Canon 90D with Sigma 70-200 overexposes all pictures taken through the viewfinder (live view ok!)

[philippelang]

Hi,

I'm the happy owner of a Canon 90D. I have just bought a Sigma 70-200 lense, and I noticed that all pictures taken through the viewfinder are overexposed, no matter what I do. If I want to have a picture that is close to reality, I have to compensate the exposition with -2/-3. Tha't's a lot, not just "fine-tuning". With the other lenses, I never had this problem: Sigma 18-35mm f1.8, Canon 50mm f1.8...

Is that Sigma firmware problem? 90D firmware problem?

[deebatman316]

Sigma claims compatibility with the Canon EF Mount. Canon DOES NOT tell 3rd Parties how their electronic lens communication works. If you have problems with your lens you need to contact Sigma NOT Canon. Canon doesn't know how Sigma is making there lenses work on their mount. In fact newer Sigma lenses DO NOT work on older EF Mount bodies. Sigma also has their own lens mount too. Sigma has the SA Mount which uses the same electronic communication as Canon's EF Mount.

[ebiggs1]

" In fact newer Sigma lenses DO NOT work on older EF Mount bodies."

Nonsense, care to point out the "fact"? And where or what lens won't work? Its always possible to find a lens made by an off brand maker that has trouble but that is not an indictment of every lens. I have probably tested more lenses than any one here and I haven't seen that at all.

[deebatman316]

No not every lens. What I meant say was some Sigma lenses. It was the Sigma 85mm F/1.4 Art lens. For some reason it doesn't work on older EF Mount cameras. But it works fine on my 5D Mark IV.

[ebiggs1]

"No not every lens. What I meant say was some Sigma lenses. It was the Sigma 85mm F/1.4 Art lens."

Well that's quite a different story.

But you know for a fact it is every Siggy Art 85mil lens? I hope not because mine works on my 1D.

[deebatman316]

That particular lens causes my EOS 40D to lock up and cause Error 99. But my personal owned Sigma 17-50mm F/2.8 EX DC OS HSM lens does work. The particular Sigma 85mm lens I'm talking about is the 85mm F/1.4 DG HSM.

[ebiggs1]

The point I wanted to make is what you said, " In fact newer Sigma lenses DO NOT work on older EF Mount bodies.", is in fact not true. Again one lens does not indite the entire Sigma line. OK you had/have issues with one Sigma lens. It happens, who knows why.

Look all lenses are basically the same. A collection of glass and metal and plastic. Once the electrical pin assignments are known, a simple matter to figure out, the only difference is the FW.  Some newer lenses have the ability to update their own FW while others do not. Is this the reason in your case again who knows. Perhaps,  perhaps not.

If I was to make a statement like that I would have said older Sigma lenses do not work on newer cameras. The exact opposite of your statement. However, even though I have done enough lens testing on my own, to my own satisfaction, I would hesitate to state that as a fact.

[deebatman316]

Yes sometimes older 3rd Party lenses have incompatibility with newer cameras. I experienced that when testing out an EOS 90D. It would not work properly with the Sigma 17-50mm F/2.8 EX DC OS HSM lens. I already was prepared for a potential incompatibility. IS and AF were playing tug of war. Turning off IS solves that problem. I probably came across a rare case where a new 3rd Party lens. Wasn't compatible with an older body.