Downsizing again: The Sky-Watcher 102mm Mak

I'm not one who tends to buy a lot of telescopes. I started in 1991 with a 4.5 inch Tasco 11TR reflector on a German equatorial mount and a tripod. I used that regularly for 13 years, so if you think you'll outgrow a small telescope quickly, think again.

Then I decided to go for a Dobsonian because the 4.5 inch's tripod had literally fallen apart from use. I built a Dobsonian mount for the tube and it worked great. But I wanted more aperture, so I went as big as I could comfortably go, physically and financially, and got a 10 inch GSO Dob. I used that regularly for 20 years. 

Nine months ago, as a result of declining health, I could no longer manage the 10 inch. I separated the base into two parts that could be easily reassembled with four knobs, and I devised a simple rope harness to go around my shoulders to help carry the tube, but that wasn't enough. Very reluctantly I realized it was time to start downsizing. 

I chose the Sky-Watcher Virtuoso GTi 150P 150mm (6 inch) f/5 tabletop scope with a go-to/tracking base. I figured the tracking might help soften the blow of the loss of 4 inches of aperture. It helped a little, and I've gotten used to it, but the views in the 10 inch are just so much better. You do what you have to do.

As my health continues to decline, I can sometimes no longer even set up the 6 inch comfortably, so I decided I would need to downsize again, this time to a true "grab and go" telescope. My requirements were:

• 15 lbs. max total weight
• Carryable out the door in one piece (it's okay to come back for the observing stool)
• Good on the Moon, bright planets, and double stars because I would be using this from my light polluted home, reserving the 6 inch for any dark sky forays
• No cool down required

I settled on a Sky-Watcher Skymax 102mm (4 inch) Maksutov-Cassegrain. This scope, made by Synta, is an F/12.7, with a 1300mm focal length. The optical tube assembly (OTA) weighs less than five pounds.

This means my Svbony SV135 6-element 7-21mm zoom is all I need, giving me 62-186x in a single eyepiece, with exit pupils (aperture in mm / magnification or eyepiece focal length in mm / telescope focal ratio) of 1.6 to 0.5, good for seeing detail in bright objects.

Now I have the smallest telescope I've ever had (not counting the little Svbony dedicated solar scope), but...and this is the key...I can use it! 

I mounted it on the Svbony SV225 alt-az mount that I used on my trip to Arizona in 2024. I had bought this as an alternative to the go-to/tracking mount that came with the 150P. I can mount the 102 on the Virtuoso mount if I want tracking. In fact, Sky-Watcher sells a Virtuoso package with a 127mm Mak.

I don't really like tripods, but decided a tripod was the way to go with this setup for several reasons:

• With a tripod, I can lift the telescope and bring it in and out of the house without bending over or crouching down. Those of you with bad backs, bad knees, or similar issues will relate. This makes a big difference.
• The tripod is adjustable to match the height of the very lightweight GCI PackSeat observing stool I've been using with the tabletop scope. I can easily pick up that stool with one hand under the seat. It weighs about a pound. My homemade adjustable observing chair weighs around 15 lbs.
• I can mount other small telescopes on it as long as they have a standard Vixen style dovetail. That includes my 150P.

I chose the Sky-Watcher Star Adventurer tripod. It's pretty sturdy for being inexpensive and I like that it has a tray for my eyeglasses, since this is my "quick look" scope and I don't want to have to put my contact lenses in for very short sessions. To fold up the legs to get through the door and around objects more easily, I can easily take off the tray with a simple twist, then put it on again outside.

I took the Svbony SV182 6x30 right angle correct image (RACI) finderscope off my 4.5 inch and put it on the Mak in place of the red dot finder that came with it (image at left). I can't do the contortions necessary to use straight through finders anymore. I wasn't using the 4.5 inch much anyway. It uses .965 eyepieces, and although I have some decent ones from Orion, they just aren't as nice as my 1.25" eyepieces.

A 6x30 finderscope is not ideal for a light polluted sky, but good enough for quickly finding the Moon or bright planets and stars. There just aren't that many stars bright enough to be visible in a 30mm finder in bad light pollution.

The 102 is designed to be mounted on top of a mount, not side-mounted, as I would have to do with the SV225 mount. I wasn't sure it would work, but it does. I just rotate the diagonal off to the left side a little and I can use both the main eyepiece and the finder well at any altitude setting. I had to partially take apart the mount to free up the setting circles so I could adjust them as needed, but now I can find anything using them and the finderscope.

The whole setup weighs about 15 lbs. I can move it easily in and out of the house for quick looks at Jupiter, Saturn, the Moon, or maybe some double stars or brighter deep sky objects. That's all I can see from my light polluted neighborhood anyway. It is truly "grab and go."

Avoiding cool down thermals

My fourth requirement was that no cool down be required, because I wanted to be able to pop outside with it to take advantage of a break in the clouds or just a quick look. But it's a Mak, which needs cool down, right? How can that work?

A few years ago, Cassegrain users started wrapping their telescope tubes in an insulating material, usually Reflectix, which is basically bubble wrap with a reflective layer on both sides. This prevents the scope from cooling unevenly and developing internal heat plumes as a result, which ruin seeing.

The wrap will slow this cooling down and keep the remaining heat distributed more evenly thoroughout the interior of the tube as it slowly cools. This allows observing immediately without waiting for the scope to cool down. It won't fix bad seeing (rats!), but it will make sure the scope is not to blame.

I got a 16" x 5' roll of Reflectix and found that 16" is a great length for the wrap on this scope. This includes about five inches of overlap in front for an integrated dew and glare shield, with adhesive-backed black craft felt such as this lining the inside to avoid reflections. Attached to itself with adhesive-backed Velcro, the "jacket" can be removed easily. Some say it looks ugly, but I say it makes it look like I'm observing with the Hubble Space Telescope!

I've had it out a lot already, and although it appears to be very slightly out of collimation, it's not enough for me to start fiddling with it. On nights of decent seeing (about the best we get here), I can see the five brightest moons of Saturn and detail on the planet. Stars in high power are nice and sharp with crisp Airy disks. 

For example, Alpha Piscium (4.1 and 5.2 mag at 1.8" separation) splits cleanly in 7/10 seeing, although component B is right on the first diffraction ring. That's about the practical resolution limit of the scope. I'm happy. 

Above: Simulated view of Alpha Piscium in the 102mm scope at about 170x.

Note: I noticed in writing this that a lot of what I have bought lately is either branded Svbony (products manufactured in Mainland China) or Sky-Watcher (a distribution company for Synta products of Taiwan). While I'm not beholden to either of them (I buy my own stuff with my own money and don't have any brand loyalty), they seem to be among those offering some of the better quality inexpensive astronomy products lately, with the caveat that most inexpensive gear requires some tweaking or modifying to work to its fullest potential.

(Human evolution silhouettes by M. Garde after José-Manuel Benitos, Wikimedia, CC By-SA 3.0, modified with telescopes by Astronomerica)