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At the 24 mm setting The Hyperionseemed to have a little higher magnification.

...because...your hunch is correct!

Yep, I just checked the exit pupils at the click-stop settings. All the settings seem to correspond with their stated focal length within a fraction of a millimeter EXCEPT the 24mm setting. With my f/6 refractor, I'm getting a 3.7-3.8mm exit pupil (I don't have the steadiest of hands; using a handheld 8x comparitor with a millimeter scale). That would mean a focal length of 22.2 - 22.8mm, not 24mm. Call it 22.5mm for lack of a more refined measurement.

That also means the effective AFOV (factoring in distortion) is (660mm) * (1.52°) / 22.5mm = 44.6° (~45°), not 42°. This closely matches the measured AFOV from the arctan method.

The Celestron zoom's focal lengths corresponded well except at the 18mm setting. That should have generated a 3.0mm exit pupil; it was 2.7mm instead (16.2mm focal length). But it was a 4.0mm exit pupil at the 24mm setting.
"Trust, but verify", indeed!

Clear Skies,
Phil
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ATM, Optics and DIY Forum / Re: Over hauling my newtonian
« Last post by ropnolini on Today at 11:45:30 AM »
Ok update time. I have the moonlite focuser, mirror cell and I'm just waiting to the new aluminum tube. Evan tells me it's going to be ready by next Saturday. Working on pictures. Then the work starts to fit all the parts together then test, test and test to get everything in it place. After that start the painting. First the tube and then I'll start working on the fork mount. Not to much to do on the mount. Clean it up, grease up the bearing and the repaint it.
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Those lazy susan bearings on cheaper Dobs are a non-solution to a real problem (skimping on the correct surface materials and amount of teflon) that the standard Dobs had. They are _spectacularly_ non durable; I've seen a lot of them where wear makes everything ride on a random set of three rollers after some time -- and those usually have burrs and dings so it's all wobbly.
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ATM, Optics and DIY Forum / Re: Min. distance to artificial star ?
« Last post by loraderclot on Today at 11:44:52 AM »
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Will it be safe to view thru a lensed system as my point source ?
Where would I find such a thing? My lapse from a long-ago electronicscareer is showing
CS
Bob
If you keep it below the lasing threshold - the point at which it really develops a beam, and its unlensed, you will be fine. Shout if you want one. I have 10 in my desk drawer in my office.
Sent you a PM Steve
CS
Bob
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Mounts Questions & Expirience / Re: Orion HDX110 EQ-G Mount
« Last post by Stanley Edwards on Today at 11:44:47 AM »
I bought an EQ8 which is the HDX110 in the EU/ROW in mid 2015 and regard it as transportable only. It seems to be substantially a copy of Gemini's now-obsolete G41 mount, which (given Andras Dan's superb design engineering) is a very good thing (for Synta and its customers at least). I use it with an I-M 8" Mak-Newt and a perpetually-evolving 10" F6 planetary Newt. I keep the thing set up on its tripod/pedestal and polar aligned under a quality telescope cover which provides a reasonable degree of protection from awful Irish weather. This factor of exposure to weather needs consideration, as the materials of construction of the accessories are typical of low cost Chinese products - plated carbon steel fasteners and fittings and low end engineering plastic motor covers. The main assemblies of the mount head are made of SS and what you Yanks call billet aluminum. Most of the tripod is mild steel.
The controls comprise adequate quality motor and transmission bits (given the load duty) combined with the basic budget capability that is the Synscan handpad, cabling and connectors, firmware and position feedback. Fortunately the weakest part of this - the Synscan handpad, firmware and cabling can be bypassed using EQMOD which brings ASCOM compliance.
The mechanical package including the provided Losmandy-style dovetail clamping adapter is stiff and damps well. Counterweights are stable and the 32mm diameter counterweight shaft stiff enough to resist the low frequency resonance that used to afflict the original EQ-6. There seems to be a small amount of high frequency vibration transmission to my badly-balanced 25kg Newt OTA but the optics are mounted stiffly enough to shrug this off without image resolution being affected. I am fairly sure I could reduce this by balancing properly and/or overhauling the mechanics if I could be bothered. And here is an important point. Despite some rough edges this mount does a tough job in my hands respectably well - well enough that I have not felt the need to strip and rebuild it.
In my experience it delivers the functions of pointing and tracking to medium aperture imaging standards, without the image and ambience that goes with premium EU and US alternatives, at value-for-money pricing. I bought it as a cheap G41 clone whose mech design I've always admired and it delivers for me. I plan to add a QHI Polemaster this w/e.

Tony
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ATM, Optics and DIY Forum / Re: Relatively quiet power tools?
« Last post by halubicom on Today at 11:44:13 AM »
Well, because some folks live in urban apartments..... I have an acquaintanance who builds very elegant carved furniture - in a modified bedroom on the 6th floor of an apartment building.
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Eyepieces Questions & Recommendations / Re: Tak HI-LE eyepiece
« Last post by vicareeti on Today at 11:44:00 AM »
Tak Hi-LE 2.8 is $310 Australian, which is 219€.

Here:http://www.astronomy...k.htm#eyepieces

They are the only authorised Tak dealer in Australia

REMEMBER, those prices are AUSTRALIAN DOLLARS, so you need to convert to your currency of choice (xe.com is a great online converter)
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How do you plan to block them? It is better to allow them to float on the polisher. The test may be fine on the block only to have them spring out of shape when de-blocked.

Starry Nights
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No zooming ... bare bones for pointing modeling.
Seems reasonable to me since there are so many charting applications available.
A work in progress ...

Thanks just poking around on it today.. any reason why you'd want use it over the ascom star maps, maybe its more accurate via direct cable, or more direct control over scope?
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Problems already, despite measuring the shaft and bore before ordering the pulleys, the bore supplied in the pulley is slightly too big for the transmission shaft. It fits but i don't want any slop in the fit. Not a big problem, but i am going to have to shim the shaft i think. A Coke can makes good shims, so i will see what i can come up with.

BTW, that $15 was my retail cost for two, i am sure that supplied in bulk to the factory they would be way less than that, maybe $2. Have a look at what they are selling for on the Chinese Alibaba website.

Glen, do you know what the length of the motor shaft is? That is, from the top of the gear housing to the end (where pulley is). We already know it's short and can't measure it right now.
   The motor (actually transmission) shaft is 12mm long from where it emerges from the bracket. The stock unflanged pulley is 10.85mm wide, with the grub screws in the mid point (so about 5.425mm from either edge). The inboard edge of my stock pulley is sitting 5.3mm offset on the shaft from the bracket, this means the center of my grub screws are locked to the shaft at 10.725mm, as you can see that is very close to the end of the 12mm shaft. In fact looking in the hole i can see the grub screw right on the end of the flat section of the shaft. Be aware these are my measurements after i shimmed my motor bracket to improve the pulley position, and moved my pulley outward as far as i could on the shaft, however the shaft length will not change for anyone (12mm). This is also the reason i wanted to use an offset flanged pulley, so that i get much more of the pulley body actually on the shaft, and can lock the grub screws in the offset collar section. I think it improved the range of movement for belt alignment purposes. The offset section is 6mm wide, but i am thinking i will trim it down a mm or two.
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