Phd settings

[samir_ansari]

Hi everyone, just had a few questions about using phd in the most efficient way. Are there rules such as "if your target is in the east you do not have to track DEC" etc... as I seem to remember reading something like that a while ago.

Another thing is that when I select my HEQ5 through the ascom interface I get the option for N or S, which should I be using?

Also I have my calibration steps set to 1600 as I found anything lower would give me the "star did not move enough" error, is this value too high - will it affect the quality of guiding?

And one more thing, what tracking aggressiveness have you all found that works best with your setups?

Thanks very much!

Samir

[jgs001]

Samir, I'm using the PHD defaults, the only thing I changed was to set the calibration step to 2500. Never had an issue. As I understand it, you need to vary the calibration step dependant on the location in the sky...

[samir_ansari]

Thanks for that John. I was just curious as I am getting a fair bit of field rotation in my latest images and I have been sure to tighten everything up to try and illuminate flexure as a culprit. There was a thread somewhere (which I can't seem to find anymore) where users were posting their phd tracking graphs and talking about settings to smooth it out a bit more.

[jgs001]

The calibration step is just used to allow PHD to determine the movements required for the guiding process itself. It won't have any effect on the operation once calibrated (unless of course, something goes wrong in callibration that is ).

I don't think adjusting PHD settings is going to affect field rotation. That, as I understand it, is more of an effect of polar alignment, rather than inaccuracies in guiding.

[rfdesigner]

I don't think adjusting PHD settings is going to affect field rotation. That, as I understand it, is more of an effect of polar alignment, rather than inaccuracies in guiding.

Correct. Field rotation is a direct result of polar misalignement, not much else can achieve that error.

Agressiveness?.. I'm around the 100 level. With the mount at 1x guide rate, ~1 arc sec / pixel at the guide cam.

Derek

[samir_ansari]

Ok great, thanks John and Derek. When the weather sorts itself out I will have a look at what could be causing such inaccurate polar alignment. I never had a problem and always achieved a good polar alignment by using the clock on the hand controller, maybe my polar scope reticule has been knocked off centre...

[rfdesigner]

The polar scope will only ever get you close.

With long imaging shots you may well have to drift align.

I haven't drift aligned for a while now, used to have to do it every time when I was stuck with 1 hour shots to prevent field rotation, but with shots of a small handful of minutes it isn't so bad.

Derek

[samir_ansari]

I used to be able to manage 30min subs with no field rotational problems at all, it's only recently that I've been getting such severe trails

[samir_ansari]

Ok, I found out what the problem was. The front leg of my mount was loose!

[jgs001]

Ah... that would be problematical.. ... did something similar with mine... lostened the head (just by a small amount) to allow me to adjust the Alt position more easily and forgot to tighten it up again ... wasted the whole session before I realised what I'd done (carrying it in again and felt it shift slightly..)

[samir_ansari]

Well mine was much more of an obvious realisation - the leg snapped off my mount altogether! It must have cracked a long time ago and been shifting ever so slightly over time.

I'm just glad I was around to catch my telescope and camera before it all smashed into the ground! I must say I am very disappointed that this can happen with a mount that cost as much as an heq5 pro.

[jgs001]

Ow that could have been very nasty... I thought you meant it hadn't been tightened up properly. Glad everything (except the mount) and you is ok.

[Reggie]

Wow, I have a heq5 pro and haven't seen any issues with the leg breaking, however, my nexstar mount suffered the issue where the thumbscrew fitting broke off, it's relatively cheap plastic so it's pretty prone to idiots (me) overtightening when you first get used to using them, it took a number of years for it to finally break, did a fix with polymorph though, so all good now.