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I've never experienced it myself, but if it's a spring-loaded objective barrel, oil can potentially leak through the gap between the spring-loaded section and the outside barrel and make it's way down through the objective - maybe. This is why I wipe oil off objectives as soon as I'm done using them. Hard to imagine any other way oil could get there, unless maybe oil dropped onto the nosepiece at the base of the objective? Or maybe someone removed the objective to clean it and accidentally set it down on a surface with oil? In any case, it should be fine to clean it off it it's only on the outside surface of the bottom lens of the objective.

Sending good vibes your way,

John Oreopoulos




On 2016-04-04, at 5:48 AM, Gary Laevsky wrote:

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> Post images on http://www.imgur.com and include the link in your posting.
> *****
> 
> Hi All,
> 
> Trying not to be cynical here, but, can anybody please explain to me if
> there is a way for a drop of oil to end up on the center of the back focal
> plane of an objective (oil immersion objective) on an inverted scope.  No
> smear from the side.
> 
> Thanks.
> 
> -- 
> Best,
> 
> Gary Laevsky, Ph.D.
> Director, Confocal Imaging Facility
> Nikon Center of Excellence
> Dept. of Molecular Biology
> Washington Rd.
> Princeton University
> Princeton, New Jersey, 08544-1014
> (O) 609 258 5432
> (C) 508 507 1310