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Posts Made By: Dan D DuBal

October 14, 2005 11:13 AM Forum: Mounts

polar scopes

Posted By Dan D DuBal

I'm not aware of any right-angle RA-axis borescopes for polar alignment, but I wouldn't be surprised if there were a few made (perhaps for high-end &/or custom equatorial mounts). RA bore diameter and borescope aperture would be key factors. A relay lens or group might also be advantageous (again, depending on mount and scope dimensions/parameters).

Vixen's 8x50 right-angle "Polaris" finderscope -- found on older Celestron Ultima SCTs and also available as an accessory -- included a polar alignment reticle and illuminator. I believe it's now extinct. There may have been a few other finderscopes which utilized polar-alignment reticles, as well, but I don't recall any.

Cheers & best wishes.
-Dan

October 15, 2005 08:31 AM Forum: Eyepieces

Tak LE vs RKE vs TV Plossl

Posted By Dan D DuBal

Interesting report, Jeff. Thanks for sharing your perspectives. Which scope did this particular Martian "cruise" utilize?

I just realized: My "shortest" eyepiece with a rubber eyeguard is an 18mm Superwide. 8O I used to have a 7.5mm LE, but I didn't find myself using it as often as it deserved -- not for any comfort- or view-related issues, of course (great comfort & fidelity). Rather, the 7.5mm focal length simply "favored" one particular scope (150mm f/12 Maksutov), and nights which support 240x in my area (north suburban Denver) are uncommon. Planet views through my other (shorter) scopes typically rely on the 4mm-6mm range.

Cheers & best wishes.
-Dan

October 18, 2005 12:56 PM Forum: Equipment Talk

Schmidt Newt vs SCT's

Posted By Dan D DuBal

Depends on context and your goals or needs for the optic. At a given magnification -- all other system parameters being "comparable" (they couldn't be equal), axial fidelity would likewise be comparable. Potential field of view, on the other hand, is another context (advantage: the f/4 system). Field curvature would be yet another context, as would photographic "speed," coma, and other optical/visual parameters.

The biggest visual difference between f/4 and f/10 would be potential field.

Cheers & best wishes.
-Dan

October 18, 2005 06:02 PM Forum: TeleVue

Tele Vue 85 Obsolete?

Posted By Dan D DuBal

The author wrote this:
"There is now a long list of telescopes under this one's cost which will outperform it by any criterion you choose."

Gee, I'd like to see that "long list."

His/her experiences regarding this particular TV85's false color are like none I've read or heard of before. If I'm seeing false color around the moon at 25x as he/she described (albeit not described very well), then I'm thinking something aint right -- perhaps misalignment (objective, prism, eyepiece?), lateral color, atmospheric dispersion, or some other anamoly.

Cheers & best wishes.
-Dan

October 20, 2005 01:14 PM Forum: CCD Imaging and Processing/Solar System

Mars 10/18/05

Posted By Dan D DuBal

Outstanding work, Wes! Olympus is very nicely shown -- wonderful subtle details.

I'm continually boggled by how far and how quickly planetary imaging has evolved, these past few years. 8O

Cheers & best wishes.
-Dan

October 20, 2005 04:41 PM Forum: Refractors

Orion ED100 fix

Posted By Dan D DuBal

If you have a professional/specialty or fine tools retailer in your area, they may carry proper spanners. (I've never found any at Ace, Sears, Depot, or Lowe's.) Unfortunately, good spanners aren't cheap. If such a retailer isn't available, your best bet would be to borrow one, buy one online, make your own, or use a substitute tool (I keep an old compass around for this very purpose).

The cell assembly on my Stellarvue 80 is very similar to that of the ED100, and in my case, the retaining ring was not at all difficult to remove (with care, of course). Your own thumbnail might actually provide enough strength to start the ring on its way. If one slot doesn't work, try the opposite one. If neither slot cooperates, and a little more force is needed, try a small flathead screwdriver (or, better yet, a bit of copper or brass -- perhaps a section of tubing or thin pipe) and gently/firmly push against the slot-set blade along a tangent. Once the ring starts, put the driver/tube/pipe away and finish with a thumbnail or toothpick.

If the ring remains very stubborn, and you're worried about gouging or scratching, then a proper spanner may be your safest option.

Cheers & best wishes.
-Dan

October 23, 2005 06:33 PM Forum: CCD Imaging and Processing/Deep Sky

IC 1396 Region

Posted By Dan D DuBal

First-rate and absolutely lovely, Jim. Many thanks for sharing.

Cheers & best wishes.
-Dan

October 23, 2005 06:38 PM Forum: CCD Imaging and Processing/Deep Sky

NGC891

Posted By Dan D DuBal

Outstanding image, Ralph -- very impressive. Edge-on galaxies are among my favorite deep-sky targets. Thanks for the brilliant view!

Cheers & best wishes.
-Dan

October 25, 2005 04:57 PM Forum: A Day in the Life of the Administrator

Can users program an automatic counter-bid respons

Posted By Dan D DuBal

I'm guessing his high bid was already significantly higher than either of yours and that what you were seeing were simply incremental bids (i.e. just enough to outbid your highest bid) managed by the auction/bid application itself.

The "current high bid" for any auction is not necessarily that high bidder's own maximum bid. In most cases, it's merely the lowest "high-enough" amount (plus a minimum buffer, ala $0.50) which outbids any or all other competition.

Sample scenario:
1. Bidder A inputs $500 and, for now is the first and only bidder. Let's say the opening price was set at $0.00. The bid application would increment
the opening price by a "buffer" until either any/all other bidders were outbid, or until Bidder A's maximum bid was reached.
2. Current auction "high bid" increases to $0.50, and (since there are no other bidders) sits there. Bidder A's max remains unknown and "ready" for more auto-bidding action.
3. Bidder B inputs $400 as his max. No other bidders.
4. Bid app increments price until either all other bidders are outbid or until Bidder B's max is reached. In this scenario, his $400 max is reached before Bidder A is outbid. Almost instantaneously, Bidder B receives his "outbid" message -- not because Bidder A saw the current auction price shoot up to $400 and decided to counterbid higher, but because he'd already bid higher.

The simplest way to bid in an online auction is to:
1. Determine your own true maximum bid based on your own budget -- the actual price you'd be ready and willing to pay for that item -- and bid that amount.
2. Wait, watch, & hope.

Cheers & best wishes.
-Dan

November 6, 2005 08:25 PM Forum: Telescope Making

Now Here is a Newtonian!

Posted By Dan D DuBal

"Lowly?" Holy schmoly. wink

Alan, in my book, your & Sue's f/9.5 is no less impressive. I'm willing to bet the two of you have logged countless more grin-inducing hours at the helm of that spaceship. -And, when all's said & done, that's what really matters. Besides -- the "French 10-inch" is likely a wee bit more portable than Lassell's. 8)

Speaking of that ol' Newt of yours (ol' = purely a term of respect, I assure you): would you mind relaying a little more about its history -- i.e. when was it "born?" who ground/figured the primary? still using the original mount & "tube" structure (or mostly so)?

As always, best wishes.
-Dan