Understanding ISO

[Deillub]

I usually use ISO 100 for most of my shots... but am sometimes disappointed when shooting indoors under poor light. After reading a discussion regarding us of other ISO settings a gave it a try. I used various ISO setting... hand held, AWB and aperature priority. The result invariably ended up with quite yellow looking pictures. As well - it seemed to be extremely sensitive to the slightest movement....almost like using a long time exposure.
Any thoughts ?

[.Ray]

It's more than likely your camera used a long exposure because you're in aperature priority mode, which means you set the aperature size and the camera decides how long to open the shutter for in order to properly expose the shot. Try use as wide an aperature as you can (lowest f number) to allow more light in so the shutter don't have to open for as long.

The long exposure is most likely responsible for the yellow colour cast too. Try changing from AWB to incandescent bulb setting, but do remember to change it back to AWB afterwards or your pics will come out blue during the day.

By all means try higher ISO settings, ISO 200 should half the shutter speed required at the same aperature and light level than ISO 100. The only drawback of increasing the ISO is noise in the final picture, the higher the ISO the nosier it gets. Depending on which camera you have, the noise level will vary.

[Bev Davies]

I never use 100 ISO even outdoors so indoors in poor light you have no chance of getting a decent image. Ray is right that increasing ISO will increase the noise in the final image but it is barely noticeable until you get to around 800/1000 ISO (depedning on the camera you are using)

The yellow looking images you are getting is the result of a colour cast and this is caused by the artificial lighting. You can either change the white balance to tungsten or shoot in RAW and adjust the white balance in Lightroom or Photoshop.

[Keitht]

The colour cast is probably caused by the AWB not coping with mixed lighting. If you shoot in RAW that's easily addressed after the event. You can adjust after the event when shooting JPG but it's not as effective.