Amazing Photo of M51-Whirlpool Galaxy

[Drakkith]

Topher what program do you use to process your images?

 

[Andy Resnick]

Looks good Andy. You sure are putting a lot of work into these shots. What level skies are you shooting in?

Urban skies. High humidity, seeing generally ranges from bad to poor.

Nice work on M51!

 

[Topher925]

Topher what program do you use to process your images?

Other than DSS, I only use GIMP. Although I do all my noise reduction using the utility that came with my camera before stacking.

 

[Andy Resnick]

I re-stacked all my M51 images now that I know more as a result of all this discussion- here's the 'whole' image (about the central half of the full frame), a total acquisition time of 1 hour at f/2.8 ISO 1600, no noise reduction etc:

http://img191.imageshack.us/img191/6002/maxm51totalsmall.png

and a 1:1 crop of M51:

http://img171.imageshack.us/img171/3142/justm51crop.png

And then with noise reduction:

http://img155.imageshack.us/img155/2697/justm51cropfiltered.jpg

One 'constraint' I used while doing the final stacking was to keep the doublet located between '10 o'clock' and '11 o'clock' on the full image (bottom edge, far right on Topher925's full image) distinct- that helped prevent clipping on the high end.

 

[Drakkith]

Given your constraints I would say that is an excellent picture Andy!

 

[Topher925]

I'm using a different monitor than I normally do for my photography work (I'm in my office) and I'm noticing a lot of yellowish "flare" on my latest images of M-51 which just isn't there on my other monitors. Seeing as how the monitor I'm on now is new and has brilliant colors I'm guessing my monitor at home is a piece of junk. Does anyone else see this yellowish flare in these images?

Very nice Andy! Maybe you already mentioned it but what focal length are you using? 300-ish?

 

[Andy Resnick]

Thanks, guys- it's a 400mm focal length lens.

 

[Andy Resnick]

Here's the second batch of images, two-thirds of a 'deep sky survey': Blue are Messier objects, yellow are NGC:

http://img196.imageshack.us/img196/2383/bigsky.jpg

The image size is close to twice a full 35mm frame size, call it a 2" x 3" image, covering about 8 degrees of the sky (is that the right unit? 0.0024 steradians...). I'm not sure I'll be able to get the segment including the Pinwheel galaxy before it gets too far into the light pollution- there's always next year, tho...

Some technical information- the brightest objects in these images are mag. 7 stars, the dimmest objects are around 15 magnitude- the image has a dynamic range of 8 magnitudes, or a SNR of 10^(8/2.5) = 1585 ~1600. This is an 8-bit image with a noise level is about 14 for a dynamic range of 255/14 = 18. That's what I mean when I say stacking compresses the dynamic range of images: stars from magnitude 7 - 10 are all clipped at white, the brighter stars (mag. 7, 8) are larger than the lower magnitude stars. Below 10, the stars resolve to Airy discs of uniform size (7 pixels FWHM here) and of varying brightness.

 

[nitsuj]

Wow Drakk that is a wicked photo(s)!

I'm shocked how clear that image is.