2 Minute DSO Blitz

[Knight of Clear Skies]

I'm down in Cornwall for a few days and managed to sneak in a quick imaging session last night before the clouds rolled over. Was testing out an EQ5 mount after trying to align the polar scope and the forecast wasn't promising, so I didn't want to do anything ambitious. I decided to have a quick trawl across the sky shooting various DSOs with my 135mm Super-Takumar f3.5 lens and modded 1100D, to show their relative sizes, brightness and colours. I limited myself to a single 2 minute exposure on each target:

Took me 45 minutes to shoot the above, including framing shots and a few re-shoots due to satellite trails and cloud intruding. Here's the Heart & Soul with the Double Cluster from October, same kit and exposure length.

I don't have a picture of the Moon taken with a 135mm lens but I resized one taken with at 250mm to show the relative apparent size compared to the DSOs above.

The images have been processed identically to preserve relative brightness and colour across them as much as possible. I used the Canon DPP software to get a rough balance on the Veil, one of the more challenging targets, and copied this recipe to the other images. I also decreased saturation slightly and performed noise reduction (4/20 luminescence and 8/20 chrominance) to clean up the background before converting to TIF files - I think it removes hot pixels when doing this. To fix the vignetting I used Gradient Xterminator (a freehand selection of the DSO, inverse selection and med for both settings). To boost the Ha I dropped cyan in reds by 100% (an Olly tip). Finally, I had a bit of a problem with magenta stars, either due to my colour balance being off or a bit of CA from the lens, or possibly a combination of the two. To fix this I used selective colour again, I dropped magentas and boosted cyans in magentas. I could post up a couple of the out-of-the camera shots if anyone is interested.

In short, they've scrubbed up well, I'm pleased with how they have come out. They certainly aren't deep images and the framing is a bit rough but they are fit for purpose, I hope to add to them when I get the opportunity. I need to re-shoot the Pleiades as it was quite low at the time. Other suitable targets include IC1396, the Wizard, Claw Region(?), California, Hyades, Orion's Belt & Sword, Angelfish, Witch's Head, Rosette, M101, M81/M82 and M13. I suspect some large Ha targets such as the Jellyfish will be too faint to show up at all. Are there any others people can think of please? How about some clusters and Dark nebulae to add to the list?

Hope you find them interesting, they might also be of help to beginners looking for suitable targets.

[wimvb]

That's quite a trawl full. It shows how much there is going on in any part of the sky. But they also show that it is necessary to spend time on one target at a time. I think that when you revisit some of these targets and collect much more data, you can end up with some great images.

Thanks for sharing

[Knight of Clear Skies]

Yes, I completely agree, there is no substitute for data and that takes time. That wasn't what I was aiming for here though, I found it a fun and instructive way to use less than ideal conditions. The DSOs are sketches but just show enough to make useful comparisons. Looking at M31 and M33, it shows how subtle the galaxy colours are compared to nebulae, and the different brightness profile of each. This gels with my visual observations of the pair, with its very bright core M31 slowly grows the darker the sky becomes while M33 pops into view at once on the very rare occasions that it does appear. But to me the starfields are more interesting than the DSOs themselves, comparing the density and variety in and away from the plane of the Milky Way. I often struggle with processing of star fields, particularly in my M31 and M45 images. Looking at the above I now understand part of the problem is that there is less colour to work with. In future I'll try a quick process on single sub to give me some guidance on what I should be aiming for in a stacked image. Processing them was quick and easy compared to some of the stacks DSS has presented me with, I spent less than an hour on the lot.

Beginners are often unaware how large some of these DSOs are in the sky and can have trouble finding guidance on suitable targets, if I can take some more of these and find a good way of presenting them it might make a useful resource.