|A Beck of London Diamax 44282. Fitted with a 6x eyepiece and four rotary mounted lenses this microscope has been excellent in confirming the presence of spermatozoa in seminal fluid used in artificial insemination for the propagation of falcons, hawks and eagles.
The four mounted lenses are marked as follows;
x10/.25 oil immersion
1/12 oil imm N.A. 1.30
40x Cooke 4 mm N.A. 0.65
For the work that I used this microscope the x100/1.3 oil immersion lens gave me a magnification of 600x and was more than adequate to see the viability and motility of spermatozoa in eagle seminal fluid.
The paintwork shows signs of usage but the instrument is excellent and has worked perfectly at all times.
A small amount of knowledge is needed to operate an oil immersion microscope but is easily picked up.