Talk:Star trail

A fact from Star trail appeared on Wikipedia's Main Page in the Did you know column on 29 October 2012 (check views). The text of the entry was as follows:

Did you know... that star trail observations of Polaris (example pictured) have been used to measure the vibrations in telescope mounting systems?

A record of the entry may be seen at Wikipedia:Recent additions/2012/October. The nomination discussion and review may be seen at Template:Did you know nominations/Star trail (photography).

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DYK nomination

I've added this article to the DYK nominations today:

Let's see if it makes it to the front page! AstroCog (talk) 15:47, 9 October 2012 (UTC)[reply]

Polaris vs North celestial pole

I think the article should refer to the star trails in the north being centered on the north celestial pole, rather than on Polaris. At present, Polaris is 45 arc-minutes from the north celestial pole (about one and a half moon diameters). The article refers to testing the seeing at an observing site by examining the Polaris star trails. Two star trail photographs in the article clearly show Polaris leaving an arc.

NitPicker769 (talk) 03:21, 4 November 2012 (UTC)[reply]

An excellent nit to pick, NitPicker. I think that's an appropriate update that you can make if you like. Cheers, AstroCog (talk) 00:16, 5 November 2012 (UTC)[reply]

Done... NitPicker769 (talk) 02:44, 6 November 2012 (UTC)[reply]

Are you sure?

This sentence from the article:

Even though star trail pictures are created under low-light conditions, the long exposure times allow for fast films, such as ISO 200 and ISO 400, to be used.

leaves me confused. Long exposure times should allow slower films to be used, shouldn't they?

or is it a case of: "The whole idea is impossible, but if you use long exposures and fast film, it becomes feasible"?

NitPicker769 (talk) 16:03, 11 November 2012 (UTC)[reply]

This is what the photographers said in the refs. Fast is relative. My own experience in B&W photography and photographers is that anything above ISO 100 is fast. I also think your conclusion is reasonable - that better results come from a faster film + long exposure (for film at least). Cheers, AstroCog (talk) 17:49, 11 November 2012 (UTC)[reply]