Another PHD2 Graph question

[Shelster1973]

A bit like buses these things......guess it was the outbreak of clear skies last night that managed to drag the lesser spotted Astro Photographer out of hibernation and be seen in their envornment of cold and blumming dark.

Anyway .... this is a screen grab of my graph from last night which as you can see looks fairly flat, but the target is showing somehting is not quite right.

The other image is a screen grab of one fo the subs which you can just about see is showing some streaking in the stars.  I did notice that in all the subsequent subs, the streaks were the same and heading in the same direction and the main target (M106) was central so am not sure if the issue with the smearing is down to the tracking being not great or something else that is going on (primary is pretty dirty after having been sat out, but under cover, for a few months).  Collimation was spot on and I even adjusted my PA using polar scope prior to imaging run.

Any help or pointers or suggestions are greatly appreciated

[Davey-T]

The target looks a bit scatter gunned, mine are usually all inside the circles.
Colour cams aren't the best thing for guiding.
Did you put your equipment into PHD to see what settings it suggested ?
Check for flexure in the guidescope mounting
Have you tried the PHD drift aligning thingy ?

Dave

[Shelster1973]

Davey

I did put the numbers in when I first set up a while back, but will revisit and check this

Was also told several times that colour cams are not the ideal for guiding, but due to budget constraints, this was only viable option then and now.

Guidscope was solid last night

I have used the drift align tool and will use it again after I have taken the mount of to do some routine maintenance on it over the weekend, but did not use it last night due to this impending removal

[Owmuchonomy]

It's not that bad.  If it were me I wouldn't touch anything in PHD UNTIL you have orientated your guide camera and imaging chip so that the RA and Dec axes are aligned straight up/down and left/right. This will help significantly in diagnosing irregular star shapes.  Looking at your red line I would bet a few jaffa cakes that if you did that it would show a lot of backlash in the Dec axis.  Tick the "Trendlines" box next time you guide and watch it for a couple of minutes.  If it shows a North drift then alter your correction to South only or vice versa (you currently have it set to Auto).

[Shelster1973]

Cheers Chris...some good points there.  The imaging camera goes in the same orientation each time, but have to admit the guide camera is a bit hit and miss.  Will get that out in teh day light and orient it in a true up down left right fashion when the mount is set at datum marks and then mark it off on cam body and scope body too, so that it goes in the same each time.

Will get the jaffa cakes on order ready :-)

[Freddie]

Have you taken a short exposure shot (i.e. no guiding errors) to check your stars are round? If they aren't round on a short exposure it is not a guiding issue but a cam to scope connection issue.

[Shelster1973]

8 minutes ago, Freddie said:

Have you taken a short exposure shot (i.e. no guiding errors) to check your stars are round? If they aren't round on a short exposure it is not a guiding issue but a cam to scope connection issue.

Will have a look see at the images that were taken for my plate solving.  These are 7 secs long, so should show what the stars are looking like.....after a whole butt load of stretching

[libraryman]

First thing....you ra corrections are mostly on one side, that would suggest your pa is out quite a bit, your polar scope won't get you close enough.

dec corrections point to a bit of backlash,     if you are using Eqmod your tracking rate might be low, run the guiding assistant, it will help you.

your dirty mirrors are unlikely to make a scrap of difference.

actually, it looks like you are using an old version of PhD....update to 2.61 and ascom. 6.1

Ray

[Shelster1973]

1 hour ago, libraryman said:

First thing....you ra corrections are mostly on one side, that would suggest your pa is out quite a bit, your polar scope won't get you close enough.

dec corrections point to a bit of backlash,     if you are using Eqmod your tracking rate might be low, run the guiding assistant, it will help you.

your dirty mirrors are unlikely to make a scrap of difference.

actually, it looks like you are using an old version of PhD....update to 2.61 and ascom. 6.1

Ray

Cheers for that...has been a while since I updated on that computer.  Also need to update BYN too.

Not using EQMOD am using Celestron driver through ascom which connects through USB>serial then through handset.

Have dropped on a single sub converted to JPEG from last night.  Has only had a very rough and ready stretch and curve done to it in PI, nothing else

[Shelster1973]

well...i would have put the picture in but am getting a 20Mb warning pop up each time.....let me find another way.....

[Shelster1973]

 

Sorted it

[Davey-T]

Helpful bits in this video by one of the blokes what wrote it.

Some of it not very clear, the explanation or the video, but worth a look.

Dave

http://openphdguiding.org/getting-the-most-out-of-phd2-guiding-video/

[Shelster1973]

Will have a look see at that.

Also just noticed the pic I posted above was only 60 sec sub too.....guess I should be a bit more judicious with my filing of subs