Portaball Optics

Our objective is to make each PortaBall the very best telescope of its size available, optically as well as mechanically. Knowing that the heart and soul of any telescope are its optics, we are proud to produce our telescopes exclusively with primary mirrors from Zambuto Optical Company, and secondaries by ProtoStar. Many years ago when we sought a supplier, we looked for someone not only with proven optical skills, but also someone who shared our commitment to deliver only the highest quality product, on schedule at a fair price.

We were fortunate to find that rare combination in Carl Zambuto of Rainier, Washington. As word of the high fidelity views seen in his work has spread, Carl has quickly developed an international reputation for his astronomical mirrors. Zambuto has never made unsubstantiated and/or inflated blanket statements about their optical quality, but has consistently relied on the time proven methods of knife edge testing which have been confirmed by other sources as accurate. Instead of playing a game of numbers with no meaning, every PortaBall's primary mirror comes with their exclusive signed guarantee of performance at the only place that counts - the eyepiece. Zambuto Optical Company guarantees that MAG 1 mirrors will perform to their respective aperture's theoretical limit of magnification - 50X /inch of aperture - without any detectable breakdown in the image.

To be certain, exceptional optics are more expensive. In fact, at MAG 1 we pay more for our optics alone than many of our competitors sell their complete telescopes of the same aperture and focal ratio for. Are the images you'll get really worth the extra expense?  Absolutely!  You can readily see the result of "bargain optics" as soft, low contrast, high power images, and stars that don't snap to a sharp focus. PortaBall owners who also own high quality apochromatic refractors often report that the planetary images in them are as good, or better in contrast and detail, as those seen with their refractors.

How do we consistently deliver superior results? We simply do the many little things that others skip to save money. First, we design our optical and focusing systems to minimize obstruction and diffraction. We use construction materials that will assure maximum contrast by minimizing stray light. We start with a mechanically and thermally optimal thickness, Pyrex blank, that has been CNC curve generated. Then Zambuto does what other sources don't even consider, they check the glass for strain. A significant percentage is rejected and re-annealed by Zambuto, a capability found at no other source. The mirror is only then ground, polished, and meticulously figured, to deliver the high contrast, true color, diffraction limited images that PortaBalls are known for. Finally, each and every PortaBall is star tested before it is shipped, something that is not done by most competing manufacturers. That's why you can have exceptional confidence that the optics in your PortaBall are the very best available and will not be outperformed by competing optics of the same size and focal length. They are a fitting complement to the superior mechanical features of the PortaBall design. In short, you cannot get a better performing visual telescope anywhere in the world, at any price.Our objective is to make each PortaBall the very best telescope of its size available, optically as well as mechanically. Knowing that the heart and soul of any telescope are its optics, we are proud to produce our telescopes exclusively with primary mirrors from Zambuto Optical Company, and secondaries by ProtoStar. Many years ago when we sought a supplier, we looked for someone not only with proven optical skills, but also someone who shared our commitment to deliver only the highest quality product, on schedule at a fair price.

70-zone edge-zone
Figure 1 Figure 2

 

The photos shown here are Foucault shadowgraphs of a typical production mirror. (Mag 1 10-011, 10" F/5) These images were shot using a 3X zoom digital camera, through a 25mm achromat telescope working at about 2.5x, which was positioned directly behind the knifedge. These are raw images, they are totally untouched. No sharpening, masking or any kind of digital effects have been done to them. The faint vertical lines seen are diffraction effects from the knifedge, superimposed on the image. Like the mirror shown here, all Zambuto mirrors observed on the bench appear essentially the same as this one. They clearly show the exceptional smoothness and low primary ripple which is the primary reason Zambuto mirrors deliver such high contrast images. Figure 1 is of the 70% zone null, while Figure 2 shows the edge zone when nulled by the knife edge.

 

*Zambuto Optical Company is a wholesale manufacturer of primary mirrors for commercial telescope makers only. Zambuto mirrors are available only in finished telescopes from the current manufacturers supplied. Mirrors are not available for individual sale either through the telescope makers or Zambuto Optical Company. Furthermore, their products are not available to manufacturers other than the ones currently supplied at this time as their limited production is at maximum acceptable backlog with their currently established customers.

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