Wednesday, March 19, 2014

Jupiter under poor viewing conditions

The weather is starting to clear up but the air is still quite soupy (lots of atmospheric turbulance.)
But I thought I would give it a try anyway last night since Jupiter was right overhead at about 9 pm.
Celestron C8 Classic
Canon T2i
Eyepiece projection right onto the CCD with 28mm eyepiece.
Cropped 620x480 movie mode
Lynkeos software
Stack of 20 images, cropped
Final sharpening with Macbook Preview

Tuesday, March 18, 2014

Review of the Bushnell NorthStar 78-8890 90mm Catadioptric Telescope

Last weekend I picked up a Bushnell NorthStar 90mm Catadioptric Telescope for a reasonable price of $150 off of craigslist.

I bought this with the idea of a cheap "goto" scope that is small and very portable.

The downside was that, though it is a motored scope, it cannot be used in the equatorial mode.

The upside is that the scope can be removed from the mount and mounted on a tripod via the typical tripod socket and used as a super long telephoto with the addition of a t-adapter. In addition it can accept my 0.5x Focal Reducer 1.25" which both reduces the power and lets in 50% more light. I also have in mind to piggyback this on my Celestron C8 scope as it is reasonably light.

As is, it produced a good image but upon further inspection it was out of collimation
Since the from secondary mirror can't be adjusted I checked out the back cell and found there were three Allen wrench screws that adjusted the back mirror.  I inserted a home made plastic cap with a tiny hole in the center.

By making tiny adjustments I was able to bring it closer to collimation.  But when I inserted the right angle mirror it appeared to be out of alignment by a big amount! What happened?  Upon more inspection I found that the rights angle unit fits too loosely in the rear cell and when secured by the two set screws they pushed the unit out of alignment.

By adding a few small strips of ordinary tape to one side of the unit and spinning the screw housing around 189 degrees it brought it back into collimation!

Now I can take it to a more precise collimation with higher powered eyepieces.

As for the "goto" part of the mount... not so good. Even when I selected and followed the directions (what there were of them would be confusing for an absolute newbie) when I asked it to go to a known planet or star... it missed it by enough that even the low power 25mm eyepiece wasn't even close. If you didn't know where the object really was, you would be lost.

Anyway, the optics are more than acceptable and I look forward to using it as a guiding scope or a quickie scope (I will have to do the pointing) for an "out and in" session.

Here is where you can download the manual for this Bushnell NorthStar 78-8890 90mm Catadioptric Telescope

UPDATE: One nice thing about this scope is that the tube at the back of the scope that holds the eyepiece only needs a T-adapter that is made for one's DSLR camera. Since I have a Canon DSLR all I needed to use the scope as a telephoto was a Canon T-adapter (like this one from

Crisp 15 degree F morning yields 4 astro beauties!

This morning I captured four astronomical beauties with my small Bushnell NorthStar 1300mm x 100mm 4" Maksutov Cassegrain Telescope (Model 78884). Didn't even turn it on, just attached my Canon Rebel XSi body to it and fired away. Didn't get as sharp a focus as I could have...hey, it was 15 degrees outside at 6 pm here! Give me a break! Plus I had to get back into the house quickly to make breakfast for my wonderful wife!

In crescent phase, Venus was as bright as ever! (Discoloration due to optics not being ultra-inline)

Next to the west was Saturn. I was surprised that I was able to capture it as well as I did with such a small scope!

Then next to the west of Saturn was Mars. Once again I didn't have the best focus but the southern polar cap is hinted at in this photo, anyway.

Finally, I captured the tail end of the "Worm Moon" (given that name by farmers who realized that worms began to become active in their fields with the full moon closest to spring equinox.

Friday, March 14, 2014

Back in the Observatory Again!

It finally cleared up enough on March 12, 2014 to shoot the Moon for a few minutes.  This shot, though incomplete,  is actually a composite of 12 shots into one. Using eyepiece projection (25mm eyepiece onto the Canon T2i body CCD directly) and in the 1920×1200 movie mode, I eliminated all but the best shots, then used a panorama program to stitch the individual shots together. Add some post processing contrast and sharpening and the results you see. I'd better pay more attention next time to capturing ALL the parts of the Moon next time!
Also included here is Tycho and Copernicus craters from the same shoot.