Trouble setting ISO on Canon 40D

Lamar May · #1 05-09-2008, 01:14 AM

I can not get my 40D to change ISO to 100 OR to the H position (3200). I've read the book, tried and retried. I owned a 20D before this camera and it worked the same way. I thought I had been able to set ISO at 100 and at 3200 some time back on this 40D, but maybe not.

In trying to set 100 ISO, I make sure I'm in "Creative Mode", mash the ISO button and turn the dial, but when it gets down to 200, the next thing that appears is "auto"!

Same thing on the upper end.....I go into Custom Functions and turn the expanded ISO feature on, but when changing the ISO, it won't go above 1600!

Any ideas? Anyone else having this problem?

Thanks for any help!

DougAxford · #2 05-09-2008, 09:15 AM

First, I'm pretty sure there is no 100 ISO. We made the switch to 200 and actually, I've been shooting a lot of 400 as standard with no loss of quality.

To get 3200, you have to turn off highlight tone priority. The setting is just under ISO expansion.

I use the 3 presets C1 - 3 to enable and disable the settings much faster. IOW, C1 will be 200 ISO, highlight priority, jpg, 5300K, etc, : C2 will be 3200 ISO, raw, 2500 ISO for a dark church interior. It switches with 1 click and retains your presets.

DougA

Doug_Kerr · #3 05-09-2008, 09:26 AM

Hi, Lamar,

Quote:

Originally Posted by Lamar May

In trying to set 100 ISO, I make sure I'm in "Creative Mode", mash the ISO button and turn the dial, but when it gets down to 200, the next thing that appears is "auto"!

Same thing on the upper end.....I go into Custom Functions and turn the expanded ISO feature on, but when changing the ISO, it won't go above 1600!

As Doug Axford notes, you probably have Highlight Tone Priority in effect. Then, the range of ISO settings is limited to 200-1600. As a reminder of this, in the status panel and the viewfinder, the "0"s in the ISO display are replaced by the smaller "o" (e.g., "16oo").

You can see this in the manual on p. 157 under C.Fn II-3, Highlight Tone priority.

Ron Metz · #4 05-09-2008, 09:31 AM

I just recently purchased a 40D and mine does have the 100 ISO. ISO 3200 will show as "H".

Ron

Lamar May · #5 05-09-2008, 11:31 AM

Thanks, guys....you're great! I THOUGHT I had used both 100 and 3200 before and the book clearly says they're there, but I didn't pick up on the highlights priority thing. Does anyone have an opinion on the highlight priority feature....I've had it turned on for a while, and have been pleased with the results I'm getting, but I have not done any tests to compare with and without that feature. Has anyone done that or read any test results?

Thanks again for the reminder!

LM

Lamar May · #6 05-09-2008, 11:35 AM

Thanks, Doug....I have not used the custom settings, but that is a great idea....will try it.

LM

Noel_Carboni · #7 05-09-2008, 01:40 PM

I think Doug is saying "under the covers the sensor doesn't really do ISO 100 and the camera is doing digital machinations to provide ISO 100", but I might be wrong. Doug, do you have a reference for this? I find ISO 100 still the most noise-free setting, but I really haven't experimented to find out if I'm losing dynamic range.

Lamar, do you shoot primarily raw or JPEG?

From what I gather Highlight Tone Priority really gains you nothing if you shoot raw.

Even if you shoot JPEGs, expose for the highlights and you can fix the images digitally later.

-Noel

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