My take on M45 - 3hours of unmodified DSLR

[sagramore]

Hi everyone. I've not posted in a while - combination of summer, laziness, and very poor weather. However, I am back!

I recently gave M45 a go. My main problem is local light pollution combined with being surrounded by tall houses, which means I only get something like 2-4 hours of visibility on a target if it ever gets in the right part of the sky. As such my first session only bagged me around 80 minutes of subs. Last night I managed to get another 100 minutes for a total of 3 hours. Coupled with this I learned a couple of new noise reduction techniques courtesy of Doug German's Youtube channel (https://www.youtube.com/channel/UCvL...DVQr1JDptAsbQg) I recommend anyone new to this and processing in Photoshop takes the time to go through his absolutely brilliant tutorials!!

Anyway, here we are. I know I still pushed the noise up too high in the end, but I really wanted a hint of the dust, so I decided the tradeoff was worth it.

Thanks for looking, and please do try the Flickr link to the full-resolution image as the small version here is very compressed.

Hamish / sagramore

CLICK HERE for Flickr link for full resolution version

Messier 45 (Pleiades)

2016-11-07 and 2016-11-29, near Swindon, England

Gear:
* Skywatcher 130-PDS with 0.9x coma corrector (585 mm, f/4.5)
* Skywatcher NEQ6-Pro Synscan
* Canon EOS 550D (unmodified) and Skywatcher 2" LP filter
* ZWO ASI120-MC guide camera
* Skywatcher Startravel 80 guide scope

Acquisition & Processing:
* AstrophotographyTools (APT) and PHD2 guiding with dithering
* (15 + 21) x 300s = total 180 minutes @ ISO 800 in two sessions
* Flats, library darks (12-14 C and 7-12 C), library bias
* Stacked in DeepSkyStacker and post-processed in Photoshop CC 2015 with Gradient Xterminator

[Allinthehead]

Nice.

Must be frustrating having such limited time to catch your target especially if something was to go wrong. I think you did the right thing pushing it for the dusty stuff.

[sagramore]

Thanks! Yeah, I lost almost 30 mins of time last night just because of a problem calibrating PHD for the guiding....

I forgot to add that this is my first ever image processed with data from two separate sessions - something I had to learn to do today. Perhaps a 3rd session will help bring that dust out with less noise?

[Allinthehead]

1 minute ago, sagramore said:

Thanks! Yeah, I lost almost 30 mins of time last night just because of a problem calibrating PHD for the guiding....

I forgot to add that this is my first ever image processed with data from two separate sessions - something I had to learn to do today. Perhaps a 3rd session will help bring that dust out with less noise?

Keep on adding to it. Are you using a plate solver?

[sagramore]

A plate solver to ensure I frame it correctly each time? If so, no, just eyeballing it  I use some harsh dithering anyway so a small amount of movement is actually helpful really. If that's not what you meant, then I am intrigued to know more!

[Allinthehead]

I've just recently learned to plate solve using sequence generator. One click on an image from a previous night and i'm back in position within about a minute. Amazing software.

[sagramore]

Thanks, I will take a look! My biggest problem really is that I have to completely dismantle my kit between sessions as well so setting up requires full alignment again so I often can't rely on the goto until it's properly configured!

[Adam J]

Just never ever remove the scope from the rings when multi night imaging with a Newtonian or your diffraction spikes will not line up between sessions.  Getting the same framing is less of an issue....especially with M45 I can see the seven sisters in live view on my 1000D. 

[sagramore]

6 hours ago, Adam J said:

Just never ever remove the scope from the rings when multi night imaging with a Newtonian or your diffraction spikes will not line up between sessions.  Getting the same framing is less of an issue....especially with M45 I can see the seven sisters in live view on my 1000D. 

I had actually never considered that, so thanks for the warning! While I do dismantle the setup between sessions, I generally don't take the scope out of the rings (or remove the guide scope from the rings that are also attached) - tends to be stored as one unit. However there is a chance I'd be moving to use the 200P and forget that this is a problem, so thanks again