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Eos r switches to 1600 iso when shooting with studio strobes


Hi there. I've been using the r5 for studio/fashion work, but yesterday I decided to go with the r and 24 105 f4l, both of them with the latest firware. I was using godox strobes (please dont tell me sbout 3rd party stuff because canon doesnt provide this stuff). I selected 200 iso and locked it. I was shooting hand balancing performers doing extremely difficult poses, wich some required several tries and shot at the precise moment. One of the girls tried one of the hardest maneuvers she could and, when she finally did it, she was so happy, we even celebrated, but when we saw the photo... overexposed, unusable image. She was so upset she asked if I could fix it in post, but of corse no chance. Now, imagine my face in front of her. At first I thought it was a flash discharge for some reason, but then I realized the auto iso and 1600 in the metadata. I didnt understand and kept going with the shoot, but it just happened over and over again, resulting in a session full of lost shots. Im sorry for sll my criticesing but as you must imagine Im really upset about this situation, and I wanted to know if someone could tell me whats happening here, is it some kind of an "r bug"? Is it safe to rely on the r5 or is it also prone to happen with it? Thanks



There are too many variables in play so we'd need more information to help understant the situation:

  • Your exact camera settings (mode.  Manual?, AV? other?).  Shutter speed as well.
  • What mode was the flash in (TTL, manual)?
  • How many strobes where you using and what were their positions in terms of the camera (e.g. detail if any of the strobes would be aimed at the camera).

Did you try things with auto ISO disabled?


EOS 5D IV, EF 50mm f/1.2L, EF 135mm f/2L, 600EX-RT (x6), ST-E3-RT
EOS C70, RF 24-70 f/2.8L IS, EF-EOS R 0.71x

Hi Ricky, thanks for the reply. Everything was in full manual, camera and flashes. Ss 125, f16 iso 200. I was using 2 heads, none of them facing the camera, my main light was 45° high to my right and a fill light on the left. Af single middle point one shot, single shot drive mode, evaluative metering, exp sim off. I dont know if it matters or not but was using a neutral gray background and a white reflector on the ground. As for the auto iso disabled, I didnt even know it was possible to completely disable the setting, at the moment I select my desired value manually I dont expect the camera to override my command by itself. Thanks

Not applicable

There are some reports of Godox/flashpoint flash triggers causing this issue on R series cameras.

See this thread: