M13 with a large Dobsonian, March 11 - 2007

Conditions: no wind, no clouds, no haze, very good conditions

Setup: Obsession 18" f4.5 Dobsonian with alt-az tracking, unfiltered, Lumenera Skynyx 2-2M camera (0.44"/pixel).

Aquisition: 1000-frame sequence with 128ms expsoure time and gain=17.5 (total file size is 3.8 Gb)

Processing (MaximDL, Registax, Photoshop): using batch processing in MaximDL each image was dark corrected, hotpixel filtered and derotated. All images were then aligned and stacked in Registax. Finally, a digital development filter was applied, followed by cropping and curves/levels tweaking in Photoshop.

This image is just a quick test shot using a 'planetary' imaging setup producing thousands of short exposures. Unlike with planets I did not exclude blurred images, going instead for maximum signal-to-noise ratio. Still, the resulting image is quite noisy - I should use many more images next time. The resolution, however, is quite good, around 1.5 arcsec - this hints at the advantages of classic deep sky imaging methods where guiding corrections can be made many times pr. second. With more careful attention to focussing and collimation + maybe a 2x powermate I am optimistic about reaching ~1 arcsecond resolution with this technique. Stay tuned!

Here's my main page where you can see more of the pictures I have taken so far.

Comments greatly appreciated! (mikael@leif.org)