Carl Zambuto – Rainier Telescope Maker Has Eyes in the Stars

zambuto optical
The mirror-making process begins with cutting 500 pound sheets of raw glass which are 2 1/4 inch thick into squares and rectangles.


By Heidi Smith

mullinax fordIf you’re one of the nine out of ten people who has never seen a planet or the face of the moon through a telescope, a whole dimension is waiting for you, says Carl Zambuto. He should know. He’s created over 2,000 Newtonian telescope mirrors in his Rainier workshop, and today they are in use all over the world. “I am fascinated with the heavens,” he says. “My passion has to do with the optics in the telescope – the primary mirror and the related optics of the Newtonian reflector.”

The primary mirror is “like the engine of the telescope,” he explains. “That’s what gathers the light. The whole thing is set up to hold those mirrors in position so they can gather the light and bring it to a very, very, small point, like a ten-thousandth of an inch in diameter.”

zambuto optical
The mirror-making process begins with cutting 500 pound sheets of raw glass which are 2 1/4 inch thick into squares and rectangles.

His Newtonian reflectors are renowned for their high degree of contrast. “You can have larger aperture, but if you don’t have the contrast, you’re not going to get the equivalent performance out of it,” says Zambuto. “The smaller telescope that has very high contrast can outperform a larger telescope that doesn’t. It can show you better detail and more information.”

Zambuto’s adventure with astronomy began with a defective telescope during the opposition of Mars in 1988. That experience prompted months of research and eventually he purchased a new telescope – and realized right away that it needed work. But when he took it to an optician, he was told, “You really need to grind your own mirror.” Despite initial resistance, he finally did. Then, “I made that six inch mirror and made a telescope for it, I made an eight inch and built a telescope for that, and I just kept going and never stopped,” he says.

During this period, he started doing Sidewalk Astronomy at the yacht harbor in Olympia on summer evenings.  “I’d be out there with the telescope and show people the moon and the planets. It was a lot of fun,” he says. “I’d entertain up to 300 people a night.”

He noticed that for every thousand people who looked through the telescope, somebody would want to build their own. “So I said, ‘Let’s put a class together,’” he explains. “We taught telescope making at my workshop from 1994 to 1997.” At that point, Zambuto and his students were hand-grinding the mirrors, but one of his mentors pointed out that he could achieve the same level of precision using a machine.

zambuto optical
Zambuto uses a glass mill to machine the glass with diamond tools.

“I found the formula where I could get the kind of control I was getting by hand and then surpassed it very quickly. That’s when I knew I could make a living at it,” he says. “My mentor opened the door to two scope makers, and I went in and started supplying them with small mirrors and the business took off like a rocket.” By 1998, he was working full time as an optician.

When he first started, the Newtonian reflector was not typically regarded as a high performance instrument in the amateur astronomy community. “In general, if you go to a star party and look through a bunch of telescopes, with the big reflectors, stars typically look like fuzz balls or balls of snow,” he says. “Really high performance began to develop as we came on the scene, with my mentor before me. He led the way to where you could get much higher performance out of much bigger telescopes.”

The process begins with 500 pound sheets of glass that are 2.25 inches thick. Zambuto and his assistant Chuck Smith cut it into squares and rectangles with a diamond saw, then cast them into round discs in an oven. “Then we machine it on our glass mill in the garage so that it looks like a mirror blank and it’s fairly thick,” he says. “We grind and polish the face and the back.”

zambuto optical
Carl Zambuto holding one of his finished mirrors. He wears a protective mask so that nothing lands on the perfectly clear surface.

Next, they polish the optical curve, which is a parabola. “Technically it’s a paraboloid, because it’s three dimensions and a parabola is just two,” he says. “A parabola will take parallel rays of light which are coming from the universe and bring them to a point.” Finally, they use a vacuum chamber to create a very thin aluminum coating on the front optical surface, followed by a protective glass overcoat.

Once complete, the mirrors go to amateur astronomers and telescope makers around the world, plus a few observatories. Zambuto’s intent is “to create the greatest possible experience for the end user. That’s why people look through telescopes – to have an experience with the universe,” he says. “With our product, I believe that they can go further, they can go deeper and see more. In those rare instances when the veil gets pulled away, that’s when everything’s right. The atmosphere becomes very stable. Then people can see what the optic can really do. That will be the night they remember, the night that changes their lives.”

Even if you’ve never looked through a telescope, you can still appreciate the heavens, he says. “If you just look up, you’re an amateur astronomer. All you have to do is walk out the door and look up. I never learned to spend time under the night sky until I was an adult. Now, every night, if I’m up in the middle of the night, I walk outside and I just look up. I see where the planets are. That’s our universe. It’s really big and really cold and really dark, and it’s fascinating and amazing.”

To learn more about Carl’s work, visit Zambuto Optical Company.


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