Wyvernp

It's great to have the tools available so that we no longer have to waste precious subs due to flybys. I've used winsorized sigma clipping since I found out about it from one of Chris woodhouse's videos and it's always done a very good job.

Without spending any extra money;

 - Dither if you aren't already.
 - Can't think of anything else

Other than that a cooled CMOS/CCD is a fantastic upgrade in a lot of ways but it is an expensive one, more so if you decide on mono. But you'll be able to have a dark frame library so will save time not having to take them every time as well as greatly reduced noise.

1 hour ago, Ianw said:

I am almost ready purchase the HEQ5 Pro mount as recommended,  if I get that and say the Sky Watcher 200PDS would that enable me to do what I want and last me a number of years before needing to upgrade?

 

Thanks for all your advice so far

My recommendation would be to look on astrobin for images taken with any scope you want to purchase, this will give you a good idea of what to expect.

https://www.astrobin.com/search/?q=+200PDS

5 minutes ago, Laurin Dave said:

I'd assume that the WO page is more up to date and therefore suggest you try 62.1mm with the flattener adjustable distance set to 7.1mm and see how this works, hopefully pretty close..  Mine GT71 is set to 9.1mm and I shall be testing soon ..  

Yes, this is exactly the discrepancy I saw, I am 7.6mm tonight as I'm .5mm short of 55mm.

Thank you all for your help.

edit. I may even have to go a bit further to compensate for filter thickness.

I'll give it another go tonight and see what I can do.

9 minutes ago, david_taurus83 said:

Your centre stars look out of focus BTW and this can exaggerate the effect at the corners.

Yes, in addition to the backfocus I'm also fighting backlash issues on my autofocuser.

I think my confusion comes from different backfocu distances being stated for the flat6aiii depending on which site you look at. i.e.

https://www.cyclopsoptics.com/flattener-reducer/william-optics-flat6a-iii-0-8x-adjustable-reducer-flattener/

and

https://williamoptics.com/2019-all-new-adjustable-flat6aiii-t-mount-not-included

Thanks, I've already done a little analysis with various backfocus distances but I'm still too much of a beginner to be able to know what they mean.

61mm

73mm

Hopefully someone can point me in the right direction.

Additionally I'm sure I remember seeing a picture somewhere where it indicated that depending on which direction the stars streaks were pointing i.e. from the corner to the centre or 90 degrees from that. That the backfocus distance needed to be increased/decreased? an I just making that up?

Morning,

I'd love to get some advice from anyone who uses the GT81 and Flat6aiii, what are you using as your backfocus distance? I've read online anywhere between 55, 60.1 and 62.1 and am struggling to get my corner stars shapes to be anything but streaks.

any advice would be appreciated.

Wyvern

All stacked in pixinsight, because  processed the HA frames a day later I forgot which frame I used as ref so I used the stacked OIII as a ref which I think should give the same result.

23 minutes ago, iwols said:

only have a ha filter ,can anyone suggest anything in ha only

 

Off the top of my head the Heart/soul Nebulae and Veil nebula both have very nice Ha signals. Lots more too but they are also in a good position at the moment, at least from my location.

35 minutes ago, iwols said:

would that include just ha

Yep! Ha, OIII and SII.

Unsurprisingly there is a more noticeable difference at the moment in the snr between my Ha 7nm and OIII 3.5nm so the tighter the filter the better.

It's definitely one of those,  I'm guessing tilt.  Going to research how I can alleviate it as I can't find anything glaringly wrong. 

Just now, MarkAR said:

Around 11.30 till 2.45 for me.

Exactly the same for me, NB only mind you.

just to add a bit more troubleshooting info I have done an alignment and combination on just the top frame and they align perfectly albeit the focus making the stars look like blue doughnuts with a red hole

Weird things happening when I'm aligning and combining my mosaic frames, I can see the top OIII frame has focus issues to will try and retake them tonight. But even after a star alignment some stars do not line up in the top frame. If anyone can point me in the right direction i'd be grateful.

Hi, 

A Bahtinov mask does exactly what you say It helps you achieve focus by creating diffraction spikes which you adjust the position of as you adjust your focus. I wouldn't say its for either/or, it's just a tool. Saying that, it can be very useful to manually find focus for astrophotography.

That's really nice! Makes me with I had received my SII before starting my veil project.

27 minutes ago, MarkAR said:

So far so good. Keep going it'll be a great image.

Thanks, Actually looking at it again i've way overprocessed the bicolour image.... prefer the original I think.

OK... so it's only going to be a 2 panel mosaic so not all that dramatic but it will be the first time I attempt it.

I specifically chose the veil nebula as I am still short a SII filter and I know that the veil in bi-colour HaOO looks great. I'm now 2 nights into this project however due to my inexperience with SGP I missed off the 2nd panel in Ha, so I'll have to redo that tonight.

So after lots of googling and youtubing i have now combined my OIII panel. ( I will list the resources I have used once complete as I'll have a better idea of which work best)

I'm still fighting elongated stars in the bottom right hand corner of each frame, which I'm sure is tilt somewhere but I cant find it for the life of me. Everything is tight as far as I can tell.

Whilst I wait for tonight's data so I can complete at least the narrowband portion ( I plan to get some RGB for the star colour). I decided to  do a quick process  of the data I did have in HAOO and I'm actually pretty happy with the results.

Hopefully I should have the a rough final mosaic tomorrow as long as it all goes well tonight.

Thanks for looking all and as always constructive criticism is very welcome!

Wyvern

1 minute ago, Freddie said:

That’s for DSLR cams not an Atik.

Ahh my bad, I re-read and lost the camera mentioned at the start and just picked up on dslr mentioned later...doh

Does N.I.N.A work with atik cameras? should do as long as they have an ascom driver right?

The only software I'm aware of is called backyard eos/nikon, I've never used or even seen it but I remember the name mentioned somewhere so not sure if they can stretch though.

Hi, I strongly suspect this is because you haven't stretched your image.  What software are you using to post process?

Here's a quick video on how to stretch your images 

I think it's referred to as the propeller nebula. 

Well I finally got first light with this filter tonight and I have to say I am impressed, really nice contrast.

Here's a single uncalibrated 360sec shot from the veil nebula mosaic I'm currently shooting

I believe in southern England we start getting night time back around the 21st of July