Could you please check my PHD settings?

[Johnboy2011]

I have been having trouble finding a guide star, I've focused during daylight and even checked craters on the moon. I'm wodering if the settings are the problem as they seem alot different to others I have seen here. What do you think?

RA Agressivness: 70

RA Hysteresis: 50

Max RA duration (ms): 1000

Search region (pixels): 15

Min. motion (pixels): 0.115

Calibration steps (ms): 1483

Time lapse (ms): 0

Thanks,

John

[George]

You dont say what scope or guide camera you are are using plus it's FL.

As a starting point have you tried increasing the exposure settings and gain?

[Johnboy2011]

Good point!

C9.24 - FR6.3 - OAG - QHY5

[steelfixer]

please ignor this. just getting a link so I can follow this thread. I need help as well.

[George]

Good point!

C9.24 - FR6.3 - OAG - QHY5

The trouble with OAG's is that if there are no suitable guidestars in your targets FOV your always going to struggle, you don't have this problem with dedicated guiders as you can pan the scope around to fund suitable guidstars.

Increasing the exposure and gain should always be your first task if you carnt see a suitable guide star, the settings you mention wont stop you finding a guide star they will only effect calibration and tracking.

[ollypenrice]

...but with an SCT I think you do need to use an OAG, not a separate guidescope, since the possibilities for flexure are considerable. I don't really know PHD but what is the duration of each guide exposure? And are you binning 2.2 with the guide camera?

On the EQ sixes I find they like lots of rapid guide subs, maybe even every 0.5 secs if there are bright stars enough. If not I just up the sub length to a second, two seconds... I always have binned for guiding though I think RobH said he didn't on a recent thread. You could give it a try if you're not doing so already.

Olly

[blackparticle]

What exposure lengths are you taking? Depending on the patch of sky, your guide stars will be faint and few and far between. You might have to go up to 5s to pick one out. A longer exposure will also help guide through the atmosphere.

I'm not convinced that an OAG is essential with an SCT though. I managed 10m subs with a NEQ6/Mak150 guided via a Lodestar+9x50 finder/guider attached to the finder shoe on the scope. If you're really struggling to pick anything out to latch onto for guiding and you've got a finder, then Modern Astronomy do an adapter here > Accessories @ Modern Astronomy

I like the finder/guider approach. You put it slightly out of focus and lock the lens, screw the alignment adjusters down tight so its clamped in there, pick a star and (with some minor settings tweaks) away you go.

[Johnboy2011]

Thanks for the replies. I have tried all gain and exposure settings. Due to cloud I am struggling for opportunities to practice at the moment though, I think I may be resigned to the fact that with some targets I may not be able to find a guide star with the SCT. On my last try I did find a star but then cloud killed the session!

Excuse my ignorance but allthough I have heard of binning I don't understand it or how it may help me guide??!!

Thanks,

John

[Starflyer]

Changing those settings won't help you find a guide star, they're there for tweaking your guiding performance once you've found a suitable star. Having said that your calibration step does look a tad too high for that focal length, I'm using ~200ms at 1200mm fl, you should be aiming for calibration to complete in around 15 -20 steps.

As suggested, increase the exposure time, maybe even up to 5s. When I used a QHY5 / OAG I found that using PHD's dark frame function together with noise reduction brings out many stars that I just couldn't see otherwise.

Are you certain that both cameras focus at exactly the same point? You should get the Canon focused first and then focus the QHY5 in the OAG - from reading your post I'm sure you already know this

[Johnboy2011]

Thanks for that, I have set up the focus during the day so I am happy with that. The last time out I found that taking the dark frames did help quite a lot. Noise reduction is new to me though, how do I go about that?!

John

[blackparticle]

Excuse my ignorance but allthough I have heard of binning I don't understand it or how it may help me guide??!!

Binning is where the camera or software adds up a number of pixels to produce one big one. Binning is a digital version of a focal reducer in some ways.

2x2 binning takes a square of 4 pixels and reduces your image scale by 50% but increases effective sensitivity by 400%

3x3 takes a square of 9 pixels, reduces the scale by 66% and increases effective sensitivity by 900%

I'm not sure if PHD has the option for binning though. It's doesn't appear in my version that I can find.

[Starflyer]

Thanks for that, I have set up the focus during the day so I am happy with that. The last time out I found that taking the dark frames did help quite a lot. Noise reduction is new to me though, how do I go about that?!

John

Click the Brain icon, it's in there under Noise Reduction, play around with the options to see what works best for you

[Johnboy2011]

Thanks for that, some good ideas for me to try!

John