Will an autoguider help here

[peabrain]

Currently i am using an ioptron skyguider pro with the ipolar. even with "shorter" focal length like 20 or 300, it often struggles to not start trailing with longer exposure times then 60-90 secs.
even at shorter focal lenght most targets will slowly creep out of frame. (exept wide angle milky way fun)
here is an example of the seven sisters slowly creeping out of frame over 2 hrs, where i have deleted some frames that where trailing.

[StevieDvd]

If your shorter exposures are OK and PA is good then yes use the autoguider, a quick peek of the mount manual shows it has an ST4 port so that option has been allowed for.

[peabrain]

my mount has the option for guider and i have looked at an option from ZWO wither their camera that fits into it.

My normal procedure is to, mount everything, and balance everything looking at the target. then make shure my polar alignment is as close as possible where i also spin the setup about 120 degrees. (even making a few micro adjustments to make my dot not move away from the X)
 

[Stargazer33]

Is that a stacked image? If so then it looks like you are stacking on hot pixels. There are some points without trailing in your image, which would suggest hot pixels as they remain in the same place in each frame. If your stars are at all elongated then the stacking software won't see them as stars and will instead think the hot pixels are stars and use them for reference. 

Guiding will always help as long as it is set up correctly; but it's not a miracle cure all.

[peabrain]

there are not that many hot pixels in general on the pictures, this was just a series i made the stacking software stack at star trails. was to get a general look at how the trails point, just to get an idea of how the tracker is wandering around.

currently the stars are moving down the frame, most stars are not elongated at this point. ( might have missed the focus a bit)
 

[bobro]

7 hours ago, peabrain said:

Currently i am using an ioptron skyguider pro with the ipolar. even with "shorter" focal length like 20 or 300, it often struggles to not start trailing with longer exposure times then 60-90 secs.

Seems ok for a simple tracker intended for holding a camera or short FL scope. Shorter FL should allow longer subs without trailing. My tracked EQ2 mount could typically provide 30 sec subs with a 650mm FL scope.

 

7 hours ago, peabrain said:

even at shorter focal lenght most targets will slowly creep out of frame

Depends on polar alignment and accuracy of tracker though a single sub will normally be much shorter time than overall imaging time - hence a bit of slow creep is ok. Guiding will not necessarily stop slow creep, especially if dithering is used, though it will improve single subs.

Edited October 15, 2021 by bobro

[peabrain]

I know this setup will never give me the super long single shot times, but i was hoping that 2-3mins should be possible with an added guider.

 

[bobro]

Yes, guiding should easily allow 2-3 min subs. Guiding would be in RA only. Slow movement of the field of view isn't a problem as stacking software will de-rotate/align subs. Good polar alignment will help eliminate any movement as only RA corrections would be required.

[peabrain]

i try and make shure the alignment is as perfect as possible.
hench the routine of pointing my camera and lens in the direction i am going to shoot, then turn about 120 degrees and adjust so my alignment does not shift over time.
one of the reasons i have the ipolar mounted in my skyguider. ( designing a leveling plate to make sure my mount is as level as can be also)

[michael8554]

I gather you made a stack of exposures that had round stars ?

Then that drift in Dec over time is due to Polar Alignment error.

Perfect PA is not possible, so guiding Dec would help.

But I don't think your mount has Dec motors ?

So get best PA and expose for as long as gives round stars, those subs should stack well.

Michael

 

 

 

[bobro]

5 hours ago, peabrain said:

hench the routine of pointing my camera and lens in the direction i am going to shoot, then turn about 120 degrees and adjust so my alignment does not shift over time.

I don't understand this. The iPolar should give correct alignment using alt/az adjustment without the need for any subsequent adjustments. What are you adjusting?

Note: a mount does not need to be perfectly level as polar alignment points the RA axis correctly to allow tracking in RA.

[peabrain]

Since my current setup is right at the limit the mount can handle and my lens it heavy, i am unable to get the balance perfect.
so when the mount turns the weight shifts slightly, and the dot will move slightly away from the +. after i started doing this i noticed my exposure times get better, but right now it is the speed i am guessing is not right.

this led me to believe that adding a guide scope might help, so currently i am looking at a few options.

ZWO Mini Guide Scope
with ZWO ASI 120MM Mini USB 2.0 Mono Camera
but atm i am wondering what the focal lenght limmit of that combi is for future tracker and deepsky use.

[bobro]

Thanks for the clarification on the additional adjustment. My EQ2 had a similar weight capacity issue with the scope and guider mounted, so I screwed a short extension on the end of the weight bar to allow the weight to be moved further away from the axis and achieve balance. As your setup is already carrying a lot of weight, I suppose a guide scope and camera could be added on the counterweight shaft rather than on the lens side.

If you haven't already seen it, this thread has useful info on startrackers https://stargazerslounge.com/topic/303949-imaging-with-a-star-adventurer/   There is a photo on page 2 of the thread with the guide scope on the counterweight shaft.

A rough figure for guide scope/imaging scope combination that is often quoted is the imaging scope FL can be up to 10X the guide scope FL, assuming equal camera pixel sizes. Even staying well below this rough limit would allow for a useful imaging scope FL in a future setup. FYI - I use a guide camera with the same AR0130 sensor (colour version) as the ASI 120MM and a 162mm FL guide scope to guide my EQ5 with a SkyWatcher 150PL (1200mm FL). 

[peabrain]

Thanks for the feed back.
will start saving up for a guide scope, the Zwo mini might be a good start i can use later.
Although i might save for the ZWO ASI290MM instead of the ZWO ASI 120MM. (since i keep reading good stuff about it and can use it later)