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Posts Made By: Vahe Sahakian

April 7, 2007 08:30 AM Forum: Eyepieces

Barlowing Orthoscopics

Posted By Vahe Sahakian

You probably do not want to hear this but my take on barlow is a bit different.
First, I also use Orthos all the time, but my scopes are all long focus and require no barlows, but if I am forced to use barlow and am willing to accept additional glass in the light path then for me the best solution is to get an eyepiece with some form of built-in Barlow, most of these have generous eye relief and work reasonably well on planets.
Another option is Tak LE series, their 7.5mm is my choice planetary eyepiece with binoviewer.

Vahe

April 15, 2007 01:07 PM Forum: Takahashi

doublet fluorite obsolete?

Posted By Vahe Sahakian

My guess is that demand for shorter, faster & imaging optimized apos are the force behind this trend, doublets flourites are ideal for somewhat slower visual instruments but that market has taken a back seat to astrographic triplets.

Vahe

May 27, 2007 07:32 PM Forum: Equipment Talk

advice on alt-azimuth mount

Posted By Vahe Sahakian

I have been looking for an Alt/Az mount to be used as a grab & go for my TEC6 Maksutov, I looked into all models mentioned here as well as Tak/Lapides, at the end I settled with a Vixen GP mount with slow motions, no motors. The reason for going with Vixen GP was the tracking problems at high powers with most Alt/Az mounts, being GEM once the Vixen is polar aligned tracking planets at 200x is not very difficult.

June 17, 2007 02:44 PM Forum: Eyepieces

Nagler 9mm Type 1 vs. Nagler 9mm Type 6

Posted By Vahe Sahakian

I started with one some years ago, after I got into binoviewing I decided to order a second N9 T1, well I was surprised when it arrived, as it turned out I ended up with one Japan and one Taiwan models, the two had a distinctly different barrel designs at the eye end. The eye lens on Taiwan is flush with the metal body, on the Japan there is a metal ring that projects out supposedly to support the rubber shade and that makes the eye lens recessed. At any rate I had to return one and get a matching second, I went with Taiwan as it is more comfortable on the eye position allowing full eye relief without any struggle to get past the ring that comes on Japan model.

Vahe

June 28, 2007 08:05 AM Forum: Equipment Talk

Re: $40k for an apo shot of Jupiter???

Posted By Vahe Sahakian

"My guess is that a purely visual observer would have an incredibly more rich experience spending a good 50 hours watching Mars 2007 through that unobstructed 10" TMB than a C14. My other guess is that IF Damian Peach had that 10" TMB down in Barbados he would surpass his own results."

My guess is that for visual there is no contest, a high quality unobstructed 10” will beat a C14 hand down on planets .
When it comes to imaging my guess is that the C14 in the hands of Demian will beat any 10”. You do not need extreme quality for stacked imaging, contrast is a non issue since it can be electronically enhanced. For planets you need more light to freeze the seeing effects and a 14” will do that a lot better than any 10”.

Vahe

June 28, 2007 08:32 AM Forum: Equipment Talk

Re: $40k for an apo shot of Jupiter???

Posted By Vahe Sahakian

"Couple years back at WSP in the Keys you could wander between
the 10" APO and C14s and compare the views on the planets.
It was clear to me that the best 10" APO was in fact the C14.
The contrast was a bit less than the APO, but the extra
aperture made up for it."

A 10" air spaced APO requires a very long time for cooling, almost as bad as a MCT with no active cooling, was that 10" properly cooled when you made that observation?

Vahe

July 8, 2007 07:07 AM Forum: Refractors

Minimum Aperture for Planetary Viewing?

Posted By Vahe Sahakian

For serious, I would set the minimum right at 6".
5" is a good compromise if weight/cost/size/portability/price are a major consideration, 5" is just barely large enough to wet your appetite, but if you switch to a 6" you will quickly realize what you are missing.
And the most popular 4"? too small for serious planetary detail.

Vahe

July 8, 2007 10:09 AM Forum: Refractors

Minimum Aperture for Planetary Viewing?

Posted By Vahe Sahakian

A bit of clarification regarding my take on the planetary potential of a 6" apo;

The comet crash on Jupiter was one of the most memorable views, I followed that event for weeks until the black scars finally disappeared, for that application my 155 was just barely adequate and it happened to be my only scope at the time.

Last year I struggled to view the Jupiter's GRS and the Junior passing each other with the same apo, many times under decent seeing using binoviewr, 240x, no luck. The same feature was clear as a daylight in my 10"MCT.

Every time that I view Mars with my 155, during oppositions of course, my first reaction; how small the planet is and how inadequate the 6" aperture is in dealing with that particular planet, this year it will dance for us again with a size three times smaller than Jupiter's disc.

And then we have Uranus and Neptune, try that 60mm on those!!!!!

Questions like this clearly demonstrates that there can be agreement as to what "serious" means, so far we have votes for 50-60mm scopes at the low end and mid size Dob at the upper end, is there a correct answer?

Vahe

July 9, 2007 04:55 PM Forum: Refractors

New Tracking Mount for Refractors

Posted By Vahe Sahakian

With due respect, the person who did the photo editing definitely needs a bit more practice before going public.

Vahe

July 12, 2007 07:16 PM Forum: Refractors

Oil spaced & Air spaced

Posted By Vahe Sahakian

"Why would an Oil spaced triplet using FPL-53 exhibit a slight amount of CA, while an air spaced triplet using OK-4 does not?"

Were you comparing two 140 F/7 lenses one oil spaced and the other air spaced?

Vahe