Beginner Why does shutter priority select such a high ISO?

[Pants1984]

Hi all,

I nearly always shoot in aperture priority.

I was taking some shots of my daughter opening birthday presents in low light yesterday, so used f1.8 and the camera maintained 1/60 with auto ISO, fair enough.

She was moving around a fair bit obviously so I wanted to up the shutter speed. If my camera had it, I would have changed the auto ISO minimum shutter speed to 1/100. But I have a Sony A7 and it doesn't have that.

So I thought I would venture into the lesser used (for me) shutter priority.

I selected 1/100 and auto ISO.

What confuses me is that the camera is choosing to use settings like f3.5 at ISO 3200. Why isn't it choosing to use f1.8 at ISO 800? Surely it should try to use the lowest ISO rather than the highest, which is what it seems to be doing?

Is this how shutter priority works on most cameras and am I just being a noob?

 

[Box Brownie]

It does seem the minimum shutter speed with auto ISO is only there in the A7mk3

Maybe try Manual i.e. set shutter to 1/100 and aperture to one of your choice...with auto ISO. And see what ISO it picks........better an in focus with minimal subject motion blur, noisy image than low noise opposite!

Edited ~ predictive text blooper in line one above :banghead:

 

[Brentor]

I do not have that camera, but can you manually select the aperture and speed and set to auto iso?

 

[Pants1984]

I've just tried manual and that did the trick. Not really ventured there before as aperture has always been OK for me.

Will start using manual a bit more from now to get comfortable with it. I guess with that method I will just have to be a bit more mindful of exposure as I'm solely reliant on the auto ISO!

At some point I'll try to justify getting an A7 III but until then I need to make the most of what I've got.

 

[Box Brownie]

I've just tried manual and that did the trick. Not really ventured there before as aperture has always been OK for me.

Will start using manual a bit more from now to get comfortable with it. I guess with that method I will just have to be a bit more mindful of exposure as I'm solely reliant on the auto ISO!

At some point I'll try to justify getting an A7 III but until then I need to make the most of what I've got.

As is always the case ~ practice, practice, practice......and trying settings that you have yet to learn about is no bad thing.

Best of luck getting pictures of your daughter that please you and add to the recorded memories.

PS though I am not a great user of flash......it might be beneficial for you to consider/try.

 

[nokk]

i think you might be better off setting the iso yourself and only using shutter priority or vice versa. this way the camera still figures out the exposure for you, but you have more control over the settings. at f/1.8 you may not get as much in focus as you'd like.

i use a sony a7r4 for wildlife photography. i set the shutter speed and aperture (and pretty much leave it at those settings) and let the camera pick the iso. it's a noisy camera so i always make sure i'm exposed perfectly or a little overexposed so that i'm not adding to the noise when by trying to brighten in post.

 

[Tom Pinchenzo]

My camera allows you to set err on the side of higher or lower shutter speed when aperture priority and auto-ISO. E.g. if you're at 50mm focal length the camera will try and get your shutter speed to at least 1/50 - 1/60ish. You can change it so that it only lets you drop to say, 1/100. Also you can set max ISO so it never takes you about, say 3200.

If you're shooting with a prime, which I presume you are with f/1.8 then you can just set auto-ISO with a minimum shutter speed at 1/100. Or 1/200. Or 1/500 if they're moving really fast.

 

[Pants1984]

That's exactly what I want to do Tom but the original A7 doesn't have minimum shutter speed features unfortunately. I'll make sure my next camera has this as it would be perfect for the way I want to shoot.

Shutter priority seems to stick to the max of the auto ISO range, unless it can't for exposure reasons. There's no way for me to tell it to "prefer" a lower ISO. This isn't working for me as I generally prefer the lowest f number and ISO that I can get away with.

Going back to aperture priority yes I could have bumped the minimum ISO to increase my shutter speed. I used to do that on my old canon, but the ISO menu slows me down a bit and I was hoping to be able to lean on auto ISO.

I think for this camera manual is the way forward for me with auto ISO, for low light family shots etc. I think it should be just about as quick for me as aperture priority but it will be a learning process on quickly working out what shutter speeds are acceptable for the given light, as I normally let the camera deal with that.

 

[Ed Sutton]

I expect cameras are programmed to avoid the widest aperture in order to keep things in focus when in shutter priority as they have to cater for the complete idiot who would complain that all their pictures are out of focus. After all it's only a certain faction of photographers who want to shoot wide open most of the time to deliberately have next to nothing in focus.

 

[woof woof]

I have an A7. I can't remember the last time I used shutter priority so I've just given it a try and with a f2.8 lens it suck at f4 for everything. How annoying.

I use aperture priority until the light drops and the camera selects 1/60. I then switch to manual and dial in the appropriate aperture and shutter settings and let the ISO float. Setting the ISO manually is IMO too slow and I'd hate to be doing that from shot to shot.

For example, f2.8-f8 and 1/60 to 1/100 may be what I want for a static subject shot but for a subject likely to move I may want a shutter speed in the region of 1/200 or even more. Setting a minimum shutter speed in aperture wouldn't work for me as the minimum shutter speed would need to be changed from subject to subject and setting the ISO manually just seem too much of a hassle unless after a conscious decision. For example. f5.6, 1/20 and ISO 400 with flash to freeze the subject, get it adequately lit and capture some ambient light in the background. Mostly though, Aperture and Manual with auto ISO seem to work best for me.