Deep sky video with NexStar SE 5

The little Celestron 5-inch (BexStar 5 SE) can deliver a very impressive and colorful view through the Color Hyper MallinCam – but it took me two freezing nights, plus experimentation in daylight in a warm house to get it right.

I bought this scope primarily because I am switching to automated scopes for use by my visitors – but that's another story. In this particular instance I thought that tonight – March 8 – I would be helping out with a star party for school kids in a neighboring town. Turned out it was called off because it's too darned cold – temperatures are supposed to get in the single numbers and the wind speed is in the double numbers. That's bad stuff. We had the same thing Tuesday night, but I was desperate to give the video set-up a try, so I went out and about froze my hands off – not to mention getting a little frustrated.

See, here's the thing about the video – finding the focus can be a pain. I learned the next day – in the warmth of the house – that it takes about 12 turns – for me a "turn" is really one-quarter of a revolution of the focus knob – to go from an image that is in focus in a 10 mm eyepiece to an image that is in focus on the screen when the television camera is installed. This is with tw focal reducers installed. But the important fact is this – you don't see anything – nothing – on the screen until about turn eight or nine!

Now when I went out Tuesday night I hadn't used the video camera for three months and I had never used it with this scope. Logic told me that since the video camera acted like a high-powered eyepiece, I should focus clockwise – as I do when I put a higher-powered eyepiece in the scope. Wrong. The answer – arrived at by trial and error the next morning – was go counterclockwise.

But I spent a good 45 minutes fooling with this thing, making various changes and adjustments and never saw a thing on the television monitor. The problem wasn't the focus – that issue masked the problem. But because I knew focus was tricky, I kept fooling with it – going both directions. I really had two much simpler problems.

The first was the optical tube tended to easily move in the mount in altitude. Now this is frustrating. You do a two-start alignment. Tell the scope to "go to" M42, center it in a low power eyepiece, then take out that eyepiece and put the heavier video camera in. Ok Then you plug two connectors into the back of the video camera and in doing so press down and damn – the scope moves and you lose M42.

So the first thing I did the next morning was check the NexStar group on the Web and see if I could indeed tighten this axis by tightening a single nut that was revealed when I removed the mechanism that connects the optical tube to the mount. Yep. Someone else had the same problem and had written about it a month ago. So that issue was resolved pretty easyily.

I set up the scope indoors and discovered the second issue that had – unknowingly – frustrated me the night before. The connector from the camera to the monitor (a DVD player) was loose. It would stay live only if I took the strain off the wire – something a single piece of Scotch tape could solve and did.

So now I was ready to try again.
Wednesday night turned out to be clear, a balmy 23 degrees, and NO wind – really bearable. I stayed out for an hour and a half. The scope no longer moved up and down, except when I pressed the right buttons.. I experimented with the video cmaera at F10, then put in a focal reducer which moves it to F6.3 and then added a second focal reducer to the camera which comes close to cutting the focal length in half again. Bottom line – I can operate at lower power and with a field wide enough to almost take in the Pleiades.

But the only object I experimented with was M42 and after fooling with the screen setting I was able to get a very impressive vision of it on screen with lots of color – mostly red – showing in the clouds of gas. Great. I would say the view was at least as good as what you would get visually in an 8-inch – except your eye has a much greater dynamic range than the camera. It may not pick up the color, but it will show both the nebula and the Trapezium. With the camera you either underexpose and see the Trap – or overexpose and see the nebula – not both – or if you can do both its beyond the skill and knowledge I have at this point.

Bottom line – I now know I have a simple, light weight, highly-portable video demo in hand– but I may not use it. Nice to know it's there, but the 8-inch LX90 should do better and it's not that much more bulky, though it is heavier. Have other school events scheduled next week and later this month, so I'll have to make up my mind soon.