Posts Made By: Mark Eschbacher

I have included a picture (more to follow) of a 6" f/8 scope I made for a friend in appreciation for about 700 board feet of quarter sawn oak lumber he gave me. The wood came from some large trees he had to cut down to make room for an addition to his house. I thought it appropriate to make the scope from his former trees (along with some curly maple for accent). My goal was to use as much wood as possible in the construction, including in the crayford focuser. The tube was constructed of beveled staves glued up on a circular form.

The little Mead primary works great and the roughsawn flat black interior makes for great contrast (it took me about 6 months to bring myself to give it up :S ). I am currently well into my next project which is a 16" f/5 obsession clone with a Swayze Primary and 1/30 wave secondary. It may not look as artful when sitting in the living room but I expect looking through the eyepiece will leave me sockless!

Mark Eschbacher

Here is a picture of a recently finished 6" f/8 I constructed. More pictures and description can be found in the "Pictures of me and my telescope" forum.

Mark Eschbacher

Well, the day finally came last Saturday. After purchasing a slightly chipped 16-inch f/5 Swayze mirror five or six years ago, I completed the truss dob scope to house it and I celebrated first light!!

Construction was pretty much by-the-book (Kreig and Barry that is) except for some minor modifications for cosmetic purposes. Modifications such as the use of exotic woods in the focuser board and as edge banding on the top of the altitude bearings, and applying fasteners from inside the mirror box and biscuit joinery to create a clean exterior appearance. Disassembled, the scope just barely fits into the back seat of my Accord.

The mirror is reported to be one of Swayze’s better ones as described in its provenance. To maintain the optical train’s tip-top performance I obtained a 2.6-inch 1/30 wave secondary.

Saturday night was very transparent for my area (30 miles west of Philadelphia) but quite unstable following the recent arctic cold front that came through. I had the scope aligned and cooling with a single rear fan two hours before dark. At observing time I looked at a greatly defocused Polaris and could tell there was some high speed turbulence flying by and I still had a warm boundary layer on the mirror; probably because of the rapidly cooling air (daytime high in the mid 60s to a low of 29). I clearly didn’t have the right conditions to star test so I started my night’s viewing. The Milky Way was faintly visible; about as good as it gets in my light-polluted neighborhood.

The scope was moving well with no binding except for a little initial sticking that probably means my ebony star could use a good cleaning with some solvent. The combination of Telrad and 50mm finder scope worked great for locating objects quickly and accurately. I was usually able to go directly to my barlowed 10mm UO orthoscopic (404 power with 40-degree AFOV) and with only a little bit of fishing, could find the object quickly.

Views were the best I could hope for! Starting with the bright objects while the skies darkened I tested the high power with the 10mm on Uranus. A clear disk at 202X degraded to mush at 404X, but by the end of the session around midnight it held up well at 404X with a clearly defined edge to the disk. The double cluster looked great showing some color variation not visible in my smaller scopes. M13 was a little pile of diamond dust, with the fine optics showing lots (100+?) individual stars. My first view of the Andromeda galaxy was disappointing… until I shifted the scope and realized I was looking at M110 and not M31! M32 even showed more than the core with its slightly eliptical axis faintly visible. The sky was too light to get more than a hint of the dust lanes. Encouraged, I tried to push through the local sky glow to find some fainter galaxies, but no luck. I guess there is only so much that aperture can do for you. The ring and dumbbell nebulas looked great through a nebular filter as I expected from having seen them through my club’s 17 inch Coulter (focuses stars to perfect triangles at moderate powers; and no, the optics are not pinched). But the real star, pardon the pun, of the evening was the veil nebula viewed through my nebular filter. Without the filter it was barely discernable through the light pollution, but with the filter I could see the filaments within the nebula and could trace both sides quite far; things I couldn’t remember seeing in the 17” Coulter. Without the aperture the nebula looks more like a glowing fingerprint smear on a window but with the 16” it looked more like a glowing cobweb.

After catching a little sleep, I went back out to the scope before dawn. Polaris out of focus still showed the passing high altitude turbulence, but the mirror only showed a mild lazy roiling of a warm boundary layer. Orion was well placed for viewing in my narrow tree-challenged yard. Under a waning quarter moon the heart of M42 looked like the wool on a sheep’s back and the fifth and sixth stars (my first viewing ever for #6) in the trapezium were a snap at 126X with a 16mm Nagler and showed a nice black separation from there brighter companions when barlowed at 252X. I was hoping to catch Saturn but it only cleared the pine trees after the sky was growing a nice pale blue so I’ll have to save that one for a few weeks down the road.

Final Analysis:

Performance was very enjoyable;

Views can only improve with planned blackening, flocking, and baffling;

I have to get my front surface fan wired;

I have to get out under some dark skies!! (Closest official dark sky site is Cherry Springs Park, about 4 hours drive)

QUALITY APERTURE RULES!! …or is that ROCKS!! Is my age showing???


Mark Eschbacher

Well lee, I finally got my hands on a digicamera so I could SHOW you what ATMin' I have been up to in the past. (Lee and I have been comunicating off post about my plans for the 16" Swayze he used to own).

This is a photo of my first scope, built (and yet to be completed--if ever) 5 years ago of 1/2" curly cherry with a 4.25" Edmond mirror and diagonal. The plan came from a book of six scope plans that I seem to have misplaced. This is the scope that got me hooked on the creative problem solving involved in scope making.

The focuser is two layers of cherry with a friction fit on the eyepiece (no focuser). If you look closely you will see that it only has one of the two brass screws in it. That allows me to swing the top layer out of the way when I need more in-travel for some eyepieces. The small whit tab on the side is a Radio Shack adhesive wire holder that is used as an attachment point for my modified Daisy l.e.d. sight. The diagonal holder is a mitered dowel with a sheet aluminum stalk attached to a saw kerf in the dowel. Collimation is accomplished by brute force (bending). As crude as this sounds, it is a great performer. It's all about the optics! This reminds me of the realization that I came to in my photo hobby. I have a 4X5 large format camera that is really nothing more than a light tight box, absolutly NO bells or whistles, that is capable of taking INCREDIBLE photos because of the high qualiy lens that snaps on the front.

This scope was also my teacher in that we always learn so well from our mistakes! I learned that spray-can laquer dries fast so you don't have to wait long to take it outside, and it makes the cherry look FANTASTIC, but after a night of heavy dew it looks like old barnwood until I can hit it with some lemon oil. Lesson learned...check finishes for water resistance.

Project #2, my 10" truss dob that was my prototype for the future 16", will follow in another post.


Mark

Another view of the "cherry" first scope.

This photo is of the 10" f4.5 truss dob originally built as a prototype for a future 16" dob using a Swayze mirror I aquired from Lee Stock. (Has the new Zambuto taken your mind off the Swayze yet, Lee?)

Wanna guess whose book I'm using to build my dobs?

I managed to find a sheet of 1/2" plywood with a curly birch surface in the stacks at the local Home Depot. (Have you figured out that I like figured woods yet?. Keep your eyes open! Last month I found some very nice curly maple in the stacks at Lowes. I also try to find quartersawn or near-quartersawn hardwood and softwood lumber when searching the stacks because it is immensly superior in stability and straightness compared to the typically flat sawn lumber. Quartersawn means the cut to make the wide face of the board is oriented toward the center of the log, not perpendicular to it.) The single upper ring has simple split blocks and wing nuts for clamps, the mirror box is right out of... you guessed it.. Krieg and Barry. I had to get creative with my finder scope mount because I wanted it removable for weight savings when I switch to my 16mm Type 2 Nagler and 2" Big Barlow combo (just about matches the weight of the 8X50 University Optics finder). The mount is just two 1/8" slabs with split blocks using offset scallops cut to fit the truss angles, all held together with some long brass machine screws and wing nuts. The long dovetail cut was to allow for further refinement of the balance that I subsequently found was not needed because I have sufficient "sticktion" in my berings (it happens when you get older).

The truss tubes are coated with a truck bed liner material from a spray can found at the local auto parts store. It is black, durable, nicely textured, and provides a little bit of insulation against the cold aluminum. If you use it don't forget to mask off the ends for the clamp blocks, or else allow for the "paint's" significant thickness.

The 16" is still in the rough design stage. I have just recently discovered a nearby Woodcrafters store, and they stock specialty and exotic lumber. After falling in love with the tufted mahogany, curly maple, redheart, wenge, and lacewood I have used to build jewelery boxes and mirror frames, I hope to use some of that to dress up a "pared- down-not-quite-ultralight" version of the 10".

Is it just me, or does this hobby make all the problems in this world seem 'fixable' with a little better design, a little tweeking, or with something you can get at a salvage yard?

I guess this means I've graduated beyond the "duct tape" stage.


Mark

A closer view showing the finder mount and tube coating.

Mark,

All suppliers of chemicals or chemical compounds are required to provide a Material Safety Data Sheet (MSDS) for any products they handle (true for everything from dial soap to uranium hexafloouride). The MSDS provides data on known and suspected hazards as well as permissible exposure levels and appropriate precautions. My experience has been that these are usually supplied, and often faxed, at no cost.

As usual, there are lots of terms and acronyms involved that a visit to the NIOSH web site can probably help you decode.

Good luck and be careful!

Mark

Some other alternatives to adding weights, since you said the balance is pretty close, could be:

-move the finder further down the optical tube toward the center of gravity. (no rule says it has to be at the top)

-use a detachable container (box, tupperware, screw-on-the-cooler-lid-water-jug-thingy) for the bottom counterweight that can be filled with local material (water, sand, rocks, etc.)once you arrive at your destination.

-virtual counterbalance using springs and pulleys.

Rob,

Nice photo!

I was a little further East in Chester County, PA where we also had fog. It ws about 6:30 before the sun could penetrate the fog and my 1000 Oaks full apeture filter on my 4.7" Sinta refractor. I found the fog turned out to be an advantage in that it kept the air stable and delayed the daytime heating.

I was watching for the "Ink Drop" effect that was mentioned in a S&T article but noticed no such distortion in the outlines. When some minor turbulence did kick up the thin rim clearly became less distinct, but I found by slowly scanning my eye accross the image, it seemed to average out the turbulence's distortion and showed no change in the outlines. (I was using a 16mm Nagler and barlow for a magnification of 125X.)

I was wondering if anyone else noticed the "Ink Drop" in their observations and if it could be an illusion resulting from turbulence.

Mark Eschbacher