it is really useful/important/even necessary to use focus stacking for deep macro. For a deep macro shot of part of a penny, the "UM" only letters from E PLURIBUS UNUM, I had to use a stack of 10 images files to get sharp focus from the top surface of the letters to their base using a NIKON 4X APO microscope objective.

There's an awful lot to be known about working in the deep macro range. I have some experience, but there are other Pentaxians who have far more.