Sigma MC-11 Issue

[hopkins802]

Hey all,

I'm using a Sigma MC-11 on a Sony A7sII and Sigma 24-105 ART f/4. It's all been working pretty well for over a year now, and just recently I noticed a strange thing happening when opening and closing the aperture. When I open it or close it down it will kind of stutter halfway in between stops. For example, going from f/5 - 5.6 you can see the image brighten up slightly right away, and then very shortly after brighten up fully when reaching f/5.6. And you can look into the front of the lens and see the aperture blades stuttering when changing from one stop to the next.

I tested the lens natively (Canon 5D3) and it works fine, so I've narrowed it down to the adapter.

This issue isn't huge as now now since the lens / adapter still change apertures, but I'm worried about the combo crapping out on me during a shoot. Is it possible the Sony a7sii electrical contacts are dirty / faulty? Or is it more likely to be the adapter? I guess I would have to try a native Sony mount lens to test that.

Any input is helpful, thanks!

 

[NorBro]

I think the same thing was happening to me with a Sigma lens & MC-11 & a6300. I switched to the Vello adapter (just to have both on me) and didn't see it, but shortly sold the camera afterwards and not sure if it was just luck.

The contacts could be dirty or failing on either, camera or adapter...who knows.

The Vello is cheap enough to buy and see if it solves your issue (I'll probably sell mine if you're in the USA and would like to grab it for cheap):

https://www.bhphotovideo.com/c/product/1186674-REG/vello_lae_se_cef_canon_ef_ef_s_lens_to.html

 

[hopkins802]

Thanks! Yeah, I found out it isn't the camera's contacts because I tested a native sony e-mount lens and it worked fine.

I know the Sigma MC-11 has a firmware update out right now, but it doesn't state anywhere that it fixes bugs like this.. I've contacted Sigma to see what they say. I believe I still have a warranty for like 3 years since I bought it new.