Polar Alignment Result - What do you think?

[bendiddley]

Hi guys. So I finally made it out with my EQ3-2 tonight to test out setting up and polar aligning for the first time since buying it about a month ago, I am a newbie to EQ mounts having been a dob user till now so wanted to spend an evening just doing this to get my head round it. I am intending to use the mount for wide field imaging up to 300mm using only a DSLR. Having set the mount up I used the polar align app to view the position of polaris and matched the position by eye by rotating in RA until it looked the same, then I tweaked the alt/az bolts and got polaris in the centre of the small circle. Basically having positioned Polaris here and switching on my motors, it stayed within that small circle for 30 mins. By the end it was just touching the edge of the small circle. So what I want to know is, how does that rate? Is that the normal amount to be expected for a visual polar align, better than normal, worse than? Let me know what you think so I know if I need to try harder or if I'm doing OK. I'm hoping this is good enough for my intended purposes. Cheers.

[Knight of Clear Skies]

Sounds good to me. I sometimes check where Polaris is at the end of a session, I've never had it still touching the circle so that's probably better than I've managed. The longer the focal length and the longer the sub the more critical alignment is. I've managed 150 second at 135mm without problems but I have more trouble with periodic error from my EQ3-2, causing me to discard maybe 20% of my subs. When I can find the time I'll try stripping the mount down.

[JRWASTRO]

Greetings Ben D.

Re:  ... it stayed within that small circle for 30 mins ...

Sounds pretty good to me  BUT you have lined up on a star pretty close to the NCP . The test will be to see how long an object stays centred when the object is on the celestial equator (0 degrees or there abouts in declination ... the star delta-orionis for example.

Jeremy.

[bendiddley]

Sounds good to me. I sometimes check where Polaris is at the end of a session, I've never had it still touching the circle so that's probably better than I've managed. The longer the focal length and the longer the sub the more critical alignment is. I've managed 150 second at 135mm without problems but I have more trouble with periodic error from my EQ3-2, causing me to discard maybe 20% of my subs. When I can find the time I'll try stripping the mount down.

Thanks. What's periodic error?

[bendiddley]

Greetings Ben D.

Re:  ... it stayed within that small circle for 30 mins ...

Sounds pretty good to me  BUT you have lined up on a star pretty close to the NCP . The test will be to see how long an object stays centred when the object is on the celestial equator (0 degrees or there abouts in declination ... the star delta-orionis for example.

Jeremy.

Good call.

[Knight of Clear Skies]

Periodic error is any unevenness in the gears or smooth running of the motor causing uneven tracking. Lubricating the gears and adjusting the tension may help but at the moment I'm just living with it.

[bendiddley]

Periodic error is any unevenness in the gears or smooth running of the motor causing uneven tracking. Lubricating the gears and adjusting the tension may help but at the moment I'm just living with it.

Cheers