Category Archives: Nebulae

Veil and Cave Nebulae: L-eNhance Filter Test

West Veil Nebula. 46×30 sec, QHY183c @ -15C, Gain 42, Offset 100, L-eNhance filter, Televue TV-85 at F/5.6.
The Cave Nebula. 26×240 sec, QHY183c @ -15C,, Gain 20, Offset 31, L-eNhance Filter, Televue TV-85 at F/5.6.

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.

M42 – 114×30 sec, QHY183c @ -15C, Gain 42, Offset 42, L-eNhance filter, Televue TV-85 at F/5.6.
M35 – 20×30 sec, QHY183c @ -15C, Gain 42, Offset 42, L-eNhance filter, Televue TV-85 at F/5.6.


6 Minute Veil and the Moon

East Veil Nebula. 6×60 sec, QHY183c, Gain 25, Offset 31, -15C, UHC filter, TV-85 at F/5.6.
The Moon on Nov 5th, 2019. TV-85 at F/5.6, QHY183c, UHC filter, 200% enlargement.

I am amazed at how much signal is in just 6 minutes of sub-images for this new camera, QHYCCD’s QHY183c.  When you take the shot, there is really not much there  without significant stretching of the image.    But, since the noise is so low with this cam, it can be boosted beyond anything a DSLR image could keep up with.

Now, I did do quite a bit of noise reduction on the Veil image included here, but it had enough signal to preserve enough detail to make the image adequate for a display image.  I reduced it 50% to smooth it out more, but the original size is OK, too, just quite large to be downloading on a mobile phone.

Clouds were why the session was so short.  I was clouded out when it was in a prime position early on, then it went completely overcast at the end.  In between, I manged to get the 6 x 1 minute subs .   I gave up and tore down and stowed the rig after I couldn’t shoot anymore.   Almost as soon as I had put away the last piece of gear, I went back out and it was totally clear, just like when I had started setting up.   Sucker holes and I fall for them all the time.   lol

I was actually just testing some tweaks to my laptop I did hoping that they would improve performance.  I added memory and updated a few drivers. Stability was vastly improved, but the speed of the machine lacked.   I could not do a, “live,” shot of the moon at the lower exposure needed.   It would not stream with the exposure less than 350ms.  Too many frames per second for it to keep up with, I guess.    Means I need another field laptop.   🙁

Orion Nebula and The Crab

M1, The Crab Nebula. 100×30 sec, QHY183c on TV-85 at F/5.6, UHC filter. Gain 25, Offset 31, -23C.
M42, The Orion Nebula. 100×30 sec 15×120 sec and 4×4 sec for the core. QHY183c and TV-85 at F/5.6. Gain 20, Offset 31, -15C.
Lighter Version of M42, The Orion Nebula. 100×30 sec 15×120 sec and 4×4 sec for the core. QHY183c and TV-85 at F/5.6. Gain 20, Offset 31, -15C.

I started this session at midnight on Sat/Sun, Nov 2nd/3rd, 2019.  It was cloudy, but the forecast said it would eventually clear.   I went to bed early and woke up at midnight and checked and sure enough, it was clear.   I managed to get these two objects plus some other stuff that I haven’t had time to mess with.

The seeing was horrible when I shot the Crab and it shows.   I decided to take that data and combine it with previous efforts to see how it would look.    The image below is the result of 3 different sessions, 3 different cameras and 2 telescopes.   Check it out:

The Crab Nebula – Combined Data from a DSLR, Sony IMX224 eyepiece cam and a QHY183c astro-camera.

Test of Canon 200mm F/2.8 Telephoto with QHY183c Camera

M45, The Pleiades. 56×30 sec, QHY183c, Gain 20, Offset 31, -15C, Canon 200mm F/2.8.
The North American Nebula. 167×30 sec, QHY183c, Gain 2, Offset 31, -15C, Canon 200mm F/2.8.
The Horse Head Nebula Region. 8×120 sec, QHY183c, UHC Filter, Gain 20, Offset 31, -23C, Canon 200mm F/2.8.

I bought the adapters needed to mate my new QHY183c camera to my Canon lenses.   I tried it out with the 200mm F/2.8 telephoto.   No way to control the F-stop diaphragm, since it needs a Canon camera to do that, so I had to shoot with it wide open.  BTW, this was from the light polluted metro area I’ve been shooting from lately.

Since this is one of the cheaper lines of Canon lenses, it suffers from optical imperfections like astigmatism.   That makes the red focus to a line up and down and blue and green focus to a line left to right.   It really messes up the star shapes and there is no way to fix it except to stop the lens down to F/3.5 or higher.   Oh, well…

Horse Head Nebula Region Composite

Horse Head Nebula Region. BW 93×30 sec as lum layer on 180×8 sec color composite. QHY183c, Gain 30, -15C, TV-85 at F/5.6.

I’ve been trying to get enough data in one session for a rendition of the Horse Head with my new camera.  Each time, my session was cut short due to trees in the way, the break of dawn or clouds.  This morning was no exception and clouds ruined my session even before the sun could.

No matter.  I took all the short, incomplete sessions I had and combined the data into one composite image.   I even used the BW stuff I had before I got the camera working correctly with the right drivers.   I estimate I have about 70 minutes of time in the above image, with up to 4 separate stacks combined into it.