Plate solve and deep sky image annotation

[dasman]

I have an issue with getting my desired object into the image or FOV with my 9.25 SCT. I have the proper focal length selected in sharpcap settings (2350). I have tried with both ASTAP and the new native sharpcap plate solver and the results are the same. When I plate solve and resync it is successful. Then when I go to an object (let's say Capella), the object is not in the image. I will plate solve again (successfully) and then use deep sky image annotation. In here I will hit the tab that says objects nearby. It will show Capella and tell me that it is just off the image by X number of pixels. Then with Capella highlighted I hit the button that says center in view. Capella is now off of the image to the opposite side. So, if sharpcap knows the image is say 1500 pixels above the image, why does sharpcap not put the image in the center when the center in view button is hit?

The number of pixels the object misses my image by varies, but it is usually close (between 200 and 2000 pixels). Am I missing a setting? When I was plate solving with my 132mm refractor(925FL), it was perfect.

I have 2 mounts an HEQ5 and an HEQ6. The problem is the same on both mounts.

[admin]

Hi,

you could try using the 'plate solve + sync' button more than once to see if it helps - normally once is enough, but if your mount movements are not accurate for some reason (backlash, etc) then maybe a second try would help as it should have less correction to do than the first try, so less chance for error to creep in.

Certainly with the plate solving succeeding, but then not bringing the target to the right place, I am thinking about mechanical issues (backlash, movement in the imaging system, etc) as being the most likely cause. Obviously the longer focal length makes everything more sensitive to errors, and potentially the increased weight of the 9.25" over the refractor may put more load on the mount. Thinking about it, do make sure that the mount is relatively well balanced with the SCT as bad imbalance could cause issues with movements being inaccurate.

cheers,

Robin

[dasman]

Thanks for your reply. I will try 2 plate solves. However the Heq6 pro mount has a belt drive so I believe backlash should not be an issue? The HEQ6 mount is good to 44 lbs and the total weight of my astrophotography equipment is 28 lbs. So weight shouldnt be an issue? My HEQ5 mount is gears and a lower weight limit (30lbs), and the errors were consistent with the HEQ6. Hopefully someone else has experienced these issues and will chime in. Thanks again!

[kaymann]

... Hopefully someone else has experienced these issues and will chime in. Thanks again!

Yes, same here planets are never centered and when I use the crosshair reticle to confirm it is not centered I find it 1/8 screen diameter away. My polar alignment is such that once I manually center the planet, I am good to go for the entire night. This makes planetary hard as I have to use my guide to plate solve and my scope camera shows nothing. (C 9.25 with a 2.5 Barlow never shows enough stars to plate solve. This is after PS SYNC RECENTER for at least 3 tries always show up in the same wrong spot. Next clear night I will try PS SYNC REC in NINA to see if the problem is replicated...

[Chris_h]

Backlash. My EQ6-R Pro has belts as well. It has less backlash than my geared EQ6, but still enough to cause ''problems'' at long focal lengths.

I have also found that resyncing in Cartes du Ciel only works well for that night. The next time I am out, it will miss again. Then I was told to recenter the telescope manually by loosening the clutches (remember to clear all stored alignment points before you start). A real pain at these focal lengths (make sure your finderscope is aligned!), but it cured the problem. GoTo might not put it dead center, but it is usually on the chip somewhere. That is with my C9.25, 3x barlow and ZWO585MC.

[kaymann]

... I was told to recenter the telescope manually by loosening the clutches (remember to clear all stored alignment points before you start). A real pain at these focal lengths (make sure your finder scope is aligned!), but it cured the problem. GoTo might not put it dead center, but it is usually on the chip somewhere. That is with my C9.25, 3x Barlow and ZWO585MC.

Could you clarify above because loosing the clutches on my C9.25 with a 2.5 Barlow and my ZWO ASI533MC Pro is a deathtrap for my sanity. Owning one I think you know what I mean. My guide scope with a Askar 32mm f/4 is aligned and the only thing that keeps me on the sane side of life... In fact, my above setup simply will not allow me to plate solve on the main scope not enough stars ever So it is guide scope or nothing at all

Just a bit more detail please as I would like to resolve this, and thank you for passing on anything that worked for you!

[Chris_h]

Well if you have a guidescope that is dialed in, you should have no problem with this step

I just remove the barlow, and inserted a diagonal and a low eyepiece. It will be out of focus, but you should still be able to center the star/planet. Add the barlow and redo the step. Then finish off with your camera. One tip is to not open the clutches all the way, just enough so you have a bit of smooth friction going on. Not saying it is easy, but it is very doable. Took me about 5 minutes