PHD guiding - first use, got some questions

[troypiggo]

I'm very new to this. The 3 opportunities I've had so far to set up with clear skies have been spent just setting up the mount, learning a few "important" stars, and practising aligning using the SynScan 1, 2, or 3 star alignments. Haven't taken a single photo yet.

Last night I got to a point where I was pretty happy with the alignment, so thought I've give PHD Guiding a go and try to take my first exposures. This is where some questions come in.

1. Selecting the camera - I have the Philips SPC900NC and GPUSB, and chose the Windows WDM(?) camera (I assume this was correct?), then the camera (choice of 2 here since laptop has a built-in webcam also), then got a list full of resolutions with letters after them (eg 640x480 QYUX or something like that). At this point I had no idea which one to select, so picked one with max resolution. There were several choices all with same resolution. What do the letters mean and which one should I be selecting?

2. I couldn't get the thing to focus. Was just getting a screen full of white noise. Eventually pointed at the moon and focused on that, then pointed back at some stars. Realised the gamma correction slider was half, so slid it all the way up and could finally make out some of the brighter stars only. Was surprised at the amount of noise. Any way to improve this other than what I did? What if I'm shooting something in a region where these isn't a star bright enough to show over all the noise?

3. After selecting a star and starting guiding, all appeared to be going well for a bit. It was tracking ok (I think). But then the star started drifting out of the "box" and PHD Guiding window started beeping and flashing, and I noticed the star was out of the guide crosshairs. How did this happen? Sort of defeats the purpose of autoguiding?

Any answers, tips, help appreciated.

PS - still didn't get to take any exposures http://www.iceinspace.com.au/vbiis/images/smilies/sad.gif

[Nighthound]

Troy, be patient, you'll have to get the settings right and you'll have to be sure to pick a guide star that is bright enough and very well focused. I'm not familiar with your camera so I can't be of any help on the selection. You can email Stark Labs and ask, the good Dr. will get back with an answer.

What was the exposure time set for on PHD? I use between 1 and 2 sec. Usually 1 to 1.5.

Is your mount going through the calibration process completely before you start guiding? You'll get a feel for star brightness and the exposure needed but you don't want to expose too long or fewer corrections will be made which will result in erratic guiding. Be sure to keep the guide graph on screen so you can watch the corrections and work to get them to a minimum by changing exposure slightly, etc.

I use a calibration time between 2000-3000ms. Calibration takes about 3-5 minutes at these settings. This is a critical process to guide accurately and needs to be performed when you move to different regions of the sky.

Very poor seeing conditions can cause problems for the guide camera/software. Thin clouds and fog can also cause drift off the guide star. Also a good alignment will keep the guider from working excessively hard. I do a quick drift align before I start when possible just to tighten it up a bit.

[troypiggo]

Thanks Steve. The exposure time was set for 0.5s. I'll set it back to the default, which was 1s IIRC.

I did let the calibration process complete. The cursor crosshairs changed to green, so I assume that was it.

I'll sort out the correct settings for my camera in another forum. There are quite a few using same camera at IceInSpace.

Next time I venture out I was going to try drift aligning, so that will help.

Thanks again.

[Nighthound]

No problem Troy. .5 seconds is not long enough. I switched to 1 second to 1.5 and things improved. It's a good idea to watch the calibration for movement in all 4 directions and to make sure there are enough steps being taken in each direction. Don't want it too short or too long. About a dozen in each direction is good.

Good idea to check out IIS. I need to hang out there some, seem like some very nice folks.

[troypiggo]

Been doing some more googling. Discovered that the letter suffixes after the camera resolutions in the camera mode window refer to camera codecs YUY2, IYUV, and I420. The YUY2 codec is newer and so I'll use 640x480 (YUY2).

choose the YUY2 codec, which delivers a higher quality image (and a larger file for the same amount of data).
A 100 frame AVI at 640x480 is about 65Mb with the YUY2 codec, compared to 45Mb with I420 or IYUV.

[A.S.I.G.N. Observatory]

I found that a worn worm and gear drive (sloppy mount) can be a real problem. Once PHD loses the guide star from the box, if it has gone too far the program doesn't know where it is to re-aquire it.

A good drift alignment prior definately helps.

Baz.

[troypiggo]

Thanks Baz. If you could possibly make these clouds go away, I'll be attempting some drift aligning when the weather permits. Since posting above, I have been doing much more reading and noted some things I did wrong last time. :)

[Adrena1in]

I found that a worn worm and gear drive (sloppy mount) can be a real problem.

My EQ5 is worm and gear drive, so perhaps that's partly why guiding's never really worked for me. :rolleyes:

As for the SPC900 Troy, is this the modded one for long exposures? Because I didn't think you could set the exposure time to more than about a fifth or tenth of a second for this webcam. (I've got one...used it a couple of times on the moon and Jupiter, but never saw any stars through it.) :confused:

[A.S.I.G.N. Observatory]

My EQ5 is worm and gear drive, so perhaps that's partly why guiding's never really worked for me. :rolleyes:

As for the SPC900 Troy, is this the modded one for long exposures? Because I didn't think you could set the exposure time to more than about a fifth or tenth of a second for this webcam. (I've got one...used it a couple of times on the moon and Jupiter, but never saw any stars through it.) :confused:

THe worm and gear is not neccessarily your problem, but it could be worth checking the wear. Some scopes have a backlash problem too, this is the space between the splines that gives you play whenever the direction is reversed. Some scopes have an anti-backlash facility that can minimise this.

I have the long exposure mod on my ToUCam.

It can be used for limited long exposure photography, but I think the main aim is to allow you to use dimmer stars to guide with.

The longer exposure gives you more stars to use. Some deep sky objects have virtually nothing around them to guide on.

[troypiggo]

It's not modded. Might try playing with exposure times to see what I can see.

[troypiggo]

It's not modded. Might try playing with exposure times to see what I can see.

[A.S.I.G.N. Observatory]

My EQ5 is worm and gear drive, so perhaps that's partly why guiding's never really worked for me. :rolleyes:

As for the SPC900 Troy, is this the modded one for long exposures? Because I didn't think you could set the exposure time to more than about a fifth or tenth of a second for this webcam. (I've got one...used it a couple of times on the moon and Jupiter, but never saw any stars through it.) :confused:

THe worm and gear is not neccessarily your problem, but it could be worth checking the wear. Some scopes have a backlash problem too, this is the space between the splines that gives you play whenever the direction is reversed. Some scopes have an anti-backlash facility that can minimise this.

I have the long exposure mod on my ToUCam.

It can be used for limited long exposure photography, but I think the main aim is to allow you to use dimmer stars to guide with.

The longer exposure gives you more stars to use. Some deep sky objects have virtually nothing around them to guide on.

[troypiggo]

It's not modded. Might try playing with exposure times to see what I can see.

[troypiggo]

It's not modded. Might try playing with exposure times to see what I can see.

[A.S.I.G.N. Observatory]

My EQ5 is worm and gear drive, so perhaps that's partly why guiding's never really worked for me. :rolleyes:

As for the SPC900 Troy, is this the modded one for long exposures? Because I didn't think you could set the exposure time to more than about a fifth or tenth of a second for this webcam. (I've got one...used it a couple of times on the moon and Jupiter, but never saw any stars through it.) :confused:

THe worm and gear is not neccessarily your problem, but it could be worth checking the wear. Some scopes have a backlash problem too, this is the space between the splines that gives you play whenever the direction is reversed. Some scopes have an anti-backlash facility that can minimise this.

I have the long exposure mod on my ToUCam.

It can be used for limited long exposure photography, but I think the main aim is to allow you to use dimmer stars to guide with.

The longer exposure gives you more stars to use. Some deep sky objects have virtually nothing around them to guide on.

[troypiggo]

Where can I find more about this mod? Is it a software/firmware thing or hardware mod?

[A.S.I.G.N. Observatory]

Where can I find more about this mod? Is it a software/firmware thing or hardware mod?


Heres a link to the camera on my site.
http://www.asignobservatory.com/webcam_astrophotography.aspx

And where to get it....
http://www.telescopes-astronomy.com.au/toucam_philips.htm

Hope this helps mate.

Baz.

[Adrena1in]

Were there Net problems last night? You two posting multiple copies of the same message?! Or is it my eyes this morning! ;)

I think the main problem with my mount was the grease used to lube it...it was like tree sap! Gave it a good clean over the weekend, loosened the RA worm-drive as well as it was very stiff, but I do have a little bit of slop in the RA axis...we'll see when I next give it a try.

I'll report back with any findings on PHD Guiding though. I'd also be interested to hear how you get on, Troy, with using the SPC900 for guiding, in case my Meade ever dies and I need to use the SPC. Ta.