2nd night of tracking (ever!)... still very much a work in progress.

[djdurance]

This was my 2nd night out with the Star Adventurer mountb... Went for M13 due to the position of the moon last night. Single shot at 150sec. No edits except for cropping in. Canon 450d, 55-250mm lens @ f7.1. I was shooting at 250mm. I didn't start stacking the pictures as there is a bit of star trailing. Any over 30 second had a bit. I assume I'm not getting my polar alignment right? It seemed "just right" and I'm on a good tripod that appeared to be level! New to the tracking business but I would like to be about to get 1-3 min subs!

[Gfamily]

Have you checked the alignment of the polar scope itself? There's a good SGL post here that outlines what's needed, and it can be a daytime check.

 

[djdurance]

6 minutes ago, Gfamily said:

Have you checked the alignment of the polar scope itself? There's a good SGL post here that outlines what's needed, and it can be a daytime check.

 

I did a quick check of this when I got this a few weeks ago... but probably should check again in more detail to make sure! I'll do it before another try tonight. Btw, do you find that you can get the stars to be "sharp" in the polar scope? No matter what I do with the focuser it always seems a bit blurry to me.

[Marvin Jenkins]

2 minutes ago, djdurance said:

I did a quick check of this when I got this a few weeks ago... but probably should check again in more detail to make sure! I'll do it before another try tonight. Btw, do you find that you can get the stars to be "sharp" in the polar scope? No matter what I do with the focuser it always seems a bit blurry to me.

You should be able to gain focus by rotating the eyepiece, unscrewing/screwing in. If that fails unscrew the polar scope ep and check to see it is clean. When installed they are quite greasy and mine had a decent smudge on the optic.

M

[Gfamily]

1 hour ago, djdurance said:

I did a quick check of this when I got this a few weeks ago... but probably should check again in more detail to make sure! I'll do it before another try tonight. Btw, do you find that you can get the stars to be "sharp" in the polar scope? No matter what I do with the focuser it always seems a bit blurry to me.

The other point raised in that thread is the benefit of using the L bracket as it means you can re-check the polar scope after centring on the target.

But that's only an issue if you're not using the L bracket.

Hope you get it sorted anyway.

[djdurance]

2 hours ago, Gfamily said:

The other point raised in that thread is the benefit of using the L bracket as it means you can re-check the polar scope after centring on the target.

But that's only an issue if you're not using the L bracket.

Hope you get it sorted anyway.

Yes, this is a great idea. I may try using my ball head right on the L bracket tonight and leave things as 'untouched' as possible. 

[Kyle Allen]

I might be wrong but it looks like the stars trails are along the RA axis so that would be periodic error not polar alignment. Before I started guiding my Star Adventurer, I found that exposures longer than 30 seconds would have slight star trailing. 

[Seelive]

To check if it's perodic error and/or polar alignment, take a sequence of short exposures (say 15 sec each) with a reasonably bright star (near the meridian and 0 deg dec) in the field of view for over a period of at least 8 minutes (1 worm wheel rotation for the SA?) without disturbing the mount/camera position. Keep the gap between exposures as short as possible (say 5 sec max) and then stack the images without alignment. Any polar alignment error will show as a vertical drift and any periodic error will show up as a horizontal 'wiggle' either side of an imaginary straight line representing the drift.

[djdurance]

I had a much better night last night. I backed off to 135mm on my lens and was able to take 25x80s exposures that were good. I took this under bad light pollution and a moon that came out in the middle of the night.  More work to be done! But feel okay as this is my 3rd time trying this!