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Old 24-06-2021, 03:39 PM
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Tony Leece
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Helix Nebula

Data acquired over two nights here in Perth Bortle 6-7
Five hours and fifteen minutes of 3 minute unguided subs
with my SW ED80 and optolong L-extreme, no flattener
AZEQ6gt mount
ZWO asi 533 mcp gain 101 offset 70

I do not have Pixinsight but my mate in California does and help offered to help me out with processing, he is also going to teach me when i do get it, to which i am eternally grateful Bill


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  #2  
Old 24-06-2021, 04:29 PM
AdamJL
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Very nice!! What an awesome nebula
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Old 24-06-2021, 04:50 PM
RyanJones
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Very Nice Tony. One of my favorite nebs. Iíve had a couple of goes at it over the time but none that do it justice. Well done
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Old 24-06-2021, 05:54 PM
Startrek (Martin)
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Tony,
Superb image of a very difficult target
Detail and colours spot on
You must have had some late ones as Helix doesnít get up to a decent altitude until close to midnight
My only observation is your stars are slightly ovoid which I suspect is due to relying on tight polar alignment with longish unguided subs ( any reason why you donít guide ? )
Well done !!
Martin
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Old 24-06-2021, 11:20 PM
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Thanks for the kind comment guys
Yes Martin the stars are a problem
I don't guide yet as I can't afford a guide camera atm, but I do intend getting one.
Just another thing to add to the list bro
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Old 25-06-2021, 07:30 AM
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Hi Tony

You have done very well ...good on you.

I have a guide setup but dont use in more than not because something so often plays up ...as a result I goto short exposures and trust me just do the same overall exposure using shorter exposures and you get the job done...the star movement means with short exposures you will get "automatic" dithering for a start, ( which means drizzle can be employed ( which I believe does wonders and worth the longer stacking time)..also you wont hesitate to throw out a poor capture ( perhaps one of the most important steps I have found) and I think there may be a benefit from the noise point of view.

I am about to get a RASA 11 and my plan is to go for the shortest exposure it can handle which may be around 10 seconds to really push the short exposure approach and really minimise atmospheric movement.

Anyways lets not overlook all that you have done right as that is what you need to focus on and remember most folk dont notice if the stars are a little oval like...
Again good work.
Alex
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Old 25-06-2021, 09:26 AM
Alchemy (Clive)
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Respectable result with no guiding, some have taken on the lucky imaging method with interesting results, although having a very fast scope would help there.
The LxTreme filter has proved to be a great asset for the OSC followers, particularly under city skies.
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Old 25-06-2021, 09:31 AM
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Thanks Alex, I'm a bit more relieved about not guiding now mate.
Hope the RASA works to plan, look forward to seeing your images with it
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Old 25-06-2021, 09:36 AM
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I have a 10 inch Newtonian that I was reluctant to use because I couldn't guide.
I think I will give Alex's short exposure method a go with it.
Yes Clive the Extreme works very well with my zwo 533 in my bortle 6-7 Perth suburb
Thanks again for all the support guys
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Old 25-06-2021, 11:12 AM
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The other thing Tony is make sure polar is spot on..keep on it..check it again and again...however lets assume your polar is spot on and treat RA as the only contributor to star movement...what I found was I could almost eliminate stars trailing by repeated adjustment of the counter weights but I am adjusting constantly ...it seems to me that a perfect balance we aim for when setting up does not give us what we want and that a bias works better...also it is most important to have the motor getting good voltage as a little down really makes a good mount bad.

Also if you have not done so train your mount ..its in the hand paddle somewhere ...

Also keep an eye on cables their "strain" on things changes during a session and its something not to underestimate.

The RASA is between post offices but not sure if the camera is on its way...I cant change a thing so I will wait. I just hope I can use it and not pass out or similar...it will go on a EQ 6 which will be interesting but an EQ8 takes months to get here...so again I am somewhat forced to go short exposure...my hope is also that instead of being up all night that I can get all I need in an hour and bit ...also that I can last an hour and s bit...not much to ask but a lot to expect.
Alex
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Old 25-06-2021, 01:29 PM
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Thanks Alex, i use the 2 star and polar alignment routines on the hand set but have never found out what is a good or bad reading. the one below was the readout for this particular night.
i know there are other methods to polar align but they cost
i don't have a permanent setup, but i do run off the mains, so power isn't a worry.
i only have a motorbike so a dark sky sight is out of the equation
Cable management is cool as i only have 3 to worry about.
Is the weight bias you refer to so the motor is pushing slightly against the weight as opposed to holding it back?
Yes postage is in the lap of the gods atm mate. i hope it all comes very soon.
Thanks for all your help mate

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Old 25-06-2021, 01:31 PM
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To be honest I am not sure pushing or pulling its case of try things and note the responce.
Alex
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Old 25-06-2021, 05:09 PM
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Cool, i will try both Alex
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Old 25-06-2021, 09:15 PM
AdamJL
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Before I got a guide camera, I'd get about 3-4 minutes (sometimes 5 near the poles) of exposures before I saw trailing. Yes, balance is very important. Back then I didn't know about east/west heavy balancing so just balanced everything equally. But the most important thing is polar alignment. I spent a lot of time making sure my polar alignment was spot on. I had a Polemaster, but you can do the same with Sharpcap and your telescope (though I don't know whether Sharpcap requires a minimum focus distance).
If you're polar aligned correctly, you'll be surprised what your mount is capable of. You won't compensate for gusts of wind, and periodic error, but you'll get a lot of things done better.

Also make sure you're level. Get a level from bunnings and ensure your tripod is correctly setup.

These small things are free or next to free and should enable you to get good longer exposures. Or if you're still chasing shorter subs (90-120 seconds) then you'll have more confidence of better performance.

Good luck!
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Old 25-06-2021, 10:16 PM
Startrek (Martin)
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Quote:
Originally Posted by Tony Leece View Post
Thanks Alex, i use the 2 star and polar alignment routines on the hand set but have never found out what is a good or bad reading. the one below was the readout for this particular night.
i know there are other methods to polar align but they cost
i don't have a permanent setup, but i do run off the mains, so power isn't a worry.
i only have a motorbike so a dark sky sight is out of the equation
Cable management is cool as i only have 3 to worry about.
Is the weight bias you refer to so the motor is pushing slightly against the weight as opposed to holding it back?
Yes postage is in the lap of the gods atm mate. i hope it all comes very soon.
Thanks for all your help mate

Attachment 276918
Tony,
I have used the Synscan Polar Alignment routine for 4 years and get below an arc minute each time
Your Azimuth and Altitude ( Elevation ) readings on the handset are in Degrees/ arc Minutes / arc Seconds
Example: Az 000 05 18 and El 000 10 25
So Azimuth would be 5 arc minutes and 18 arc seconds
and Elevation would be 10 arc minutes and 25 arc seconds ( which both are way off in regard to polar alignment)
For good tight polar alignment you really want to be below an arc minute on both Azimuth and Elevation ( an arc minute is expressed as 000 01 00 )
So an example of good polar alignment would be say 40 arc seconds on both Az and El expressed as 000 00 40 ( but in reality you can never get Az and El the same but the closer the better )
Attached is my Synscan polar alignment routine I put together a few years ago to help members on IIS
Hope it helps
Cheers
Martin
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Old 26-06-2021, 03:28 PM
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Thanks for that guys and thanks for the pdf Martin i will read that in a minute mate
last night i setup and ran the 2 star alignment first and got a good (i think) result (below) but when i did the polar align routine it was out. should i have just accepted the first good one and started imaging?



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Old 26-06-2021, 08:54 PM
Startrek (Martin)
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Originally Posted by Tony Leece View Post
Thanks for that guys and thanks for the pdf Martin i will read that in a minute mate
last night i setup and ran the 2 star alignment first and got a good (i think) result (below) but when i did the polar align routine it was out. should i have just accepted the first good one and started imaging?



Attachment 276943

Attachment 276944
Tony,
Your either lucky when you plonked your mount down and set up and just fluked it after a 2 star alignment, but the first Polar alignment numbers are spot on ( ie less than arc minute ) I recommend to adopt my procedure as itís proven time and time again. Itís an iterative process to get your error down as low as possible, I usually do 2 or 3 iterations but sometimes 4 or 5 if seeing conditions are poor and your polar alignment Star is jumping around a bit
The choice and location of your 2 star alignment stars ( one of which will be your polar alignment Star ) is super important, just follow my procedure
Cheers
Martin
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Old 09-07-2021, 09:43 AM
johnnyjetski (John)
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Martin.... Thankyou for sharing your syncan polar alignment routine.
You have explained your routine wonderfully.
Tony....Great shot of Helix, probably one of the best ive seen. I also have not started guiding yet because im happy sticking with short subs. The whole idea is to have fun.
Cheers,
John
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