Is my polar scope fitted correctly?

[SmokeyJoe]

I have one of the new type skywatcher polar scopes. When looking through my polar scope with the mount in the home position the display is upside down compared to the illustration in the manual and the graphic on the synscan innit app.  The instructions say to rotate the RA axis to put the 0 displayed in the polar scope eyepiece to the highest (I.e.12 o'clock) position.  This is impossible as the mount cannot rotate 180 degrees in RA.  My fist thought is that the polar scope is upside down.  Am I missing something and what do I unscrew to fix it.  There are 3 or four Allen bolts plus a couple of little screws.

[Jiggy 67]

I’m not sure there’s any need to bother. I don’t use the synscan app cos I’m on an I phone but if it’s just a graphic of the circle with the position of Polaris on the circle the when you polar align just reproduce that image in your polar scope, the numbers on the scope are irrelevant..... some may disagree but it might only become an issue when using the handset calculation to align. You could rotate in ra to put 6 at the top

Edited December 4, 2019 by Jiggy 67

[SmokeyJoe]

Thanks for your reply, you are right about putting 6 at the top but there is also a diagram of Cassiopeia to help alignment, this is in completely the wrong place.  

[Jiggy 67]

Do you have the reticle with a little bubble to put Polaris in on the large circle (that one has Cassiopeia on it) or the one that is just basically a clock face with gradient markings around it?? The second one is the new one and I have that one, it doesn’t have Cassiopeia on it. If it’s the second one (or a variant with Cass on it,) my first post still applies, ignore Cassiopeia, it doesn’t matter. If it’s the first one, it needs calibrating and you will have to adjust it

Edited December 4, 2019 by Jiggy 67

[SmokeyJoe]

It has a clock face  with gradient markings and Cassiopeia. Just waiting for clouds to clear and then will attempt polar alignment again!

[Anthony1979]

Dont you just need to get polaris in the centre of the polarscope for it to be align or is there more to it... Sorry for intruding

[Davey-T]

1 minute ago, Anthony1979 said:

Dont you just need to get polaris in the centre of the polarscope for it to be align or is there more to it... Sorry for intruding

Probably good enough for visual need to get Polaris in the right place on the clock face circle for imaging otherwise it gives the guider too much to do.

Dave

[Anthony1979]

I find it all complicated lol

[joe aguiar]

13 minutes ago, Anthony1979 said:

Dont you just need to get polaris in the centre of the polarscope for it to be align or is there more to it... Sorry for intruding

Polaris is half a degree off from true north for visual it's ok

for imaging its need to be closer.  Even if u got closer like quater degree is not good enough so getting as close u can is ideal.

Joejaguar 

[celestron8g8]

I installed a Polar Scope on my German EQ5 mount a few years ago and yes it's confusing and yes viewing is up side down . But on a non go to mount you have to use the setting circles with adjustments which i always had a hard time with and still don't understand it . But purpose is after you adjust it correctly then when you do polar alignment your suppose to put Polaris in a tiny circle off set center and that is suppose to be correct alignment . But i find it easier to just point my scope at Polaris and center then adjust the Finder scope to center Polaris . Then i use a bright star close to the Ecliptic line and do manual polar alignment using the azimuth and altitude adjustments knobs . Basically called the drift alignment method which i like best since i don't have a GoTo mount  .

Check out this video and see if it will help some :  https://binged.it/33Lw7bL

https://binged.it/34SdC6z

 

[dannybgoode]

Assuming you’re in the northern hemisphere it really doesn’t matter how the reticule is orientated. It’s just a circle so it matters not whether ‘6 o’clock’ is at the top, the bottom, 2/3’s of the way round - whatever. 
 

Just use an app (I use PS Align Pro for iOS) and make sure Polaris is at the right place on the ‘clock face’.  The app already has the orientation sorted out etc. 
 

I only do a quick visual PA and have excellent visual and astrophotography results with guiding error less than 1”. 

[Jiggy 67]

1 hour ago, dannybgoode said:

 

Just use an app (I use PS Align Pro for iOS) and make sure Polaris is at the right place on the ‘clock face’.  The app already has the orientation sorted out etc. 
 

 

I also use PS Align Pro. It is an outstanding app, I really can't fault it. It is extremely accurate. For example, I centred the double star Gamma ari in a 4mm ep on Tuesday night, went inside and had a glass of wine. I came out an hour later and it was still centred!!...pretty amazing accuracy....I know the mount is pretty good but you need accurate PA to achieve them results I think

[Marvin Jenkins]

On 04/12/2019 at 16:36, SmokeyJoe said:

I have one of the new type skywatcher polar scopes. When looking through my polar scope with the mount in the home position the display is upside down compared to the illustration in the manual and the graphic on the synscan innit app.  The instructions say to rotate the RA axis to put the 0 displayed in the polar scope eyepiece to the highest (I.e.12 o'clock) position.  This is impossible as the mount cannot rotate 180 degrees in RA.  My fist thought is that the polar scope is upside down.  Am I missing something and what do I unscrew to fix it.  There are 3 or four Allen bolts plus a couple of little screws.

I had the same problem with my EQ5 factory fitted polar scope. Turns out they screw in the polar scope until it tightens and where ever the reticule ends up is your problem.

You can change the position of the reticule by slightly loosening the tiny Allen key grub screws (three) and rotating the reticule until you have the 0 top dead center whilst the mount is in the home position.

Be aware that if you loose too much the reticule will fall out onto the floor, plus there is some grease in there that you don’t want in your polar alignment view.

Once rotated and gently fixed in place (don’t over tighten grub screws) you can have ago at centring the reticule. By using the grub screws in the same way as collimating a secondary mirror.

I found all this on YouTube, so I am sure you will too. I certainly understand previous comments about perfect polar alignment not being necessary but a degree of accuracy can’t be a bad thing when we spend money on this kit.

Marvin

[Marvin Jenkins]

Forgot to say before you loosen the grub screws unscrew completely the eyepiece to get access to the reticule.

[Marvin Jenkins]

On 04/12/2019 at 22:22, Anthony1979 said:

Dont you just need to get polaris in the centre of the polarscope for it to be align or is there more to it... Sorry for intruding

No intrusion, these questions are just what this part of the forum is for. To a certain degree your comment is quite true. Level your tripod facing north, roughly level the thing and get Polaris in the cross hairs of the polar scope. You have a rough polar alignment.

However. If you require more accuracy in your tracking say for photography, then polar alignment needs to be spot on. As a basic the reticule in the polar scope needs to centred (already touched on). And using a phone app to tell you where to adjust your mount to in relation to the pole star is invaluable.

The more accurately you can follow the app after following the previous stuff the better your alignment and tracking will be. The flip side is if you are doing a one hour multi target visual session then that much effort is far less important.

Its up to you how much to sweat it.

Marv

[Anthony1979]

Thats what it i what to try.. A bit of basics astrophotography.... But trying to understand polar aligning really baffles my head 

[Jiggy 67]

Can be quite hard to explain in a post, maybe this will help

[SmokeyJoe]

Thanks all for your help, this is my third 'restart' with astronomy, after a couple of breaks enforced by illness.  Polar alignment still escapes me, but with some decent skies I shall crack on and get it sorted, practice makes perfect!

[jif001]

 

Sticking my neck out a bit here...

This is aimed at SmokeyJoe and Anthony1979 with whom I share a frustration at having an angled reticle and difficulty getting to grips with the machinations of polar alignment. Many kind folk here and elsewhere have tried to explain these things but I have yet to see an explanation that a newbie like me would fully understand without raising new questions about why it’s like that. Understanding the ‘why’ is at least as important as knowing the ‘what’. Anyway, I believe I have had a Eureka! moment and the penny has finally dropped inside my capacious but seemingly vacant cranium, hence my post...and I’d be grateful if those more experienced than I could (constructively) put me right if I’ve got any of this wrong. Please don’t say ‘you don’t need to do that!’ unless it is absolutely unnecessary for imaging, for that is my ultimate aim - this post is not about visual observing. I also go a bit beyond the original question because these are the issues I needed to get to grips with, and did the hard way. It may help the aforementioned folk too.

 

Polarscope Reticle Orientation 

Firstly, there is a difference between ‘polarscope reticle orientation’ and ‘polarscope RA alignment’ and this isn’t the only thread in which the topic has unhelpfully drifted from a question about the former into an answer about the latter. Polarscope RA alignment is about ensuring that the axis of the polarscope is aligned with the mount RA axis, and has been explained well enough here. But that wasn’t the question, which was about polarscope reticle orientation - i.e. which way up it is. 

My advice is that you should not dismantle the polarscope to reorientate the reticle. You may end up ruining it. There’s an easier, quicker and safer way to solve your reticle orientation problem. Read on...

 

Solving the reticle orientation issue (clock-type reticle)

1) Firstly, level the mount and set it up pointing north as if making it ready for polar alignment. Try to be quick with steps 2 to 4 because Polaris is on the move (slowly though, so no need to panic). 

2) Next use the Alt and Az bolts to centre Polaris in the reticle - i.e. put Polaris right in the centre of the cross-hairs, not on any circle. Be as accurate as you can. 

3) Now using ONLY the Alt bolts, move Polaris vertically upward in the reticle from its central position until it reaches any of the circles.

4) Because you started with Polaris dead centre and moved it only vertically, Polaris is now exactly in the zero (12 o’clock) position on the circle. Now rotate the RA axis to put the reticle zero* mark in exactly the same position as Polaris. Again, be as accurate as you can.

5) Lock the RA axis in this position and using a marker pen put alignment marks on the mount housing so that you can find this position again without the need to use the polarscope. 

That’s it - now you know accurately where zero (12 o’clock) is and the marks on the mount allow you to find it instantly. 

* if you can‘t get zero in this position use any number you like - it doesn’t matter as long as you treat this number as if it is zero.

 

Polar alignment

Oh how I wish someone had expressed it in these terms instead of me having to work it out for myself ... it definitely isn’t obvious to the uninitiated when small but vital details are omitted (as they often are - remember, it’s not enough to know what to do, it’s important to know WHY).

1) Firstly, level the mount and set it up ready for polar alignment

2) Rotate the RA axis to the zero position you established above and lock it there (use the marks you made on the mount)

3) Determine the hour angle of Polaris using the handset (if you have one) or other method such as the Polar Align app. 

4) Using the Alt and Az bolts adjust the mount until Polaris is in the required position on the reticle circle, regardless of what number you have in the 12 o’clock position. If the app says Polaris needs to be a third of the way around from the 12 o’clock position then put it a third of the way around from whatever number you have in the 12 o’clock position.

5) You are now polar-aligned. 

 

That’s the ‘what’. Here’s the ‘why’...

 

What you have just physically done is align your reticle with Polaris, but that isn’t your true aim. What you have also achieved using this method is alignment of the central cross-hairs with the celestial pole using Polaris as a guide. The cross-hairs mark the central axis of your polarscope, which is in turn aligned with the RA axis of your mount, and so what you have actually achieved is alignment of your RA axis with the earth’s axis. Polaris is not exactly at the pole, but it’s near to it and the method above is merely a means of finding the celestial pole. The clue is in the name: ‘polar alignment’, it is not ‘Polaris alignment’ even though the latter is what you do in order to achieve the former.  Having achieved alignment with the pole you no longer need to care about Polaris and where it sits on the circle (as long as it remains somewhere on the circle). Your RA axis is aligned with the earth’s axis, and that’s what you want. 

 

Home Position:

Not part of the original question but hey ho...

If you have a Goto mount your next task is to set the RA and Dec axes in the ‘home’ position - weight bar down and north, dec axis up and pointing at the pole. The home position is important as the Goto system needs to know where it is starting from in order to know where it’s going. Think of a pirate’s treasure map: ‘take ten steps forward and three steps right, and there be treasure!’. Well that’s great, but where do I start from? Is it the corner of my living room? How about the top deck of the bus? The instructions are useless without a datum - a starting point. That’s the home position on your mount. The controller determines its position by assuming a default start position and then counting pulses sent to each motor. That way it can drive the mount to any object you choose. Think of those pulses as steps forward / back / left / right on the way to the treasure (the object you want to view). They are only meaningful if the whole process starts from a known position. The one- two- and three-star alignment procedures are then used for fine-tuning the Goto. 

Home position has no use if you don’t have a Goto system because you need to find the celestial object yourself, and you don’t do it by counting drive pulses. 

 

 

 

[ecuador]

On 04/12/2019 at 18:24, SmokeyJoe said:

Thanks for your reply, you are right about putting 6 at the top but there is also a diagram of Cassiopeia to help alignment, this is in completely the wrong place.  

I think you are confusing Cassiopeia with Octans, which is used for the south hemisphere. I mean, you are talking about this reticle, right?

So, Octans is irrelevant, in fact in my app (I am the developer of Polar Scope Align) when you are in the N. Hemisphere it doesn't even show you Octans, it just zooms in the center. I could allow a rotated view for people who can't rotate the scope enough, but Jiggy 67 is right, in the end you just need a vertical reference, you can just put 6 on top instead and imagine it is 0.

[CaptainShiznit]

On 09/12/2019 at 22:00, jif001 said:

 

Sticking my neck out a bit here...

This is aimed at SmokeyJoe and Anthony1979 with whom I share a frustration at having an angled reticle and difficulty getting to grips with the machinations of polar alignment. Many kind folk here and elsewhere have tried to explain these things but I have yet to see an explanation that a newbie like me would fully understand without raising new questions about why it’s like that. Understanding the ‘why’ is at least as important as knowing the ‘what’. Anyway, I believe I have had a Eureka! moment and the penny has finally dropped inside my capacious but seemingly vacant cranium, hence my post...and I’d be grateful if those more experienced than I could (constructively) put me right if I’ve got any of this wrong. Please don’t say ‘you don’t need to do that!’ unless it is absolutely unnecessary for imaging, for that is my ultimate aim - this post is not about visual observing. I also go a bit beyond the original question because these are the issues I needed to get to grips with, and did the hard way. It may help the aforementioned folk too.

 

Polarscope Reticle Orientation 

Firstly, there is a difference between ‘polarscope reticle orientation’ and ‘polarscope RA alignment’ and this isn’t the only thread in which the topic has unhelpfully drifted from a question about the former into an answer about the latter. Polarscope RA alignment is about ensuring that the axis of the polarscope is aligned with the mount RA axis, and has been explained well enough here. But that wasn’t the question, which was about polarscope reticle orientation - i.e. which way up it is. 

My advice is that you should not dismantle the polarscope to reorientate the reticle. You may end up ruining it. There’s an easier, quicker and safer way to solve your reticle orientation problem. Read on...

 

Solving the reticle orientation issue (clock-type reticle)

1) Firstly, level the mount and set it up pointing north as if making it ready for polar alignment. Try to be quick with steps 2 to 4 because Polaris is on the move (slowly though, so no need to panic). 

2) Next use the Alt and Az bolts to centre Polaris in the reticle - i.e. put Polaris right in the centre of the cross-hairs, not on any circle. Be as accurate as you can. 

3) Now using ONLY the Alt bolts, move Polaris vertically upward in the reticle from its central position until it reaches any of the circles.

4) Because you started with Polaris dead centre and moved it only vertically, Polaris is now exactly in the zero (12 o’clock) position on the circle. Now rotate the RA axis to put the reticle zero* mark in exactly the same position as Polaris. Again, be as accurate as you can.

5) Lock the RA axis in this position and using a marker pen put alignment marks on the mount housing so that you can find this position again without the need to use the polarscope. 

That’s it - now you know accurately where zero (12 o’clock) is and the marks on the mount allow you to find it instantly. 

* if you can‘t get zero in this position use any number you like - it doesn’t matter as long as you treat this number as if it is zero.

 

Polar alignment

Oh how I wish someone had expressed it in these terms instead of me having to work it out for myself ... it definitely isn’t obvious to the uninitiated when small but vital details are omitted (as they often are - remember, it’s not enough to know what to do, it’s important to know WHY).

1) Firstly, level the mount and set it up ready for polar alignment

2) Rotate the RA axis to the zero position you established above and lock it there (use the marks you made on the mount)

3) Determine the hour angle of Polaris using the handset (if you have one) or other method such as the Polar Align app. 

4) Using the Alt and Az bolts adjust the mount until Polaris is in the required position on the reticle circle, regardless of what number you have in the 12 o’clock position. If the app says Polaris needs to be a third of the way around from the 12 o’clock position then put it a third of the way around from whatever number you have in the 12 o’clock position.

5) You are now polar-aligned. 

 

That’s the ‘what’. Here’s the ‘why’...

 

What you have just physically done is align your reticle with Polaris, but that isn’t your true aim. What you have also achieved using this method is alignment of the central cross-hairs with the celestial pole using Polaris as a guide. The cross-hairs mark the central axis of your polarscope, which is in turn aligned with the RA axis of your mount, and so what you have actually achieved is alignment of your RA axis with the earth’s axis. Polaris is not exactly at the pole, but it’s near to it and the method above is merely a means of finding the celestial pole. The clue is in the name: ‘polar alignment’, it is not ‘Polaris alignment’ even though the latter is what you do in order to achieve the former.  Having achieved alignment with the pole you no longer need to care about Polaris and where it sits on the circle (as long as it remains somewhere on the circle). Your RA axis is aligned with the earth’s axis, and that’s what you want. 

 

Home Position:

Not part of the original question but hey ho...

If you have a Goto mount your next task is to set the RA and Dec axes in the ‘home’ position - weight bar down and north, dec axis up and pointing at the pole. The home position is important as the Goto system needs to know where it is starting from in order to know where it’s going. Think of a pirate’s treasure map: ‘take ten steps forward and three steps right, and there be treasure!’. Well that’s great, but where do I start from? Is it the corner of my living room? How about the top deck of the bus? The instructions are useless without a datum - a starting point. That’s the home position on your mount. The controller determines its position by assuming a default start position and then counting pulses sent to each motor. That way it can drive the mount to any object you choose. Think of those pulses as steps forward / back / left / right on the way to the treasure (the object you want to view). They are only meaningful if the whole process starts from a known position. The one- two- and three-star alignment procedures are then used for fine-tuning the Goto. 

Home position has no use if you don’t have a Goto system because you need to find the celestial object yourself, and you don’t do it by counting drive pulses. 

 

 

 

I might be a bit late to this so apologies but I'm still confused as to the point of the first steps in this. I've seen the videos on YouTube where he describes some similar method of 'calibration' but still fail to see why. More so, my question is, what is lost by skipping this and simply finding out the current position of Polaris within the circle, rotating your RA axis so the bubble in the polar scope matches the intended position, and then aligning Polaris into the bubble with alt-az controls? I just can't get my head around what is actually happening in the prior steps.

[jif001]

I can’t comment on the ‘bubble’ reticle with any authority because I have the clock-type (as above) but I’m sure the principles are the same ...

if you look at the reticle screen shot above you’ll see a yellow cross. That’s where I need to put Polaris in my polar scope reticle in order to polar align. Get it there and I’m done. However, for my polar alignment to be accurate I need to know that when I do this the reticle zero marker is at the top - i.e. exactly at the top, dead centre, with the line between it and 6 exactly vertical and the line between 3 and 9 exactly horizontal. That’s something I cannot achieve by eye because my eye is simply not accurate enough. I may get zero to look like it’s at the top, but is it exactly at the top, I mean, EXACTLY? 

So I used the method I described - get Polaris (actually any star will do for this bit but Polaris is best placed) dead centre in the cross and then using ONLY the vertical adjustment of the mount move the star up to the circle.  Having done that I know EXACTLY where the zero should be and I adjust the RA axis so that the zero in the reticle exactly coincides with the star position, then I lock it and mark the mount so that I can find this position again without using the polarscope.  I can then be confident that my reticle is in the precise rotational position for aligning with Polaris when I need to polar align.

All of this is aimed at finding the correct reticle position only. It’s a one-off procedure and the marks on the mount are now my reference points for getting the reticle in the correct position prior to polar alignment. 

The video you’ve seen elsewhere using the bubble reticle is just applying this principle - getting the reticle in a known rotational position so that polar aligning can be done accurately. You can polar align without doing this, but it won’t be as accurate. That doesn’t matter for observing where a bit of drift won’t spoil it, but if you are imaging then any drift at all is to be avoided.

Let me know if it’s still not clear - I’m happy to try and explain it again if necessary because I would have been glad of some guidance like this myself and I get why it might be difficult to grasp! I’ve already suffered your frustration!

Edited January 15, 2020 by jif001

[CaptainShiznit]

5 minutes ago, jif001 said:

I can’t comment on the ‘bubble’ reticle with any authority because I have the clock-type (as above) but I’m sure the principles are the same ...

if you look at the reticle screen shot above you’ll see a yellow cross. That’s where I need to put Polaris in my polar scope reticle in order to polar align. Get it there and I’m done. However, for my polar alignment to be accurate I need to know that when I do this the reticle zero marker is at the top - i.e. exactly at the top, dead centre, with the line between it and 6 exactly vertical and the line between 3 and 9 exactly horizontal. That’s something I cannot achieve by eye because my eye is simply not accurate enough. I may get zero to look like it’s at the top, but is it exactly at the top, I mean, EXACTLY? 

So I used the method I described - get Polaris (actually any star will do for this bit but Polaris is best placed) dead centre in the cross and then using ONLY the vertical adjustment of the mount move the star up to the circle.  Having done that I know EXACTLY where the zero should be and I adjust the RA axis so that the zero in the reticle exactly coincides with the star position, then I lock it and mark the mount so that I can find this position again without using the polarscope.  I can then be confident that my reticle is in the precise rotational position for aligning with Polaris when I need to polar align.

All of this is aimed at finding the correct reticle position only. It’s a one-off procedure and the marks on the mount are now my reference points for getting the reticle in the correct position prior to polar alignment. 

The video you’ve seen elsewhere using the bubble reticle is just applying this principle - getting the reticle in a known rotational position is that polar aligning can be done accurately. You can polar align without doing this, but it won’t be as accurate. That doesn’t matter for observing where a bit of drift won’t spoil it, but if you are imaging then any drift at all is to be avoided.

Let me know if it’s still not clear - I’m happy to try and explain it again if necessary because I would have been glad of some guidance like this myself and I get why it might be difficult to grasp! I’ve already suffered your frustration!

I really appreciate your thorough posts so thanks for that. I'm a visual learner so maybe I need someone to show it to me in person so I can ask questions as it's happening, because I still don't really see the difference that the original one time calibration is having. I'll take your word for it because I do want accuracy for imaging but I still can't get my head around why it matters what orientation the polar scope begins at when polar aligning 😂

My train of thought, if that helps you understand my confusion, is that I'm thinking of the end result: from either

a) performing the calibration and then polar alignment

b) just performing polar alignment

as both being the exact same result: I read my polar alignment app to see the current position of Polaris within the circle, rotate my RA to match it (either from the starting position achieved from calibration of from a random position if not calibrated) and then use alt-az controls to align Polaris. What am I not seeing?

[jif001]

See if this helps ...

Here I have two reticle screen shots. One has zero exactly at the top, which is what I want, and the other has an error whereby zero is not exactly at the top, and I’ve grossly exaggerated this error to illustrate the point I’m about to make (I’m not good at judging when it’s exactly vertical but I’m better than this!). Ignore the blue lines for a minute  

Remember, what we want to achieve is polar alignment, which means the red cross in the reticle needs to coincide with something we cannot see - the celestial pole. Luckily there’s a nearby star that we can see, Polaris, and we use it as a guide. By getting Polaris in the right position in the reticle, at the correct angle, we know that the red cross hairs are aligned with the celestial pole. An app or other means will tell us the angle we need.

Look at the broken line joining the position of Polaris (yellow cross) to the central red cross in each case. In the second image my exaggeration of the tilt has made this line deliberately vertical so it’s easier to illustrate the error it creates.

The true position of the celestial pole is where the red cross is in the first image, but you can see that the rotation of the reticle in the second image has moved the red cross to the left of where it should be - imagine superimposing the second image on top of the first so that the two yellow crosses exactly coincide. What you would see is the red cross of the superimposed second image approximately where my blue lines cross each other in the first image.

What this shows is that if my reticle is tilted when I polar align then my scope is NOT aligned with the pole. If I used the tilted reticle below to polar align then I would be aligning with the blue cross in the first image. The real error you might get by having your reticle not exactly vertical is much smaller than this, because it won’t be this far out, but it’s an error nevertheless and will affect your tracking. 

Remember also that you need to establish the correct (vertical) reticle position (as in the first image) once only, and then mark your mount so you don’t have to do it again - just align the marks on the mount and you know you have the equivalent of image 1 and no tilt as in Image 2. 
 

Edited January 14, 2020 by jif001

[CaptainShiznit]

49 minutes ago, jif001 said:

See if this helps ...

Here I have two reticle screen shots. One has zero exactly at the top, which is what I want, and the other has an error whereby zero is not exactly at the top, and I’ve grossly exaggerated this error to illustrate the point I’m about to make (I’m not good at judging when it’s exactly vertical but I’m better than this!). Ignore the blue lines for a minute  

Remember, what we want to achieve is polar alignment, which means the red cross in the reticle needs to coincide with something we cannot see - the celestial pole. Luckily there’s a nearby star that we can see, Polaris, and we use it as a guide. By getting Polaris in the right position in the reticle, at the correct angle, we know that the red cross hairs are aligned with the celestial pole. An app or other means will tell us the angle we need.

Look at the broken line joining the position of Polaris (yellow cross) to the central red cross in each case. In the second image my exaggeration of the tilt has made this line deliberately vertical so it’s easier to illustrate the error it creates.

The true position of the celestial pole is where the red cross is in the first image, but you can see that the rotation of the reticle in the second image has moved the red cross to the left of where it should be - imagine superimposing the second image on top of the first so that the two yellow crosses exactly coincide. What you would see is the red cross of the superimposed second image approximately where my blue lines cross each other in the first image.

What this shows is that if my reticle is tilted when I polar align then my scope is NOT aligned with the pole. If I used the tilted reticle below to polar align then I would be aligning with the blue cross in the first image. The real error you might get by having your reticle not exactly vertical is much smaller than this, because it won’t be this far out, but it’s an error nevertheless and will affect your tracking. 

Remember also that you need to establish the correct (vertical) reticle position (as in the first image) once only, and then mark your mount so you don’t have to do it again - just align the marks on the mount and you know you have the equivalent of image 1 and no tilt as in Image 2. 
 

Yes! I get it now, thank you so much for creating my click moment. What I was thinking while reading this, and before this, was: If I rotate the RA (and the reticule), the red cross won't move, it'll stay centered, because it's a circle obviously. Now it's just clicked that because it started in the wrong position, the alt-az corrections to get Polaris in the (in)correct position will have shifted the view in the scope slightly to the right (of the celestial pole) in your example. Am I on the right track with this now? Thanks again

Edited January 14, 2020 by CaptainShiznit