Question

If you observe a perfectly focused image through the 10x objective, but a blurry specimen upon switching to the 40X objective, what should you do first?

If you observe a perfectly focused image through the 10x objective, but a blurry specimen upon switching to the 40X objective, what should you do first?

a. check that your specimen is within your field of view.

b. open the diaphragm to let in more light

c.check that the objective is "clicked" into place.

d. check if there is oil on the 40x objective lens

Answer 1

The correct option is D. i.e. check if there is oil on the 40x objective lens. Good laboratory practices include cleaning of the microscope lens using a soft tissue paper. Sometimes the user does not realize that the lens comes in contact with the paraffin oil that is placed on the specimen. Thus when users change the magnification from 10X to 40X if there is a presence of oil initially the image may appear blurr. Thus it is recommended to clean the lens properly prior to observing any specimen. Also, presence of oil on lens can contaminate your specimen and give wrong observations as oil may contain samples from the previous specimen and the same oil-covered lens getting dipped in your specimen can lead to the exchange of materials.