star adventurer Another Star Adventurer Polar Alignment Question...

[PunchyPariah]

Sincere apologies if this has been covered previously in the numerous newbie SA questions. I had a search here and on Google using many different ways of asking but can't quite find the answer.

I've just received the SA astro imaging bundle and have been familiarising myself with it before the skies clear. Am I right in assuming that by setting the date/time to October 31st at 00:00 is just to align the polar scope reticule squarely?

As I understand it, once polar alignment is completed, it will rotate as the L bracket and camera are positioned. I have the PS Align app on my phone and the reticule set in that matches what I can see through the polar scope (clockwise 0, 3, 6, 9) so I think I'm on the right track and know what I'll need to do there.

However, the month markings on my SA have a wider division at the end on the October range, as do all the months with 31 days. You can see them in the attached pic. The only images I've been able to find on-line (and the diagrams in the manual) show equal divisions throughout.

So, I guess what I'm really asking is, do I align as per the attached photo with the 0 on the last division mark in October? The reticule looks pretty level to me but I didn't know quite how crucial it was.

(I'll try not to have such a rambling question next time.)

Simon.

[gtis]

Hi as far as I know you don't have to use them

what I do is this align the wedge to your latitude 

turn the polar reticule so that zero is at the top and six at the bottom 

them put the pole star in the circle using the adjustment 

screws and that should be it

somebody might come along with a better explanation 

[MarkyD]

If you look at Feburary it has one less mark.  There are 15 marks per month

[PunchyPariah]

2 minutes ago, gtis said:

Hi as far as I know you don't have to use them

what I do is this align the wedge to your latitude 

turn the polar reticule so that zero is at the top and six at the bottom 

them put the pole star in the circle using the adjustment 

screws and that should be it

somebody might come along with a better explanation 

Thanks for that. I've got the zero at the top but I just wondered how "at the top" it needed to be, accuracy wise.

[PunchyPariah]

7 minutes ago, MarkyD said:

If you look at Feburary it has one less mark.  There are 15 marks per month

Yeah, I spotted that whilst turning it about last night. it's just a shame that the user manual (and other scales on images of the red version that I've seen) have equal divisions across all the months. I may be over thinking it but I assumed that the reticule would have to be properly square/level to align the pole star correctly.

[Davey-T]

I think the circles are more for decoration than use as I've never used them and PA'ing it is pretty easy by just putting the 6 at the bottom and Polaris in the circle from any PA app.

Bearing in mind that you're trying to accurately aim a six inch tube at a star some 400 odd light years away I doubt the setting circles will help much.

Dave

[8472]

I've often wondered about the October 31st setting myself, and yes, the owner's manual is useless, and information online is sketchy to say the least. 

I'd would have thought this is vital for long subs with longer focal lengths. Merely replicating Polaris's position from an app is not sufficient if the reticule is not pointing perfectly vertical north to south. 

Personally, I have been calibrating the 0-6 vertical reticule line in daylight against a known tall vertical object (e.g. a building of some sort) after setting the SA up as level as possible, with a spirit level. This invariably gives me the reading similar to your photo, as far as the setting circle is concerned. Wouldn't it have been simple to make the 31st graduation a little easier to see at manufacture?

Either way, it would be nice to know if anyone else agrees with this or even better, has a more accurate method that doesn't involve purchasing a Polemaster?

[PunchyPariah]

10 minutes ago, 8472 said:

I'd would have thought this is vital for long subs with longer focal lengths. Merely replicating Polaris's position from an app is not sufficient if the reticule is not pointing perfectly vertical north to south.

That was exactly my thinking. The attached pic is what I envisaged if the scope wasn't straight.

The vertical object/building idea is interesting. I'll give that a try too. Thanks!

[Davey-T]

Once you've got Polaris on the circle it's easy enough to tweak it back on track while you're imaging, I have no problem using a 300mm camera lens and that's about a reasonable limit given what it's designed for, not for long focal length telescopes.

Dave

[willinliv]

I have something to add to this. When I was using it last I spun it so that the pole star should be on the inner ring, but the main thing I wanted to say was that I highly recommend PolarFinder app for the PC (is freeware). It had an update recently but looking for a mac alternative. It basically gives you an idea of the placement of the northstar within the ring at any given time, and it takes into account the finderscopes back to front-ness (for want of a better description in my limited vocab!)

[PunchyPariah]

24 minutes ago, willinliv said:

I have something to add to this. When I was using it last I spun it so that the pole star should be on the inner ring, but the main thing I wanted to say was that I highly recommend PolarFinder app for the PC (is freeware). It had an update recently but looking for a mac alternative. It basically gives you an idea of the placement of the northstar within the ring at any given time, and it takes into account the finderscopes back to front-ness (for want of a better description in my limited vocab!)

Thanks Will. I have the PS Align app on my iPhone which does the same sort of thing. You can sent the reticule to suit the device you're using so it knows whether your view is mirrored/inverted and puts the mark in the right spot.

[knobby]

Or the SAM app has an image of the reticule also.

 

[knobby]

Didn't the date and time dials used to be to move the circle on circle to the correct position of Polaris ... Sure I read that somewhere.