I just got a new 60x dry objective and am getting the hang of it. Even with a 0.17 cover slip there is so little working distance that I have to draw excess water from under the cover slip by holding a piece of toilet paper against the edge of the slide to keep the cover slip from floating.
Here are a few desmid stack tests:
Cosmarium biretum
Michael Reese Much FRMS EMS Bethlehem, Pennsylvania, USA
These are great shots, Michael, especially that last Micrasterias. I've generally found when working with this sort of sample that large 22mm x 50mm coverslips are really helpful. Also, there's a bit of an art to letting just enough of the water to evaporate to suit the particular thing you're shooting: not enough and the little darlin's have too much freedom; too long and they're squished.
Thanks guys.
When I bought my microtome, the retired doctor who sold it to me me threw in a couple of thousand slides and several thousand 25x40 and 25x50mm cover slips all of which are .22 mm. ( I test them with a digital caliper). This new objective requires .17 mm cover slips, but the working distance is so close that when I go from the 40x objective to the 60x, before I rotate the turret I have to drop the stage for clearance and then walk the focus into the subject. If I try to use the .22 slips, the objective strikes the slip before I can achieve focus. That said, for $60 on ebay, I can't complain and am please with the image quality.
I have an Olympus 60x that has very generous working distance but because of the lens flare, it is useless unless I stop the condenser all the way down and the image quality gets very poor -- primarily chromatic abberation.
Michael Reese Much FRMS EMS Bethlehem, Pennsylvania, USA