DSS stacking alt az images

[Bruceaust]

I have recently acquired a Alt Az scope (Meade LS6) for my portable scope.I am having a great time using this little unit for public viewing and as a really easy set up for my portable setup.
I would like to do some astrophotography without using a wedge . Ie.. alt az mode.
I have tried stacking 20sec subs in DSS without success. I know field rotation is an issue.but I am willing to push the boundaries and see what can be achieved with my scope.
Can anyone point me in the right direction in regard to successfully stacking images in DSS.For example .. 200 X 20sec subs plus darks etc..when I tried recently it only registered 1 frame for stacking!
Any thoughts will be appreciated.

[RyanJones]

I'm going to chime in here as f/10 Astrophotography on an Alt-az has kinda become my thing. I'm going to say that although not impossible, it's going to be hard without the wedge. Keeping stars round at your/our focal length is hard, then add field rotation to the mix and that is going to make it really difficult. So much so that DSS may not even pick up the stars. Having said that, with a wedge, on an alt-az, I can happily say that 20s ( my mounts sweet spot is 22sec ) can produce some pleasing images.

So to sum up my thoughts...... Use a wedge

[raymo]

Can I suggest that you make a simple non adjustable wedge out of plywood.
If you know your latitude you could knock one up in an hour or so.
raymo

[silv (Annette)]

A wedge isn't even necessary for DSS stacking. This IIS user Wayne Anderson was doing it for ages without a wedge in Alt-Az and DSS .
Here's a collection of his wedge-less imaging and processing results.
Here, which was 2 months or so later than the first, he shows M42 and ponders using a wedge sometime in the future.
He also mentions some DSS settings which might help Bruce's stacking, as well. It could be just a little thing like forgetting to tick "register all frames" or something.

[Bruceaust]

Thanks for the replies.
I will recheck my DSS regiter settings.and check out the links to Wayne's thread.
Please accept I am not trying to get "the perfect image" , l am just trying to get the most out of what I have and enjoy the simplicity of my setup.
I do my more serious work (hobby ��) from a permanent pier mounted scope in a an Observatory.
I am exploring this alt az setup purely as a fun option for club observing nights and while travelling (camping). There are plenty of targets that are bright enough for 20 or 30 sec exposures.
I don't want to get into the alt az verses eq wedge discussion ..... I know the limitations of what I am trying to do��!
From what I have experimented with so far , I believe I am either having problems with the DSS stacking settings and/or lack of data in the image. I am still unsure though, of DSS's ability to stack frames with field rotation?
I recently tried to stack 47 tuc, 150 X 10sec subs plus darks. ,FL 945mm, f6.3, .......DSS only registered 1 frame.

[RyanJones]

Originally Posted by Bruceaust

Thanks for the replies.
I will recheck my DSS regiter settings.
Please accept I am not trying to get "the perfect image" , l am just trying to get the most out of what I have and enjoy the simplicity of my setup.
I do my more serious work (hobby &#128522 from a permanent pier mounted scope in a an Observatory.
I am exploring this alt az setup purely as a fun option for club observing nights and while travelling (camping). There are plenty of targets that are bright enough for 20 or 30 sec exposures.
I don't want to get into the alt az verses eq wedge discussion ..... I know the limitations of what I am trying to do😊!
From what I have experimented with so far , I believe I am either having problems with the DSS stacking settings and/or lack of data in the image. I am still unsure though, of DSS's ability to stack frames with field rotation?
I recently tried to stack 47 tuc, 150 X 10sec subs plus darks. ,FL 945mm, f6.3, .......DSS only registered 1 frame.

Very early on before I worked out how to set my alt az to wedge mode and polar aligning it, I was stacking short subs. I remember some times it would stack them then other times it wouldn't. That may just have been how bad my shots were. What I do know now though is that DSS is happy with at least 10% rotation from when I've not mounted my camera exactly the same over a couple of sessions. That last set of subs you mentioned of 47 tuc should have no problem. Maybe because they are such short subs, you need to turn down the star detection threshold ?

[bojan]

I also tried A-Z mount quite some time ago with good results, see here.
The scope I used (10" Newt, bartelized dob mount) will one night be on EQ6, but until then, I intend to use it as is for AP.
Since the bartels system supports field rotator, I will try to put something together soon, for longer exposures....


Also, field rotation is not the same across the sky, it is minimal (zero) for azimut 90° and 270°.. see here.

[Karlzburg (Karl)]

The links Annette put up the guy is using a focal reducer as well, it'll reduce sub times.

[RyanJones]

Originally Posted by Karlzburg

The links Annette put up the guy is using a focal reducer as well, it'll reduce sub times.

And it's a 12"

[Karlzburg (Karl)]

I forgot to put that in. Big difference between 12 inch and 6 inch in light gathering and detail.

[Karlzburg (Karl)]

I used to have an alt az mount, I found tracking an issue so I would get star tails, zoom in on your pics and check for them. Plus use one of your good subs as a reference frame, DSS won't stack subs with star tails is it, so if you have 100 subs but 95 of them have star tails it won't stack them after they're registered. Go through them and delete the ones that aren't good then just stack them without registering them and see what happens.

[Bruceaust]

I am using a focal reducer.
I will have another go when i get a clear sky and try a number of different exposure scenarios to test stacking in DSS.

[RyanJones]

Originally Posted by Bruceaust

I am using a focal reducer.
I will have another go when i get a clear sky and try a number of different exposure scenarios to test stacking in DSS.

I'd maybe reduce the star detection threshold in DSS too given the small data collection.

[Bruceaust]

Thanks Ryan, I have done that!

[RyanJones]

Originally Posted by Bruceaust

Thanks Ryan, I have done that!

Do you have a sub you could post so we can see if there's anything we can see that might help ?

[Bruceaust]

Not at the moment. I cleaned all the rubbish off the Laptop.