Posts Made By: Philip Blanda

The brightness of the mirror depends on the coating, not the substrate. Cost aside, Pyrex is a better material for a mirror due to it's lower coeffecient of thermal expansion compared to BK-7. It's less than 1/2 of BK-7's (3.25x10^6 vs 7.1x10^6 for BK-7).

Word is that BK-7 is very cheap in China and Pyrex like glass rare and expensive, so Chinese mirror makers are using BK-7. It's not a bad choice at all and a good mirror can be made from it.

Philip

Here is my daughter Isabella and her new, Santa delivered, Hardin DSH 6" dob (it was the $99 closeout special). She placed the alien and planet stickers all over the OTA and kissed it after eack and every thoughtful placement. No pink paint needed.

Anacortes did a great rush job on the telrad, and it made it here in time for Santa. Thanks guys!

Daddy did take it out last night and took a peak at Saturn. The scope wasn't cooled down, and Saturn low so it wasn't all that it might be, but it works!

Philip

I have read that the new EQ6 has a smooth periodic error of +/- 7.5 arcseconds. Have these mounts reached new levels of mechanical fabrication? Are the users of these mounts mistaken? I am skeptical, given the level of construction I have see such mounts so far.

The what? Is Meade going to get back in the APO business? With a triplet?

[I]Anybody got good intell on the new Meade Series 5000 ED APO Trips?

I see a trend that when a new refractor of a new design is introduced, folks assume that the scope will be as fine as the very best that have been produced in the past. As if it isn't hard as heck to produce a fine optic.

Pictures of fine painted tubes seem especially to get the people to assume that the optics will be as good as the paint job. I don't get it.

When I take a chance on a new design, I scrutinize the optic and OTA very carefully. When I got an AP 160EDF I reserved judgment until the scope proved to me what it can do - sure I expected it to perform well but I didn't assume it would. There was no question that the designer and optician is a good one, it was not any stretch to believe the scope would be good.

But new designs from unproven designers and opticians are coming out, and people are already placing them on the same level as the expamples that have already shown themselves to be superlative.

I feel that reputations must be earned, not granted.

I have come to a definite preference - I hate steeply curved eyelenses. For me, the slightest bit of fogging that in other eyepieces goes unnoticed causes a bright object in the field to be surrounded by a very bright halo of light. When the curvature of the eyelens is just right, I get a bad halo around a bright object in the absence of any fogging.

I have sworn off the Tele Vue Radians for this issue - the 6mm was unusable by me for planetary viewing and the 14mm Radians I used for binoviewing had to be used extremely carefully to avoid a halo. Since few others report this annoyance, I suspect that the curvature of my eyeball is just "right" to cause me these issues.

The TV 13mm T6's show nothing of the halo, and my old 13mm Nagler and 9mm Nagler (original types) never showed this halo tendency either.

Philip

I just saw something indicated that a lens on an AP 180 f/9 had been recoated recently (~2 years ago) by AP.

I has no idea that this services was available! What are the reasons for recoating a lens on an AP refractor? Damage to coating, upgrading light throughput, something else? Would the lens have to be polished out and refigured to remove the old coating?

I posted here because I think that this issue is of general interest to AP refractor owners.

I had never used my Baader Mk.V with my AP Traveler/Baader AstroSolar film setup before. Just inertia I suppose.

Anyhow, I did today. Wow! There is a nice spot group that has almost made it to the center of the sun, and it's trailing companion group moving to be nicely placed as well.

I used a pair of 24mm Panoptics and 13mm T6's with the 1.25X glasspath compensator. Very nice views. The sun really takes on a 3D ball shape, with the limb darkening helping the illusion* along. The solar granulation was very evident, and good inner detail was seen in the penumbra of the main spot. I think that the Sun is a good target for binoviewing.

I want to say again that the 13mm T6's are really spectacular eyepieces in a binoviewer. I like 'em!

Philip

*Is it an illusion? The Sun is, after all a ball even if depth peception fails to detect it. So if an illusion is closer to reality than ordinary reality, is it an illusion? And what about that lonely tree falling in the forest?

I had a great time on Saturday night at the South Jersey Spring Star Party. Attendence was sparse, but it was a good bunch of people, including Paul Rini (of eyepiece fame) who is a nice guy to observe with.

I brougt my AP 160EDF on my AP 900GTO mount - I was the only refractor there. The closest to a refractor was an Oberwork 100mm Binocular. Had a great night of observing with many objects, but I want to mention two views that were highlights.

The first was the bright C fragment of comet Schwassmann-Wachmann - it was pretty close to Zeta Hurcules and easy to find. The head looked a bit squashed which was interesting and the comet was so fast moving across the star field.

The other, to me, amazing view was of the M86 (NGC4406) area of the Virgo cluster. Using the Baader Mk.V Binoviewer, 1.25X glasspath compensator and a pair of 24mm TV Panotics, I and others identified at least 6 galaxies in the field of view with a possible 7th and 8th! I can't positively claim the 7th and 8th because I am not sure I spotted them before checking the positions out on the star chart, but I think I did.

The trio of M86 (4406), M84 (4374) and 4388 was easy and the close pair of 4438 and 4435 framed above them in the field of view. Almost in the exact center of the trio 4387 was visible with averted vision. I think that I could occasionally see 4413 and possibly 4425, but I can't positively claim them - I feel I did but it was close. For my own accounting I will therefore claim 6.5 galxies in a single field of view.

I'm pretty happy about this as the Virgo galaxies are just about completely invisible from my home, no matter what size scope one cares to use.

Philip

The 40mm Paragon was there, and I looked through it when it was in an 80mm scope of some sort. The rafters were straight to the edges so it has little to no pincushion or barrel distortion. It seemed sharp, but there was some field curvature evident, but how much was attributed to the telescope or the eyepiece was impossible for me to tell.

I thought it was a nice eyepiece.