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Building an Auto Bellows for Sigma SA Mount


Aim: To convert a bellows into an auto bellows to have connections for automatic diaphragm release and transmission

of lens information to permit open-aperture metering.
Additionally, all of the functions for Sigma SA are transmitted, e.g. data in exifs are correct.

Whether such a conversion is of any use, the readers may decide on their own. :)

Parts I used:

A Canon FL type bellows (other models might be suitable as well!)
A bayonet and some bits and pieces from a broken Sigma (kit)lens (any other SIGMA SA lens will do!)
A Sigma SAxx camera (to be canibalised)

A few details still have to be finished off in order to achieve a "professionell"look.

Firstly, the bellows itself, it should have a reasonable size with about 70x70 mm front-and back plates,
to comfortably fit the bayonet and the modified mirror housing.

I chose the Canon FL type bellows for the following reasons:
1.Front and back plates are big enough.
2.The moving parts with their drivings are hollow, so cabeling is done much easier and looks more professionell.
3.The front bayonet fits perfectly into the rear bayonet with the attached locking lever.
Doing so allows the camera to be locked straight and easily to the bellows instead of twisting it on.
4.The bellows is of very good mechanic quality, everything is screwed and can be disassembeled easily.
5.The guiding plates at both sides of the boom are adjustable for smooth and stable movement.
6.The bellows has a limiting pin, similar to a "depth limiter" at a drilling machine, it helps to protect the front lens.
7.At the front is a 3/8" thread to take up accessoires, a duplicator for example
8.Last but not least, a focusing rack is built in.

To prepare the bellows for conversion, all parts of the mechanical diaphragm release have to be removed.

The mirror housing has to be cut down and must be perfectly flat to match with the front plate.
It will be fixed with 4 screws. The holes for this 4 screws have to be drilled and threaded with a M 1,5 , 1,8 or 2mm
thread, whatever is at hands.
The front side of the SAxx camera case has to be cut down to fit.
The release button is very important. It must be functional in order to hold the lens in its exact position.
This is necessary for the electric contacts.
Care has to be taken not to damage the flat ribbon cable, the cable leading to the back is soldered to it.
The rear part is relatively simple.
I used the bayonet with the contact block and the matching rear ring from a broken 24-70mm lens.
Into this ring I glued the FL bayonet from the front plate.
Pay attention to the mark, it should be in the 10 o´clock position when attached, viewed from the back.
Now the cable has to be connected and you are done.:)
You will need a cable with 7 wires.I took a cable from an old PS2 keyboard extension (6 wires + shield)
It only has a Ø of 4,5mm and is very flexible. The wires are connected 1:1 front to back.
Please check with a multimeter for connectivity and short circuits!!
It might be a good idea to put a male/female connector onto the cable, so it can be used reversed for a retro mounted

lens. But that can be done at any time later as well.
I fixed the cable at the back with a small 3mm cable tie and at the front I cut a small groove, just big enough
to get the cable fixed.
I think the pictures show enough details and also the "Mark II version". ;-))
I did the "Mark II" with emphasis on minimum extension, as the first one has 70mm :-((

Any comments, questions and suggestions are welcome and should be discussed here to the benefit of all.
Have fun and good luck building your own Sigma Auto Bellows.








More pictures on following page

Guest .

Hi All,

well Uwe's auto bellows is really fantastic. In fact I was one of the first users, who managed to copy it .... although I did it slightly different for different purposes ....

The most important difference is that mine is mini! I need it outside in nature ... there it cannot be small enogh!

The steps:









to be continued ....

Guest .

... there I am again ....





If you are interested and do have questions .... do not hesitate ... post your questions! Uwe and I am going to help you!;)

See you with nice pictures



Hi Klaus,
thanks for your additionel info.
This should help other users to find their way into the interesting field of macros.
Good light for more breathtaking pictures


Well-Known Member
You guys are pretty handy on the hardware scene! I'm afraid my abilities in that field don't even come close.

Then again, if you have any questions about Photoshop, I might be able to help out.

Here is one of my "hand" illustrations completed in PS, using a Wacom tablet and many hours of patience.

Sincerely, Jim Roelofs


  • Sortsman.jpg
    33.6 KB · Views: 179

Guest .

Hello Jim,

I really admired your cars watching your gallery. It is brilliantly done and somehow in between photographic reality and a well done drawing!! :z02_respekt::z02_respekt::z02_respekt:

I certainly would not be able to do anything comparable!
In fact, I would be very grateful if you could do a short introduction on how to do such things?! ;)

See you with nice pictures



Well-Known Member

Thank you for your kind comments. This brings me to the main reason why I switched to Mac. It seems to have better memory management. With my replaced Windows machine, I was forever having to reboot to clear memory and get it back.

The work files are created at A2 dimensions @ 300dpi, and because of the many hundreds of layers (each component being placed on its own individual layer) the file usually end up in the vincinity of 1,2GB or more!

If you send me a PM, I will be happy to send you an A2 poster. I get them commercially off-set printed.

As for the actual process in PS, I actually draw the outlines in Adobe Illustrator and then fill them with (any) colour. Then I cut and paste those into PS and then use the necessary tools such as air brush, paint bucket, dodge and burn, brushes, lassoo, and layer styles etc until I'm pleased with the result, which usually means about a week's work plus the necessary time for research, because some of these cars are no longer readily available on the everyday street.

Sincerely, Jim Roelofs


Well-Known Member
Wow, far away of what I could cook by myself!!
Congratulations, this is high tech... :(

I don't mean to necro this thread, but I found FotoDiox sells bellows for $35~$40...
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Now before I go and trash my old SA-7n and 28mm-70mm kit lens and spend $40+ship on bellows I was curious if the fact that they're small aps sized bellows would affect my photos?

Also if anyone has used these bellows I'd love to hear some feed back!



Well-Known Member
iD...I have not seen either one of them around for a while...KR was banned...if you pick-up an old SA300 with lens for about $25.00 off would not have to worry about trashing your SA7n...or you can contact:

Kathy Solano
Parts Coordinator
C.R.I.S. Camera Services
250 N. 54th street
Chandler AZ 85226
P: 480-940-1103 x101

And just buy the parts...then make it work...probably cheaper to just trash an old SA camera....

I want to do this...but I want to make macro-tubes instead...

Good Luck... Tony C.


Active Member
Buying the parts makes the most sense to me. I find it very difficult to destroy a working camera, if I don't have to. Broken cameras seem hard to come by. They really aren't worth much of anything to most people, so they usually get tossed in the trash.
So, I started this project yesterday! :D

I was using my old SA7n and a kit lens (both had been dropped and damaged beyond repair) but while I was taking the SA7n apart I made an uber bonehead move and cut the ribbon cable that goes from the contact pins on the bottom half of the lens mount.

Any recommendations?

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Well-Known Member
I would pick-up an old SA-300 or SA-7 on ebay...and start again...the cable itself is about...$45.00 from C.R.I.S....Did that on an SD14...don't feel bad...

If your good at cold soldering you might be able to attach the two pieces together with a thin copper wire..(don't use twisted pair...make sure it is a sold wire)...the problem you might run-into is the resistance might muck-everything up...

Let-us know what you do...Tony C. :z04_cowboy: