ISO settings and DSLR

colintinto · Jun 21, 2005

Hi All,

Have had my 300D for about 8 months now. Never had an SLR before, but I think I'm getting the hang of it, and I've started playing with some of the less automatic modes with some success.

One thing I often forget though is to correctly set the ISO for the conditions, but it got me thinking - exactly what happens to a digital camera when you change the ISO setting? Does it actually change the sensitivity of the sensor?

I guess it does something, as you can see the increased level of digital noise at 800 and 1600.

Anybody got a good explanation?

Colin

Ant · Jun 21, 2005

colintinto said:
Hi All,
Does it actually change the sensitivity of the sensor?
Colin

Yes, that's exactly what it does. It turns up the gain on the sensor to boost the signal. Of course, as you said, the side effect is that you get more signal noise.

SLOShooter · Jun 21, 2005

You and Ant have it exactly right and that reason is percisely why noise starts coming through especially in darker areas. Keeping it as low as possible is basically what you want to shoot for, unless lighting conditions force you to move it up. There are some good noise reduction programs out there like noise ninja and neat image but they will never beat a low noise negative.

Big Mike · Jun 21, 2005

One thing I don't like about my new camera (20D)...is that the ISO is not constantly displayed in the viewfinder or on the LCD panel.

It's just as important to exposure as aperture & shutter speed...so why is it hidden? Sure you only have to press one button to check it...but there have been a more than a few times when I have taken a good handful of shots at ISO 800 or 1600 (in bright sun) because I forgot to check it.

SLOShooter · Jun 21, 2005

That's so true, I did that just hte other day, I was shooting inside and had to go up to 800, the next day, outside forgot to check it and pow, runined a bunch of shots with noise. Ahhh welll....

Ant · Jun 21, 2005

Big Mike said:
One thing I don't like about my new camera (20D)...is that the ISO is not constantly displayed in the viewfinder or on the LCD panel.

It's just as important to exposure as aperture & shutter speed...so why is it hidden? Sure you only have to press one button to check it...but there have been a more than a few times when I have taken a good handful of shots at ISO 800 or 1600 (in bright sun) because I forgot to check it.

Same with the D70, and quite a few people moan about it. Why do experienced camera manufacturers miss out little things like this?

Big Mike · Jun 21, 2005

Ant said:
Same with the D70, and quite a few people moan about it. Why do experienced camera manufacturers miss out little things like this?

I think it's because the design engineers and marketing execs. are not really photographers. They design the cameras in the lab/office but don't get out into the real world and use the darn things.

All it would take is for one of these guys to forget to check the ISO and they would say..."Gee, maybe the ISO should be displayed" :roll:

My guess is that this is just a carry over from the film days when 'most people' didn't need to check the ISO every shot...just every 24-36 shots.

tr0gd0o0r · Jun 21, 2005

While we're talking about ISO speeds on digital cameras and what not, has anyone else had the experience that their camera doesn't shoot as well at the lowest ISO speed? On my istD I seem to get better quality with 400 than 200. 200 produces a lot of haloing and glowing, but 400 looks wonderful. This happen to anyone else?