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Originally Posted by avandonk
No Mike, it is a Canon 300mm F2.8L, and has a perfect (artificially grown) multi coated Fluorite element as well as two ED elements (lenses) plus many more. The front element is an optical flat, so when it gets scratched or damaged it is much cheaper to replace than an expensive objective lens.The Fluorite element is in a hermetically sealed (O rings) nitrogen atmosphere as Fluorite is slightly hygroscopic. If Fluorite absorbs moisture it goes cloudy. It costs a packet but it performs as well as it's exhorbitant price.. Just zoom in to any level there is no CA. Also the MTF on this lens is close to 100% to 15 or 20 mm off axis at F2.8!
You can see some secondary astigmatism and aberrations only on the brightest stars near the corners. Check out the the dimmer stars at the corners. No CA or astigmatism!
Bert
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Is the lens an auto focus type or could it be adapted to a CCD camera?
What do they sell for do you know?
Cheers
Mike