EOS R6 Mark II: Question about why my shutter speed and ISO are acting the way they are

[stcapp1426]

I have an R6 Mark II that I got about 6 months ago, and I am an amateur-level photographer. I shoot in manual most of the time with auto ISO and exposure compensation if I need it. I have the ISO capped at 12800. Today, I volunteered to shoot people at an event, so I set the camera to aperture priority so I could set my f stop and leave it since I was shooting them in front of a prop. I used my Canon EF mount (with adapter) 24-105 lens. My ISO was also on auto. My friend, who also has a Canon mirrorless (don't know which one) was there as well, with a Canon 70-300 EF mount lens. She set hers up the same way as I did. I noticed that my camera chose a very fast shutter speed combined with a high ISO. Shooting the same scene, her camera chose shutter speeds of around 1/200 with a much lower ISO. Why is that? Is there some setting I don't yet know about that's doing that? This has happened once before but I didn't think much of it then because I didn't have another photographer with me where we could compare settings. It seems like the shutter speed and ISO are competing with one another. What's going on? I'd greatly appreciate your help!

Sherri

[stevet1]

stcapp1426,

Perhaps, and this is just a perhaps, you didn't say what aperture your friend chose. If she had set a very small aperture like f/11 or so, her camera would have set a slow shutter speed to compensate.

If you had chosen a wide aperture like f/2.8 or f/4.0 or so, your camera would have sped up the shutter speed to compensate for your aperture setting.

If your camera has selected a fast shutter speed, this will darken the exposure. If you have your ISO on Auto, your camera would have set a high ISO to compensate for this darkened exposure.

It's also possible that your friend was taking photos of a different part of the scene than you were. Perhaps a darker area, which would have slowed her shutter speed down..

Steve Thomas

[stcapp1426]

No she shot at the same f stop. As I said, we set our cameras up just the same. We shot the same scene, since we had a chair to sit in as we shot the kids in front of the prop. I don't know what the deal is.

[deebatman316]

The camera will try to use the fastest shutter speed possible. But it also factors in the focal length. The camera applies 1/focal length x crop factor rule. If the lens has more stabilization the slower the shutter speed will drop. Also if the camera has IBIS it will also drop the shutter speed too.

[stcapp1426]

I still don't understand why my camera is choosing 1/1250 and hers is choosing 1/200. The only difference I can see is the difference in our lenses. I don't like the fact that the camera is choosing a high shutter speed and has to compensate with a high ISO. Not good and that's what I want to hopefully fix.

[deebatman316]

Do they have a max ISO set. The camera also chooses Auto ISO based on EF vs RF too.

[stcapp1426]

Yes she had max ISO set the same and we are both using EF lenses. But it was my camera that chose the high shutter and ISO, not hers. The only differences were the camera model, hers is an older model, and the lenses - mine 24-105 and hers 70-300.

[deebatman316]

Older lenses with less stabilization will crank up the ISO. Newer lenses will reduce ISO because of the better lens stabilization.

[stcapp1426]

Our lenses are the same age with mine perhaps being newer.