Amazing place, amazing lens

I thought I'd do another little advertisment for my equipment and holiday. The lens used in this 30 second shot covers from Scorpius to Polaris! This view was from the plinth at AstroPalma looking across to the astrotrak and remote dome. I hired the f/2.8 Sigma 4.5mm 180 degree fish eye from lenses for hire, and it JUST (or maybe not?) focused with my modified Canon EOS1000D. The trouble with modifying a camera is that the removal of glass makes a tiny difference to the focus. Fortunately most lenses focus a bit beyond infinity, but with this one the tiny TINY focal length made the focus point crucial and it only just made it to focus with the ring at full turn. Phew! It is impossible to use live view at night with this lens - no star is bright enough and Jupiter wasn't risen from behind the mountain. I had to find a street light in this dark sky location. Fancy that, wanting light pollution? Mad.

Modified EOS 1000D vs EOS 350D

Here is the crab nebula, a supernova remnant that exploded in 1054AD(our time), and was witnessed as the ‘daylight star’ in China. It is a nice target to image for a test, as it contains red filaments surrounding a blue cloud. The red light comes from “hydrogen balmer alpha”, which means an electron in an excited atom of hydrogen drops from quantum level 3 to level 2. The blue light mostly comes from “hydrogen balmer beta”, which is from 4 to 2, a larger drop in energy giving a more energetic photon of light, i.e. a ‘blue’ photon is more energetic than a 'red' one. The purposes of “modifying” a new 1000D (thanks dslrastromod) is to enable most of that alpha light to get to the camera sensor. Roughly 4 times as much. You can see that effect here in this before and after shot. It’s not a proper comparison as the first one was about 10 x 30 second pictures on a 350D, and the second was 6 x 1 minute pictures and both could have been taken with different background brightnesses. But I think you can work out how pleased I am to have improved my astronomical capabilities by such a large jump.