DIY Telescope Dew & Light Shield

Sunday, 18th November, 2007 :: 12:14 EST - Astronomy

I made a dew/light shield out of long sheets of craft foam and stiffened sticky felt. The sticky felt to act like flocking, and I chose the stiffened version to help support the rather large quantity of less than super sturdy foam. The stiffened felt has the nice side effect of being significantly easier to apply than the stretchier standard felt.

I used strong double-sided tape to join the sheets of craft foam together. I needed a few more inches than two sheets would provide, so there are three seams, one of which has the velcro.

To apply the felt I cut it into 4.5″ wide x 9″ long strips (cut the sheet in half lengthwise). I applied a strip of velcro on each end of the shield so as to be able to tighten the shield if necessary and also allow it to fold flat for travel.

With a little rolling up to curve the felt and release the flat tension a little, I now have a nicely round and sturdy light shield for about $7.

foam dew shield

You’ll notice the rectangular cutout, that’s for the knob that suddenly became necessary.

Zhumell with Dewshield

Here you see both the main light shield and the miniature one for the finder scope. They’re constructed in relatively the same manner, except for the finder I made used much narrower strips so as to avoid making it too stiff.

Zhumell Knob

I found this knob for next to nothing at Lowe’s. It’s made of ceramic and relatively light weight. I found really nice similarly sized metal knobs, but aside from the cold factor, they were seriously heavy. This knob is threaded for #8 screws.

I attached it using a 3/4″ long #8 screw through one of the holes that holds the ring onto the front of the scope. The metric threading for those screws isn’t quite the same as the #8, but it’s close enough that it can be made to fit with a bit more oomph using the screwdriver. I figured this was a good way of going, it’s in the right place and I didn’t need to drill a new hole in the OTA.

You’ll notice there’s a little gap because the knob is larger than the space available; I took up the gap with a pair of rubber washers, it’s nice and tight now and won’t scratch the finish of the tube. The white ring is a reflective tape I added to the front and back of the tube, helps notice where the scope is better in the dark.

I tried to use the clevis/cotter pin mod, but couldn’t find one long enough to work well with the magic (vs. super) sliders. I found that a 2.5″ hex bolt with a mix of nylon & steel washers, topped off with a lock nut, has been as close to perfect thus far. It’ll keep the ground board from falling off, eliminates wild wobbling, but provides no downward tension to effect azimuth motion. There is probably just a hair more than 1/32″ of an inch spacing, one more 1/16″ washer would fit, but then it’d be tight.

I superglued 3 1/16″ nylon washers together to go between the two bottom “plates” around the center bolt. It sort of acts like a slightly more sophisticated version of either the milk jug washers or the cdrom washers (which I had used before). I’m going to be on the look out for UHMW washers, or something similar that is slightly more slick.

The Moon & 17P/Holmes

Sunday, 28th October, 2007 :: 01:21 EDT - Astronomy

Whilst out observing, albeit briefly due to cloud cover, I snapped a dozen or so photos of the moon with my D40 held up to the telescope. This is just about as ghetto as you can get to still have a result, but… I think I did a fairly decent job with my first moon photo, haha.

the moon

The enhancing is just running it through Gimp’s USM, as the camera was set to soft contrast, etc.

The comet was pretty awesome. As soon as I found it I ran into the house and screamed “COMET!!” Well, really, it wasn’t so much finding it that was the problem, but the constant cloud cover flowing through the view.

Comet Explosion

Thursday, 25th October, 2007 :: 00:38 EDT - Astronomy

I’m not quite sure that ‘explosion’ is the right word for it, but apparently if it were not completely cloudy and rainy here, I’d be able to see the 17P/Holmes comet having brightened from magnitude 17ish to nearly magnitude 2. This takes it from a very faint smudge in a large telescope to a bright naked eye star, with clear non-stellar detail viewable in binoculars and better.

Alas, it’s going to be horribly cloudy and rainy for days yet, I hope I’ll actually be able to get a look at this before the outburst is over and it dims back to normal.

First Dark Sky Trip

Sunday, 14th October, 2007 :: 13:33 EDT - Astronomy

Lastnight I bravely packed up my astronomy gear, fiddled with trying to get the telescope (with its 12″ diameter tube) into the car, and began my journey to the top of Piney Mountain in the Pine Grove Furnace State Park.

Halfway to the park I felt so nervous. I was going up to the top of a mountain all by myself with the goal of sitting in the darkness. It seems absolutely insane, but that’s astronomy, hah.

I almost turned around and went back home, but I really wanted to see how much better objects would look at an actual dark sky site. Granted, it isn’t the darkest, it’s even yellow on the light pollution map, but there aren’t any street lights!

I was so relieved when I pulled into the ATV parking area and saw vehicles. I was extremely happy when I realized they were really fellow astronomers. It turns out that some ASH members were having a small observing session, mini star party, whatever you want to call it. I definitely need to join! I’d have known about it before I actually arrived, lol.

Everyone was very friendly and helpful. I even had quite a few great views through a 20″ scope with Nagler eyepieces. I even saw a comet or two! The 20″ scope wasn’t actually an Obsession, but they look very similar, enough to give you the impression of just how large such a thing is.

I felt like I ‘earned my keep’ by having some eyepieces the guys haven’t yet looked through, so it was nice to be able to give everyone a look through my Agena 32mm SWA, and my 17mm Hyperion.

Here at home there’s so much light pollution that the Milky Way is completely invisible. Sometimes there might be a hint at zenith, if it’s exceptionally transparent, but otherwise there’s no hope. At the ASH observatory the Milky Way looks, well… visible. At Piney Mountain it was pretty amazing (at least for a first time view from such a dark area). I really look forward to getting up to the Tuscarora mountains and especially heading up to Cherry Springs (one of the darkest sites in the eastern US). It’s such a shame that so many people haven’t seen it, it’s our own galaxy after all!

I didn’t really spend much time finding new objects, I was somewhat overwhelmed with the sheer number of stars that I could barely find things I knew the locations of. I did view M52 and M1, first times for me, otherwise I ran through my list of previously observed items. The view of the Orion Nebula was mind blowing in my 10″ … in the 20″ … there are no words to describe how stunning it was. The level of detail was impressive to say the very least.

Somewhat random, but I’m also stunned by the fact my scope held collimation perfectly (with the exception of a very minor tweak using the Catseye Infinity Autocollimator. The springs from Scopestuff, along either their knobs, really seem to do the job at keeping things in place. I suppose the trip isn’t really bumpy, the worst was probably going down my makeshift ramp from the shed door using the hand truck. I really need to put a little work into the ramp, but it’s ‘good enough’ for now.

I still need to figure out how to arrange the telescope in the car without occupying the entire back seat and the passenger seat, hah. It’ll probably work sliding it through the trunk/back seat opening if I take off all the finders. Looks like I’ll be buying another pluck foam case! Thankfully pretty decent ones are only $9.00 at Walmart.

I had a very good ‘first night away from home’ with my telescope. I arrived a bit after 7pm and didn’t leave until about 4:45AM…. which was so much later than I ever expected. It’s amazing how the chance to view with experienced observers really boosts the willpower to stay awake.