Guiding problems

[MarkS]

Amongst other difficulties last night, I had one of those weird guiding problems. 
Guiding quite happily and then for no obvious reason the guidestar drifted off. 
Reselected guidestar but it drifted off again immediately.
Restarted PHD but GPUSB was unable to find the mount. 
Aha!  That must have ben the cause.
Pulled out the GPUSB USB cable (N.B. it wasn't loose) to reset GPUSB electronics and plugged it back in.
Restarted PHD,GPUSB found the mount, I recalibrated, then all was fine.

[mickw]

A little bird is reminding me that you never  read instructions.....................

Shuddup 

[Carole]

Right well I have checked everything now methodically and can't eliminate anything, and guiding STILL will not work on either of 2 Mounts, or 2 laptops.  

I have come to the conclusion that it might be the guide camera as I could not seem to get sharp focus on a star last night no matter how much I tried, calibration failed every time, so am wondering whether it has got some moisture inside the camera from leaving it in the Observatory despite having a dehumidifier in there.  YES I had the dew heaters on and the scope was not misted up.  

This is the same camera that I had problems with last year which would not work on LX and so it got relegated to a Guide camera.  Up until now it has worked OK, but just as the damp weather is starting suddenly things start going wrong.  I would quite happily buy a new camera if I knew for certain this was the problem or at least keep ithis one indoors in future if drying it out works. 

Mark has kindly offered to help me as apart from keeping the camera indoors over the next week to see if that makes any difference I have run out of ideas now.  

Carole

[The Thing]

Stick the camera in the airing cupboard, even my scope goes in there if its got really dewy.

[Carole]

Yep I think I'll give this a try.

Carole

[Rocket Pooch]

I love my QSI QHYCCD and AstroArt, I just don't have these problems......

[MarkS]

Can't get focus on a star?  That would certainly cause problems with guiding.

What do you mean by it?  Do you mean that there is not enough movement on the focuser to bring the star into focus.  Or is it that the star does not appear very sharp even at the point of best focus?

Try it in daylight (focus on a distant tree for example) before you dry the equipment out.  If again it is "blurry" at the point of best focus then build up of condensation somewhere in the imaging train does sound like a likely cause.  But this ought to be pretty obvious just by examining the CCD itself and by looking through the guidescope.

Is it still the Nikon lens you are using?  I'm still using mine.  But they do need to be stored in the dry to stop fungal growth inside.

Mark

[Mac]

apart from keeping the camera indoors over the next week to see if that makes any difference I have run out of ideas now.

Stick it in one of those zippy food bags with a desicant pack inside.

you know the ones.

[Carole]

This one -

the star does not appear very sharp even at the point of best focus?

Try it in daylight (focus on a distant tree for example) before you dry the equipment out.

Oh dear, already started drying it out.

Will try a tree today. 

Carole

[Mike]

You'll have a job trying to dry a tree in this weather.

[Carole]

Not been able to get any further due to cloud, but tonight I got outside after having had the guide camera in the airing cupboard for 1 1/2 weeks and thought I'd try guiding on a bright star and picked Aldebaran.  Calibrated in W & E, but failed in N and it automatically switched the Dec guiding off, this happened several times, but when I clicked OK to the "Dec guiding closing down box", it went into guiding happily in RA only.  then after about 5 minutes lost the star which wandered away from the crosshairs and eventually PHD gave up.  

Scratching my head I rang Mark who is down with a cold and unable to come over as planned, and he said he could offer no explanation.  I'm now completely foxed.

Anyway, went back to scope and thought I'd do some unguided imaging instead, and by this time the Guide scope was no longer pointing at a bright star, and I clicked on guiding for the hell of it, and hey presto, it's now working.

So it looks as though it must have been moisture in the Guide camera.  But not sure why it wouldn't calibrate on Aldebaran.  

Been a nightmare to sort out.

So busily imaging at the moment - Yippi

Carole

[The Thing]

Hi Carole,

Try picking dimmer stars. I calibrated PHD while pointed at Cappella, but I didn't use that, I used a nearby star that was just visible on my QHY5 using a 2 second exposure. Bright stars are too big (that's what I've been lead to believe), small stars are more pointy sources that PHD can more easily work out the centre of when doing it's calculations.

Happy guiding.

Duncan

[Carole]

Bright stars are too big

Yes I hope that was the reason.

QHY5

I'm seriously thinking about buying one of these now as this camera has given me nothing but grief ever since I bought it (do you remember it was the one that wouldn't do LX and in the end I gave up and bought a DSLR and decided to use it as a guide camera. 

Carole

[The Thing]

Hi Carole,

The QHY5 was a good purchase. It just works, nice wide fov (big chip) so plenty of stars to choose from. Also with your mount you could use an autoguider cable and have fewer things connected to your laptop which must be a good thing.

Duncan

[Carole]

you could use an autoguider cable

Is that different to what I have now?

I have a GPUSB cable attached to an RJ12 which is one USB plugged into laptop.

Thanks
Carole