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This blog contains recent projects, activities, and musings about astrophotography and space, to view my main webpage with prints for sale, final images, and Annie's Astro Actions, please visit: www.eprisephoto.com


Saturday, November 14, 2009

A Balancing Act

I knew it would be inevitable - I would have to get a counterweight system at some point to balance the CPC. Yes, it is perfectly balanced when you get it from the factory, assuming you keep with the 1.25" eyepieces (EPs) and you add nothing else onto it. Eventually, almost everyone who gets into the hobby semi-seriously adds on, so enter the counterweights.

I kept reading how difficult it was going to be, esp if I piggybacked a semi-heavy (80mm or larger) scope on top of my CPC. This made me nervous. The Meade DSI II Pro I have (with filter wheel and Outback Razor cooler) added weight to make it tail-heavy already, but conveniently enough, the aluminum Astrozap dew shield countered this perfectly so no weights were needed. However, if I piggybacked my Nikon D40 on top or thought about a piggyback scope I needed a counterweight set as what I had wasnt cutting it - so I ordered Starizona's counterweight set. Initially I just ordered the bottom rail with one weight, but they sent me just the top weight instead. A phone call later they had the right parts sent out and I had decided just to go ahead and keep the top weights - I heard they helped with dynamic balancing anyways.

A week later, I got an Orion EON 80ED scope to piggyback for widefield imaging. I do use my Nikon D40 on an AstroTrac TT320 for very widefields, but I am still having light pollution issues with that and I was only able to go up to 200mm leaving quite a gap between that and my main scope, which with the focal reducer it only went down to 1280mm and was normally at 2032mm. Now I needed to balance.

I only had the one 2.5lb weight that came with the set which was not enough to balance the CPC with the EON piggybacked and I did not want to pay $50/weight for more 2.5 lb weights. I decided to go with 2.5lb gym weights, which cost all of $2.13 each. I also had a 1.5lb weight from my old Meade refractor that I was able to use. I horizontally balanced the scope first, which required moving the weight bar as far back as I could on the dovetail rail and adding 2x2.5lb gym weights, the 2.5lb weight that came with it and the 1.5lb Meade weight. I stacked them so that the weight that came with the set screwed on the bottom to hold the gym weights up and the Meade on top tight against the gym weights to keep them from moving when the scope changed angles.

I then went to balance the scope vertically. It wasnt too far off, I had to lower the weights as far as I could on the screw-in bar and add the small top weight from the Starizona set to the CPC. I went back to double check the horizontal and thankfully it was still balanced as well! This was alot easier than I was told it was going to be and saved me coming up with some creative solutions for balance. The EON does sit pretty far back on the scope so I have to watch my head when looking through the CPC's EP if I have my DSI II Pro attached to the EON, but not too hard to avoid conking myself I would imagine.

So there you go, 9lb of bottom weight, 1.5lb of top weight (as well as the dew shield) a little red fingernail polish to mark the spot the weight bar needs to go to for future set up and we have a balanced scope. Assuming the clouds stay away I will have the setup out tonight and hopefully, now that it is balanced, the GoTo and tracking will be alot more precise than it was with the unbalanced attempt I made last night.

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Monitor Calibration

Monitor Calibration
The grayscale above presents 24 shades of gray from pure white to solid black. If you cannot see all 24, your monitor needs calibration to view the astrophotos correctly: I recommend the site linked in the image