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Retro Lens for Sigma Cameras


Nothing new:
Instead of using a bellows you can simply turn the lens of the camera around to take

macro-pictures. You have to use a so called retro-adaptor. But the disadvantage is that you can

not control the apreture or it is very laborious to adjust it. There are a lot of proposals and

solutions and some of them are quite "adventurous".
I was aiming to find a solution which is simple but sofisticated and above all easy and safe to

I converted a Sigma lens, 28 -105 mm Asherical IF with a defective AF, to be used as a

retro-lens with a control for the apreture. I used this Sigma lens because it is stable enough to

carry it's own weight when it is attached the wrong way around to the body of the camera and

you want to adjust the focal length. Just try if for yourself: take a lens, hold it at the front where

you would usually attach the filters and try to ajust the focal length and you will see what I

I still had one plastic-ring with sigma-bayonet left from the auto-bellows.
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This ring has a Ø of 65 mm and fits perfectly for the 28-105. So I just glued it.
I soldered a short 7 conductor cable directly to the PCB* of the lense. The other end of the

cable is connected 1:1 to the contact block of the sigma-bayonet. On the open side of the lens,

the former back side which is now the front, I screwed a left over canon-bayonet to protect the

lens. Well, what else can you use a canon-bayonet for? The retro-lens is well proctected with

one sigma and one canon lense-cap. You do not need a lenshood because the front-lens is

retracted deep enough inside the lens-body.
This might be different when you work with other lenses but it should be no problem to use the

lens-cap and attach a lens-hood to it. (Just cut out a hole big enough for the lens-hood to fit in

for example)
*Printed Circuit Board

I attached some pictures I took with the retro-adapter to give you some impression of various
See you with nice pictures
@105mm distance ~60cm
@78mm distance ~35cm
@60mm distance ~25cm
@72mm distance ~30cm

Guest .

Hi Uwe,

absolutely great!! :z02_respekt::z02_respekt::z02_respekt:

As I am a fan of macro-photography, it is a "matter of honour" that I must have my own retro-macro-lens.

So far, I just ordered some second hand SIGMA-stuff on the internet right for this project.

As soon as I will have the whole boodle at hands I am going to report here.

Thanks again for your efforts as this is very busy work on a great idea!

See you with nice pictures