Supplemental and change to an original post from about three years ago: July 7th 2024:

A few nights ago (July 2nd) while observing some asterisms, star images were ragged and would not properly come to focus. It was exhibiting the classic problems of pinched optics. The telescope had worked fine over the years, but I’d never taken the mirror out of the tube. However, on this night when the problems began, it was in the mid-80’s. Really hot!

So, the next day I removed the mirror and discovered that the clips were indeed tight. After a mirror wash, I reinstalled with care.

Using the corner of a sheet of notebook paper as a gauge:

I used a sheet of notebook paper to carefully slide between the mirror clips and the mirror, before lightly tightening the dual screws on each of the clips. This insures that the mirror has room allowance for expansion with changes in temperature, especially on hot summer nights.

Then using a Cheshire collimator and a follow-up using an artificial star (Christmas ball about 100 feet out in the backyard) and a bright sun. Everything was ready for another night sky observing session.

Defocusing a star both inside and outside of focus, presented almost identical and very smooth rings. A good mirror, especially for a mass-produced telescope. This OTA was made in Taiwan, which is producing some really good products these days.

Taiwan has taken over the very “high-end carbon fiber” bicycle market. And I’ve been told by some race engine builders, Taiwan has some fine and very modern CNC metal working machinery…possibly some of the best in the world. A $50,000 race engine cannot use substandard parts, and many race engine parts now come from Taiwan.

Now back to my 6-inch Newtonian:

I’ve always liked Newtonian’s because of their simplicity, and most amateurs will agree that a “good” 6-inch can be a very versatile instrument. Good for both visual (and with an f/4 focal ratio) excellent for imaging.

With the extra purchase of a nice quality 8 x 50 finder and stalk, a 13-inch Vixen narrow-rail dovetail to allow better balance of the telescope, and an extra ~10 pound “Vixen brand “counterweight.

An essential product for all Newtonian’s: A set of “Bob’s Knobs” for adjusting the secondary mirror. I’ve been pleased with this telescope.

The sky was very stable in the very morning hours, as I was anxious to see how the telescope who perform. My first test was the double-double as it was in good position. Very nice! I then tested with a few other stars, using both very high magnification and then observing some asterisms with low magnification. All looked good.

What a difference using the corner of a notebook paper edge under the clips, and then lightly tightening the mirror screws made. So, I took the telescope and mount back into the house with a smile, and ready for my first cup of coffee. Then it was time for an early morning bicycle ride. Life is good! 🙂

My second telescope in the late 70’s was a Criterion RV-6, which was really a step up from my 4.25-inch Edmund EQ Newtonian. Life got busy and I sold the RV-6 and then took a five year hiatus, or maybe more from amateur astronomy.

Becoming a “very serious student” of amateur astronomy with a 10-inch f/4.5 EQ reflector in February 1992. The 10-inch became my most used telescope with about 2,500 hours at the eyepiece as of 2024. Then in 1997 purchasing a 102mm refractor, and a 6-inch f/6 Newtonian in January of 2017. Then an 80mm f/5 refractor as a birthday gift from my youngest son.

When I first became interested in amateur astronomy during the late 60’s and 70’s, the 6-inch reflector was definitely the most popular telescope for the backyard observer.  

I really missed having a 6-inch Newtonian, especially for certain deep-sky objects, and portability. So, I saw an advertisement for the 6-inch f/6 Newtonian OTA and bought it. I’m glad I did as it performs well, especially for objects requiring low magnification and wide-field views. And this telescope allows for portability and ease of set-up, as compared to my 10-inch solid tube Newtonian, especially on those nights when time is limited.

The optical tube assembly: Purchased from OPT (Ocean Pacific Telescope)

6-inch OTA, f/6 with a 2-inch Crawford style focuser, a 6 x 30 finder (I replaced with an 8 x 50) 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 for proper balancing, but I found a unique way to utilize. I flipped it over or upside down which made for a nice carrying handle and for setting up on the mount.

A nice combination as following with a GoTo mount, and with an 80 mm f/5 refractor piggybacked.