fivemack: (Default)
Tom Womack ([personal profile] fivemack) wrote2009-01-25 10:55 pm

The winter sky viewed from Castle Hill. Annotated.






(click on the picture for a large version in which you can read the labels)

I've wanted to do this for ages, but never managed to get a set of photos without gaps in to make the panorama. I now have a ridiculously wide-angle lens (12mm), with which you only need to take thirteen pictures; I can manage to take thirteen pictures without making a mistake, and here's the result. 20 second exposures, f/4, ISO 1000 on a D90.

Castle Hill has probably the clearest horizon in Cambridge, apart from the tree to the north, but Cambridge is quite brightly lit. You can see Shire Hall (obviously), New Hall, the University Library, King's Chapel and the tower of St John's.

[identity profile] major-clanger.livejournal.com 2009-01-25 11:40 pm (UTC)(link)
Mmm, very nicely done!

Any nebulosity visible on the original pictures? I remember seeing an image of Orion taken with a relatively brief (circa 1 minute) exposure through a normal 50mm or thereabouts lens but with Kodachrome 64, a film that was particularly sensitive to H-α emission. Both the Orion Nebula and the larger but fainter Barnard's Loop were surprisingly evident.

[identity profile] fivemack.livejournal.com 2009-01-26 12:07 am (UTC)(link)
The image scale is a bit low for nebulosity, and the lens a bit slow; really aggressive contrast-enhancement shows up a fuzzy blob where M31 should be and indicates the middle star of Orion's sword looking slightly blurrier than the others, though Rigel also looks a bit fuzzy because there was some thin cloud around there.

(the original images are Nikon raws, which I can convert to 16-bit-per-colour TIFFs, but my tools for manipulating them after that are at the stone-knife level)

It's not too bad for star clusters; see Coma in the big image, and http://www.chiark.greenend.org.uk/~twomack/messier-near-gemini.png

I think the big image is about the resolution and limiting magnitude that you would get naked-eye from a perfect site.
Edited 2009-01-26 13:05 (UTC)