Posts Made By: Herbert Kraus

My thanks to all of you who have responded to my original inquiry about where to obtain field stop diameters of the various makes of commercially available eyepieces. Apparently such information is not readily available, except for data based on the formula that divides the APOV by the magnification power of the eyepiece in question when used in a particular telescope. Unfortunately, I need something more precise than the rough approximation of TFOV yielded by this formula.
I tried a Google search which furnished me two sites that were helpful to some extent:
http://www.astro-tom.com/technical_data/eyepiece_specs.htm contains data for many eyepieces. However,field stop diameters are given only for eyepieces made by Clave, Edmund Scientific/RKE, and TeleVue (which still seems to be the only manufacturer from which this information is readily obtainable anyway).
http://www.petersonengineering.com/spreadsheets/Eyepieces-for-14_inch_SCT.htm does have measured field stop diameters for substantially all of the eyepieces it lists, including Meade and Celestron models, although its list seems somewhat more limited and may be somewhat out of date.

My NexStar 8i was acquired two years ago. Its 23 pound weight does NOT include the tripod or any accessories that I might place on the OTA.

I believe all your requirements are satisfied by Cartes du Ciel, except that the limiting DSO magnitude may be closer to 10 than 12. Cartes du Ciel can be downloaded for free from the Internet (I don't have the address handy, but you can get to it by using "Cartes du Ciel" on your search engine).

Alex: Your post and Ben Kokes' response lead me to make this suggestion: Draw a distinction between (a) beginners who seek information about astronomy and the objects and phenomena they can observe with their telescopes, and (b) beginners who seek guidance regarding telescopes, their accessories and their uses. As one who has studied astronomy as a hobby for many decades, I don't consider myself a "beginner," but I only took up observing a couple of years ago and I could always use more information about the hardware. By the way, I commend you on your workshop project. Good luck with it.

Andrew: It sounds to me as though your telescope is only offering you the non-GPS methods of aligning. Apparently you've gone to the "Utilities" menu and made sure the GPS is "on" under the "GPS on/off" submenu. Then when you go to the basic "Ready" condition you can get GPS alignment in one of two ways: Either punch the "Alignment" button, or punch the "Enter" button and then select the GPS Alignment alternative. If your scope doesn't select any alignment stars for you in the alignment process, something must be broken. Sorry I can't help you fix it. Good luck.

With all due respect: I think all this righteous indignation is misplaced. Buying a pretty certificate that says a star is named for you is like like buying a "pet rock," or a Disneyland ride through a "haunted house," or your photograph in one of those cutouts that makes your face appear on the body of Arnold Schwartzenegger or of a voluptuous gal in a bikini. Very few, if any, buyers of these certificates believe that professional astronomers will refer to the star by their names; and they don't really care whether the International Astronomical Union does or does not accept the fact that someone loved them well enough to want to put their name on a star.

Andre: In another thread you indicated one of your scopes is an 80ED. Last year I also wanted a big field of view for my 80ED in order to have a true field of view that would take in the entire Veil Nebula or the entire Andromeda Galaxy. Not having any desire to pay hundreds of dollars for any of the high-end TeleVue eyepieces, I bought a BW-Optik 30 mm Ultrawide (APOV 80º) for less than $100 from Anacortes. It gives me a 232 arcminute TFOV in the 80ED and works fine, if you can accept something less than perfect performance around the edges.

Like some of the others whose replies are posted here, I viewed the impact from the LAAS site at Lockwood Valley. A large gang of viewers had shown up. My observations were through my modest 8-inch SCT, using a 15 mm Panoptic eyepiece (135x). I thought I glimpsed the comet before the impact, but that might have been my imagination as I was staring at the spot where I knew the comet to be. The impact itself did not cause any visible spark or flash, but during the minutes following the event the comet did indeed appear to become brighter until it showed me a star-like image just at the lowest limits of visibility for me and my equipment. I don't know how long this increased brightness lasted, as I then slewed the scope eastward to view some of the celestial marvels in Scorpius in dark and transparent skies.

I suggest you search the Astromart classifieds to find what is a reasonable price for a 2nd hand Questar. It will depend on which model and what features (e.g. type of glass) are being offered. Several different versions of the 3.5-inch Questar have been offered on Astromart in recent months for between $2,200 and $4,000 (U.S.), with a median price of about $2,950.

Dan: Your Bubble Nebula image is breath-takingly beautiful. Allow me to express a minority view: Stick with the black/white views of nebulae (Ha? whatever that means) and eschew the color. As a strictly visual observer of DSOs who does no imaging whatsover, I look for photos that reproduce the ghostly silvery glow that these objects display at my eyepiece. I am not at all fond of the highly processed garish crimson or scarlet versions of emission nebulae produced in contemporary color images which look to me like thickened clouds of coagulated blood that often obliterate the sparkling stars within them. Just one guy's opinion, with no disrespect intended for the work done by skilled imagers of DSOs who like to work with color.