>I bought one (brand Bresser, price 40 euros) to look at Varroa family groups and count offspring. 

That is interesting.  I gather you were doing some varroa research?

>It works perfectly for its price. However, the field of vision that you can take a picture of, is small.

I don't see these things described in the specs of many of the microscopes that are offered cheaply.  

Can you say how wide the field of vision is at the working magnification you found optimal, and also
 the depth of field?

>...a normal binocular at 20X that shows everything in a square inch and take reference pictures 
> with the USB-microscope. 

From that, I gather that the Bresser width of field is much smaller than one inch, then?

>The USB is easily good enough to look at damage to varroa or tracheal mites at higher magnification
but the small field of vision hinders easy manipulation. 

I can see that would be a problem.  I would like to be able to use the unit much as shown in the picture 
at http://www.honeybeeworld.com/diary/images/2005/harbo(1).jpg.

Apologies, BTW.  In my original message, I posted the link to a thumbnail.  This link is to a large image
showing his setup.

Any descriptions of user experience in operating one of these USB 'scopes would be helpful, as I cannot
quite visualize the pitfalls.

Thanks.

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