HELP! Guiding Now Trouble!

[Astrosurf]

I'm tying to guide using PHD and it keeps saying the star is not moving enough. I'm not on a hot pixel. This has been happening lately. I've increased my calibration steps and ensured my leads are all connected well. What's happening?!!!

Alexxx

[Stephen]

ST4 or pulse guiding?

[Stephen]

How many pixels is it moving during calibration? (Watch the status bar)

[Astrosurf]

ST4 I think??? it's a finder-guider with a QHY5. There are numbers on the status bar but they mean nothing to me! I've reduced the min motion pixels in the brain option to 0.20 hoping that would help.

Now a band of clouds has move over. Only a small one but, grrrrrrrrrrrrrrrrrrrrrr!!!!!!!!!!!!!!

[Astrosurf]

Nope, it's a big cloud. I've had nothing but trouble setting up and now this. I'm selling my kit! :mad: :mad: :mad:

[Stephen]

OK the number I'm really interested in is the last one, I think it's in brackets. This tells you the amount in total (in pixels) the image has been moved by PHD

If this is not increasing, the image is not moving at all

[Astrosurf]

Thanks Stephen, but tonight's a washout. I've got clouds. I don't know why PHD has started saying this. It never used to.

The number in brackets is 25 from the last failure.

[Stephen]

Right I'm wrong then, it's the next one in as 25 is what it's trying to get to.

Might just be easier when you try this again to let it get half way through calibration (30 steps) and take a screenshot and post that?

[Astrosurf]

Here's a screenshot. I've increased the Min motion (pixels) in the brain option to 1.0. No luck.

[swag72]

If it's been getting worse over time, I'd be looking at replacing the ST4 cable and seeing if that sorts the issue. I've got through a few cables in my time, both ST4 and EQDIR - It starts off as total unreliability and little explanation as to what is going wrong. Ends in a lack of communication to the mount in any way.

[Astrosurf]

Thanks Sarah. I did that. I got a cheap on from eBay which was useless then I got one from FLO. It worked last time by increasing the calibration steps. Here's a screenshot of my current PHD settings.

[Stephen]

Right, well we can see it's moving from the screen shot - increase the calibration step to 1500 and you should be good.

Sara's point is good though, the cable could be going out

[malc-c]

Alex,

You need to increase the calibration steps and MAX RA foruse with short focal length scopes.  I use an ST80 with teh Qhy5 and mine are in the region of 2750ms steps... I'm guiding now but when stopped I'll post up my calibration settings later

Edit:

Clouds coming in now so I'll call it a day - here's my settings

And a screen grab of it in action whilst capturing subs on the supernova

[Astrosurf]

Thanks Malcolm. I'm using my 200P 1000mm FL.

[James]

+1 for Malc-c and Stephens advice to up the calibration step, with my little 50mm guidescope my calibration step is 2200ms 

James

Edit, in my case the Max Dec is much higher too

[Astrosurf]

It's guiding now but what the &*&&(*& is this?!

[Stephen]

It's drifting terribly, is your PA ok? Backlash problems? Balance?

It's basically pushing the same way each time and it thinks (OSC index) that it's never going to have to push back the other way

[Astrosurf]

I didn't understand that, except balance! Dunno about PA. It's normally OK.

[Astrosurf]

I'm now having to image unguided. I can do 45 secs OK so have increased the ISO to 3200. I know it'll be noisy but if I take enough I hope I can process some out. I'm doing M81 and M82 for the SN.

Thanks for your help guys. I think I might need one-to-one if this carries on!

[malc-c]

Alexx,

Reset everything back to default as you had it before, except change the calibration steps to 2000 and see how that fairs.

Guiding can be a pain in the proverbial, one target works fine then the next is all over the place.  This normally suggests that the scope is either not Polar aligned, out of balance, binding (gears or cables) or all the above !

You also might want to increase the exposure to 1.5s if the calibration step is 2 seconds or more.  This will also make the stars more prominent so you can move the slider to get a darker background, which helps PHD detect the movement

[malc-c]

Thanks Malcolm. I'm using my 200P 1000mm FL.

That's the FL of your 200P.  But you are using your finder as the guidescope which has a much shorter focal length, hence the need to increase the calibration step settings

[Astrosurf]

I've just thought, could I be polar aligning the scope too well which is why the star doesn't move that much??

[Stephen]

I've just thought, could I be polar aligning the scope too well which is why the star doesn't move that much??

No

[malc-c]

I don't think so...

[malc-c]

I was trying to be polite... Stephen says it a sit is