I got a Exakta 100-500mm 5.6-8 for like 30 to 40€ incl. Shipping, a Converter to Nikon (native Canon FD-Mount), and a 3x Teleconverter some Years ago, because it was Aparently Broken according to Seller (which is really was not, pretty good working Condition).
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Its Acceptably sharp on my D500, but certainly good enough for the Chronos 2.1 Resolution. Like Solscud007 with his Mirror Lens, i absolutely wont complain for the Price i got it for. Has served me Well, when i needed it, and so far has Performed well enough that i could not justify replacing it with something more Modern.
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Was Thinking about getting something like those new 50-500mm or 150-600mm Lenses, but Price is way too much for how much use / Improvement over what i already have, i would get out of it (use that Range of Focal Length somewhat rarely in comparison to all my other Lenses), and they are also pretty bulky and Heavy in Comparison to carry around every Day. The Exakta i have is still far larger than a 500 or 600mm Mirror Lens, but for being a Zoom, its reasonably Compact. 75mm Diameter; 250mm Long (will extend up to 340mm long at full Zoom and close Focus); 1490g. very Comparable to a 70-200mm 2.8 DSLR Lens in Weight and Size, bit longer but Slimer.
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Just looked up the Price these Currently go for, and seems like ~250 to 300€; which i am not too sure about, if i would have bought it at that Price. Up to 100€ pretty sure; up to 200, maybe if i Specifically Liked it for some Reason, but at 300 or more, i personally would probably have considered getting one of the earlier Mentioned Long Range Super-Tele-Zooms instead used, as its not much more money spend from there and much Sharper, also Faster Aperture.
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Have to Say though, Zoom is pretty nice to have on such long Lenses, but much more Bulky and annoying To carry Around than a nice Mirror Tele.
