Some time ago I bought an OEM "Nikon 20x 0.75 VC" objective. A few months ago a thread appeared here giving the critical information that this had come from a gene sequencing machine, and was corrected to image through a non-standard glass cell wall. I approximated this cell wall thickness with cover slips, and found the lens performed very well, with no color fringing. I got excited and bought two other versions of this objective; first another OEM version for presumably nonstandard cover slip thickness, and then the original Nikon version corrected for standard coverslip thickness. The latter version solves the problem of approximating the correct coverslip thickness. Then I found a true VC corrected Nikon-labelled version and bought that, at more than double the cost of the other versions.
So I have four versions of these, one tested version in Ecuador and the latest three here in the US, as yet untested. I don't need all of these. For now I am selling the Nikon-branded version that is corrected for standard 0.17mm coverslips. This is the middle objective of the three in the photos.
I ask $100 plus shipping. I can't test these here, but for forum members, if there is any problem I will accept a return for a full refund. They all look pristine though they have been removed from gene sequencers, so are not new.
Some links about this family of objectives:
http://www.photomacrography.net/forum/v ... hlight=20x
http://www.photomacrography.net/forum/v ... hlight=20x
