Is this Polar scope beyond alignment?

[theeruditefrog]

I'm on an EQ3 and I have had trouble calibrating it.

I'm trying to calibrate the reticule but ....

It seems that barrel of the polarscope is off axis in the tube  - it sort of moves the whole image around, as if you were swirling a pair of  binoculars around.

Maybe I can make a video.

Is it time for me to buy a fresh one that I didn't meddle with?

The outcome is that I can only shoot 20second images before the stars elongate.

[Cornelius Varley]

The polarscope needs realigning in its mount. 

1.  Aim the mount at a distant fixed object ant adjust to centre the target in the cross hairs of the polarscope.
2.  Release the RA axis and rotate 180 degrees. Relock the RA and use the three grub screws to remove half of the error.
3.  Rotate the mount back to the original position and repeat step 2.
4.  Keep repeating 2 and 3 until no more error is observed.

[theeruditefrog]

Thanks @Cornelius Varley But I think the barrel itself is off alignment? - in the video clip the whole thing is swirling around. So I'm guessing either the mount in the tripod is off, or I've moved the barrel of scope in its housing.

 

(During the move, I think the foot of the tripod slipped on my wooden floor.)

Edited May 1, 2020 by theeruditefrog

[ThomasF1234]

Hi on your mount is the spirit level bubble in the middle? If not try and get it so it’s pretty much in the middle and see if that makes a difference 

[theeruditefrog]

I'll got try that. Thanks @ThomasF1234

 

[ThomasF1234]

19 hours ago, theeruditefrog said:

I'll got try that. Thanks @ThomasF1234

 

Hi just wondering if that worked?

[theeruditefrog]

@ThomasF1234Hi - I levelled the scope, that didn't make a big difference, but the I did something spotted on another thread which is to add a grommet round the barrel of the polarscope.

In my case I used plumbers PTFE jointing tape. I wrapped it round the top of the barrel and tried to get it snug in the tube of the EQ3 - assuming that's accurate.

That seems to have made a difference. But I'm not sure it will be accurate enough to get me up to 1min or over exposures. I'll be happy with 45s.

Being a novice, I seem to cause more damage than good due to lack of knowledge.

Will try and post results if I can.

[Neil H]

Hi found the polar scope was hard to start off , a tiny tiny adjustment moves it a long way , but what the guys have said does work , only do the polar scope adjustment when you have loads of time you can't rush it 

Set up the tripod level and at a height so you can sit and look into the polar scope then follow what the guys have said , if it starts to get worse stop walk away have a cuppa then go back to it take your time and move the grub screws a tiny tiny adjustment it will come right in the end 

If you have a long living room / dining room you can put a target at one end of the room and do the adjustment in doors you want a dot  about an inch in size , I found this video helped

 

[Cornelius Varley]

On 01/05/2020 at 14:40, ThomasF1234 said:

Hi on your mount is the spirit level bubble in the middle? If not try and get it so it’s pretty much in the middle and see if that makes a difference 

Whether the mount is level or not won't make any difference to the RA axis, it will be still pointing in the same direction. 

[theeruditefrog]

@Neil H Can you see that swirling as I rotate the RA in  my video - that's the bit I'm worried about (the camera was in a fixed positions) - the reticule target was a bit off at this point and it's better now.

[carastro]

Presumably the camera is attached to the Polarscope and it is definitely crooked.  You can adjust the polascope using the little grub screws, but that normally affects the centre of rotation in the reticule which looks to be reasonably good in this video, but as you say the camera is moving around.

If you want to ditch the polarscope altogether a much more accurate way is to use either Sharpcap and I think you use a finderscope with it (I have never used this personally), but it's relatively cheap, or buy Polemaster not cheap but brilliant.  Saves all that kneeling down and cricking the neck.  this would certainly solve your issues.

Carole 

  

Edited May 5, 2020 by carastro

[theeruditefrog]

@carastro Hi - the camera (my iPhone) was fixed to the tripod legs to look down the polarscpoe - and this is what my eyes are seeing too.

My problems may have started when I loosened certain bits of the new polarscope - there were parts of what I assume was a polarscope? already in the tripod, and that had me confused.

I think what I really need (post lock down) is some time with some people who can take a look at my set up and advise.

Is there a North Kent, SE London Astrophoto group that have meetups?

 

[TerryMcK]

+1 on the Polemaster or Ioptron Ipolar.

You don't get a crick in your neck, get muddy knees, have to discern some unfathomable scale, nor have to fiddle around trying to get the polarscope aligned.

[Neil H]

If you fancy trying something out I have an app called polar alignment pro it does everything right from levelling the tripod , it will let you do a day time polar alignment by mounting your phone on the mount were the dove tail will fit , I did a few polar alignments  over a few nights using the polar scope and then checked it with the app and the app showed as spot on , I would not say use it for photography long exposures but for visual it's 100%  

It's worth a try it is not dear  they do it for Android and iPhones 

[carastro]

Quote

Is there a North Kent, SE London Astrophoto group that have meetups?

Yes there is the group that I belong to Orpington Astronomical Society.  I presume you are local then.  The monthly meetings are not for practical stuff, but a good way to meet up with like minded people,  there is a guy who lives further out in Kent, who might be the one to ask.  PM me your E Mail address and we can talk further.

Carole 

[theeruditefrog]

Thanks @carastro - yes, that would be great.

I'm trying to enjoy this on a budget, so when my lack of knowledge ends up costing me, it's really frustrating!

[theeruditefrog]

@Neil H

I have the free version of Polar Align - unfortunately my iPhone's compass system is dead jumps all over the place (not helpful) but I could use another phone!

Observing and using the GOTO on the Synscan is good enough with even my slightly off polarscope.

PE with Joe Wickes exercises are helping with the crouching needed!

[Neil H]

This is what mine looks like like I said does everything , I use it in day time alignment to line the tripod to polar

Then level the tripod , fit the mount then attach my phone to the mount were the telescope would fit and do polar alignment of the mount then your ready , you don't have to see Polaris to use this or your polar scope 

[theeruditefrog]

@Neil H - I'd have to borrow my wife's phone as my iphone compass is broken.

I'll take a look - the standard PS Align app is great - even has my reticule stored.

Will see how it goes tonight.

[Neil H]

10 minutes ago, theeruditefrog said:

@Neil H - I'd have to borrow my wife's phone as my iphone compass is broken.

I'll take a look - the standard PS Align app is great - even has my reticule stored.

Will see how it goes tonight.

Hi I tested it a few times and it has been spot on 

[theeruditefrog]

So this is what I'm getting at 32 seconds:

(I'll not sure what the exposure should be like ideally)

There's quite a lot of movement/distortion? away from the centre of the image - bottom left for example.

There is also quite a bit of drift in the set of images.

Thank you for your advice here.