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Hi, 

last night I PA with SharpCap and got an excellent for PA. 

I looked through my polar scope out of curiosity and Polaris wasn’t where I would of thought it would be? This normal? 

Also  even after PA in SharpCap I was still getting oblong stars (especially the smaller ones) for 60s unguided. 
 

ive checked my balance and everything seems balanced. 
 

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How far out was Polaris in the polar scope? I use Sharpcap every time also. Its very good. But perfect polar alignment doesn't mean you will get perfect tracking. Still need to guide to compensate for periodic error etc

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9 minutes ago, david_taurus83 said:

How far out was Polaris in the polar scope? I use Sharpcap every time also. Its very good. But perfect polar alignment doesn't mean you will get perfect tracking. Still need to guide to compensate for periodic error etc

When looking through the polar scope it was inside the middle circle of the reticle but not where an app like PS align says it should be. 
im just asking as I’m trying to figure out why after PA with SharpCap I was getting oblong stars unguided at 60s. I’ve checked the balance and to me it’s balanced. 

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The tripod being level makes no difference. The polar axis has to be aligned regardless. I would suspect that the polar scope reticle is not aligned in the polar scope. 

I use to scope to make sure the polar axis is roughly aligned and then sharpcap to align.

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1 minute ago, david_taurus83 said:

I've had 3 SW mounts. EQ5, AZEQ6 and Star Adventurer. Not one of them had an aligned polar scope when I got them. The AZEQ6 was brand new and the polar scope reticle was loose!

This is my second pole scope for my mount as the first one I tried to calibrate it and one of the small screws fell into the chamber... that’s why I bought SharpCap pro! 

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Set up SharpCap PA tonight, got an Excellent for setting it up took like 5mins all good. By the end of my play around it was sitting at Fair... 

Should it really shift that much?

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  • 2 weeks later...

I recently used SharpCap to polar align my EQ6 and I have to say I was impressed by how quick and easy it was to do. As you probably know the software provides two methods of adjusting the PA. The first is by adjusting the mount until a highlighted star - later two parallel lines - coincide with each other. The second is by watching the RA and DEC offsets reduce in magnitude as you adjust the mount.  If using the latter method it is important that SharpCap knows your latitude and longitude for accurate results. I managed to get my PA down to 25 arc sec, and the reason I could not get better than this is because the adjustments on the EQ6 were just not fine enough to achieve any better, so it is a very sensitive procedure. Just mounting a scope on the mount can shift the alignment by a small amount, particularly if it is a big heavy OTA.

As for your star trails, if they are east-west then it is most likely down to periodic error, if at some other random direction then probably polar alignment.

Since doing my PA I haven't had a clear night to try it out. When I do I will report back and let you know my findings

Good luck and clear skies

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  • 2 weeks later...

Are you guiding or planning to guide?

Do you have backlash in your RA? You may find a perfectly balanced mount is 'floating' between the gear teeth. Try and offset the balance to the E so the weight pulls the gears together and hopefully reduces the bouncing / floating.

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Having precise polar alignment doesn't compensate for backlash  or PE in the mounts drive train.  Even if perfectly adjusted your EQM-35 has a 2.8 arc second resolution, so you can expect some drift.  If you factor in PE, backlash and any balance issues then it can be noticeable when imaging (visually you wouldn't notice).  This is why we all use guiding when imaging.

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