Night exposures

[ronlamarsh]

Hi All,

I am going to be trying to get some night sky images but would really like to capture the REAL sky not the long lines representing the stars. Could this be possible with HP5+ rated at 3200, developed in microphen with a reasonable exposure of under 10sec so I can maintain some sharpness to the stars, or is this hopeess?

 

[domaz]

You may be better off using an astronomy unit that moves a telescope in line with the stars movement. That's a whole 'nother forum though as they say.

 

[Dave Swinnard]

It might be worth spending a roll of film on to find out. Depending on your focal length (wider angles mean longer exposure times before the stars start to show trails) you may get shots matching your expectations. However as domaz points out, a tracking mount (equatorial mount with clock drive) is necessary to produce the types of images seen on sites like Astronomy Picture of the Day or seen in magazines like Sky and Telescope.

(if you want to explore inexpensive tracking mount options search "barn door mounts" and "scotch drive mounts" - a couple of boards, a hinge, a nut and piece of threaded rod and you might be good to go...)

 

[Robert Budding]

You'll struggle with reciprocity failure.

 

[Toffle]

You'll struggle with reciprocity failure.

Yes, and no. In a way, it works in your favour, allowing you to capture the point-source light of the stars, while keeping the background night sky dark. Unless you are trying to capture gas clouds or nebulae, you are not all that interested in shadow detail, so a black sky is probably what you want anyway.
That being said, I agree with Domaz that you might want a tracking unit, and with Dave, that wide angles will allow longer exposures. You may get upwards of 30 seconds that way, which might give you the results you want.