Tuesday, July 31, 2012

Comparing DSS and Nebulosity stacking

Looking more into focusing. Another cool gadget would be this motorized focuser - though I don’t really have a problem with too much shaking when I focus the telescope. But this is something I would like to have for my camera when I make photos through a lens.

But I’ll get to try out lots of new gadgets soon:

  • The focal reducer already arrived at work
  • The DSUBS cable should arrive tomorrow
  • The GPS unit for the Nexstar remote should arrive tomorrow

Can’t wait to try them out (especially DSLR Shutter with the DSUBS cable). Unfortunately, the focal reducer will probably reduce the range of the telescope even more with the camera attached.

I took flats and flat darks tonight - but it’s cloudy again. So, I won’t be able to shoot more pictures my last night here :-( Only back in San Jose with all the other lights and such, too bad!

In the absence of taking new pictures, I played more with the ones from a few nights ago.

First, I wanted to compare DSS stacking with Nebulosity stacking:



DSS stacked:




Nebulosity average stacked:


Nebulosity std dev (1.5) stacked:




Ignoring the diagonal lines of Nebulosity (I need to buy a license for it - I’ll probably end up using it anyway), the images are quite different. The Nebulosity pictures have some greenish hue towards the upper left corner - the DSS stack doesn’t. There shouldn’t be any hue at all (Lyra is next to the milky way). But somehow the Nebulosity pictures look much richer.

Zoomed into the main stars of Lyra:

1. DSS



2. Nebulosity (average stacked)



3. Nebulosity (std dev stacked)



The resulting colors are quite different. Vega itself is blue with DSS ad red’ish with Nebulosity - the DSS color seems to be much more realistic. On the other side, delta2 lyr is red with DSS and blue with Nebulosity - and in reality it’s red.

Somehow, Nebulosity seems to have mixed up the color palette (in the originals, the colors are correct) and introduced this strange hue.

But I still haven’t made much progress with post-processing of the pictures themselves...