Problem with PHD

[Looking Up]

Hi, I have an eq 6 pro and guide it with PHD but I can't seem to get consistent results, I tried to guide with it a few days ago and the graph looked like the Himalayas:mad:! I took this pic of the Leo Triplet last night, it's 10 mins unguided and although the stars are slightly elongated I must be close to aligned as there's not much movement. I have noticed when I press a move button on the handset it keeps going a little after the press. The second pic is a 4 image stack x 10 mins, with 2 darks. I do have problems finding stars for phd, is this because the etx 105 is a very slow scope?

[jgs001]

Wow, 10 minutes unguided, that's excellent. I think the etx105 is a Mak, which means a very long focal length, a narrow FOV, which when combined with the QHY5 with it's small sensor, becomes really tight, and it's slow. You're best bet, is either to make a finder guider and use that, or to invest in an ST80 or clone. The ST80 makes a great little guidescope, 400mm f/5, short and fast. I very rarely fail to find a star directly in the FOV with my QHY5v (and that has an even smaller sensor than the 5).

I don't know much about reading the graph, but it might be that the focal length of the guide scope, in this case, means you have to decrease the aggressiveness of the settings, so that PHD doesn't fight itself on small motions of the mount...

[Zakalwe]

I'm new to guiding as well, and was really struggling. I set up the other night and had a decent result though....The biggest change I made was to unbalance the scope. I set it up camera heavy in Dec and counterweight heavy in RA. Not massively, but enough that it would rotate down under it's own weight.

Also, make sure that you aren't selecting a hot pixel....my QHY guidecam has a few, so I am super-careful not to select on by mistake.

My PHD graph looked like this...before unbalancing it was all over the place.

[Zakalwe]

Ohh...and if I could get 10 minutes unguided, then I wouldn't bother guiding at all.

Is there any need for a sub longer than 10 minutes if you are using a DSLR or CCD??

[Looking Up]

John,sounds like i need a st80 then, I thought the 105 would be unsuitable but since i had it anyway.... I am in the process of choosing an APO which is proving difficult as I can't decide, and I'm not sure if the canon fd 500mm has lost some of it's quality, it is quite old!

Zakalwe, I think I do need to guide, the stars are elongated and that must introduce loss of detail, and i get much move movement at lower elevations - your trace is nice and flat - will try the unbalancing - when you say camera heavy in dec do you mean the scope is biased towards the camera end? Difficult to do with my Canon lens, its very heavy at the objective end cos of short foot it uses, maybe that is a problem!

[martin_h]

I dont think it matters which end is heavy in Dec, its only to keep the gears tight against each other. Its best to get it balanced first then move it a bit.

[jgs001]

It's always worth a try, but I think an ST80 type scope is gonna work much better for you. You should also, still be able to balance the camera and lens combo on the mount... if you can't then consider getting a longer dovetail and mounting the camera onto that... than you have the flexibility to adjust it's position in the mount.

[astromerlin]

I have noticed when I press a move button on the handset it keeps going a little after the press.

I had the same problem on RA axis. Read somewhere it's the worm shaft binding on the worm wheel. I slackened the adjustment off a bit and the problem went away.

Worth a check..

[Looking Up]

John, Can you remember the procedure for slackening off the adjustment?

Spencer