Jim Smith

15 minutes ago, Pitch Black Skies said:

You can power your guide cam with a very short cable running from your main cam

??? My guide cam doesn't have a separate power cable.

7 hours ago, alacant said:

Rotate the whole tube in the rings ~180º so that the camera is toward the ground.

Done! Yes, that is a better arrangement for balance and cable runs. Thanks.

14 minutes ago, barbulo said:

Why would you need a finder having the capability to plate solve?

At the moment I have not yet researched plate solving. I do not know what I need or how it would work with other software. But fear not, it is on my list of things to do!

7 minutes ago, spillage said:

@Jim Smith

How is the balance of the scope when you release the clutches? I would route the cables from the scope down the dec and along the ra if you have enough cable to allow dec full movement. Not sure if you are aware how much rotating the scope in the tubes also helps with balance.

 

*Might be worth loosing the telrad and using plate solving instead.

I took the photo after loosening the clutches and balancing in RA and DEC. It balanced just fine as shown. 

I probably need longer USB cables. Are there special light, flexible ones that can be used?

Good point about rotating the scope. I can see how balance would change if you did.

I like the Telrad for "sanity" checking that the scope is pointing in about the right direction!

Once I have autoguiding working I'm going to take a look at dithering...plate solving could be after that...

Here is my new set-up with the longer, Losmandy dovetail bar. (Since fitting the Telrad finder, I had a lot of trouble finding good positions for the tube rings that also allowed me to get balance with the original Vixen dovetail with it's screwheads poking out the bottom. Also, it was green!) This should be much more stable and might help with my autoguiding problems. I also need to think about organising the cables a bit better. It's too easy for them to catch and rub at the moment.

1 hour ago, Clarkey said:

Thinking about this a bit more I was wondering how you are guiding - I assume a directly from the PC using a EQDIR cable.

Yes...Lynx Astro FTDI EQDIR USB Adapter for Sky-Watcher Mounts to Windows 10 laptop running PHD2, EQMOD and Sharpcap.

1 hour ago, Bibabutzemann said:

Is this a new mount?

About 6 or 7 years old I think.

3 minutes ago, alacant said:

That's fine.

Post the phd2 log if you like.

Thanks. Guide and debug logs attached.

PHD2_DebugLog_2022-05-04_220035.txt PHD2_GuideLog_2022-05-04_220035.txt

1 minute ago, alacant said:

EQMOD under windows defaults to 0.1; make sure the guide rate is set at at least 0.5.

I think it was at 0.7 ... but I will double check.

29 minutes ago, alacant said:

I doubt the graph corresponds to the image, but who cares? Look at the image, not the graph!

For such a short length of time, it's an excellent shot, with nice stars which are free from the usual skywatcher diffraction spikes and Baader cc edge abberations. You have a well collimated, adjusted and tweaked 130pds there. Like it.

Exposures are timestamped from 22:40 to 23:35 and I only had one mount set up so I think they are coincident with the graph.

Thanks. I was pleased with the result. It made me wonder if autoguiding is worth the effort for 30s subs at 650mm focal length. I might throw away fewer exposures but if I spend time getting autoguiding to work is it gaining me anything?  I will try again though.

1 hour ago, Bibabutzemann said:

this looks strange. Are you sure the mount received guiding commands? Normally you can hear that. What type of guiding setup are you using? Ascom Pulse Guiding? 

Im still impressed of how much signal you could gather. Do you have low light pollution?

I'm new to autoguiding so I'm not tuned into the mount noises yet. I zoomed in to the graph in the log viewer and there are lots of long pulses shown. It was trying. I don't think the scope was very stable relative to the dovetail bar in the mount. The tube rings were only about 4" apart for various reasons. I received a new longer dovetail bar today and my new configuration will be much more stable. I'm going to try that out and see if it helps.

Yes, Ascom pulse guiding - EQMOD and PHD2

I'm Bortle 4.

Leo Triplet from last night. I've been trying out autoguiding and it's not working out very well. See graph at bottom from session which gave me the image below! 

But as I only use 30 second exposures I can use most of them anyway.

16 hours ago, Astro Noodles said:

Noticed a periodic error on my iOptron Skyguider Pro.

Never had it before, but I think I might be getting close to the weight limit the mount can cope with.

Would using a mount close to it's weight limit cause periodic error to be more pronounced?

If it is closer to its weight limit because you are using a greater focal length optic then that would make periodic error more noticeable.

2 hours ago, michael8554 said:

The fact that you tried to Calibrate at Dec=90 suggests you haven't read the PHD2 instructions ?

Well...I read some of them! Thanks for the suggestion regarding guide rates.

Jim

1 hour ago, Jim Smith said:

Thank you. Dithering is on my list of things to try. Can I do dithering with my Sharpcap, EQMOD and PHD2 software or would I need to use NINA or similar?

I did a bit more research and I now see that I can dither with Sharpcap Pro and PHD2.

16 minutes ago, malc-c said:

I think you are supposed to calibrate on a star close to the intersection of the meridian and celestial equator as there is where the Earths rotation is most noticeable.  Calibrating near the NCP is practically the opposite.

Yes, calibrating near the NCP failed...even though I tried it several times!

4 hours ago, barbulo said:

Next step should be dithering

Thank you. Dithering is on my list of things to try. Can I do dithering with my Sharpcap, EQMOD and PHD2 software or would I need to use NINA or similar?

I bought a small WO guide scope, inserted my Altair GPCAM3 178C planetary/lunar camera and attached it to my Redcat 51 with ASI 533 MCP. This was mounted on my SW AZ-EQ5. I used PHD2, Sharpcap and EQMOD on my laptop with 3x USB cables running to the cameras and mount.

It all went pretty smoothly apart from trying to calibrate PHD2 using a star too near the North celestial pole. I heeded the error messages and all seemed OK when I pointed further south and recalibrated.

The video below shows an unguided run using the same set-up, followed by a guided run from a few days later. Each run was 120 x 30s exposures. The video is at 10 fps so each approx 1 hour run lasts 12 seconds. The images are 1000px X 1000px crops of the original 3000px X 3000px exposures. So each frame is about 52 arcminutes high and wide.

The guiding has clearly improved the mount's tracking. Should I be happy with this result or should I expect be better? I have posted PHD2 log analysis below.

2 minutes ago, neil phillips said:

The jet stream forecast was way off by hours.

I seem to recall that MeteoBlue forecast 39 m/s for my location so I wasn't expecting much. I think computer modelling of complex systems like the weather has some way to go yet!

16 minutes ago, neil phillips said:

Was this last night. 

Yes, it was. About 21:00 to 22:00 BST

Two, five minute MONO8 .avi videos captured with Sharpcap. Best 1200 frames of 7500ish chosen by PIPP. Best 57 frames stacked by Autostakkert. Levels and curves in Affinity Photo. Noise and sharpening in Topaz Denoise AI.

Altair GPCAM3 178C 1/250s gain1600

StellaLyra 8" Classic Cassegrain on SW AZ-EQ5 GTI

1 hour ago, bottletopburly said:

bit of walking noise which Dithering would sort

I have yet to try dithering. I'll put it on the list!

1 hour ago, rotatux said:

I can see double spikes on some, but none clearly offset from centre ; I read this can be caused by twisted spider vanes.

I will check the spider vanes.

4 hours ago, barbulo said:

Might be wrong but I'd say it is a bit out of focus: the four long diffraction spikes should be thinner.

I used a Bahtinov mask but focus may have slipped afterwards.