Vet Tips

40X objective fuzzy and dirty?
05/17/2008

Try placing a dry, fresh cover-slip on top of the glass slide. Do not add oil, just look at your preparation with the 40X objective and it should be fine. No oil is needed; slide the dry cover-slip off and on, refocus each time and note how just adding a cover-slip "clears"
the fuzzy field. High dry objectives are made as if there is a cover-slip on the slide, and if none is added the field will always appear "fuzzy" and look like there is oil on the objective. You will seldom need oil immersion for cytologic diagnoses if you use a cover-slip. This also permits you to go back to lower mags without dragging oil onto other objectives. If the field of vision is still fuzzy with a cover-slip on top of the slide then try cleaning the objective with a Q-tip and an alcohol swab. It is best if you take the objective off to clean it, as it is difficult to get sufficient contact with the objective still on the nose piece.

Submitted by:
Donald Meuten, DVM, PhD, DCVP
N.C. State University, College of Veterinary Medicine
Raleigh, N.C.