Camera and Tripod

[johnb]

Hi

Ive read the skicky about using a camera and a tripod and have a couple of questions.

It suggest and ISO of 800 and an exposure of 30 seconds - is this a linear scale so can i set an ISO of say 1600 and an exposure of 30 seconds ? (im using a Sony A350, max ISO is 3200)

The sticky says: "take at least 10 exposures at these settings, as the number of individual shots increases, the more detail you get"

Err why ?

Regards

John B

[Beyond_Vision]

The higher the ISO setting the more noisier the image will be. If you take several short exposure i.e. ten or more they can be added together ( commonly called stacking). An example of a free program that can do this is called Deep Sky Stacker. Do a google search for it and have a look at the tutorials on there website. A lot of people use Canon DSLR for Astrophotography as they tend to suffer from less noise than most other DSLR's. The Sony should be ok to use but I'm not sure how the ISO setting on it compare to a Canon in terms of noise.

Regards

Kevin

[johnb]

Thanks, im still not quite understanding how many exposures to capture, I guess 20 is better than 10, but at what point do you stop, 30, 40 ?

is there a ratio of lights to darks ?

Thanks in advance (a table with common ISO, exposure times etc would be handy ?)

John B