auto ISO on the canon 40D - DPChallenge Forums

12/05/2008 06:47:49 AM · #1

how is this supposed to work??

the book says that in 'manual' mode an ISO of 800 will be set.
in Av mode, an ISO to give a shutter speed for hand holding will be set.

to me this is seems next to useless.
i would expect with the camera in 'manual mode' and auto ISO mode, the camera would set an ISO to match the shutter speed and aperture value entered!

tell me what i am missing here??

12/05/2008 06:51:52 AM · #2

I may be missing the point, but if you are in full manual mode you would also set the ISO manually?

12/05/2008 06:57:04 AM · #3

I've just looked on my camera and it always sets the ISO to 400 in Manual mode and doesn't seem to change it. In fact in tv and av it keeps ISO 400 and doesn't seem to go below that. In program modes however it does go down to ISO 100.

Message edited by author 2008-12-05 07:00:15.

Canon EF 28-135mm f/3.5-5.6 IS USM

12/05/2008 06:57:20 AM · #4

Originally posted by bobonacus:

I may be missing the point, but if you are in full manual mode you would also set the ISO manually?

i know that is the normal method.
but the last clic (past ISO 100) is auto.
i am asking what this does and how to use it.

Kelli

Canon EOS-D60

12/05/2008 07:51:09 AM · #5

I can't tell you what it's thinking, but I tend to use auto ISO and it's almost always either 400 or 800. I can vouch though that it uses a pretty good range under certain conditions. Even odd numbers that you don't normally see like 500 & 640.

CEJ

Canon EOS-40D

Canon EF-S 18-200mm f/3.5-5.6 IS

12/05/2008 08:00:13 AM · #6

Try reading pages 59 - 60 of the manual. It explains it quite nicely. One thing to remember is that just setting the ISO to AUTO causes the LCD to display the default setting for the other parameters set (shooting mode, etc.) and does not change until you press the shutter button halfway.

Message edited by author 2008-12-05 08:03:55.

Canon EF-S 18-200mm f/3.5-5.6 IS

12/05/2008 08:51:59 AM · #7

Originally posted by CEJ:

i did read page 60. That is what i quoted in my opening post (although i did say 800 instead of 400)

i still don't see how it is that usefull.

CEJ

Canon EOS-40D

12/05/2008 09:52:46 AM · #8

It is useful because it tells you HOW the camera selects the ISO, what ISO range it will select and under what conditions it will select that ISO value or range of ISO values. It is that simple. It sounds like you are expecting the camera to perform in a manner it was not designed. Perhaps the nomenclature could be better - as in not calling it AUTO ISO, but Camera Selected ISO.

Canon EF 70-200mm f/2.8L IS USM II

12/05/2008 10:17:05 AM · #9

Originally posted by CEJ:

i guess your right!.. i was expecing something that is not!

but... why would you would dial in auto iso in manual mode??
you might as well just set it at 400 and be done with it!!
and when i had my 200mm lens on in Av mode, it was giving me shutter speeds to slow to hand hold safely!

that it what i meant when i said it wasn't a usefull function.

do you use this function at all??... if so what situations??

PhotoDave

Canon EOS-5D Mark II

12/05/2008 10:22:05 AM · #10

Personally I never really used the auto ISO, I prefer to just set it manualy. Ive gotten pretty good at while looking through the viewfinder can change most settings without looking away...

-dave

Canon EF-S 18-200mm f/3.5-5.6 IS

12/05/2008 10:26:09 AM · #11

Originally posted by dainmcgowan:

that it what i meant when i said it wasn't a usefull function.

do you use this function at all??... if so what situations??

I came to that conclusion as well, I think it should be far more intelligent than it is. One thing I was interested in when I upgraded from the 350d was the auto ISO as I didn't pay enough attention then. With so many user configurable options on the 40d I'm surprised there is not some options to add some kind of user control to the Auto ISO.

I'm surprised that when I point the camera at the sky on Auto ISO in av mode the ISO is still 400 even though the shutter is 1/4000

Personally I tend to pay a lot more attention (most of the time) to shutter speed than I did 6 months ago so I always set the ISO manually

CEJ

Canon EOS-40D

12/05/2008 10:34:56 AM · #12

I never use Auto ISO. I did experiment with it when I first got the camera though. I recall seeing the 400 on the LCD and viewfinder, but I also recall that the EXIF said something different.

Also, remember, when in AUTO ISO, regardless of what the display says, you MUST press the shutter button halfway to actually get the camera to select a value. Just setting to AUTO does not do it.

MattO

Nikon D4

Nikon AF-S Nikkor 70-200mm f/2.8G ED VR II

12/05/2008 10:58:19 AM · #13

I would think that auto ISO could be used in harsh lighting conditions, IE varied sun and clouds, where you want to maintain a certain Shutter speed and aperture and let the ISO float to keep it there. Personally though I would rather make changes on the fly to prevent the camera from being tricked by dark or really bright backgrounds.

Matt

ETA I think this would be similar to using AV mode but instead of varying shutter speed it keeps that constant and allows the ISO to float to maintain them

Message edited by author 2008-12-05 10:59:00.

Strikeslip

Canon EOS-5D

Canon EF 100-400mm f/4.5-5.6L IS

12/05/2008 11:08:52 AM · #14

Originally posted by dknourek:

Personally I never really used the auto ISO, I prefer to just set it manualy. Ive gotten pretty good at while looking through the viewfinder can change most settings without looking away...

-dave

We are both like Ninjas that way! ;-)

PhotoDave

Canon EOS-5D Mark II

Canon EF 70-200mm f/2.8L IS USM II

12/05/2008 11:39:53 AM · #15

Originally posted by MattO:

IMHO it would prob be better if it were a little more intelligent and went from ISO 100 to 1600 rather than the 400-800...