Crose01

I wouldn't tinker with colimation just yet unless you know it's out

Pop a new battery in the Telrad and switch it on low. it works like a gunsight for getting a rough alignment.

Hi Robin Yes I was thinking along those lines but I'm wondering if it may introduce a false positive if I do this process but the Polar Scope Arm doesn't have the same rotational axis as the AstroTrac Mount. I've seen this before doing a PA and then moving the arm and finding that after rotating the PA scope it's quite some distance out. Regards Chris

I have another question if for my AstroTrac I'm getting perfect PA could I use this to calibrate my AT polar Scope? I'm suspecting the answer is no. The PA Scope would have to be perfectly aligned with the polar axis. I use it the other way to get me into the ball park with SharpCap.

Nice setup how did you attach your red dot finder to your camera? Regards Chris

Although I was pretty pleased with the Pleiades image. It was unguided with around five minutes polar alignment error it was unguided. This image was combined using five minute exposures which for 300mm is on the upper edge of the envelope for this mount I am seeing trailing in the 769 Tatjana blog images. This you can see on my blog on my website http://www.digitalastroimager.com/my-blogs/ I eliminated flex and bounce as much as possible and will see if I can improve PA and run with the autoguider next chance I get. Astrotrac claim five arc seconds peak to peak with this setup (RA onlly). It is fun getting good PA though!!! Regards Chris

Have managed a second night and got PA Error down to four arc minutes. Downloaded the latest build of SharCap 2.9 and it seemed to solve quicker. What I noticed was the boxes around the stars didn't have four sides to some of them. What I am finding is if you go through the PA routine a couple of times it gets more accurate. Below is a picture I took of M45 300s x 10 unguided with the AstroTrac

Well I managed to get Sharpcap 2.9 to Polar Align my AstroTrac. SC didn't like the SSAG as it kept erroring out so I had to switch cameras to my Altair Astro GPCAM which worked sort of okay. Had the initial solved in the first image then took ages to solve the second and then didn't seem to register the changes. Did this a few times and eventually got better and better PA. Stopped when I got it down to 6" as I believe the AstroTrac is only accurate to 5" unguided. Anyway hooked up the Nikon D7000 and the 300mm lens and although the images are poorly focussed they show no trailing at 300 second images. Will try again tomorrow night

Well the bits have been ordered and I'm almost ready to try this with my AstroTrac setup where Polar Alignment using the provided PA Scope has been very unpopular and has been the subject of thousands of forum posts. Some users have engineered the QHY PoleFinder to fit the AT Head but after a successful PA they have to remove it and carefully attach the cameras etc which in itself given its a lightweight setup will push it out of PA.. Now with SharCap and an Altair GPCAM plus finder scope I'm going to be able to nail this and get plus 20mins at 300mm unguided and much more using the guiding using AT's auto-guide capabilities. All I'm waiting for now is the German Postal Service and a few clear nights. I will post my results as soon as I've processed them. Well done to Robin this is a superb piece of software . Regards Chris

I used the latest version last night and had sub 30 Arc Secs of Polar Alignment error with my HEQ5 and Altaiir Astro GPCAM. Looking now how I can get it to work on my Astrotrac. Will this work with the Meteor Lens that you get with the GPCAM?

I'd rotate the tube so that the camera and focuser are between the tube and the mount. I would suspect that the combined weight of the focuser and camera maybe twisting you tube ever so slightly as to throw out your secondary. It will have less momentum than on the outside of the curve. I know this is a rigid tube as I use mine for visual work. Regards Chris

I did notice when it got close to PA that the arrow disappeared and was replaced by two yellow lines reminded me of the artificial horizon cursor you see in aircraft. My PHD2 noticed the difference with a much flatter DEC line. RA was a bit chattery but the seeing was pretty awful last night. Regards Chris

I did the Polar Alignment last night with 2.9 using an Altair Astro GPCAM Mono and their 60mm Finder Scope. managed to get my PA down from ~ 12 Arc Mins down to around 57 Arc Seconds. I must admit I'm impressed with this version. It took some tinkering with as I'm having issues focusing this setup but I found it works best with 8 second exposures