topic EOS R6 Mark II: Question about why my shutter speed and ISO are acting the way they are in EOS DSLR & Mirrorless Cameras

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

stcapp1426 — Sat, 27 Jul 2024 21:45:43 GMT

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

Re: Question about why my shutter speed and ISO are acting the way they are

stevet1 — Sat, 27 Jul 2024 21:41:04 GMT

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

Re: Question about why my shutter speed and ISO are acting the way they are

deebatman316 — Sat, 27 Jul 2024 21:41:09 GMT

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.

Re: Question about why my shutter speed and ISO are acting the way they are

stcapp1426 — Sat, 27 Jul 2024 23:41:45 GMT

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.

Re: Question about why my shutter speed and ISO are acting the way they are

stcapp1426 — Sat, 27 Jul 2024 23:44:14 GMT

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.

Re: Question about why my shutter speed and ISO are acting the way they are

deebatman316 — Sun, 28 Jul 2024 00:01:59 GMT

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

Re: Question about why my shutter speed and ISO are acting the way they are

stcapp1426 — Sun, 28 Jul 2024 00:33:26 GMT

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.

Re: Question about why my shutter speed and ISO are acting the way they are

deebatman316 — Sun, 28 Jul 2024 00:50:57 GMT

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

Re: Question about why my shutter speed and ISO are acting the way they are

stcapp1426 — Sun, 28 Jul 2024 01:11:45 GMT

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

Re: Question about why my shutter speed and ISO are acting the way they are

deebatman316 — Sun, 28 Jul 2024 01:15:05 GMT

What ARE the full model names of the lenses in question. Age doesn't matter because they're multiple version of the lenses mentioned above.

Re: Question about why my shutter speed and ISO are acting the way they are

stcapp1426 — Sun, 28 Jul 2024 01:22:38 GMT

I can't tell you what hers is and I'll have to figure out how to tell what mine is. Can that really make so much of a difference?

Re: Question about why my shutter speed and ISO are acting the way they are

stevet1 — Sun, 28 Jul 2024 01:29:06 GMT

Sherri,

My apologies. I didn't read your initial post carefully enough.

As you said, the only variables I can see are the cameras and the lenses.

Any chance you can borrow her lens for a few test shots?

Take a couple with your lens, and then a couple of the exact same scene with hers at the same focal length.

See if there's a difference. You could also run the same test on her camera.

I do not know, and have never read anything to suggest that Canon has changed their algorithms for how they achieve that 18% gray in determining "proper" exposure in the intervening years between when her camera came on the market, and when yours did.

I'm just not that knowledgeable.

Steve Thomas

Re: Question about why my shutter speed and ISO are acting the way they are

deebatman316 — Sun, 28 Jul 2024 02:03:41 GMT

Yes different focal lengths make a difference so does how much stabilization a lens provides. My uncle and I both own EF 70-200mm F/2.8L IS lenses. He owns the version 2 and I own the version 3. Both cameras are the 5D Mark IV. Camera set to Av with the aperture set to F/4. His camera set the ISO to ISO 100. My camera set the ISO to ISO 200. Same exact lighting conditions taken a few minutes apart.

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

Waddizzle — Sun, 28 Jul 2024 06:15:15 GMT

Your experience is hard to explain and may not have an explanation. I used to have similar experiences, which defied explanation. I would have random bad exposures. But at some point it seemed to have stopped. I will never know why. All I have is circumstantial evidence.

The best explanation I have is operator error. I suspect that my thumb would wander around the rear panel lightly touching controls. I was still new to the body, but not cameras.

One day I set up BBF. In hindsight I realized that this gave my thumb a place to go and something to do. Weeks later I noticed that the occasional over/under exposure issue hadn’t occurred in a while. In fact, it has gone away and stayed away.

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

Finelld — Sun, 28 Jul 2024 08:34:32 GMT

It sounds like you might have exposure compensation set. This is a feature that allows proper exposure if you are shooting a scene that is predominantly darker or lighter than average. An example of how this feature is used isn if you were shooting a person in a white ski suit on a snow covered mountain. If you let the auto exposure set the scene normally the snow and the person would come out as grey rather than white. the image would be under exposed. To adjust for this your camera has an exposure compensation function that allows you to adjust the default exposure up or down by a few stops. I would check to see if this is mis adjusted.

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

Waddizzle — Sun, 28 Jul 2024 11:42:47 GMT

After a little more investigation into the issue, I noticed that the over / under exposures would occur when I was using One Shot AF. My tentative conclusion has been that my wandering thumb was touching [AEL] and locking exposure between shots.

Since I almost never use AEL, I disabled the button. I can lock exposure by using One Shot AF, which locks the exposure when it locks down focus.

Re: Question about why my shutter speed and ISO are acting the way they are

stcapp1426 — Sun, 28 Jul 2024 12:29:46 GMT

OK I get that different lenses would produce somewhat different results. But this was a stationary scene, and lower light, so it seems odd to me that my camera would choose such a fast shutter speed, dramatically faster than her camera did. It then forces the ISO up creating potential noise.

Re: Question about why my shutter speed and ISO are acting the way they are

stcapp1426 — Sun, 28 Jul 2024 12:30:46 GMT

Thank you. That's a good idea.

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

stcapp1426 — Sun, 28 Jul 2024 12:35:00 GMT

It may not. I've been using BBF for some time now, even before I got this camera. The resulting image was exposed OK, it just leaves me scratching my head as to why the camera would choose such a high shutter speed (over 1/1000) in a stationary scene in lower light, and then have to compensate by raising the ISO.

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

stcapp1426 — Sun, 28 Jul 2024 12:42:14 GMT

I have it set to AI Focus and I don't even know where the AEL button is on my camera since I've never used it. Worth checking into. Thanks.