Some thoughts on Auto-ISO … this isn’t intended as a definitive tutorial, but more to start a discussion on the technical aspects of Auto-ISO in exposure. For those who have decided that Auto-ISO has no place in their lives then you may prefer to exit this page now :-)
The discussion on Auto-ISO has opened up an interesting new world to many people. Especially when used in conjunction with M … this to my mind isn’t manual per se but what I’ll call Iv (ISO value, cf Av and Tv) in that shutter speed and aperture stay constant and ISO will change as light changes. With recent cameras, higher ISO settings are much more usable for everyday photography (rather than as an emergency). So using ISO up to 800 [or 1600 or higher on some bodies] isn’t going to impact quality too much or indeed produce so much noise a photograph is all but unusable.
The following is for a 7D with firmware 2.0.x (you’ll need to check your manual if you are using a different ‘Truly Auto-ISO capable’ camera [Some early implementations of Auto-ISO on Canon and other bodies, weren’t quite what you might expect]).
You can set the ISO increment (the native ISO of the 7D is probably 100-ISO and consequently speeds of 200, 400 et seq are achieved by ‘hardware amplification’ … intermediate speeds are done by a combination of ‘hardware amplification’ and push/pull a 1/3rd if a stop by software (well as far as I can tell). So I set C.Fn1-2=1.
You can limit the high water mark for Auto-ISO using the menu system, say to 800-ISO. But in M you don’t have a Safety feature.
If you have Safety-Shift set (C.Fn1-6=1) this only comes into use if you are in Av or Tv.
So I would meter off grass (or a grey card) and set my base aperture and shutter speed (with 200-ISO set say). Then switch to Auto-ISO.
Exposure compensation still works in Av/Tv with Auto-ISO and Safety Shift … although that does seem a complex solution to a problem to my mind !
So feel free to correct my understanding (head already on block) … this is really just a pump priming exercise for others to share their thoughts and experiences. Especially when flash is introduced into the mix …
The discussion on Auto-ISO has opened up an interesting new world to many people. Especially when used in conjunction with M … this to my mind isn’t manual per se but what I’ll call Iv (ISO value, cf Av and Tv) in that shutter speed and aperture stay constant and ISO will change as light changes. With recent cameras, higher ISO settings are much more usable for everyday photography (rather than as an emergency). So using ISO up to 800 [or 1600 or higher on some bodies] isn’t going to impact quality too much or indeed produce so much noise a photograph is all but unusable.
The following is for a 7D with firmware 2.0.x (you’ll need to check your manual if you are using a different ‘Truly Auto-ISO capable’ camera [Some early implementations of Auto-ISO on Canon and other bodies, weren’t quite what you might expect]).
You can set the ISO increment (the native ISO of the 7D is probably 100-ISO and consequently speeds of 200, 400 et seq are achieved by ‘hardware amplification’ … intermediate speeds are done by a combination of ‘hardware amplification’ and push/pull a 1/3rd if a stop by software (well as far as I can tell). So I set C.Fn1-2=1.
You can limit the high water mark for Auto-ISO using the menu system, say to 800-ISO. But in M you don’t have a Safety feature.
If you have Safety-Shift set (C.Fn1-6=1) this only comes into use if you are in Av or Tv.
So I would meter off grass (or a grey card) and set my base aperture and shutter speed (with 200-ISO set say). Then switch to Auto-ISO.
Exposure compensation still works in Av/Tv with Auto-ISO and Safety Shift … although that does seem a complex solution to a problem to my mind !
So feel free to correct my understanding (head already on block) … this is really just a pump priming exercise for others to share their thoughts and experiences. Especially when flash is introduced into the mix …
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