Does any one of you encounter occasion in which you have to take photo in dim condition?

It must not be a problem if you have a tripod, because you can still use a low ISO in order to take photos with low noise level.

But how about if you do not have a tripod? or tripod is prohibited to be used in that occasion? What will you do?

You may use a high ISO to take photos in order not to get a blurred image. However, photos taken by the highest ISO provided by your camera, usually 1600, have terrible noise when you view the photos in full size.

Could we select a lower ISO to take photos, with the same settings in aperture and shutter speed, and subsequently "re-expose" the underexposed photos in photoshop? Which ways would provide cleaner images?

I try to get the answer by using my existing gears.

Below photos were taken with Nikon D70, with manual focus and manaul WB. Raw files were saved and subsequently converted to JPG by Photoshop CS2.

What I did was to "re-expose" the photos taken with ISO 200, 400 and 800 to exposure compensation of +3, +2 and +1 respectively in order to get photos with same exposure as what was taken with ISO 1600.

For sure that I have some conclusions after the experiment. But I would like to leave you to comment on them.

Welcome all comments.