Star Trailing & Alignment

[coxy322]

I am getting to grips with photographing the night sky now and am trying to understand how to tweak the mount alignment in order to reach a long exposure length.

Although 30-40 and even reached up to 50 seconds this seems to be hit and miss. I decided to try a very long exposure and assess the star trails, perhaps to understand if Alt/Az or Latitude needs going left/right or up/down.

Here is said image (of Vega);

So if trails are coming down and left, then do I adjust up and right? I tried to adjust so much last night whilst at the same time get loads of frames with slight success. Although some frames are much better than others, even on same exposure time.

Any advice welcome. I have a Polar Scope in the EQ5 supplied with the 200P.

Ash

[Astrosurf]

I'm not familiar with the EQ5 (I have an HEQ5 Pro) but I have always been told that to get longer exposures you would need to do drift alignment to ensure as good tracking as possible (time consuming!) or use an autoguiding set-up. I can only get max 50 secs without autoguiding and that's towards the zenith. But I don't know if autoguiding is possible with the EQ5. I'm sure someone be along to help who's not a newbie like me!

Alexxx

[bamus]

Star trials will be combination of PE (periodic error) and PAE (polar alignment error). Providing that you will minimise PAE by doing drift alignment, EQ5 PE will still play significant part in producing star trials on longer exposures (especially with quite big focal length and quite weak EQ5 mount). You have got following solutions:

- Use smaller scope (or lens) with much shorter focal length

- Upgrade your EQ5 to synscan version and do autoguideing (mount will still struggle due to heavy weight of 200P, but 2-3 minutes should be achievable)

- If your founds are limited, you can perform this mod to your scope: http://stargazerslounge.com/diy-astronomer/172701-guiding-conversion-project-200p-eq5.html

[Cloudwatcher]

Was it windy at the time or perhaps the mount nudged during the exposure?

I've had results like that........a flock of birds look......that are not the result of trailing,especially on short exposures but usually due to external forces.