01-14-2021 03:23 PM
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?
01-14-2021 03:57 PM
Since Sigma has to reverse engineer the lens mount to get it to work, it must be a Sigma issue.
Is the aperture wide open when measuring the exposure? Try the depth of field preview button to see if the viewfinder lightens and darkens.
01-14-2021 04:35 PM
Yes, I've been taking test pictures at aperture wide open: f2.8.
And apprently the depth of field preview button works just fine: when I press on it the viewfinder darkens when I increase the aperture f-number. And depth of field increases in the same time.
Someone mentioned having the same problem years ago with another Sigma lense, and that it was solved with a Canon 90D firmware update.. Could that be a body firmware has to be updated in order to offer support for lenses that appeared after the firmware release?
01-14-2021 06:48 PM
@philippelang wrote:Yes, I've been taking test pictures at aperture wide open: f2.8.
And apprently the depth of field preview button works just fine: when I press on it the viewfinder darkens when I increase the aperture f-number. And depth of field increases in the same time.
Someone mentioned having the same problem years ago with another Sigma lense, and that it was solved with a Canon 90D firmware update.. Could that be a body firmware has to be updated in order to offer support for lenses that appeared after the firmware release?
Go to the Sigma support site.
01-14-2021 10:34 PM - edited 01-14-2021 10:39 PM
Bravo John!
@phillipeliang, you'll need a Sigma USB dock. Great investment if you own one or more of Sigma's Global vision lenses.
01-14-2021 11:57 PM
I love this USB dock, and I have used it a lot for the past weeks, for calibrating my Sigma lenses. A great investment, yes!
01-15-2021 07:28 AM - edited 01-15-2021 07:33 AM
I found the culprit: it's the 90D body. A test with another 90D body shows the lens works great. I guess some hardware must be faulty, because cleaning configuration and even re-flashing the same 1.1.1 firmware did not help.
But still, that's strange: other lenses have no problem on this 90D body, only the 70-200.
01-15-2021 11:41 AM - edited 01-15-2021 11:42 AM
Maybe the problem is not a hardware problem on one of my 90Ds. I took the time to make tests, with two 90Ds and 3 lenses:
Sigma 70-200
Canon 50
Sigma 18-35
It shows the problem is Sigma-specific, when taking pictures through the viewfinder. And apparently not all 90Ds are equal: some overexpose more than others. It really looks like a complex Sigma firmware bug.
01-18-2021 11:32 AM
"It really looks like a complex Sigma firmware bug."
I can't tell you any useful info about using the Siggy lens on a 90D since I don't own one but I can tell you the Sigma 70-200mm f2.8 zoom lens works perfectly on both my 1D Mk IV and 1DX.
You might want to reset your 90D back to factory default. You could have a setting incorrectly set and not be aware of it. Make sure you clear all "custom" settings when you do the reset. That is probably where the error might be.
01-18-2021 12:57 PM
I did a reset, and even a firmware reinstallation. I checked all menu configurations one by one between both 90Ds, but nothing that explains this behaviour on my second 90D.
It's really strange... Either it's a Sigma firmware bug with 90Ds or one of my 90Ds is faulty in my humble opinion.
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