Of the non-0ilobjectives let me say this - they suck. No contrast and apparetly designed to be used without a cover slip for evaluating blood smears. One of them had virtually no working distance with a prepared slide, so the design was obviously for driectly observing blood smears.
For those of you who haven't tried an oil-immersion objective, without oil the images look like mud - soft with almost no contrast.
Here are the results on my tests with my two oil objectives.
Note - somemicroscopists put oil on the top of the substage condenser and bring the condenser up from below to make contact with the underside of the slide for even better contrast, but that means even more cleanup with Xylol (Xylene) to remove the oil.
SWIFT 100X OIL
![Image](http://www.photomacrography.net/forum/userpix/2226_100X_Swift_oil_1.jpg)
AMSCOPE 100X OIL
![Image](http://www.photomacrography.net/forum/userpix/2226_100X_Amscope_oil_1.jpg)