Disappointing Saturn from a 130PDS and T7C (ASI120MC clone)

[BrendanC]

Hi all,

I don't often 'do' planets, but given that Saturn's close to opposition I thought I'd give it a go.

The results are underwhelming - as in, they're alright, but I expected better:

Details are:

* Best 50% of 2,000 frames
* Hardware: Sky-Watcher 130PDS scope (F5), Sky-Watcher NEQ6 mount with Rowan belt, Datyson T7C (which is essentially a ZWO ASI120MC, uses the same drivers, which I usually use as a guide cam), Bresser 5x Barlow
* Software: Capture with Sharpcap, tracking with Stellarium, stacking and post-processing with Registax, PIPP, Topaz AI Denoise and Photoshop CS2

My questions are:

* Why is it so pink? Is it because it's low in the sky (this is from SE England)? Is it something to do with Registax or PIPP? (I had to use PIPP to debayer the output from Sharpcap, Registax wouldn't do it for some reason).I have a Jupiter shot from last week that, while I'm much more pleased with, is similarly a sort of red hue. This was taken using the Live View on my astro-modded DSLR and a 3x Barlow, so the optical train is quite different:

* Why is it so blurry? I had real trouble getting it into focus. The only way I could find was to use the digital zoom in Sharpcap to get it as sharp as possible, as big as possible. However, it still looks quite fuzzy  and indistinct to me. Is it my 5x Barlow not being up to the job? It's the first time I used it and it's not a cheapo thing - a Bresser, about 50 quid, seems fairly good. Perhaps it just isn't suited to the rest of my setup, and I should continue with the 3x instead?

* Should I just accept that my setup isn't optimised for planetary? I usually do DSOs but as I say, I thought I'd give Saturn and Jupiter a blast with the T7C (which is usually my guide scope). Having said which, I've seen examples using a 130PDS and an ASI120MC (which the T7C is, effectively) that are much better.

Any/all feedback please?

Thanks, Brendan

 

Edited August 11, 2021 by BrendanC

[CraigT82]

I'd advise to ditch registax and use Autostakkert for the stacking. It is leagues ahead (Registax hasn't been updated for years) but Regi does still have some useful features, namely the RGB align function, the RGB balance function and of course the wavelets sharpening.

Autostakkert will autodetect the bayer pattern and debayer the capture correctly hopefully, but if it is still pink  then you should still be able to adjust the RGB balance using registax, or even in CS2.

With my camera and using firecapture I can set the 'white balance' before capturing... basically you can tweak the RGB gain independently so that you get a nice natural looking colour planet on the preview screen before capturing. I'm not sure if this is possible with your camera in sharpcap but worth checking?

As for the blurriness, seeing is your main culprit, but also poor focus and collimation can reduce the sharpness of the image, as well as thermal issues within the scope, though it is less likely to be thermals with a small scope like the 130pds. I think the 5x barlow is too much but the 3x should be just right.

It is unrealistic to expect great results which fulfill the potential of the equipment on the very first go, keep practicing and you'll get the results you want. It is usually just a case of getting out as often as possible in order to catch that one night of great seeing where everything comes together.

I would say to aim to collect a lot more frames and stack a smaller percentage of them. I'd probably aim for 10k frames and then stack best 10% maybe, depends on how good the seeing is, when it is good you can stack more frames. 

Edited August 11, 2021 by CraigT82

[BrendanC]

Wow, great response, thank you! I'll check out Autostakkert. 

[happy-kat]

My hesitance to using autoskakkert was that when I last looked it wasn't on behind a https site same with pipp

[Pete Presland]

Good advice from @CraigT82 Autostakkert is an excellent piece of SW, Registax 6 is also very useful for processing after stacking