Night Shot: What Next?

[porterd2nz]

I travel past this rest home every night on my way to work and I've been planning to take a shot at photographing it for a while.

EXIF:
Sony DSLR-A100 f/4.5 4 sec 28mm ISO 800 7/10 EV

While I like this shot IMHO the ISO is way high but I only had a few minutes. If I understand my theory correctly, if I drop the ISO to 400 I can compensate by increasing the exposure time to 8 sec and get basically the same exposure?

[jiminyClickit]

porterd2nz,

Uhhhh, OK. My camera is night-blind, so I can just say how attractive the subtle lighting is in the trees, the reflection, and the building site generally.

What about this scene caused you to think about photographing it?

[porterd2nz]

Originally Posted by jiminyClickit

porterd2nz,

Uhhhh, OK. My camera is night-blind, so I can just say how attractive the subtle lighting is in the trees, the reflection, and the building site generally.

Thanks. The lighting of the trees didn't show up in the viewfinder or the LCD when I was out taking the shots.

Originally Posted by jiminyClickit

What about this scene caused you to think about photographing it?

I liked the way the lights lit up the building. The reflections in the river in the forground also helped. I'm trying to teach myself how to do these low light photographs.

[inkista]

Originally Posted by porterd2nz

... If I understand my theory correctly, if I drop the ISO to 400 I can compensate by increasing the exposure time to 8 sec and get basically the same exposure?

Yes, that's right. Or dropping the iso to 100 and exposing 32 seconds. However, a longer exposure in the minute-or-more range might also begin to exhibit hot pixels, at which point you might also want to consider using the A100's long exposure noise reduction feature, which will double the amount of time it takes to take the picture (the camera essentially creates a dark frame by making an identical exposure with the shutter closed, and then using the data from the dark frame to remove the hot pixels in the image).

Another feature to play with for these long exposures on a tripod, if you haven't explored it yet, is mirror lock-up. This swings the mirror up out of the way before the shutter is opened, to eliminate all possible camera shake.