Posts Made By: Thomas Dey

Tough one. I was a vac-coating engineer for 10 years, among myriad other things and know enough to keep hands off. I have myriad old TeleVues (including the original 20mm Nagler!) with coatings still wonderful. FYI, most all MARC coatings are many layers of alternating TiO2, SiO2 which are considered "hard" coatings AKA as hard as the glass and able to withstand moderate cleaning. Preferred sequence is (as needed) DI H2O, isopropanol, acetone. On eyepieces I go right to the iso to dampen a Q-Tip, and have never had to go beyond that. All it takes is one aggressive "cleaning" by someone who thinks he's scrubbing eyeglasses with a T-shirt and can ruin it. But the customer sounds sincere. I would take it back and eat the loss even though it might be his fault. If you could look at the PMs at the BIG professional observatories, you'd be amazed! Most all are FILTHY from use yet perform well. Recommended coating houses for readers: Cary at OWL and Evaporated Metal Films for really big stuff. I'm drifting off topic so will bid adieu. Tom Dey

I'll chime in substantially agreeing with the others. Testing to small fractional wave requires the same mount you will be using AKA the wiffle cell and sling must already be built. Knife edge will reveal overt problems like bad zones, turned edge, etc. Overall correction can be deemed approx correct by zonal scrutiny (KE on a mike slide). Astig (Nemesis of most big thin mirrors) requires an in-plane V-knife, but can be bent out in use with some little springs from the back. Only "proper" test is AC pointing up off a BIG, certified plano. Cary at OWL and Normand Fullum (in Montreal) do testing. A 32 incher in-hand is best kept home and star-tested in the scope...just no getting around it in that size. [I'm retired from optical testing of large optics for Uncle Sam...interferometry pointed up off big flats. The testing is a big part of the expense of making big mirrors!] I have a nice 36" and dread the thought of shipping it out for someone to test it. It was built at a reputable shop so my 1st light will actually be my 1st "test"! Tom Dey

I've spent (thousands of?) hours staring at the sky while my scope is doing long exposures and have seen most of the unusual yet explicable stuff. "Point" meteors can indeed do that but would last only a couple seconds. the Iridium (and non-Iridium) satellite flares can be astoundingly impressive. I've recorded lots of those with my all-night all-sky "roof cam" that uses a high-end FLI camera and good lens. Even geosync (and therefore "stationary") can flare but would be close to the celestial equator. An experienced friend and I saw one "next to" the moon at dusk and SO bright and stationaryish that even we were tempted to imagine it as some magnificent celestial event. Nowadays the professional all-sky survey cameras (astro and mil) are SO complete...that a true celestial event of that magnitude would near certainly not go unnoticed (software would flag it and we would find it in the news). I believe some monk witnessed and recorded a giant flare on the moon long ago...and now we know a large "fresh" crater is in that location! Tom Dey

I could be wrong of course, but think Hitler and advisors decided it was too much of a technical stretch to blow limited funds on a project that they felt could not succeed in time affect the War. Our scientific advisors also had their misgivings, but the MASSIVE effort was commissioned and the rest is history. My wife is Japanese and was a toddler (on Okinawa!) when Fat Man and Little Boy were dropped. Interestingly, she (and history) agree that the shock and awe ultimately saved hundreds of thousands...more likely millions of lives on both sides. The Japanese otherwise would have continued fighting indefinitely. War ain't pretty.

I know the sky very well and am about your age. Took interest as a kid and just sat on the roof of our inner-city house in Rochester NY under skies that would be considered superior clarity and darkness now-a-days! I had little more than a paper planisphere and small book. Eventually got to where I (still can) ID most any constellation just by catching 2 or 3 brighter stars thru a hole in the clouds. That actually became a useful skill when I was deployed to the jungles. The stars are awesome from the tropics too! I think knowing the sky is substantially a lost art for these reasons: Light pollution, mesmerizing electronic toys (kids don't play outside any more), and most new-comers seem to want to do imagery immediately...with no learning curve. Tom Dey

Hi Joe, The ST4 was (and IS) an absolutely WONDERFUL auto-guider. Requires no PC, completely self-contained. But to adapt it to your guide scope (or off-axis as I did) requires a little practice and know-how: The CCD chip is TINY by today's standards, so you need to pre-select your guide star with either a surrogate parfocal eyepiece or equivalent flip-mirror. And when you insert the guide head need to (roughly) clock it to the RA/DEC directions. The beauty is the "calibrate" set up. You just hit that (per directions) and it will calibrate itself, sensing the directions and magnitudes of +/- Dec and +/- RA. It will say it's happy and you then just hit "track" and it locks onto your guide star like a bulldog. You also need to know some basic electronics: The ouptputs are DPDT solenoids and I think NO/NC contacts which you wire up depending on how your scope is set up. I amended a cheap Edmunds geared-down 12V reversible DC motor to my homebuilt DEC tangent arm and a commercial frequency controller to my RA (Byers 11 3/8). After some fiddling - it was tracking my 650-lb newtonian flawlessly for many thousands of hours of use at 2000mm EFL. All that said - you of course need a decent mount with good, smooth, reliable drives and decent polar alignment. I consequently collected hundreds of multi-hour exposures on film (yeah-way back then) with sub arc-sec tracking better than I could do "by hand" and I was in bed sleeping! All that said, i believe there are mounts and "idiot-proof" plug 'n play guiders today that would be WAY easier to use but maybe quite pricey once you get everything you would need. I'm old-fashioned (and now just plain OLD) so still prefer to build my own stuff and understand how and why it all works...or doesn't. I recently got a fine 36-inch PM that will fit in my dome!...ALL I need do is build the scope - Yikes! It will replace my very nice little 29-incher... The ST-4 can indeed collect images...but was never really meant for that because the chip is miniscule. Tom Dey

Here in NY (as in CA) we have similar punitive taxes on gas, sales, houses, schools, roads, fees, surcharges, food, income...endless list. Now what do NY and CA have in common...Hmmmmmmm. Oh Yeah! Fleeing businesses and skilled workers; once thriving economies driven into ruin by---blue bureaucrats. The most productive are voting with their feet!

Hi Jeremiah, Before my retirement from aerospace work a few years ago, I enjoyed the luxury of doing self-directed independent research as an ITT Tech Fellow. Among that was a 16p unpublished paper, "Photometric Throughput of Visual-Use Astronomical Telescopes." I measures the VRGB transmittance of a bunch of eyepieces to 0.2% accuracy or better and also the performance of the coatings. Here are some of the (V-only throughputs and coating loss per surface) results: old Orion Big Barlow 97.3/1.2%, old TV Paracorr 95.0/1.1, TV Dioptrx 98.5/0.7, old UO 55mm Plossl 88.0/3.0, old Celestron 26mm Plossl 95.5, 1.0, old UO 24mm Konig 90.6/2.3, old UO 12mm Konig 92.3/1.9, old TV 13mm Nagler 90.2/1.2, old TV 9mm Nagler 90.7/1.1, old TV 20mm Nagler T2 88.4/1.1, TV 13mm Ethos 93.8/0.6, old Zuiko SLR lens 50mm f/1.4 92.7/0.6, old Zuiko SLR lens 100mm f/2.0 93.5/0.5. I traced the surprisingly high loss in the 3 old UOs to the coatings...they cheated by only MARC-coating the one outside surface toward the eye. The only really superior coatings were the Ethos and (old!) Olympus camera lenses! The old Naglers and (surprisingly!) the old Celestron were decent. I also did papers on mirror coatings and 20 commercial Star Diagonals (wavefront, throughput, alignment). A new Antares "Dielectric 99%" measured a pathetic 88% and was horribly misaligned! The (reputable) dealer didn't want to hear about it, just the middle-man but did offer me a refund. I kept it as an example of a really crappy defective diagonal. I also did a very ambitious paper on scatter and one (long time ago) "Telescope Quality - How Good is Good Enough" wherein esteemed co-author Daniel Malacara and I did a performance analysis of telescopes suffering (among other things) Primary Spherical Aberration. That was pre-launch of Hubble and damned (negatively) auspicious, considering the later-discovered Hubble SNAFU! Most of these (and a couple hundred other) tech papers are available. I usually incorporate such material into presentations, many in the amateur astronomy community.

But back to your question, I agree with Rod that it hardly matters. But the TOTAL throughput of your system will affect your ability to see such subtle stuff like remote galaxies. Oh yeah, most coatings measured deficient in the blue = spiral galaxies! For wide-field DS, nothing beats a good fast APO or Giant Newt with modern WF eyep (Delos, Nagler, Ethos). For high-mag resolution, nothing beats a slow-feed scope with a nice Ortho! That's just my opinion part...

Bio: The vast majority of my work was professional aerospace and put bread on the table. Satellite docking, Hubble-Class imagers, Keck 1&2, KPNO (light pollution), Night Vision, GPS...myriad others. But I've always been an amateur astronomer at heart and now enjoy that in retirement - 36-inch scope! Woo Hoo! And my eyes still work...?! Tom Dey

Hi Paul, I have the same Zeiss 20x60 IS binos and absolutely LOVE them. I'm sure that with solar filters hand-held (IS engaged of course) that would be steady enough to get a quick look at spots. Biggest problem in-use would be even FINDING the sun in an otherwise black sky. At 20x, we know how tough that can be. So a tripod would make sense. Also, the same goes for ergo comfort...with the straight thru view, it can get uncomfortable looking up for much more than a minute. Regarding filters, I had found with my TeleVue Genesis 100mm telescope that those glass filters have TERRIBLE wavefront so went instead to a LUNT Herschel wedge which is absolutely wonderful. You (actually WE!) would need unusually-good foil or glass front-filters to take advantage of the superb resolution of the Zeiss binos...but at what the 20x60 IS cost...expect we would pay the price if such filters can be found. All that said, the foil would seem to be the best bet because if you get a big sheet you can search around for good regions with a telescope before deciding which pieces to cut out for use. Bio: I was an aerospace (optical) scientist so spent my whole life building stuff. Usual disclaimer - don't look at the sun without proper filter! And don't send raw sun thru ANY binos! It would probably fry the structures around the prisms before even getting out the tail end! Tom Dey

Yeah - when I got mine, I had the same curiosity but found no details. But, being a physicist...I'll just guess! I DID learn there are magnets in there and of course oil. I can see where the viscosity of oil might serve as high-freq dampening while still allowing the pointing drift which would of course be the intentional part of using the binos. So the prism(s) are literally "floating" in oil in some tandem fashion that only addresses the 2 DOFs associated with pointing while leaving the others associated with focus and field rotation unaffected. When you engage the safety clutch that "clunk" would be (other?) magnets engaging the benign but effective lock-down. I have used (Newport) ON/OFF magnets that accomplish that via rotating one magnet within another so they cancel or add...giving the magical sense if turning the clutch on/off with no power needed of course. All other IS binos use powered accelerometers and servos...which I understand have responsivity and time-delay problems. I LOVE the Zeiss 20x60 IS and they have been around a pretty long time without users complaining...unless they abuse and break them! Damaged IS system repair is $2500 last I looked. Mine are fine and I'm very careful who I even share them with. The MSRP on these binos has recently INCREASED from $7333 to $8000 - Yikes! Must mean there are deep-pocket users out there willing to pay the price and that these continue to enjoy deserved reputation as "the best." Tom Dey