View Full Version here: : First 5128 through main scope
Partly due to always imaging from one corner of the courtyard, I hadn't attempted 5128 before through the main scope. Pretty funny considering I have been doing alot of fairly unusual stuff instead. So here finally is my first attempt at 5128 through the C9.25". It looked really promising when I was imaging, but I am a bit disappointed with the final result... such is life.
Scope: CGEM 925.
Camera: Atik 320E.
Guiding: 80mm refractor with QHY5 using PHD.
Processing done by my wife using AstroArt and trial Pixinsight.
30 x 5 min images plus darks and bias frames.
Definitely room for improvement... as always! :)
20-07-2012, 04:32 PM
now that is where i would like to be grant..... with the five minute exposures so much more detail happening!
its one of my favourite objects
Funny thing was I usually plant the tripod on the premarked dots on the pavers. Since I was changing positions, I did a polar align using the CGEM polar alignment feature. The first couple of hours I spent on Eta Carina - and it was terrible. Lots of trails for the 5 mins images. I then switched to 5128 - which was beaut. Then I switched to M16 and M8 and had trails and trouble again. Finally, I did 6 x 5 mins on M27 as an experiment... and the stars were perfectly round with 5 min images. Wierd night! :rolleyes:
20-07-2012, 06:44 PM
funny grant last night i was out and indeed it is the second night i have found that my images at zenith seem to trail, like m16 last night but objects lower down i can rattle off 10 exposures at 2 mins unguided and have round stars...but at the zenith they seem to trail or are fuzzy
it could possibly be a little moisture i realised last night because the OTA is straight up and it may settle a little more readily.... perhaps
20-07-2012, 07:03 PM
by the way grant why is your 5128 image size much bigger than mine through prime focus, my image is a little further down on the posts
1480mm focal length with a small chip size. The ATIK 320E is 1620x1220 with 4.4 um pixel size.
As for trailing, I am wondering if it is a balance issue. Maybe near zenith when the counter weight is level with the scope the balance is more critical. Having said that, it doesn't explain Eta Carina being bad. Anyway, it was a first night at the new spot in the backyard so it might take me a while to find a good polar alignment. I still need to learn to drift align some time... I always just use the CGEM polar alignment function... I also need to do a PEC some time too but the hassle of putting the hand controller through the laptop always seems too much effort when the skies and clear and calling "image me! image me!"
21-07-2012, 02:01 AM
i dont know grant.... we tend to balance our scopes with counter weight bar horizontal which for all intensive purposes is the zenith
i too only use the polar align assist on my g11 but i can still get round stars with 2 min unguided
drift alignement is another universe to me at the moment and as much as i have read...... well it still seems to be all double dutch!
too grant i have read enough to hear that autoguiding and the PEC function operating together can work against each other
21-07-2012, 08:34 PM
A really really useful program I have found for polar alignment is Alignmaster. As you have a CCD it should be fine running the mount along with the camera. Just run through a few iterations with different stars and you can get 5 minuten exposures anywhere in the sky as long as everything is balanced. :) It is SOOOO much more effective and time saving than drift alignment...
Thanks for that - I will take a look at Alignmaster. My problems isn't that I can't get 5 min round stars. It is more that it seems very inconsistent. Sometimes I get them fine on one object, but then the next I don't. Strange...
I don't usually hook up a computer to my scope though, which I might have to do for Alignmaster. I have a feeling though that alignmaster basically does the same as the polar align function on the CGEM.
21-07-2012, 11:55 PM
I'd be happy to get something like that Grant, very nice.
23-07-2012, 09:44 AM
I would definitely do a PEC run in that case, it might be worth it.
Yeah I thought the same at one stage, but I did a manual PEC run and it didn't make a huge difference. When I image an object, I am usually on it for a couple of hours which is far more than a PEC cycle. So it wouldn't really explain why one object is great for a couple of hours then the next isn't... It isn't a problem every night - just some nights. It is almost like the astro-luck gods are frowning or playing games! :rolleyes:
But I will take the advice and do a proper PEC run some time soon. Thanks!
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