Auto ISO setting question

[Aze]

I just looked through my last session and noticed something that seems a bit strange. I shot in rather bright light, so my shutter speed was regularly above 1/1000. I believe I got about 1/2000 for a good portion of the pictures (don't have all the data with me now). Anyway here is the strange part. I was shooting Manual but left ISO on the auto setting. I find it strange that the camera chose ISO 400 as the lowest setting to use. Was the camera still trying to compensate for exposure and thought I was somewhat underexposing with my aperture and shutter settings? I noticed this because there was a little more noise than I'd like in the picture. That said I believe I'll set the ISO manually next time, but still is there any reason why it would have gone so high?

 

[Light Guru]

Some cameras let you set a range or max ISO when using auto ISO.

Bit I think ISO is the first thing that should be taken off auto and put into manual.

 

[KmH]

In manual mode most cameras will use whatever ISO setting was last used in manual mode.

In North America a Canon 500D is known as a Canon EOS Rebel T1i. In the rest of the most of the world it's a Canon EOS 500D, and in Japan it's a EOS Kiss X3.

Page 61 of the Canon T1i/500D/Kiss X3 User's manual shows that when Auto ISO is set, ISO is fixed at 400 when the Manual mode is used.

 

[480sparky]

This is one of the problems with using Auto anything. The choices made by the camera are really choices made by some nameless, faceless software engineer years ago who has no interest in whether your images end up the way you want them to.

Perhaps the camera chose ISO 400 because you're using a long focal length (i.e., 300mm). In order to prevent camera shake, the software decided to use 1/2000 for the shutter speed. Since the aperture was already wide open (f/3.5 or 4 or 4.5... whatever your lens is @ 300), so the only method left to maintain 'correct' exposure is to raise the ISO.

 

[Aze]

In manual mode most cameras will use whatever ISO setting was last used in manual mode.

In North America a Canon 500D is known as a Canon EOS Rebel T1i. In the rest of the world it's a Canon EOS 500D, and in Japan it's a EOS Kiss X3.

Page 61 of the Canon T1i/500D/Kiss X3 User's manual shows that when Auto ISO is set, ISO is fixed at 400 when the Manual mode is used.

Thanks a bunch KmH, that's completely my fault for not reading the manual at least before looking into this. I'll definitely be setting ISO manually now.

 

[snowbear]

Thanks a bunch KmH, that's completely my fault for not reading the manual at least before looking into this. I'll definitely be setting ISO manually now.

I don't know if this will help or not, but I set a programmable button on my D40 to ISO. I don't have to go through a menu or the multi-field display to change it, just a button and the thumbwheel.

 

[Aze]

Thanks a bunch KmH, that's completely my fault for not reading the manual at least before looking into this. I'll definitely be setting ISO manually now.

I don't know if this will help or not, but I set a programmable button on my D40 to ISO. I don't have to go through a menu or the multi-field display to change it, just a button and the thumbwheel.

My camera has a discrete ISO button so I'm already there.

 

[480sparky]

I just set mine to 100 and fuhgeddabowdit.

 

[TheBiles]

Auto ISO is amazing on bodies that let you customize it like the 5D3. I use it almost all the time, especially in manual mode. You can set minimum shutter speed and maximum ISO so that you don't really have to worry about motion blur and/or too much noise. It also helps when the camera is actually very usable from 100-6400 ISO.