Archive for the ‘Visual Observing With a 6-Inch f/6 Imaging Reflector’ category

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

February 10, 2018

 

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The above photo is my “prized” 6-inch f/6 reflector telescope.  

This telescope was a gift to me: 

When I first became interested in amateur astronomy, during the mid to late 60’s, the 6-inch reflector was “definitely” the most popular telescope for the “average” backyard observer.    

I always wanted a 6-inch f/8 Edmund Super-Space Conquerer, but due to lack of funds, I had to settle for a 4.25-inch Edmund, Palomar Jr.  However, this smaller reflector allowed me many nights of observing enjoyment.  There was just no way I could purchase a 6-inch when I was in middle school, or even a 4.25-inch reflector.  My parents needed all of their money for the essentials of life, and that did not include a telescope for me.   

Going back to the humble days of the past:    

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.  This is primarily one of the reasons for my blog, which you are now reading. 

The nights of the solitary observer in the backyard, attempting to locate and observe a few of the Messier objects…with a 6-inch reflector seem to be in the past. 

I often wish it were possible to go back to those fun days.  However, each and every night when I’m out in the backyard with a telescope, I’m a kid again.  What a great feeling!  So, I now have a 6-inch reflector, and yes…when I go outside, I am that kid again. 

Testing my new 6-inch reflector: 

But how would this telescope perform on a couple of difficult tests?  One of the most difficult would have to be seeing Sirius B, the companion to Sirius.  

I made my attempt on February 8, 2018, with the 6-inch to see if the companion would be possible?  

A larger secondary mirror:

An imaging reflector has a larger secondary mirror, and this can have a negative effect as related to resolution of fine detail, and the separation of difficult double stars.  

When I took my first look at Sirius it was obvious that seeing was pretty good.  SoI started with a magnification of 150x, but to no avail and worked my way up to 232x.  After more than an hour of patient and careful observing, I thought the companion showed itself on at least a couple of occasions.  However, fleeting and intermittent only, maybe just a wink, or was this just my imagination?  As amateurs, we all know that our mind and eyes can play tricks on us, especially when we are wanting to see something so bad. 

I’m planning to try this again, if and when that perfect night with excellent seeing presents itself.  As always, I’ll determine where the companion should be in my eyepiece.  If we know the position angle of the secondary star, it can most often help us see a very difficult companion. 

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 extremely difficult.  Only a glimpse during moments of steady viewing.  Was this just my imagination, and did I really see the F star?   I’ll attempt this test again, hopefully in the spring of 2020. 

February 8th 2018, an observation of the Trapezium stars: 

There were beautiful airy discs rings surrounding the “four” primary Trapezium stars, at the 232x magnification.   

Note:  An imaging reflector most often requires the use of an extender tube when observing visually to achieve proper focus.  

The optical tube assembly:  

6-inch OTA, f/6, with a 2-inch focuser, a 6 x 30 finder and it also included tube rings, designed for a narrow-Vixen style dovetail.  An excellent quality telescope in all aspects.  

 

The original dovetail was too short, but I found a unique way to utilize the “too short” original.  I ordered a 13-inch dovetail to replace the short one, which allows for better balance. 

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 bolted it perfectly on the top of the optical tube.  This became the perfect handle I was looking for. 

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I added an 8 x 50 finder.  This is the minimum size to effectively locate very faint deep-sky objects,  

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 mid-90’s.  I did have to purchase an additional counterweight to properly balance the reflector.   

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 have to be seated while making observations, in order to make notes and pencil sketches.  

I didn’t realize until later that Vixen offers a short tripod, designed for Newtonian reflectors, but just the shortened aluminum legs with a base sells for ~ $200 dollars.

A light bulb turned on in my head: 

About 15 or more years ago, I bought a set of Vixen (standard) tripod legs for $20 at a local astronomy event.  They appeared to have never been used, and I’d had them in storage ever since. 

Why not attempt to shorten my extra set of standard tripod legs to Vixen specifications?  

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, or what I would call….factory.  

And now, I can enjoy observing with my 6-inch while seated, using an adjustable astro-chair.  

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Another mount which allows a seated position:

Another gift:  

A slightly used Celestron CGE Pro, which has a payload of 90 pounds.  I don’t use this mount with a tripod, due to its height, but I have a system to secure to my back deck.  

I use it primarily with my 10-inch reflector, but it also works well with the much lighter and smaller 6-inch.  Rock steady for sure!  

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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