Progress

[Paul2019]

With the opportunity i recently decided to get out with my gear and see what I could achieve,

I'm still new to astrophotography, pixinsight etc. But I feel that this is a pretty good result. 

Cygnus Loop, 10x 180s, 50 x Bias, 50 x Flats. Processed in Pixinsight. Samyang 135mm, Staradventurer Mini, Canon 2000d

I got 2 hours worth of data but had to bin 75% of the lights, due to the star adventurer mini. Hoping to upgrade very very soon, 

That said with only half hour of data, I'm very very happy with the result I know its far from perfect but feel I'm slowly moving in the right direction. I cant wait for the skies to clear so I can try my new L-enhance filter out before it turns barnards loop time!

 

[michael8554]

Great result for a beginner.

"but had to bin 75% of the lights, due to the star adventurer mini."

I'm sure there are many SA users getting better percentages than that.

What errors were you getting ?

Dec drift due to Polar Alignment ?

RA due to Periodic Error ?

180 sec exposures suggest you are guiding, but I don't see mention in your equipment list ?

Post the GuideLog, or if not take shorter exposures.

Michael

 

[Paul2019]

5 hours ago, michael8554 said:

Great result for a beginner.

"but had to bin 75% of the lights, due to the star adventurer mini."

I'm sure there are many SA users getting better percentages than that.

What errors were you getting ?

Dec drift due to Polar Alignment ?

RA due to Periodic Error ?

180 sec exposures suggest you are guiding, but I don't see mention in your equipment list ?

Post the GuideLog, or if not take shorter exposures.

Michael

 

Hi Micheal, 

No guiding, very basic beginner setup and I completely pushed the mini to its limit. Advertised is 3kg (compared to the standard models 5kg). Approx weight of the gear is 1.6kg with no CW (so very unbalanced). 
 

It was my first time with this FL (135mm) and I suspect 90s subs would work perfectly ok? I have been able to manage 300s with my 50mm lens but clearly 180 is definitely out of the range for the 135 on the mini. 
 

I have got an Optlong l-enhance for my next session for which I intend to image the same target but will change to iso1600 with 60s subs and see how that changes things. 
 

I am however on the prowl for a better mount but I would like portability and g&g capability so I keep chopping and changing what I want. I did intend on getting an eq6-r but when I actually saw how big they are I realised that it wouldn’t get all that much use due to the size. So it’s left me considering the heq5, eqm35 or perhaps one of ioptrons offerings with the HEM27 looking good but then the ZWO offering might be worth the few extra quid. I think I’ve fallen very much into the proverbial rabbit whole! 

[ollypenrice]

I wouldn't concentrate too much on payload weight. Of far greater importance is the relationship between tracking accuracy and pixel scale. The finer your pixel scale, the better your tracking accuracy needs to be.

Olly

[Paul2019]

43 minutes ago, ollypenrice said:

I wouldn't concentrate too much on payload weight. Of far greater importance is the relationship between tracking accuracy and pixel scale. The finer your pixel scale, the better your tracking accuracy needs to be.

Olly

Understood, I think small tracking errors would easily be hidden in this, so they must of been relatively large. Some images had obvious star trailing, odd as on first inspection in APT before running my capture plan they looked ok. It was only when I came to do my calibration frames that I realized a chunk of the lights were unusable. My DSLR has pixels that are 3.71µm, with the Samyang 135 that gives a scale of 5.67"/pixel; obviously massive under sampling here. 

The only reason that I considered the payload is because I assume (you know what they say about that!) its pushing the max weight of the SAM so my thoughts were that I was being too hasty in my exposure time for my FL? I believe my PA was pretty spot on, well as good as it could be using the polar scope and SAM app. It definitely didn't move from where the app said it should be. 

I would very much love to hear your thoughts about pixel scale though (another rabbit hole I jumped in!), whilst considering mounts and understanding that a more portable mount will lead to more imaging I am beginning to come to the conclusion that widefield and some slight less widefield DSO is going to be my main imaging. Leading me to consider FL slightly more, looking at the astromony.tools ccd calculators I am of the understanding if I look at less FL; say 250-300mm (after reduction) that I will get better quality images with a smaller pixel scale (2.4µm ASI183) where an equivalent pixel scale to my dslr (3.7µm, ASI1600 would be better suited to FL of  400mm+ (after reduction).

That said I haven't considered other factors such as the difference in sensor size, read noise etc. But am I understanding this right? Or have I missed the point entirely? There's so much to consider and I find myself continuously reconsidering my plan on what equipment to get. 

Thanks 

Paul 

[ollypenrice]

The rule of thumb is that your tracking accuracy in arcseconds needs to be no more than half your image scale in arcseconds per pixel. Without guiding, this is going to be hard to achieve.

As far as other things go, around 2 arcsecs per pixel is nice in that each pixel gets enough light, you only need a tracking accuracy of an arcsecond and you'll be getting close to what the seeing will allow in terms of resolution. But you can make good images at far coarser pixel scales. These are at 3.5"PP.

https://www.astrobin.com/full/383965/0/

https://www.astrobin.com/full/301531/0/

In your case a star removal software would be a big help, either Starnet++ or StarXterminator. (I prefer the latter.) They allow you to remove the stars and then replace them with the same ones given a much gentler stretch. Any miss-shapes will be far less obtrusive.

Olly

[catburglar]

Assuming you’re using the lens aperture reasonably wide  - I’d be tempted to try 30-60 second lights to minimise any trailing issues… run a couple of test sequences 10x30s, 10x45s etc to see how many keepers you get.

Check the histogram from the test shots too, and as long as it’s clear from the y axis you’ll probably be OK.

[Paul2019]

Some great advice guys, many thanks. Fingers crossed for some clear skies at some point this week, no doubt I’ll be back at work before that happens mind.

Paul

[Paul2019]

Took delivery of this bad boy today 

and my god it’s bigger than I expected, a lot bigger! Now where’s those clear skies? 

[Richard_]

You weren't kidding when you said you were upgrading very soon! The EQ6-R is an excellent mount, and you won't have to worry about overloading it for a long, long time. As you've found out, it's also pretty hefty so you'll start developing a strong back in no time at all! 

PS, I like your custom "Porkies Reef" light shade over your tank 😁

[Paul2019]

16 minutes ago, Richard_ said:

You weren't kidding when you said you were upgrading very soon! The EQ6-R is an excellent mount, and you won't have to worry about overloading it for a long, long time. As you've found out, it's also pretty hefty so you'll start developing a strong back in no time at all! 

PS, I like your custom "Porkies Reef" light shade over your tank 😁

The shades a proto type, I’ve been meaning to reprint them in black for ages! Thanks, I hope it will see me through for a while 

[Paul2019]

Thought I would add this here, due to varying circumstances I only got half hour of data again! But used the eq6 and a L-enhance filter and the difference is quite remarkable