Northern Ireland Outdoors Forum - Hiking, camping and more

Outdoor Activities => Photography => Topic started by: RedLeader on February 15, 2010

Title: ISO
Post by: RedLeader on February 15, 2010
Should I keep the camera on auto ISO or  keep changing it manually depending on circumstances?

Title: Re: ISO
Post by: Kirth on February 15, 2010
For the meantime I would keep it on Auto ISO whilst you are getting to grips with shutter and aperture.
When using Shutter & Aperture priority modes, this makes you think a bit more of what end result you want from an image, like "do I want to freeze the water or make it blurry?" so you then dial in the settings you want to create it. after a while you will start realizing that to do certain images styles you need the shutter speed to be faster etc, and that is when the iso will come into play.

But for me I would leave it as is.
Title: Re: ISO
Post by: chris on February 15, 2010
How does auto ISO work then? Assuming your camera is on manual you have control over shutter speed and aperture, if you give the camera control of your ISO will it just wack it up as high as it can (3200 on a d300) tricking the meter into thinking your properly exposed and result in a super grainy image? Do I have to set my shutter speed to effectively over expose my image so the camera will bring the ISO down?
Title: Re: ISO
Post by: Kirth on February 15, 2010
Traditionally there have been two easy ways to control exposure: shutter speed and aperture (ƒ/stop). A user could also change the film to a “faster” (higher ISO) or slower (lower ISO) type but this was difficult or impractical to do from shot to shot. With digital cameras it became much easier to adjust ISO, as it is now just the push of a button.

Nikon has added an option, AUTO ISO, to many cameras. AUTO ISO allows the camera to automatically adjust ISO, just like it controls shutter speed and ƒ/stop. We now have three easy ways to adjust exposure rather than the traditional two.

When shooting images in varying lighting conditions, for instance at a wedding where images are being taken both indoors and out, AUTO ISO control is a useful feature that allows the photographer to specify both the highest ISO and the minimum shutter speed the camera can choose from.

As an example, let’s say you are shooting outdoors at a wedding and you have your camera manually set to a low ISO setting of 100 because there is plenty of light available. Then as you follow the bridal party indoors where the light level is much lower, your camera’s exposure meter indicates it will require a slower shutter speed (and/or wider aperture) to achieve correct exposure. Rather than having to manually change the ISO to make the camera more sensitive for this lower light level, the AUTO ISO feature will automatically adjust the ISO setting up to obtain correct exposure for the new lighting conditions.

The exact minimum shutter speed setting where this “jump” to a higher ISO takes place can be set on most Nikon digital SLR cameras using the AUTO ISO control in the Custom Setting menu of your camera. For example, you may want to shoot at a fixed ƒ/stop and the lowest ISO possible until a shutter speed of 1/15th of a second is required to make a proper exposure. In a programmed exposure mode the camera will continue dropping the shutter speed lower and lower until the 1/15th is reached and then AUTO ISO will automatically increase the ISO upward to keep a good exposure. The camera will continue to increase the ISO setting upward until it reaches the “Max.” setting you’ve chosen in the camera’s AUTO ISO menu, or to a maximum of 1600 ISO.

This is a big advantage to any photographer who often manually changes the ISO settings as the light quickly changes since it allows full concentration on the subject rather than the camera controls. If you return to an area where the light level increases, the camera will automatically drop the ISO setting again to the lowest setting possible for the light level you are now shooting in.

If your camera model includes the AUTO ISO feature, you will see in the Custom Settings menu of your camera availability for setting both the Maximum ISO setting you would like the camera to increase to and the Minimum Shutter Speed at which this increase in ISO will automatically take place.