Current Price: $3500.00
Buy It Now Price: $3500.00
Bids: 0

For sale is a vintage Quantum 6 classic Maksutov, Serial Number GH0153245C. The final "C" denotes silver coated optics. Only 250 Quantum 6 scopes were made by Optical Techniques Inc, a company started by former Questar employees. This particular scope was first owned by an oil company executive. It was briefly owned by a classic scope collector before I purchased it in 2007. The scope was manufactured around 1981, toward the end of production.

The OTA attaches to the single arm fork mount with a single screw and two alignment pins, so it is easily removed and set outside to cool down. The OTA weighs about 16 pounds, and the fork mount about another 16 pounds.

I worked with a local tool and die maker to improve the operation of the scope. One of the first things was to replace the Declination pinion, which had worn down over the years and would no longer hold the OTA in position. My machinist made a new pinion to the exact specifications out of hardened tool steel, and it works beautifully. A similar replacement pinion was made for the RA bearing, and a stiffer spring installed to reduce slippage. Since the tube tends to be front-heavy, especially with the dew shield extended, we performed a mod where the bronze Declination bearing is reversed, and the plastic slip bearing replaced with a stainless steel roller bearing. This allows the Declination to be secured without the knob becoming jammed, and makes for smoother operation. To accommodate the thicker roller bearing, it was necessary to make a new tension knob. The original knob is included as well. The friction mechanism inside the Declination knob was repaired. The internal moving-mirror focuser is smooth as silk with no image shift.

The finder was severely dented due to excessive pressure by the alignment screws. My machinist carefully removed the dents, but this required removing the paint from the finder tube. He also made a pair of aluminum rings which slip over the finder tube and serve as a solid surface for the adjustment screws. (The rings can be removed if desired.) He also made new alignment screws out of stainless steel. This was necessary because the original holes through the finder rings were poorly cut, and the only way to fix the situation was to widen the holes and make new screws. The original screws are included as well.

The previous owner had the primary mirror recoated with silver in 2007, but the coating is beginning to tarnish. You can just see the mottling in the photo of the primary. The scope isn't really affected by this, but the primary should probably be recoated again, either with a protected silver coating or enhanced aluminum.

Speaking of the optics, the scope gives textbook diffraction patterns in focus. The patterns are different on either side of focus, but I believe this is due to the scope being an all-spherical design, and not due to an abnormality.

Besides the unpainted finder tube, there are some minor paint scratches on the underside of the main tube, which you will rarely notice. There is more noticable paint loss on top of the tube where I had taped a red dot finder. When I removed the finder, the paint came off. I decided to leave the paint as is because of an issue with the color. The exact Ford Duplicolor paint originally used on the scope is now slightly different in coloration, so it does not match the beautiful blue of the tube. You can see this on the dew shield, which the previous owner repainted. The ultimate solution is to take a piece of the scope to a paint shop and have the original color matched. I never got around to doing this.

(Note: One of the photos seems to show an area of paint loss on the base. This is just a paper sticker I use to mark orientation, and I will remove it. There is no paint loss there.)

The OTI logo disk that belongs in the center of the turntable is not attached, so that the new owner can adjust the tension of the RA axis (another custom part) and glue on the disk when he's satisfied. The RA pointer came unglued, but I have it and can reattach it or leave it for the purchaser to attach, as you wish. The crosshairs in the finder need to be replaced, but I lack the skill to do that very well, and have left it alone.

In addition to all that I've mentioned, I have a spare mirror for the internal diagonal, spare pulleys for the internal focuser, extra power connectors if you want to make custom power cords, an extra OTI logo disk, and a rotating T adapter for photography or viewing through the rear axial port. There is a rubber lens cap that fits over the dew shield. All original and spare parts will be included with the scope, along with documentation provided by the previous owner. I will discuss any issues with the prospective purchaser.

I have a Quantum wedge, custom Losmandy tripod adapter, Losmandy G-11 tripod, and two custom made eyepiece holders which you can see in some of the photos. THEY ARE NOT PART OF THIS SALE. I will discuss them with the purchaser.

This sale includes:
- Quantum 6 OTA and fork mount with clock drive and power cord
- dew shield with front cover
- 8x50 finder
- original, split metal eyepiece holder
- original 2" to 1.25" eyepiece adapter
- tabletop leg set
- rear port T-adapter for Quantum 6 (standard T-adapters don't work)
- all spare parts and originals as mentioned
- $3500 + $100 shipping. Shipping to US lower 48 only.

Getting custom parts made is expensive. I put a lot of time, money, and effort into this scope, so serious buyers only, please. If you have thought about a Questar 7 but blanched at the price, this may be the scope for you. (It is MUCH easier to use than the Questar 7 on its fork mount.)

Local pickup is available, and I am willing to drive quite some distance from central NJ to deliver the scope. Email me with any questions.

Tagged with:

Filed under: High-End Telescope Auctions (USA)