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Posts Made By: Dan D DuBal

August 15, 2003 09:45 PM Forum: Equipment Talk

MK66 vs 12.5" F6 Cave dob

Posted By Dan D DuBal
If the bulk of the Cave did *not* bother or concern me, then -- assuming the mirror was a good one -- I'd go for the big boy.

If, however, excellent portability was required, then the MK66 would hold the advantage. My own MK67 does quite well when conditions allow. Its performance advantage over my Pentax 75 EDHF is undeniable. Low-contrast deep-sky performance of my MK67 under "blah" suburban skies (l.m. ~5) is roughly similar to the 75's performance under very dark skies (l.m. 6.5+). The MK67's advantage with regard to planets & high-contrast deep-sky targets -- regardless of l.m. -- is significant and always visible.

Best wishes and luck.
-Dan


August 15, 2003 09:46 PM Forum: Equipment Talk

Ultrablock vs UHC

Posted By Dan D DuBal
Nope.

August 15, 2003 10:06 PM Forum: Telescope Making

Cutting PVC 12" tubing >> Salvage effort

Posted By Dan D DuBal
You could build a makeshift/temporary miter rig and use a standard cross-cut hand saw. Use an orbital sander (or a block sander) to smooth as needed (say, a couple of grits -- 150 or 200 first, then 320 or 400 to finish).

Best wishes and luck.
-Dan

August 16, 2003 07:12 AM Forum: Binoviewers

Max TFOV with BV?

Posted By Dan D DuBal
The "glass path" through a typical binocular viewer is between 5 and 5.5 inches. Imagine having a 5-inch barrel on your 30mm or 35mm Ultima... Sounds pretty "narrow," doesn't it?

However -- binocular viewers with 27mm entrance apertures *can* accomodate scopes as fast as ~f/6ish *without* restricting aperture and true field of view.

Best wishes.
-Dan

August 16, 2003 05:50 PM Forum: Equipment Talk

Naming those who do a poor job.

Posted By Dan D DuBal
Reputations -- whether good or bad -- should never be based on a single incident.

By the way -- this should not have been posted in "Equipment."

Cheers.
-Dan

August 18, 2003 03:54 AM Forum: Equipment Talk

80mm Apo for $429???

Posted By Dan D DuBal
You're a few days late.

Search the Equipment forum for "$429" -- that should bring up the couple-three threads.

Nobody has one yet.

Orion used to call the Ultrascan a "hot ED apochromat." Righty-o.

I expect this new Synta offering to perform along the same lines -- a nice 80mm achromat. Maybe the new focuser works well.

Cheers.
-Dan

August 18, 2003 04:25 AM Forum: Solar System Observing

Light Cup toured dreary side of Mars

Posted By Dan D DuBal
DREARY?!?

My, we've certainly become spoiled by this year's Mars apparition, haven't we! ;-)

As always, an enjoyable read, Ron. I've previously tried my OIII and narrowband filters but found my standard "planet" filters to do a better job.

I'm trying for the "fangs," as well. I'll let you know...

Best wishes and no-less-than-dreary views :-)
-Dan

August 23, 2003 10:49 PM Forum: Solar System Observing

Jason 325 - Poor View Quality

Posted By Dan D DuBal
Can you determine whether the poor image quality you saw is due to the objective? or the eyepieces? Which eyepiece or eyepieces did you use?

My own early-60s Jason 307 (60mm f/13.3) is quite good, and I have no trouble seeing Martian details (ice cap and larger dark areas) and its unmistakable salmon-orange hue.

In early July, I wrote a 3-part report about viewing Mars with my Jason. You can find it by using Astromart's "Search Forums" tool (top of the screen). Search the "Solar System Observing" forum for "challenge revisited." That should bring up all three segments (plus two related replies).

Best wishes.
-Dan

August 26, 2003 08:36 PM Forum: Equipment Talk

REDUCER/CORRECTOR question...

Posted By Dan D DuBal
Hello, Ivan.

I'm not sure if you're looking for any/all possibilities, or if you're truly looking for an eyepiece-installed solution. So, how about this:

An SCT-specific ruducer/corrector can thread onto a 2-inch SCT-thread adapter.
An SCT visual back (either 1.25- or 2-inch) then attaches to the r/c.
The visual back then accepts eyepiece or diagonal.

The major limitation will be spacing between the eyepiece and the r/c. Non-SCT scopes will likely *not* be able to focus using 2-inch diagonals behind the r/c.

SCT-thread adapters can be purchased from APM or Scopetronix. Other retailers likely carry them as well.

Hope that helps.
Best wishes.
-Dan

August 28, 2003 04:12 PM Forum: Equipment Talk

Does a scope need to warm up?

Posted By Dan D DuBal
Disregarding potential dew for the moment...

A temperature gradient -- be it descending (cooling) or ascending (warming) -- is still a gradient. Both scenarios promote turbulence and *can* affect local seeing.

Back to dew...

If the local "dewpoint" is lower than the temperature of your scope &/or its components, dew won't form. Warmer, more-humid locales are indeed more likely to promote scope dewing, if that scope is "warming up" outside. Drier climes don't have the same "warm-up dew" potential, but it's still a night-to-night consideration.

Best wishes.
-Dan

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