Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
07-12-2020, 01:04 PM   #1
Junior Member




Join Date: May 2020
Posts: 25
Changing aperture when using bellows

Hi dear all,

Iím curious if thereís a trick of how to change the aperture when using a m42 Takumar on a bellows unit.
If I canít and itíll be wide open then Iím questioning its usefulness because of the so shallow depth of field.
I donít have the bellows at the moment as Iím waiting for the post so it could happen that I just have to wait and try it because itís easy.
But itís hard to wait hence I needed to compose this thread!
=)

07-12-2020, 01:19 PM - 2 Likes   #2
Pentaxian
photoptimist's Avatar

Join Date: Jul 2016
Photos: Albums
Posts: 4,498
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.
07-12-2020, 01:20 PM   #3
Moderator
Not a Number's Avatar

Join Date: Mar 2012
Location: Venice, CA
Posts: 7,673
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?
07-12-2020, 01:27 PM   #4
Junior Member




Join Date: May 2020
Posts: 25
Original Poster
QuoteOriginally posted by photoptimist Quote
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 ----------

QuoteOriginally posted by Not a Number Quote
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 thatís what I assumed also that the pin on the lens will be pushed after mounting on the bellows like when itís mounted on the camera.


Last edited by Laci.4400; 07-12-2020 at 01:46 PM.
07-12-2020, 02:40 PM   #5
Moderator
Not a Number's Avatar

Join Date: Mar 2012
Location: Venice, CA
Posts: 7,673
Is this the bellows you are looking at?

Vorsatz (Helios) Macro Extender Bellows reviews - Pentax Camera Accessory Review Database
07-12-2020, 05:10 PM   #6
Junior Member




Join Date: May 2020
Posts: 25
Original Poster
QuoteOriginally posted by Not a Number Quote
Yes, this is the one.
07-13-2020, 07:01 PM - 1 Like   #7
Loyal Site Supporter
Loyal Site Supporter
WPRESTO's Avatar

Join Date: Aug 2010
Location: Massachusetts
Photos: Gallery | Albums
Posts: 46,240
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.
07-13-2020, 09:08 PM   #8
Moderator
Not a Number's Avatar

Join Date: Mar 2012
Location: Venice, CA
Posts: 7,673
QuoteOriginally posted by WPRESTO Quote
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!

07-14-2020, 06:09 AM   #9
Loyal Site Supporter
Loyal Site Supporter
WPRESTO's Avatar

Join Date: Aug 2010
Location: Massachusetts
Photos: Gallery | Albums
Posts: 46,240
QuoteOriginally posted by Not a Number Quote
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.
07-15-2020, 12:18 AM   #10
Junior Member




Join Date: May 2020
Posts: 25
Original Poster
QuoteOriginally posted by WPRESTO Quote
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. Thereís 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 wonít be able to determine the dof and havenít tried it with ttl yet so I can comment on this, but Iíll 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.
07-15-2020, 04:26 AM   #11
Loyal Site Supporter
Loyal Site Supporter
WPRESTO's Avatar

Join Date: Aug 2010
Location: Massachusetts
Photos: Gallery | Albums
Posts: 46,240
QuoteOriginally posted by Laci.4400 Quote
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.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
aperture, auto, button, cable, camera, dof, focus, lens, pentax help, photography, release, switch, troubleshooting
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Macro Bellows & Slide Bellows Tighelander Pentax Camera and Field Accessories 9 03-18-2019 07:16 PM
Macro Auto Bellows - which macro lens - Takumar Bellows 100 or "normal" Takumar Macro 100? clickclick Photographic Technique 11 01-25-2017 04:55 PM
Macro Minolta macro bellows /Rokkor TC 135mm f4 bellows lens Weevil Photographic Technique 8 04-14-2015 09:24 PM
Pentax-A 50mm f1.4 sometimes sets wrong aperture when using "A"-setting qwertyazerty Troubleshooting and Beginner Help 6 05-02-2013 09:30 AM



All times are GMT -7. The time now is 10:30 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top