Strange auto ISO behaviour or not? Answered thank you.

Valvebounce

EOS R5
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Apr 3, 2013
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Hi Folks.
I was using my 40D today and found that in manual mode with the ISO set to auto it would go to 400 and sit there, adjusting the shutter or aperture would over or under expose the shot but the ISO would not budge. It was as if the camera had an external flash fitted as that seems to do the same fixing the auto ISO to 400.
The thing is I normally set an iso and go with that and just change the shutter and aperture to suit so I can’t remember if this is normal operation or something unusual.
What has me more confused is that when I had time this evening I checked other cameras, my 5DII is doing the same thing, however my 7D is going through a full range of ISOs to keep the exposure balanced.
The only things the 40D and 5DII have in common is recently being used via EOS Utility on the same PC, they have had the same assortment of lenses on them and that I was holding them, they each have their own CF cards which never get mixed up! :unsure:
They each had different lenses on when checked earlier and they both work as I expected in Av and Tv modes in that the ISO changes to balance the exposure, the issue is also present in live view when they are metering directly from the sensor and not the matrix in the viewfinder!
I wonder if some of you with either the 40D or 5DII (or both) would mind checking if they lock to ISO 400 in manual mode no flash attached please.

Thanks in advance for any input.

Cheers, Graham.
 
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privatebydesign

I post too Much on Here!!
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Jan 29, 2011
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Yeh I’d blame that on it thinking it had a flash on. Have you opened and closed the pop up flash a couple of times, and you could try cleaning the hotshoe connectors.
 
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Maximilian

The dark side - I've been there
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Nov 7, 2013
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Hi Folks.
I was using my 40D today and found that in manual mode with the ISO set to auto it would go to 400 and sit there,
...
What has me more confused is that when I had time this evening I checked other cameras, my 5DII is doing the same thing, however my 7D is going through a full range of ISOs to keep the exposure balanced.

Cheers, Graham.
Hi Graham!
I think you will have to check the manual to find out that this (constant ISO 400 in "M") is the normal behavior of those "old" bodies.
If I recall correctly Canon started the real "Auto ISO" in "M" mode with the 7D and it came to the 5D series with the Mark III.
(1D bodies could do this earlier)
I have no information when it came to the double digit series (x0D).
This and the much better AF were the two main reasons for me to switch from 5D2 to 5D3.

Edit:
Found this on page 60 of the 40D manual:
Problem is, don't look at "M" mode in the manual, p. 90. Look at "Auto ISO", p. 60.


AutoISO.png
 
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Valvebounce

EOS R5
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Apr 3, 2013
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Yeh I’d blame that on it thinking it had a flash on. Have you opened and closed the pop up flash a couple of times, and you could try cleaning the hotshoe connectors.
Hi PBD.
Thanks for the comment, yes I tried popping the onboard flash, powered in and off, batteries out, grip off and fit one battery in the body, scratched my head and moved on to taking photos!
I believe Maximillian has hit the nail on the head! Who knew!

Cheers, Graham.
 

Valvebounce

EOS R5
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Apr 3, 2013
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Isle of Wight
Hi Maximilian.
Thanks for that, I was so convinced it was a “fault” that I never thought to RTFM! :mad::ROFLMAO:
Same info for the 5DII on page 58 Of the manual!
Not exactly ”auto ISO“ is it! :unsure: Oh well, the 1DsIII has no “auto ISO” so you have to use safety shift set to ISO to achieve something similar!

Cheers, Graham.
 
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