This is data from the same dates as images in the three previous posts before this one. There were so many things I wanted to shoot in these sessions that were Ha, but needed 3 or 4 times more exposure to do them justice. I scouted for what would be brighter Ha targets and did some test stacks trying to get the feel of how much certain things would need.
This one was one of the bigger and brighter targets I tested, but I could tell the less than an hour’s worth of data would need lots of work to make it into a presentable image. Another one of those works in progress, I guess. I gave it nearly an hour but it really needed at least double that as a start and 4x that for something exceptional.
Two sessions combined to produce this shot. One was taken with the UHC filter and the other was taken with the Optolong L-eNhance filter. Total combined time is nearly 3.5 hrs. Not too bad considering the location where they were taken – a Bortle 8 Red Zone.
Well, my luck with the weather allowed me to keep my promise and try out the new L-eNhance filter on a galaxy, in this case, M33. It came out surprisingly well considering this filter is not really made for galaxies. M33 has enough H2 and OIII regions to make things interesting, however.
I used Unity gain (11) with 4 minute subs, captured and LiveStacked in Sharp Cap 3.2. I also kept all the individual frames and tried stacking them in IRIS, but the LiveStack was better in overall quality, so I did not go beyond stacking them and viewing the results and just discarding it.
Below is the combined data from the above with 10×120 sec sub-images taken with a UHC filter:
So far, the L-eNhance does well for any H alpha objects and has a much more uniform background than my cheapo UHC. The UHC filter has a red to green diagonal color gradient always present and is exaggerated by the degree of LP in the shot, with long exposure stacks suffering the strongest. Not fun to deal with, but I’ve managed. Probably a quality control issue with coating uniformity for the cheap filter, I guess.
Since there is no uniformity-caused gradients with the L-eNhance, it lets me see the scope’s vignetting with this camera setup. Looks like I’ll need to start using flats in SharpCap to compensate, since vignetting is now noticeable.
A mixture of 120×30 sec exposures taken with a L-eNhance filter and a mixture of 15, 30 and 1 minute exposures taken with a UHC filter. About an hour and 30 minutes total. The 120×30 set was at 30 gain and -20C.
I am starting to like the 30 gain setting, since it gives the best results with shorter exposures. Over 40 is too much noise and under 30 it is just too slow.
When the set began there was no matching dark to subtract, so I was using one at gain 20. I stopped after about 10 shots and took some darks and then restarted shooting. I’m glad I did since the amp glow was starting to show up bad on the right side of the frame. The new darks overcame it and the glow averaged out after a while of LiveStacking with ShapCap 3.2.
What luck! First light for new filter is the day I received it! Thanks to the clouds for staying away. What I wanted to test was my new Optolong L-eNhance dual-band nebula filter, which is similar to the UHC filter I already own but with a narrower bandwidth and a more even color rendition across the frame than the cheap UHC one I’ve been using. I got to try it out before the run of good weather we’ve been having ended.
I was a able to test it on the Veil, which I recently imaged, and the Cave Nebula, which I had never shot before. I am very pleased with the results. Even color and illumination and better rejection of LP.
The Veil nebula was shot like I’ve been doing – 30 sec sub images at high gain. The Cave was long exposures of 4 minutes and I managed to get 26 subs. The Veil is a finished image and the Cave Nebula is still a work in progress. It seems the long exposure, 4 minute darks I used were not too good of a match and there are numerous hot pixel trails left to manually repair or clone out still left to do.
I also tried it on two reflection nebulae, one being the Running Man in the image below, and it was not as good as my UHC filter. I also tried one star cluster, M35, and it is the last image below. No galaxies yet, so I’m not sure how well it will work for those. Maybe next time I will have to try for one and find out.
Images of Comets, Nebulae, Galaxies and Star Clusters