the eagle takes flight

[rmuhlack (Richard)]

When yesterday evening started out with full cloud, i decided that if the weather cleared I'd have a break from from my Centaurus A project and try a different subject. Well the weather did clear, and as I hadn't had a go at M16 since about this time last year when I first started imaging, I thought it was time to give it another shot - this time with my VC200L and the f6.4 focal reducer.

This is 33 x 5min dithered subs at ISO800 with a modded 400D. Processed with Pixinsight. I seem to have brought my tilt issue under control with a slight readjustment of the set screws on the Vixen direct-wide photo adapter, together with using a focus point between the centre and left corner, rather than focusing dead centre of the frame.
Hi res version here: http://www.astrobin.com/38542/

The second frame is my effort from last year for comparison (15x8min subs with the same camera and a GSO f4 newtonian), which was processed with DSS and Darktable (which is a linux version of Adobe Lightroom).

[Larryp (Laurie)]

Very nice, Richard. The new one seems to have captured a lot more detail

[E_ri_k (Erik)]

Nice, looks really good. You can see a good difference between the two.
Erik

[Jon (Jonathan)]

Very nice work. Interesting project to compare with earlier images to see how your technique has improved.

So why is there so much more detail in the new image? OK, 2.75 hours total exposure time in the recent image vs 2 hours last year; but that should mainly improve SNR. The exposure length last year was longer; the f-ration faster; do you put it down to your processing technique?

Very interesting. Thanks for sharing.

[astronobob (Bob)]

Vast improvement Richard I dig seeing these types of comparison shots over time as one can get a sence of achievement, well done

[rmuhlack (Richard)]

Thanks guys. I put the differences down to equipment and processing.

Previously I would battle with collimation (which seemed to slip as soon as I slewed to a new target ), inconsistent focuser slop/tilt, diff flexure with guiding, residual coma in the image corners and an undersized secondary mirror. In comparison my new scope seems to hold collimation extremely well and produces a fully corrected and properly illuminated image circle. I am now using a Robofocus unit with Bahtinov Grabber, which makes accurate focusing a breeze. A lightweight but rigid guide scope setup has improved my guiding performance. I also recently sourced a Shoestring DSUSB which means that I can now utilise dithering between subs to further increase the SNR.

On the processing side, the biggest change was moving up to Pixinsight, which allows me to extract so much more from my image data than what I was able to previously.

[tilbrook@rbe.ne (Justin Tilbrook)]

That's very good Richard!
Your image gives me something to aim for, next time I image the eagle.

Cheers,

Justin.