Posts Made By: Dan D DuBal

With all due respect, Rob, the market's right in front of your face.

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You honestly don't get this? Do you truly believe the XT10 is overpriced? or are you simply ragging? Do you think the XT10 isn't selling? or do you think the thousands who've bought one are mentally challenged?

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So, "good optics" is all about reflectivity? Do you think the XT10 has bad optics?

The previous spider's vanes were much thicker. It's called diffraction. Look it up.

Four-vane spiders have *always* outsold their three-vane counterparts (and probably always will). That's a market thing. Go figure.

Maybe XT10 buyers -- and there are LOADS more of them than buyers of any other 10-inch Newtonian -- don't care much about an extra three percent reflectivity per surface which can be effectively and easily reduced to "less than enhanced" by adding numerous eyepiece &/or barlow lens surfaces (whether by a beginning or advanced stargazer).

Maybe they can't even discern the difference (at the eyepiece) between a 10-inch scope with net/system transmission of ~82% and another with ~77%. Maybe very few humans can.

Maybe they simply want the most bang for their buck, and maybe they feel Orion's customer service (plus the XT10 itself) gives that to them.

Maybe they're just not aware of the same-priced competitor. Or maybe they *are* aware of the competitor but don't give a hoot.

The market for a very good $600 10-inch reflector (with accessories) from a long-established company with a reputation for excellent customer service...?

Gee -- sounds ludicrous. I can't imagine what all those thousands of XT10 buyers were thinking...

Oh well.

Your descriptions -- shimmering edges, wobbling and wiggling -- seem to indicate nothing more than atmospheric turbulence (and perhaps tube currents within the Intes itself. Tube currents will occur whenever the scope is moved from one ambient temperature to another (such as when the scope is moved from indoors to outdoors). The Intes must be allowed time to adjust to the outdoor temperature.

Jupiter is quite low to the horizon at sundown. It is always very likely that atmoshperic turbulence is at its *worst* down near the horizon.

Mars will face the same potential problems (shimmering and turbulent images) while it is low in the east-southeastern sky.

I believe your Intes is perfectly fine. I too have an MK67 which I bought from ITE about three years ago. Bill and his staff at ITE are all very capable and experienced -- they would *not* allow a scope to leave the ITE facilities unless it was in superb working condition.

Again: what you're seeing and describing sounds very much like turbulence, which is very common. My views this evening were also shimmering and boiling, and I know these images were *not* caused by my MK67.

You might try the following tomorrow night:
Once the sun sets, take the MK67 outside (mounted and ready to go) -- to a grassy area, if possible. Avoid concrete and/or asphalt, as these surfaces will radiate heat and compound the problem of turbulence. Allow the scope to stabilize/equilibriate and "adjust" to the ambient outdoor temperature. This "adjustment" period may take an hour (or even two hours). Be patient. When you're ready to view, try the Moon first.

Best wishes and luck.

-Dan

You bet'cha.
Anacortes sells the JMB solar filters (glass), and they are available for scopes in the 60mm range.

Orion also offers filters (glass) for their "Explorer" 60mm refractors, as well.

So, yes, they're definitely out there.

Best wishes.
-Dan

Hi, Tom.

You may well be seeing true improvement. All prisms (plano-parallel optics) add a little overcorrection to the mix. (They also add spherochromatism, too, but that's a non-factor in this case.) The larger the prism (or the "thicker" a section of light-transmitting glass), the more overcorrection will be induced.

If your XT10 is inherently *undercorrected,* what you're seeing would make perfect sense.

Best wishes, and enjoy that curious apparent correction you're seeing!
-Dan

I'll NEVER tire of Luna. She holds more fascinating features, textures, and vistas than my brain could ever hold.

Thanks for sharing, Ron.

Thanks for sharing your observations, Darren. I enjoyed reading your report.

Hey, you might try starting in *Virgo* when hunting down M5. Check out this chart:
http://www.sciencecenter.net/whatsup/05/v-stars.htm

Note the "upper leg," which ends with 109 Virginis. To its left (east) is another star. Follow that line eastward to M5. The distance between M5 and that "other" star is pretty-much the same as the distance between that "other" star and 109 Vir.

M3 is not-quite halfway from Arcturus to Car Caroli (alpha Canes Venatici), along a straight line. Also, M3 forms the third point in an equilateral triangle, with the other two points being Arcturus and Rho Bootes. (the other star in Bootes's "waist" (~west of Epsilon).
Check this chart:
http://starryskies.com/the_sky/constellations/bootes.html

Hope this helps. Let us know what you think of these two jewels, once you track them down.

Best wishes.
-Dan

I'm with you, then -- a small axial zone. If I can dig up any more specifics, I'll pass them along here.

Hope I didn't sound patronizing in my previous post -- didn't mean to. I obviously didn't read your original description as well as I should have.

Whether or not the aberration is worrisome, I guess that might depend on the "role" the scope plays in your own astronomy "realm." If my Pentax displayed the same aberration while still performing as it does (which is very well), I wouldn't worry about it at all. In other words, let the scope's history of performance (and its in-focus views) do the talking, so to speak.

Cheers,
-Dan

Hi Bob.

You might try deleting any/all astromart cookies, then log in again to let them re-establish themselves (don't forget to check the "Keep me logged in" box, of course).

Worth a shot, anyway.

Best wishes and luck.
-Dan

Try a search for these two keywords:
duplessis meridian

That will lead you to the Meridian software download (freeware). Graphics aren't fabulous, but it's a nice program. It covers Mercury, Venus, Luna, Mars, Jupiter, & Saturn.

Not sure of the status of Mars Previewer II, but recent reports note that the program was infected with a Chernobyl-variant virus. The virus is certainly removable, if you're comfortable &/or willing to play Dr. Quarantine Surgeon and try that. Hopefully, this fine program will be cured soon.

Best wishes.
-Dan

Hi Ed.
You'd end up with a "net" filter with rejection characteristics being the *sum* of both single filters. Place both rejection curves on the same wavelength scale, and you'll have their net bandpass curve.

Since the H-beta and OIII filters are essentially "line" filters (strong or full rejection of most wavelengths other than their targeted bandpass peaks), when they're combined with a narrowband or broadband nebula filter, the "weaker" or broader-bandpass filter is essentially nullified -- neither filter is enhanced nor "helped" by the combo.

Best wishes.
-Dan