Posts Made By: James Barnett

I've had great results with the Takahashi LEs in 2.8mm, 3.6mm, 5mm and 7.5mm, with the 8mm Televue Plossl and, surprisingly, the 5mm Celestron Ultima. The Ultima is close to the Takahashi LE in performance, but not quite as comfortable, and is better (brighter images at a given magnification; less scatter around bright objects) than the 5mm University Orthoscopic. I guess technically that it's no longer in production. I've had other clones like Ultrascopics and Parks Gold Series Plossls, and in my opinion the Celestron Ultimas are better (againg, slightly brighter images at a given magnification; slightly less scatter around bright objects). Perhaps the coatings differ?

Regards,

- Jim

Despite the "APO" revolution and trend toward faster refractors made possible by low dispersion modern glass types, a long focal length refractor just seems to look like a "proper" telescope compared to the chunky, stubby apochromats.

The Intelliscope DSCs on my XT12i worked perfectly out of the box and almost a year later, continue to work flawlessly. So long as he follows the instructions precisely while assembling the scope and installing the encoders, spacers, etc., it should be a troublefree experience.

After the scope is assembled, it is important to continue to follow the instructions regarding making sure the OTA at vertical rest is perpendicular to the baseboard. Use a spirit level/bubble level. Do the washer adjustment described in the manual to set the vertical stop so that the top edge of the OTA is level (parallel) with the baseboard. Once done, it is unlikley he'll have to revisit this step.

Orion has the benefit of huge volumes. Their consistency unit to unit has become quite good. These aren't fancy scopes, but the are functional, easy to use and very affordable for the level of performance offered.

Regards,

Jim

I'm in a similar boat to the one you are in - looking to upgrade from a 12" Dob to a premium 18" Dob.

I too have been waffling between Starmaster and Obsession.

I don't think that the f/4.3 focal ratio of the 18" Starmaster is meaningful in assessing which scope is ladder free. In fact, neither the f/4.5 Obsession nor the f/4.3 Starmaster are flat footed scopes near zenith.

Starmaster lists the 18" f/4.3's eyepiee height at zenith as 78" or 6.5 feet. Obsession's 18" f/4.5 has an eyepiece height at zenith of 6' 5" - about the same (or actually one inch lower) than the Starmaster.

I prefer the more compact Obsession rocker box and use of Appleply rather than red oak plywood for the wood work. I prefer the wiffle tree mirror cell on the Starmaster to the kevlar sling based cell on the Obsession. Zambuto vs. Galaxy vs. OMI is a tough call. Zambuto mirrors are thinner (1.6" vs. 2.0") for faster cool down. Starmaster uses quarz overcoated aluminized primaries rather than the dielectric coatings used on Obsession mirrors. Some claim the thinner mirrors are more prone to astigmatism. Some claim that the enhanced coatings change the figure of the mirror too much.

On balance, I am leaning toward the Obsession, though certain aspects of the Starmaster appeal to me. Now I am waffling between 18" and 20". Hmm...

Regards,

Jim

Ed Neuzil said:

All this angst over glass types cracks me up.

Yeah, me too, to a degree. But it seems important to resellers who use glass type in their formal or informal marketing, which means it likely resonates with potential customers.

It would be nice to know the truth, whatever it is. So Ed, is there such a beast as "Schott FK61"? Inquiring minds want to know!

Regards,

Jim

I installed one of these on my TV-102 (a recent black draw tube model). Though a dual speed focuser is likely superfluous at f/8.6 given its significant depth of focus, the precision of the Feathertouch was heads and shoulders above that of the stock Televue knob and pinion assembly. Prior to installing the upgrade the stock focuser displayed some side to side rocking as the draw tube was racked out, though it was quite smooth. The twisting is gone post Feathertouch and the action is even smoother.

I have two left thumbs and found the installation to be completely simple. The only "adjusting" I needed to do was adjusting the contact tension of four small nylon ball bearings against the draw tube. This sounds harder than it is. Inset allen screws pressure the back side of the nylon bearings. I had them a bit loose at first, then a bit tight, and then backing them off got them perfect. It's an amazing upgrade over the stock focuser and I would call it a "must" on any of the fast Televue Petzvals.

Regards,

Jim

Nice cases and a good deal. I would suggest adding silca gel packs to these (or any other) water-tight cases. When you close them up at the end of the night, you trap whatever moisture is in the air captured in the case in the same space as your equipment. I use Porta-Brace cases (lighter alternative to Pelicans) for my EM-200 mount head, and noticed that when I'd open it to set up, there'd be condensation on the mount castings and electronics box. Better safe than sorry. Now with a couple of desiccant pouches thrown in, the interior stays dry.

Regards,

Jim