Capella is the brightest star in Auriga constellation. It is very easy to spot in the Northern hemisphere. It is a circumpolar star, very bright one. The picture has been taken through a 300mm telephoto lens and Canon EOS 450d over a Sky Watcher EQ6 equatorial mount.
Here it is the full frame, with a lot of stars in the field and great detail:
http://www.awesky.com/Deep+Sky/Misc/Capella+-+Alpha+Aurigae/
This is a crop of the resulting stacking of 36x30s + 2x360s subframes taken this month in two different sessions. The area showed corresponds to M101 and surroundings (in Ursa Major), in which we find other 2 galaxies NGC 5474 and NGC 5477. Below, I have added a DSS2 image of the are for comparison. My stars are blobs, meanwhile DSS2 are pinpoint. On the other hand, I use to lose star colours specially in the brightest ones , when postprocessing and stretching histogram. Maybe some day I will learn how to fix all these errors …
The Tamron SP 54 is a 300mm telephoto lens, with an aperture of 54mm. I took a 60 seconds of exposition image of M42 in Orion. A few months later I took a 15 seconds image of the same field through a 6 inches Sky-Watcher non-apo refractor.
The comparison throws some interesting conclusions:
1.- A 150mm lens gives more resolution than a 54mm lens. Stars are fainter in the 6 inches refractor picture.
2.- The light captured by a 54mm lens in 60 seconds is nearly equivalent to the one captured by a 150mm lens in 15 seconds. Nebulosity appears practically equal in brightness in the two pictures. The lower image is a full frame, meanwhile the upper one is cropped at 25%.
Both images were taken using an unmodded Canon DSLR camera, EOS 450D (or Rebel XTi) and an EQ6 equatorial mount.
Computer Physics Lab 