Posts Made By: Thomas Dey

Well, you've got just about Everything, Michael! The NDs are essential for lunar else you blow your eyes out - and they are very inexpensive. I would get the 13, 25 and 50 (but the 13 is really all you need). If you are going to do solar imaging, all 3 NDs are handy to get short exposures (5-10 milisec ideal). I have found with a CCD camera (which will record NIR if not blocked) that when imaging the sun or moon, ND as needed + Green 56 make the image WAY crisper because achromats, semi-apos and apos suffer BAD chromatic in the NIR - the green filter blocks the IR, NIR, red and blue---so imagery is no longer relying on the chromatic correction nearly as much. Ummmm for solar I have found that the LUNT Herschel Wedge is WAY better than the mylar or foil front-mounted solar filters. But f/5 or slower else you fry the back of the scope. Also not recommended for scopes that have glass back in the tube (like the Genesis) --- but I have been doing that with my Genesis with impunity. It works GREAT! Lets see - single linear polarizer---just might detect polarization in some nebulae...not sure. For any other readers, a COMPLETE tunable polarizer would incorporate linear plus quater wave plate that can be rotated to create throughput of ANY selected discrete polarization state. If interested, look that up on the web---stuff called Jones Matrix and Stokes Parameters I, Q, U and V... I made one of these for use in the lab and (with a radiometer behind) it allowed me to actually MEASURE the complete polarization state of any source. For astro stuff you would find that nearly all sources are unpolarized or only slightly polarized... I'd better shut up now and clean the fish tank. Tom Dey

It should help immensely because it quells the "shakes" and off-loads the weight. Anyone wanting to simulate the affect, attach to a "regular" tripod with just one of the legs extended and try it. If you like it, either get or make a monopod...or saw two of the legs off... Tom Dey

I've never heard of that...but small (probably VERY small) particles could hang in there at arbitrarily low orbits. With all the (typically small) meteors that impact the fine dust surface (indeed helped Create and maintain it!) I can see where plenty of stuff would get ejected into low orbit. Modern multi-band imaging sats would be able to detect the stuff quite definitively---especially viewing near the dark limb and sol close by. Our imagers traditionally make this a "keep out" zone 'cause the team doesn't want to risk frying the hypersensitive detectors by inadvertently planting the sun (or even the illuminated moon) on it! All it takes in ONE error (even in slewing) and mission is screwed. There's Gota be stuff there though and all it takes is the guts and logistics to target it! I presume that is why they are doing? Hubble, Spitzer, UV? Anyway...NO, it certainly would not need an atmosphere in the traditional sense. Tom Dey

Hi David et al, Interesting that I was just musing over the exact same question then saw your post here. I was looking at the APM bino ads and noting that the trusty 100mm/45-deg Semi-Apo go for ~$1000 and include a nice hard-case and eyeps, the same Apo are ~$2500 and the 90-deg Apo are ~$3000. Far as I can tell the lenses are doublets but I believe the Apos use a more prescious glass to achieve a flat spot in the correction curve = much better color correction. The mechanical build is equivalently better. Stated mag capability for the Semi-Apo is 50X; Apo 100X+. Extreme limit would be a couple of $5000 refractors gone bino (which indeed are available elsewhere as custom-build). As with most things...you get what you pay for. I worked at Bausch & Lomb years ago (when they made world-class premium binos). So I went to the Company Store and tried all their same-sized binos side-by side. The cheapest ones were noticeably deficient but honest good for the (cheap) price. The mid-priced and premiums were nearly identical wonderful in perceived performance; and I'm VERY picky when evaluating optics because that was my job! I concluded that mid-priced binos are the best buy for picky customers. As far as the nomenclature of Achromatic, Semi-Apo, Apo and Premium Apo ... the nomenclature seems fairly ill-defined. Heck, I have a very nice TV Genesis that is without doubt true premium APO - but I STILL see a touch of (completely tolerable) color! The ONLY scopes that I judge as totally color-free are reflectors (of course) and the very $$$ Zeiss hand-helds, like the 20x60 IS that VERY expensive ... and worth it! So, with some irony...I would go more by honest price rather than wording. Ummm...I also have 100mm Obies, astoundingly inexpensive for 100mm binos, fork, tripod, case, eyeps---but (no surprise) find the color and resolution pretty disappointing! Pay more---get more? Tom Dey

Oh, I just thought of something else that pertains: The human eye has about 0.65 diopter of undercorrected chromatic, standardized in a red-green test environment target. I measured my red-blue at 0.8 D which is consistent. People's eyes all have nearly the same chromatic because it is the nature of our eyes. We also have spherical aberration. When I got the lenses in my eyes replaced with plastic ones---they are corrected for spherical and my vision is now 20/13 each eye (20/10 when using both). The theoretical res limit of the retina is around 20/7.5 which is like reading fine newspaper print from clear across the room! What I'm saying is that our eyes ultimately begin to trump even the BEST scopes. So judgment of perfection ultimately is more scrutiny of one's own EYES rather than the instrument. This is especially pertinent when judging Astigmatism. I'd better shut up now - I'm an obsessive-compulsive optics guy. DISCLAIMER: My comments are intended for novelty purposes only.

Actually, the lady narrator is pretty disinterested in her commentary and the images of that bump and those bright spots are good. Problem is when scientists use metaphorical words like Pyramid, Face, Charm, Spin... the public and press take it LITERALLY and go with it. Yeah, that guy on the History channel is a nut-job - an entertaining nut-job. Also the physiology and psychology of human pattern recognition is extremely sensitized to faces. Just look at randomized textured ceiling paint or wallpaper and you will of course see human and animal faces all over the place!

Nice! The moon and sun are ideal targets for imagery: Both are bright, big, highly-structured and change a lot. The moon with the phases and the sun with the rotation, spots, etc. I image the sun a lot - and it continues to be very "active!" The planets are interesting but "small" and Deep Sky can be large but very dim. I guess everybody knows that...but it sometimes makes sense to state it. Tom

Hi Tom, I used an original 9mm Nagler "Type Zero" for (decades?) and it was (is) WONDERFUL! The only reason I sold it off was because I got my eyes fixed and can now see the entire field of Ethos. The pre-type 2 Naglers did not correct for spherical aberration of the exit pupil, but for 13mm or shorter EFL that was OK because the aberrated pupil still fit thru the dilated pupil of most people's eyes using f/4.5 or slower. Offset eye of course gives that kidney bean effect as the eye's pupil shears off pupil-marginal rays. People who USE eyepieces seem to want the latest versions, even though most of the vintage TVs are wonderful. People who COLLECT eyeps seem to prize the really rare old ones. So it's the in-between vintages that generally sell for FAR LESS than purchase price. So much for my opinion trying to rationalize what makes and models typically go for used. Tom Dey

Hi Thomas, That is interesting! I studied insects for the Dept of Agr (in Panama) back in 1969-70. I just LOVED the field work and brought back a big personal collection as well. That finally wound up at the local high school. Some specimens are so big that one takes up a whole display box! And with the Astronomy connection - I concentrated on Insect Vision. Such best sellers as: Polarization Sensitivity of the Compound Eye of Hymenoptera Bombus and Antireflection Properties of the Moth Chitenous Cornea Surface... Yep - moth corneas are antireflection coated - Better tnan ours ! Tom Dey

Hi Roland, That's Beautiful! I notice you are in Rockford. Decades ago we made many trips from Rochester, NY to Rockford to visit a machine shop that had a BIG coordinate-measuring machine. We would show up with a truck-load of equipment and assemble our custom interferometer that was about as big as a full-sized van. We would calibrate the interferometer on the CMM there and then return to Rochester to characterize space hardware. We made numerous such trips because calibrations had to be done both before and after use to assure that it was (probably) in-cal when we used it! I did the optical design and build of the device. Nearly all of our interferometry was required better than 1/100 wave RMS SP HeNe with a repeatability noise floor of 1/1000 wave! We eventually got our own Big CMM. Now I'm retired and looking at the stars. Tom Dey