7D basic question

Trev4

Trev4

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Trev
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This is something I feel I should know the answer to, but am unsure.
With the 7D, or really any other camera for that mater, when Tv is selected, the camera meters and sets the aperture. Equally it works the other way round when Av is selected and the shutter speed is set by the camera. Now, if auto ISO is also selected, in what sequence does the camera work. I suspect it sets the aperture (or time) first, then the ISO, or am I wrong?
Its not that important, but I am curious and want to stop trying to work it out logically :thinking:
 
I have no idea, but Auto ISO is most useful when you want to set both shutter and aperture in Manual and then leave Auto ISO to set the exposure level. It's a mode I use for birds in flight, the only drawback is you don't get to dial in any exposure compensation as both dials are in use.
 
artyman said:
the only drawback is you don't get to dial in any exposure compensation as both dials are in use.
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If you are in manual, either of the dials will compensate your exposure.. you just decide which one you want to change.. speed or aperture.

that's how manual always works.
 
It's a little more intelligent that your supposition Trev. In AV, it'll move the shutter speed within a band that is determined by the focal length of the lens or lens T/C combination and then adjust the ISO if a suitable shutter speed can't be achieved....ie, different lenses will result in different switching points for shutter speed versus ISO levels.....all loosely based around the old 1/FL guideline. I haven't managed to suss out whether IS plays a part in the decision making process.

Bob
 
Janice said:
If you are in manual, either of the dials will compensate your exposure.. you just decide which one you want to change.. speed or aperture.

that's how manual always works.
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In normal circumstances yes, but not with Auto ISO only if you were fixing the ISO yourself.
 
Janice said:
If you are in manual, either of the dials will compensate your exposure.. you just decide which one you want to change.. speed or aperture.

that's how manual always works.
Click to expand...

not if you have auto iso set it will change to suit
 
AH sorry!

auto iso on the 50d which i have keeps the iso at 400 when in manual!

not much auto about that!! :D
 
Your basic question, not so basic, I have learnt something to help me with aircraft photos, thanks to all replies & thread started TREV 4.
 
frankcanon said:
Your basic question, not so basic, I have learnt something to help me with aircraft photos, thanks to all replies & thread started TREV 4.
Click to expand...

Me too - thanks for that.
 
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