Archive for February 10, 2018

Visual Observing with a 6-inch f/6 Imaging Reflector Telescope

February 10, 2018

 

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The above photo is my now “prized” 6-inch f/6 telescope.  When I first became interested in amateur astronomy, in the mid to late 60’s, the 6-inch reflector was “definitely” one of the most popular telescope during this period.     

One of my desires or ambitions has always been to bring back the excitement of the glory days of amateur astronomy, when all kids wanted a telescope.  The nights of the solitary observer in the backyard, attempting to locate and observe a few of the Messier objects.

I often wish it were possible to go back to those fun days.  However, each and every night when I’m out in my backyard with a telescope….I’m a kid again.  What a great feeling! 

A couple difficult test using my new telescope….so how would it fare? 

Would it be possible to see Sirius B and all six Trapezium stars with this scope? 

I made my attempt (February 8th 2018) with the 6-inch to see if the companion to Sirius would be possible with this telescope.   The weather was perfect, 35º and totally calm. When I took my first look at Sirius it was obvious that seeing was very good.  I started with a magnification of 150x, but to no avail and worked my way up to 232x, and there it was, but was unable to hold “the Pup” constantly.  

After more than 30 minutes with Sirius, it was time to move on to another favorite challenge of mine:  The Trapezium in the heart of the Orion Nebula.  

Starting with 232x, I was surprised how easy it was to see the E star, but the F star required a bit of patience and was difficult,   

There were beautiful airy discs surrounding the primary four Trapezium stars.  The beauty of double or multiple stars doesn’t get any better than this! 

Note:  An imaging reflector most often requires the use of an extender tube when observing visually with an eyepiece for proper focusing.  

 

After selling my Criterion RV-6, more than 40 years ago, I just wanted another 6-inch reflector, but not an f/8.

The quality of my new 6-inch:  

I don’t remember my old 1970’s Criterion RV-6 f/8 reflector being anywhere near this good, either optically or mechanically.  

The optical tube assembly:  6-inch OTA, f/6, TPO brand, made in Taiwan, purchased from OPT in California, 2-inch focuser, a 6 x 30 finder and it also included tube rings, designed for a narrow-Vixen style dovetail.  The original dovetail was too short, but I found a unique way to utilize the “too short” original.  

The telescope optical tube is fairly heavy, and it was difficult to set up on the mount.  I needed a handle to more easily mount the telescope.  So….I just flipped the original dovetail upside down, and it bolted perfectly on the top of the optical tube.  This became the perfect handle I was looking for. 

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I don’t remember my old 1970’s Criterion RV-6 f/8 reflector being anywhere near this good, either optically or mechanically.  

I added an 8 x 50 finder.  

My primary reason for purchasing this scope was for portability, ease of carrying and set-up.   

 

Fortunate for me, I had a Vixen GP equatorial mount from a refractor purchase in 1997.  

There was a problem, but not with the telescope:  

My older Vixen GP tripod was designed for a refractor, and too tall for a reflector.  I didn’t realize until the other night that Vixen offers a short tripod, designed for Newtonian reflectors, but just the shortened legs with a base sells for ~ $200 dollars.

A light bulb turns on in my head: 

About 12 years ago, I bought a Vixen set of (standard) tripod legs for $20 at a local astronomy event.  They appeared to have never been used, and I’ve had them in storage ever since. 

I thought, why not attempt to shorten my extra set of standard tripod legs to Vixen height specs?  So….for most of the afternoon, I spent several hours,  sawing, drilling and filing.  The results were worth my time and effort, and all modifications looked really good.  

And now, I can enjoy observing with my 6-inch while seated.

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I’ve found it “almost ” impossible to look through an eyepiece, make notes and a sketch, in a standing position….. 

Roger