Converting A Sigma Lens To Canon, Digital Functionality Included

These days, camera lenses aren’t just simple bits of glass in sliding metal or plastic housings. They’ve often got a whole bunch of electronics built in as well. [Dan K] had just such a lens from Sigma, but wanted to get it working fully with a camera using the Canon EF lens fitting. Hacking ensued.

The lens in question was a Sigma 15-30mm f/3.5-4.5 EX DG, built to work with a Sigma camera using the SA mount. As it turns out, the SA mount is actually based on the Canon EF mount, using the same communications methods and having a similar contact block. However, it uses a mechanically different mounting bayonet, making the two incompatible.

[Dan] sourced a damaged EF lens to provide its mount, and modified it on a lathe to suit the Sigma lens. A short length of ribbon cable was then used to connect the lens’s PCB to the EF mount’s contacts. When carefully put back together, the lens worked perfectly, with functional auto-focus and all.

It goes to show that a little research can reveal possibilities for hacking that we might otherwise have missed. [Dan] was able to get his lens up and running on a new camera, and has taken many wonderful pictures with it since.

We’ve seen some great lens hacks over the years, from 3D printed adapters to anamorphic adapters that create beautiful results. If you’ve got your own mad camera hacks brewing up, drop us a line!

Hacking A Sigma Lens To Work With A Canon Camera


[Martin Melchior] wanted to use an older Sigma lens with his Canon camera. The problem in trying to do so is that the camera uses a different communications protocol than the lens is expecting. But if you don’t mind cracking it open and doing a little microcontroller work you’ll be using the lens in no time.

The hack uses an ATtiny24 chip, two resistors, and a capacitor. You won’t need to do any coding, but you do need to burn the firmware to the chip (you can use an Arduino if you don’t have a proper AVR programmer). There’s plenty of room for the add-on hardware inside the lens so after reassembling the enclosure you won’t even be able to tell that the unit was altered. Unfortunately it doesn’t look like [Martin] took any pictures of the lens with his added electronics, but the schematic he posted should be enough for you to get the job done yourself.

If you’re into these types of DSLR hacks you should try something extreme, like using view camera parts with your modern camera.