A More Diverse Imaging Capability

It's been cloudy, or clear with a waxing moon. So I've been working on small projects and considering a purchase.

The parallelogram binocular holder

 is coming along. This week completed all the work needed to completely assemble it. Amazingly it actually worked, providing the 11x80 binoculars with smooth freedom of motion. This morning I stained the pieces and tonight (or whenever the rain ends) I'll give it a nice coat or two of spar polyurethane.  No one is going to mistake it for the handiwork of a skilled wood worker, but it will work. And in the dark of night when it's used no one will notice the rough corners.

Remounting the Finder and Autoguider on my C925

The finder shoe on Celestron's C925 sits a little off-axis, making it more convenient to use. The small stock finder is so lightweight that the torque it produces is negligible. But the torque can become substantial when I configure the scope for imaging. For imaging I use a "Y" shaped mount that carries both a 9x50 finder and Orion MiniGuider. These throw the scope quite a bit off balance around the declination axis.

One solution would be to add a counterweight on the scope's opposite side, but it could be messy trying to figure out how much weight should go where.

A better solution was made possible by a dovetail bar installed on the scope by its previous owner. The bar extends from front to back and is made of stout ADM manufacture; it works great as a sort of handle for lifting the scope.

It was short work to drill a couple of holes in the bar, tap threads into them, and fasten a spare Vixen-style finder shoe I happened to have. This shoe has a flat base and fits perfectly onto the bar. Now the finder/guider tandem sits exactly opposite the scope's base and the torque should be gone.

Now the purchase: Adding Imaging Flexibility

I'm seriously considering adding a DSLR for imaging. This isn't intended as a replacement for my ST-8300M, which gives me the ability to do narrowband imaging from my back yard.

Perhaps this is a case of gear envy brought on by lousy weather. Maybe it's just me getting a little tired of having to shoot flat frames for every channel when I do LRGB. Maybe it's just an itch caused by some unexpected funds coming from the closing of my software business. In any event, I've been investigating used DSLRs.

Let's start with a price point of $600 maximum for a modded camera body. Preferred would something under $400. Under $300 would be great! And because I'm somewhat invested in Canon lenses, I'll consider only a Canon body.

Models being considered are the 40D, XSi, 50D, T1i, T2i and T3i. I've seen and handled the 40D; it's a nice camera, better built to resist the elements than the XSi is. The 50D is said to be a step up from the 40D; of the three Tn cameras the T2 stands out because of its crop mode video capability which makes it suitable for solar system imaging.

A DIY Binocular Mount

Thanks to a change in plans--a wedding I want to attend is on the same Saturday as the Wisconsin Observers Weekend--I am going to go to this year's Nebraska Star Party. No offense intended to WOW, but NSP is a bit of a bigger show with more people and darker skies. NSP begins as the annual Jeffers Petroglyphs party ends, so I'll be able to save a couple of hours of drive time by going straight from Jeffers to NSP.

But what to do at NSP? I'll have my imaging gear from Jeffers with me, but maybe I should just make my first NSP a strictly visual affair. All that really dark sky, you know!

I've come into possession of an old pair of Celestron binoculars, their 11x80 Giant model from the 1990s:

This is not the model that was labeled "Comet Hunter" or "Comet King" apparently to cash in on Halley's Comet in 1986. What reviews I can find for this later model are mixed.

Good features from my standpoint:

• It was free
• It has a wide FOV (4.5 degrees)
• It comes with a mounting bracket. 

Cons:

• Probably not the greatest optical quality
• Heavy (6.7 pounds) 
• Exit pupil (~7mm) that is too large for my old eyes. I'm 60, and although I haven't measured, I would guess my pupils don't open past 5mm. This means that some of the objective size is being wasted, but some people suggest this has a small silver lining in that one's eyes can move a little laterally and stay in the light.

My past experience with large binoculars suggests that a mount is a very good thing to use for steadiness and comfort. A little googling turned up this plan, which I am adapting to the top of my CGEM tripod. The CGEM tripod has two threaded holes for mounting the azimuth post. These are perfect for attaching a base plate. In my case I'm changing the plan to substitute a 3/4" piece of hardwood for the 3/8" aluminum plate. The rest will be pretty much as the design suggests.

I was unable to find the nice round counterweights seen in the explanatory pictures, so I'm using lead scuba weights from the appropriately named Lead-co USA. Construction begins next week.

An update on May 20: Lead-co uses fixed-cost USPS mailing boxes, and I had paid for a medium sized-one. It turns out that the weights I bought fit in the small box, so Lead-co refunded the difference. Nice!