Impact of slow shutter speed

[ggiridhar_reddy]

Hi,

The other day I was trying to shoot with my P&S Canon A 530 during dusk. Since I did not want to use flash or increase ISO (for fear of noise), I reduced the shutter speed to 4" to capture more light and capture naturally. Though the photograph has come out well, it has noise (grains). Does decreasing shutter speed also increase the noise? I was expecting only increase in ISO would increase noise. Any one of you pl. clarify.

Thanks,
Giri

[katia]

yes, because the increased shutterspeed heats up the sensor. not sure 4 seconds would really do it though, could someone else chime in?

[ravncat]

Originally Posted by katia

yes, because the increased shutterspeed heats up the sensor. not sure 4 seconds would really do it though, could someone else chime in?

Depends on the sensor - some older ones or smaller ones will show noticable heat build after a second - others much longer. Also depends on the combination with the ISO. and the amount of hot pixels on the sensor. Noise is even affected by ambient temperature...

Also, underexposure will show increased noise. You'll probably see more in the shadows.

[ggiridhar_reddy]

Thanx for the responses.
Does this kind of noise visible (as I mentioned) in DSLRs as well with only reducing the shutter speed and retaining ISO at only 80/100...since now am planning to buy DSLR

[ravncat]

Only with underexposure
You shouldn't run into visible noise at low iso with a modern dslr. Even at 10 seconds.