The strings are "Plus 450" Archery Bow String acquired from a local archery shop. Comes in a reel, quite expensive $100/reel if I remember. Also need a reel of serving thread and you need to learn how to "serve" the ends. The thread below covers the construction of this beastie.
The strings are "Plus 450" Archery Bow String acquired from a local archery shop. Comes in a reel, quite expensive $100/reel if I remember. Also need a reel of serving thread and you need to learn how to "serve" the ends. The thread below covers the construction of this beastie.
Tim - I love your rocker box. I'm thinking of using its overall design to base my binocular on. I have already made the basic rocker box and it's very shallow too. I like the bearing extensions on yours - similar to the new Obsession ultralight. Do you have any close-ups of the box/bearing design?
Here are some closeups of the flex rocker plus pics of the reinforced top ring. For more info on flex rockers check out Mel Bartels' site, esp. the section on the trilateral mount:
BTW the Tridob uses a rigid ground ring and 'flex-rocker' rather than a rigid rocker box and thin ground board like many designs. My current work in progress is a F3.6 22" version of the Obsession UC.
Welcome to the forum down under Gary. Good to see some weird (and I mean that in the nicest way) scopes appearing. Man I can't even pronounce the name, let alone spell it.
Gary
It is a bit weird and hard to pronounce and locating targets with the tight FOV without a finder is tricky...but, with the 2700mm focal length I get about 100X with a 26mm eyepiece, 150X with an 18mm, and it can handle 225X with a 12mm - maybe more if I could get skies like you guys have...
Also all spherical optics so no need for parabolizing; and a contrasty and colorfree view with no obstruction and long eyerelief. Not exactly a rich-field scope but I can just squeeze the moon in with a 2" 30mm wide angle ep.
"Looks like I'd have to go get an engineering degree to operate it "
Not at all! In use (with a finder!) it feels like a refractor. Collimation is simple: laser in the focuser, center dot on round secondary, adjust secondary to hit center of primary and adjust primary to hit a point a certain distance above the secondary. I use a piece of aluminum held with a rubber band for a target.
The other thing to get used to is the very narrow field. With the high native magnification I think a tracking mount is called for - but even the simple one I have is sufficient. There's a fairly broad range for focus too.
Over here a lot of ATMs are engineers or have tech backgrounds. I don't (though I do tinker a lot and am fairly handy) and was able to build this and get the angles right without any major problems - there are basically two or three measurements that constrain eveything else. The mirrors weren't hard to make but I wouldn't recommend them for your first attempt. The two have to be as nearly identical in radius as possible - but convex and concave and that's maybe a little tougher than it might seem. You test the primary by nulling Foucault - no masks or calculations, and the secondary by interference against the primary. Nothing fancy needed for that - you can use a piece of green or red cellophane and a flourescent light. Also, working glass that small and thin with normal or even smallish hands and keeping your fingers off the front isn't one half as hard as a 200mm as some suggest who haven't tried it! Having said that, I believe it could be done by a first timer with patience.
I guess I'm excited about it because it performs so well and was inexpensive to make. The inexpensive part is very important to me!
Here's a handheld shot at 150X from a few days ago. It doesn't begin to do justice to the real view.
I was only joking, looks really well constructed. I'm a retired Mech Fitter so can appreciate the work that went into it.
Never got into grinding optics.. yet. Might give it a go one day.
The inexpensive appeals to me too
Nice pic, wish I could get a handheld with mine like that
No baffling, seems ok without it since I painted the inside black. Just found a perfect fit dust cover for the dew shield, the base of the Fereo Rocher "Bell" I bought Kym for Valentines Day. Someone is looking after me
Spent most of the day making the dew shield, that colourbond is springy stuff. Had to bend it around a 100mm pipe to get the initial curve, grind off the paint and zinc coating on the first 12mm of the overlap before it would take a silver solder weld, then squeeze and push it into a tube shape with me thumbs. Gee, I miss the tools that were available when I was working, could have knocked it off in an hour or so.
I don't want to hijack this thread any more than I already have but I'd be happy to provide more info and/or connect you with the scope's designer. Just PM me...
to IIS. I followed the construction of your Schief over on CN.
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Now all I need is for the rain to stop and the clouds to go away.
