Posts Made By: Gary Carter

Andre,

The Thousand Oaks Model 5000 arrived and here's my assessment.

As I stated before, the O.D. of the ED80/ED100 scopes is 4.57", slightly larger than the 4.5" I.D. specified for the model 4500 you are considering. What I should have mentioned was that the 4.57" dimension is the O.D. of the dew shield - which is how I intend to use the scope/filter combination.

I confirmed the Thousand Oaks specification is in fact the I.D. of the aluminum cell (i.e. before any felt/foam tape is applied). The 5000 measures exactly 5.0" I.D. Assuming the 4500 is exactly 4.5" I.D. on the filter cell, it would not have fit over the dew shield as I originally suspected. However, if one removes the dew shield and measures the OD of the Orion lens cell, it measures less than 4.5" so I believe a model 4500 can be used just fine as long as you first remove the dew shield.

The 5000 is somewhat oversized for the Orion dew shield so I have to add additional foam tape for a firm fit - not a problem for me.

So I believe there are two possible choices depending on your desired application. The 4500 will work if you are willing to remove the dew shield. The 5000 is what you need if you want to leave the dew shield on.

Regards,
-Gary

I have an Orion ED80 and an ED100. The Orion scopes measure 4.57" O.D. so I bought the Thousand Oaks model 5000 (5.0" I.D.). I was concerned that the Model 4500 would not fit having an I.D. of 4.5". I can always add a bit of foam tape to make the 5000 fit tighter if necessary. A filter that fits too tight may distort the image.

I'll let you know when it arrives and I've tried it out.

Andre,

The Thousand Oaks Model 5000 arrived and here's my assessment.

As I stated before, the O.D. of the ED80/ED100 scopes is 4.57", slightly larger than the 4.5" I.D. specified for the model 4500 you are considering. What I should have mentioned was that the 4.57" dimension is the O.D. of the dew shield - which is how I intend to use the scope/filter combination.

I confirmed the Thousand Oaks specification is in fact the I.D. of the aluminum cell (i.e. before any felt/foam tape is applied). The 5000 measures exactly 5.0" I.D. Assuming the 4500 is exactly 4.5" I.D. on the filter cell, it would not have fit over the dew shield as I originally suspected. However, if one removes the dew shield and measures the OD of the Orion lens cell, it measures less than 4.5" so I believe a model 4500 can be used just fine as long as you first remove the dew shield.

The 5000 is somewhat oversized for the Orion dew shield so I have to add additional foam tape for a firm fit - not a problem for me.

So I believe there are two possible choices depending on your desired application. The 4500 will work if you are willing to remove the dew shield. The 5000 is what you need if you want to leave the dew shield on.

Regards,

I've noticed this as well and my assumption is that the filters are not advertised to be parfocal as imaging filters are, thus, we are experiencing the tolerance differences in the manufacturing process.

Bob,

Sage advice, however, I find dealing with UPS is a losing proposition under most circumstances. When the ED100 arrived it had seen some pretty tough handling. Apparently dropped on-end it had broken through the styrofoam packing on the focuser end of the OTA and was working its way through the inner box.

I've had to return several other items I've mail ordered due to their incompetence - in one instance we cycled equipment no less than three times (on the last round I finally convinced the manufacturer to send me a replacement case so I could repair the damage myself. Luckily the case made the trip).

Besides, the lense will likely need to be cleaned at some point and I might as well learn how to handle this before I buy that $10,000 OTA, eh? (OW! 8O Honey! I was just joking!!!)

The December issue of Sky & Tel just ran a nice article on starter scopes you might find interesting. The Orion lineup of scopes came out front runners.

The general rule of thumb is the more light you gather, the more you can "see". So the aperture size (diameter of the objective - be this a lens or a mirror) is the first order of business. Mirrors are less costly to produce in larger diameters - so your pound will buy more performance, generally speaking, in mirror-based design such as the Newtonian.

In that price range I'd suggest taking a close look at a 6" or 8" Newtonian optical tube assembly on an alti-azimuth (dobsonian) mount. For example the Orion SkyQuest™ XT8 Classic Dobsonian Reflector. Accessorize it with a Telrad finder and a collimating device.

Rod Mollise and Robert Piekiel are recognized historians on Celestron's product line. Excerpts from Rod's review (see below) of Robert's E-book on the subject:

"What’s a White Tube? Before Celestron began mass-producing Schmidt Cassegrains in the 1970s, they had been making near-custom SCTs in a distinctly unfamiliar aperture range if you’re used to the modern litany of C5, C8, C11 and C14. These telescopes, in apertures of 6, 8, 10, 12, 16 and 22 inches, were attractively finished in white and blue, and, while obviously not as sophisticated electronically as today’s computerized marvels, they had quite a lot going for them. They were very well made, being aimed at the professional/educational market rather than at amateur astronomers--though quite a few wealthy amateurs did spring for the C10." ....

"The meat of this book, though, is the chapters on the White Tubes. Each of these scopes is examined in excruciating detail from its design to its use to its maintenance and restoration. While I’ve examined and used quite a few of these telescopes over the years--they don’t call me “Mr. SCT” for nothing—I learned a lot, and I do mean a lot from Bob’s book. Not only things I’d forgotten over the years, but much—much--I never knew."

Obviously the ad is for a C11 made in the '90's - I suppose one would need to see what Rod and/or Robert have to say about later model white tubes ....

See more at http://www.astromart.com/articles/article.asp?article_id=167

The patterns are definitely different for the more recent Grey tube models like those used on the Nextstar series i.e. the NS11. The NS fork uses front-to-back side rails in leiu of the rear-hung arrangement of the old forks. People have drilled/tapped the rear cell to mount it in the older forks. I believe the '80s model Orange Tube C11's w/grey sandcast forks and '90s model Black Tube C11's w/Ultima forks share the same mounting hole pattern, thus the tubes and forks are interchangeable.

To verify my understanding I'd recommend you lookup the following Astromart sponser:

TELETRADE
http://www201.pair.com/resource/astro.html/teletrade/
email: [email protected]

After considering all your kind advice, putting the Y chromosomes in check, I elected to contact Orion about sending it back. The interesting part about it was an initial runaround I got from Orion about the warranty return policy. Gary Pierson of Anacortes quickly addressed this with them and it was all neatly arranged including the shipping. I'll let you know how it turns out.

Scott,

The older Lumicon finders are sold two configurations - one with a diagonal and one without. Both of the older models have a helical focuser at the rear of the OTA. The newer versions come with optional tube extenders that must be removed if the diagonal is used. These have a barrel focuser on the front of the OTA. For older models the tube length was a fixed length - you had to decide at the time of order which one you wanted. The straight through had a tube length of about 8 or 9 inches. The right angle model that came with a prism diagonal had a shorter tube length to allow for the optical length of the diagonal.

A 25mm Kellner was the standard crosshair eyepiece sold with the complete setup - If you have a Kellner or Plossl in the 25-30mm range that comes to focus without the diagonal I would highly suspect the Lumicon is a straight-thru and the diagonal is adding too much length to the optical path. You can verify this by measuring the length of the tube from the center of the objective to the plate the focuser is attached to. The focal length of the 50mm Lumicon finder is 200mm (about 7.8 inches) A right angle finder has to be roughly 2 inches shorter than this for a diagonal to function.

If this is a new model - simply remove the tube extender!

-Gary