Posts Made By: Thomas Dey

Yes to Floyd's. I took a similar custom scope and tested it on a cell tower couple miles away on a hot summer's day. Capturing short-exposure images watching monitor and saving maybe 1 out of 20 "sharp" ones. Found that even among those, only 5% were decent. So that's 1/400 decent and the rest marginal to terrible. If you see occasional OK glimpses, that could exonerate your scope. Try it under good conditions with scope ambient temp at dawn or dusk over grass? That's when my solar scopes give good resolution. Other choice would of course be on a good night on the stars. Tom

Hi Charles, It is the design complexity and focal lengths of your eyeps that relate to f# of the telescope. The good news is that f/5.7 is pretty slow, so even modest eyeps (Kellner, Orthoscopic, Plossl) and up from there ... will all perform nicely. Longest efl "rich field" eyep is commonly telescope f# x 6mm = around 35mm. Anything around that is good for your "low power" eyep. Then get others of shorter efl for more magnification. The magnification is telescope focal length divided by eyepiece focal length. M=F/f So the referenced 35mm would give you 33X. A 20mm eyep would give you 58X etc. The fancier eyepieces will allow more field. I wonder if the cryptic rule of thumb you paraphrase might be the MAX magnification considered reasonable?? Note that would be a 1mm exit pupil and deliver 25X per inch of aperture. I further note that the 1mm pupil makes the Airy Core diameter appear to be 4 arc-min visual diameter ... comfortably resolved by your eye --- so arguably no point in going higher "empty" mag. Hope that made sense. Enjoy the views with YOUR mirror; Congratulations! Tom

Spectacular! And some of the "stars" are no doubt galaxies too. I sometimes wonder what a deep image would look like without the foreground stars. I guess the brighter stars could be erased in software, but at some threshold even a smart program would have the same uncertainty that we have when looking at the image. I also like the stellar core and other detail of the main attraction.

Hi Al, Forgive me for chuckling - looks like some apprentice blew thru that with a cutting torch! I frequently improve/repair stock deficiencies in my home shop, but that's ridiculous. Welding on a couple stout washers might address it, but that goes beyond “some assembly required.” In contrast, I have had wonderful experience with JMI, OWL, Fullum, Starlight, FLI, EMF, Astrosystems, Obsession, APM … myriad others. The commonality is I know every cordial principal by name and they know me. He should just send you a good yoke and be done with it! Tom

Nice! I was opposed to Mars a month ago, but got past it.

Cool! Something I'm actually familiar with. I use the old TeleVue f/5 Genesis. Have found that a green filter sharpens the raw Lunar image immensely, probably because it is also minus NIR and my (Lunt Solar!) camera seems to have typ CCD spectral responsivity. Do the blessed short exposure times feel like “cheating?” Tom

Hi Rod et al, Thanx for the update. I know I bloviate a lot but can't resist venting on this one. WAY back in 1977 I designed low pressure sodium street lights for the Big manufacturers. Our (patented) prototypes were efficient and trespass-free. Long story short: The Marketing Guys killed the development! The LPS only saw use in Europe. Why?! The Big Lighting companies only wanted more and more lighting --- because that's where the $$$ is. The IES (Illuminating Engineering Society) gave only lip-service to efficiency, health and environmental concerns. Because the IES was almost exclusively loaded with manufacturers. It was a rude awakening for me as a young scientist. From then forward I always take ~we make good things for living~ with skepticism. Far as I can see, things have only gotten worse.

That's wonderful, Maciej! I was looking at it last night. It was low and lateral dispersion correction would indeed help a lot! Tom

I find this place intriguing - http://www.spectrum-coatings.com/index.htm They offer standard and high-end dielectric coatings. Just getting the super R coating on the diagonal should improve telescope throughput immensely. Would want to ask regarding performance at 45 deg though; especially dielectrics need to be tuned/customized to that. I bought a New Antares 2-inch Star diagonal marked Dielectric 99% and measured it to be a pathetic 89%. All I can figure is that they put a normal-incidence coating on the thing and naively expected it would perform as a fold - NOT! Attached is an image of my Test Report on that. Tom

Wonderful! Tech: I believe the extreme right edge shows the radius of one of your processing filters? Like 2 or 4 pix? UM always does that to me. Tom