... The reason dew forms on scopes even though the rel humidity is <100% is because they cool below ambient due to radiative heat loss to the cold black sky....
... No, in fact using a fan will keep it closer to ambient (as long as it's not wet from dew, in which case the blowing air would increase evaporative...
That's basically what I do. I was using the word "chart" loosely since most paper atlases aren't deep enough if the aperture is large enough. -John ... ...
http://monquebec2008.sympatico.msn.ca/MonQuebec2008/ <http://monquebec2008.sympatico.msn.ca/MonQuebec2008/> -Happy New Year WE start this one in special way...
Hey group! Thanks to all for the great response to the GoTo/Push-To/Drive thread. Now for another question. The scopes I'm considering in the 10-14.5" size...
I looked it over, but wondered about the glues they used in making it. They indicated that the plywood is for interior use only, but most plywoods are just...
Greg: A faster scope is anything faster than f/6. Many feel they don't need the Paracorr at f/5. I know that some feel that f/4.5 is OK without a Paracorr....
I use an f/4.2 without a corrector, and you can see the coma in the outer parts of the fov with an 82 degree fov ep, but it isn't that bothersome to me. It...
Hello, I have played a lttle with Steve's diffract.r and I have simulated the effect of aperutre masks on the turbulent diffraction patern. Just to verfy that...
Doug, This is different then the Home Depot "Baltic Birch", right? I see the baltic birch (looks pretty bad) , but not the "cabinet grade plywood". David...
Hi Greg, generally, I feel the Coma issue is over-rated. If you have tracking, you can just keep the object of interest right in the center, and the image will...
hi Mauro, Another set of instructive simulations! The value of a sub-aperture mask has been a topic of recurrent debate over the years - but on the whole, my...
... exactly! I plan to do mtf evaluation for bad mirrors (say 1/2 wave, or TDE etc) and look whether and how much the mtf improves. I expect that in some cases...
Mauro, ... I'm happy to contribute in any way I can. I suspect that you are using a very old version of my program. I haven't worked on the star test code...
... over the years - but on the whole, my impression is that most people do not consider it helpful in general. This is my experience. I used a 7" aperature...
... In fact I am using the Jan 2007 version. I had to write four lines of code to add the masks as I needed. The mtf function looks strange in that sometimes...
And, in the opposite camp is yours truly. I find coma objectionable in my F/5 scope from nearly the center out. I HATE coma and need to squash it if I see it...
Mauro, ... values.>>> This should happen - I believe for the same reason that there is a bright center line in the dark shadow of a Ronchi line or "wire test" ...
Greetings! This is just a brief announcement of three new items at Markless Astronomics. * Battery Bracket (Product #6) * Custom Length Encoder Cables...
I used to own a Paracorr, and sold it because I didn't use it much. You can use a much faster scope. Just buy a Keller corrector (Astro Optik):) Tom...
... An interesting idea, but it doesn't sound at all easy. Wouldn't you need two separate secondaries, aimed different directions (eventually sending the light...
... mask ... separate ... an ... to ... compensate ... Nils At first blush I'm a bit unsure of this. A two aperture mask will yield two ligh cones with a...
Joe and John, you write ... can yield the latter of the above optical configurations. and ... directions (eventually sending the light to two EPs via more ...
... mask ... cones ... slightly) ... a ... beamsplitter ... plane, but ... directions ... different ... (apart ... not ... widely ... was ... and a ... used no...
Hi Don, A 14" f/5 scope, should have about 10 arcminute diffraction-limited field about the axis, for coma, which should be sufficiently wide for most visual...
... You're right I was thinking of a standard binoviewer, but still... ... ...the two light cones from the two subapertures are still converging towards a...
John, ... converging towards a single image at the focal plane. How do you separate them?>>> If you draw the light from a star as two cones from the apertures...
Nils Just one more question... Why even bother with the "Bi-aperture" mask? Wouldnt each half of the stereo microscope in effect be defining its own eccentric...
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