I read somewhere that the C90 telephoto lenses are black and either 500mm or 1000mm focal length. Anyone know if this is correct?
I think that generally the telephoto versions were black although there are a couple of early ones on the registry that are orange.
The first telephoto was essentially the same OTA as the spotter and astro and had the same specs being f/11 with a focal length of 1,000mm. A finderscope was added to make the spotter version and a single arm fork mount was added to the spotter to make the astro version.
Later on in production, there was also a f/5.6 version with a 500mm focal length. There are 4 f/5.6 versions on the Registry, all have a black OTA.