Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
09-16-2016, 04:42 PM   #1
Senior Member




Join Date: Oct 2013
Posts: 142
Metering with bellows?

I searched for this topic, and failed to find anything. If it's there and I missed it, point me to it and accept my apologies.

I've acquired a Pentax bellows, and have been playing with it a bit, on a KX (not K-X) and a K1000.

How do you meter? The lens is separated from the body, so the open-aperture metering doesn't work. If I understand my physics correctly, the f-stop depends on focal length, which varies with bellows extension, so I can't just plug in, say, f4 into an external meter and call it good.

Am I missing something? Making it harder than it should be?

Your wisdom and advice are appreciated.

09-16-2016, 04:53 PM   #2
Administrator
Site Webmaster
Adam's Avatar

Join Date: Sep 2006
Location: Arizona
Photos: Gallery | Albums
Posts: 41,600
QuoteOriginally posted by Lenscap Quote
I searched for this topic, and failed to find anything. If it's there and I missed it, point me to it and accept my apologies.

I've acquired a Pentax bellows, and have been playing with it a bit, on a KX (not K-X) and a K1000.

How do you meter? The lens is separated from the body, so the open-aperture metering doesn't work. If I understand my physics correctly, the f-stop depends on focal length, which varies with bellows extension, so I can't just plug in, say, f4 into an external meter and call it good.

Am I missing something? Making it harder than it should be?

Your wisdom and advice are appreciated.
Well, since the lens has a manual diaphragm when placed on a bellows, you can still go by the camera meter's reading. The viewfinder will just darken as you stop down, so you should wait to meter until you've focused and composed.

Adam
PentaxForums.com Webmaster (Site Usage Guide | Site Help | My Photography)



PentaxForums.com's high server and development costs are user-supported. You can help cover those costs by donating. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

09-16-2016, 05:11 PM   #3
Site Supporter




Join Date: Nov 2015
Photos: Albums
Posts: 253
Some bellows have a double cable release. One trips the camera and the other stops the lens down.

The idea is that they are timed such that pressing the release stops the lens down and then snaps the shot.

If you have one of those, you'll need to trip the lens somehow to meter/shoot at anything other than wide open. A regular cable release will do the job.

-Eric
09-16-2016, 05:15 PM   #4
Site Supporter




Join Date: Jan 2010
Location: Michigan
Photos: Gallery
Posts: 2,107
QuoteOriginally posted by Lenscap Quote
I've acquired a Pentax bellows,
Metering depends on the Pentax Bellows model.
Assuming it is K mount,
Model "Auto Bellows M " and the later "Auto Bellows A/m" had the mechanics for open aperture metering unless the lens is reversed.

I have the basic "Bellows Unit 3 " which does not have coupling for open aperture metering.
So it has the issues you mention.
But so far I only used it with the digital cameras, so just use the stop down "green button"
https://app.box.com/s/fdee986cccb6ea2d08cd

You might be able to download the instruction manual for the bellows version you have.

Edit: I learn something here, the photo shows I have the "Auto Bellows M" which can have open aperture metering with the cable mentioned by TwoUp, and I don't have that.

09-16-2016, 05:19 PM   #5
Senior Member




Join Date: Oct 2013
Posts: 142
Original Poster
QuoteOriginally posted by Adam Quote
Well, since the lens has a manual diaphragm when placed on a bellows, you can still go by the camera meter's reading. The viewfinder will just darken as you stop down, so you should wait to meter until you've focused and composed.
That's the thing, though. I can go from 1.7 to 22 with no lightening or darkening, and no change in the camera's indication of correct exposure. I assumed the mount on the bellows was depressing the aperture arm thing (forgive my ignorance of the correct nomenclature) and keeping the blades open, as if it had been mounted to the camera.

---------- Post added 09-16-16 at 07:22 PM ----------

QuoteOriginally posted by wombat2go Quote
Metering depends on the Pentax Bellows model.
Assuming it is K mount,
Model "Auto Bellows M " and the later "Auto Bellows A/m" had the mechanics for open aperture metering unless the lens is reversed.

I have the basic "Bellows Unit 3 " which does not have coupling for open aperture metering.
So it has the issues you mention.
But so far I only used it with the digital cameras, so just use the stop down "green button"
https://app.box.com/s/fdee986cccb6ea2d08cd

You might be able to download the instruction manual for the bellows version you have.

Edit: I learn something here, the photo shows I have the "Auto Bellows M" which can have open aperture metering with the cable mentioned by TwoUp, and I don't have that.
Mine says: Asahi Pentax Bellows Unit K. No place that I can find for dual cable release.

I'll try to find the manual somewhere.
09-16-2016, 05:29 PM   #6
Pentaxian




Join Date: May 2011
Location: Santa Cruz, CA
Photos: Albums
Posts: 1,990
QuoteOriginally posted by Lenscap Quote
That's the thing, though. I can go from 1.7 to 22 with no lightening or darkening, and no change in the camera's indication of correct exposure. I assumed the mount on the bellows was depressing the aperture arm thing (forgive my ignorance of the correct nomenclature) and keeping the blades open, as if it had been mounted to the camera.

---------- Post added 09-16-16 at 07:22 PM ----------



Mine says: Asahi Pentax Bellows Unit K. No place that I can find for dual cable release.

I'll try to find the manual somewhere.
Here is a picture of my Pentax Auto Bellows K with the dual release cable plugged in.



Where it is plugged in the front will stop down the lens first then fires the shutter next.
09-16-2016, 05:51 PM   #7
Senior Member




Join Date: Oct 2013
Posts: 142
Original Poster
Crappy cell phone pic of mine. It doesn't say Auto Bellows, which may be the difference.
Attached Images
View Picture EXIF
IPhone 6s  Photo 
09-16-2016, 05:53 PM   #8
Pentaxian
Not a Number's Avatar

Join Date: Mar 2012
Location: Venice, CA
Posts: 4,072
The manual for the Bellows Unit (K) can be downloaded from the Ricoh Canada site:
http://ricoh-imaging.ca/pdf/o_manuals/om_BELLOWSUNIT_e.pdf

The aperture should change as you turn the aperture ring. If it stays wide open you may have the Auto Bellows K as pictured above. Either attach a cable release as above or you can press in the button with the cable socket which will stop down the lens. The button should lock by twisting it when you press it in. You can use a standard cable instead of a dual cable. Just lock it to keep the aperture closed when you shoot.

QuoteOriginally posted by wombat2go Quote
Model "Auto Bellows M " and the later "Auto Bellows A/m" had the mechanics for open aperture metering unless the lens is reversed.
Actually with the Auto Bellows you can reverse the lens by reversing the front standard so the aperture stop down coupling will still work.

09-16-2016, 06:01 PM   #9
Site Supporter




Join Date: Jan 2010
Location: Michigan
Photos: Gallery
Posts: 2,107
QuoteOriginally posted by Not a Number Quote
Actually with the Auto Bellows you can reverse the lens by reversing the front standard so the aperture stop down coupling will still work.
Thanks,
See, I learn something every day on PF, today I learned 2 things
09-16-2016, 06:13 PM   #10
Pentaxian
Not a Number's Avatar

Join Date: Mar 2012
Location: Venice, CA
Posts: 4,072
QuoteOriginally posted by wombat2go Quote
Thanks,
See, I learn something every day on PF, today I learned 2 things
It's quite cleverly designed. Loosen the thumbscrew where the bellows connects to the front standard. There is a 49 to 52mm step-up ring in case you are using a 49mm filter ring lens. Remove the big front screw, reverse the standard. Replace the screw, reconnect the bellows to the front of the lens. The rear elements remain recessed and somewhat protected and there are filter threads should for some reason you want to use a filter. The Minolta Auto Bellows III goes one step further in that the front standard pivots around without having to reverse the whole thing. But they didn't incorporate the step-up ring into the bellows.
09-16-2016, 06:47 PM   #11
Senior Member




Join Date: Oct 2013
Posts: 142
Original Poster
QuoteOriginally posted by Not a Number Quote
The manual for the Bellows Unit (K) can be downloaded from the Ricoh Canada site:
http://ricoh-imaging.ca/pdf/o_manuals/om_BELLOWSUNIT_e.pdf

The aperture should change as you turn the aperture ring. If it stays wide open you may have the Auto Bellows K as pictured above. Either attach a cable release as above or you can press in the button with the cable socket which will stop down the lens. The button should lock by twisting it when you press it in. You can use a standard cable instead of a dual cable. Just lock it to keep the aperture closed when you shoot.



Actually with the Auto Bellows you can reverse the lens by reversing the front standard so the aperture stop down coupling will still work.
Thanks for the link. I'll download the manual and see what I can figure out.
09-16-2016, 06:58 PM   #12
Site Supporter




Join Date: Jan 2010
Location: Michigan
Photos: Gallery
Posts: 2,107
QuoteOriginally posted by Not a Number Quote
It's quite cleverly designed. Loosen the thumbscrew where the bellows connects to the front standard. There is a 49 to 52mm step-up ring in case you are using a 49mm filter ring lens. Remove the big front screw, reverse the standard. Replace the screw, reconnect the bellows to the front of the lens. The rear elements remain recessed and somewhat protected and there are filter threads should for some reason you want to use a filter. The Minolta Auto Bellows III goes one step further in that the front standard pivots around without having to reverse the whole thing. But they didn't incorporate the step-up ring into the bellows.
Here is the Pentax "Auto Bellows M" with the lens reversed according to the above instructions. Lens is SMC Pentax 1:2 55mm which has a 52mm front.
Attached Images
View Picture EXIF
PENTAX K-01  Photo 
09-16-2016, 07:18 PM   #13
Loyal Site Supporter
UncleVanya's Avatar

Join Date: Jul 2014
Photos: Gallery | Albums
Posts: 9,737
With the lens in your hand not mounted does the aperture stop down as you twist the aperture ring? Sometimes lenses get stuck.
09-16-2016, 08:58 PM   #14
Senior Member




Join Date: Oct 2013
Posts: 142
Original Poster
QuoteOriginally posted by UncleVanya Quote
With the lens in your hand not mounted does the aperture stop down as you twist the aperture ring? Sometimes lenses get stuck.
Yes, the aperture blades move exactly as they should.
09-17-2016, 12:48 AM   #15
Pentaxian
Not a Number's Avatar

Join Date: Mar 2012
Location: Venice, CA
Posts: 4,072
Could you take a photo of the lens mount on the bellows from the front, e.g. looking into the bellows. Perhaps someone had modified the mount to open the aperture. Why one would do this I don't know. Unless they wanted to use lens without aperture rings. You can stop down by unlocking the lens and turning it in the mount.
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, cable, camera, lens, meter, model, mount, pentax, stop, unit
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Minolta macro bellows /Rokkor TC 135mm f4 bellows lens Weevil Macro Photography 8 04-14-2015 09:24 PM
Vivitar Bellows (T mount) with K5 IIS(?) WONOW Macro Photography 6 03-17-2015 09:39 AM
Sharpness and metering problems with Bellows on the K-5 Matchete Pentax K-5 25 02-14-2012 12:31 PM
For Sale - Sold: Bellows Takumar 100mm/4 and Pentax Auto Bellows (Worldwide) lynch1234 Sold Items 18 11-16-2010 01:41 PM



All times are GMT -7. The time now is 10:21 PM. | 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