Beginner Auto iso question

Welshy74

Welshy74

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If for example I set max auto iso to 1600 then during shooting I changed manually to 400 would the camera then only go between 400 - 1600 or would it if it thinks it should do to less than 400????
 
Welshy74 said:
If for example I set max auto iso to 1600 then during shooting I changed manually to 400 would the camera then only go between 400 - 1600 or would it if it thinks it should do to less than 400????
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So are you saying that you are changing the maximum Auto ISO from 1600 to 400, are you saying that you are setting the minimum Auto ISO at 400, or are you saying that you are manually setting the ISO at 400?
 
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On my cameras manual ISO overrides all auto ISO settings, if that's what you mean. If the ISO is set manually to 400 it will stay there.
 
Welshy74 said:
If for example I set max auto iso to 1600 then during shooting I changed manually to 400 would the camera then only go between 400 - 1600 or would it if it thinks it should do to less than 400????
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Certainly on a Nikon DSLR if I'm in auto ISO with base set at 100 and upper limit at 1600, if I then switch to manual at 400 and then back to auto, the camera will work in the range of 400 to 1600 unless I set the base back to 100. Hope this makes sense?

GC
 
gcgraphs said:
Certainly on a Nikon DSLR if I'm in auto ISO with base set at 100 and upper limit at 1600, if I then switch to manual at 400 and then back to auto, the camera will work in the range of 400 to 1600 unless I set the base back to 100. Hope this makes sense?

GC
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So are you saying that if you manually select an ISO and then switch back to Auto ISO the camera will change the Auto ISO settings that have already been set up in the cameras menu? And also, why would the camera change the lower ISO value up, and not the higher ISO value down? It seems like very strange behaviour to me.
 
I see that in at least some Nikons there is no explicit provision in the auto ISO settings for a minimum ISO when in auto ISO mode, just a maximum ISO. But there's a separate ISO setting which, when auto ISO is off, is simply the active ISO setting. If this setting is also taken as the minimum ISO when in auto ISO mode, then you'd get this (rather unintuitive) behaviour.
d610_autoisocontrol-03.jpg
 
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j crossley said:
So are you saying that if you manually select an ISO and then switch back to Auto ISO the camera will change the Auto ISO settings that have already been set up in the cameras menu? And also, why would the camera change the lower ISO value up, and not the higher ISO value down? It seems like very strange behaviour to me.
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Exactly as @Retune posted above. The manual ISO parameter becomes the base ISO parameter in Auto ISO, tend to use auto ISO about 90% of the time for dynamic work, fast jets, military exercises etc and get on really well with it (y)
 
I cannot see any time when setting a minimum ISO would be of any benefit unless for some obscure reason you wanted to introduce noise and therefore wanted to set the minimum to, say, 3600
 
Welshy74 said:
Thanks all. Was just wondering as my camera has only a max iso and not min iso when in auto
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The minimum iso is just the iso setting. On auto-iso, the camera will choose between the iso setting, and the max-auto value - so in your example, yes it would be between 400 and 1600. I have never found it useful to set an iso value higher than the base, when using auto-iso though. Like @gcgraphs I use auto-iso all the time when working with dynamic light - ie travel and street photography. Camera in "manual", so I can control boh the shutter speed and aperture for non-exposure reasons, and still have the camera sort out the exposure automatically by increasing the iso (on Nikon cameras, the camera still obeys the exposure compensation settings even in manual mode, when using auto-iso). If the variance in light is extreme though, shoot in aperture priority with auto-iso instead so the camera has control of the shutter speed to reduce exposure if the scene suddenly becomes very bright
 
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Scooter said:
shoot in aperture priority with auto-iso instead so the camera has control of the shutter speed to reduce exposure if the scene suddenly becomes very bright
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This is how I work most of the time... and increasing the base ISO setting is a quick/easy way of pushing the minimum SS on my Nikons. It's also how I quickly/temporarily override the max ISO limit I set for auto ISO.
 
gcgraphs said:
Certainly on a Nikon DSLR if I'm in auto ISO with base set at 100 and upper limit at 1600, if I then switch to manual at 400 and then back to auto, the camera will work in the range of 400 to 1600 unless I set the base back to 100. Hope this makes sense?

GC
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I think this may have just answered a question I had about auto iso on nikons without me needing to ask! Thank you :D
 

Manual Mode​

In Manual mode, the aperture and shutter speed values are fixed by the user. ISO Auto will change the ISO when the light levels change.

*When using the ISO Auto function in manual exposure mode the electronic analog exposure display of the camera will continue to indicate correct shutter speed and aperture settings when light levels change within a four-stop range. The ISO Auto system increases or decreases the ISO value to maintain the correct shutter speed and aperture value the user has chosen.

Shutter Priority​

In Shutter Priority mode the shutter speed is set by the user and the aperture is determined by the camera system. If light levels change, the aperture will change as determined by the camera system. When the aperture determined to achieve the correct exposure is beyond the aperture range of the lens used, then ISO Auto will increase the sensitivity value.

Aperture Priority​

In Aperture Priority, the aperture value is set by the user and the shutter speed value is determined by the camera system. If light levels change and the shutter speed required to achieve the correct exposure is beyond the shutter speed range of the camera, ISO Auto will increase the sensitivity.

*As the shutter speed range of a D-SLR is very large, it is rare that a shutter speed beyond the range of the camera (i.e. 30 sec) will occur under normal lighting conditions.

Program​

In Program, Auto or any of the Digital Vari-Program modes the aperture and shutter speed values are determined by the camera system. As light levels change, the camera will alter shutter speed and aperture values to ensure the correct exposure. When the shutter speed required to achieve the correct exposure is beyond the shutter speed range of the camera and the aperture cannot be adjusted any further by the camera system, ISO Auto will increase the sensitivity.

Taken from the Nikon Website
 
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