Tag Micha,
An oil condenser used without oil will add spherical abberation to the system, and I'm not entirely sure what influence that has on the image quality. So what you are asking is that someone would show image of the same thingy with two different systems, one dry 0.9 and an oil 1.4 system. The condenser prisms are different between them. There are few people around with two systems lingering around. Also, working at that kind of apertures gets tricky very quickly, and before you know it, the day is over without images you're really satisfied with ;-)
Anyway, I can show you a couple of my latest images, quick and dirty, as I see no point in spending too much of my time on this topic. You can spend a lot of time fiddling around with these systems, there are always some variables that influence the imaging negatively, in the case here the layer of mountant on top of my specimen which adds spherical abberation for which I cannot compensate properly here.
Anyway: subject: scales of Mallomonas teilingii, whole cells embedded in Pleurax. System: Olympus DICT-HR for oil 1.4. Images straight from the camera, no enhancements. First image without, second image with oiled condenser. Last image however with aperture slightly closed: at full aperture of 1.4 the system gives so much glare as to make the image useless. Might be due to the mountant layer on top of the specimen(?).
Last two images show another specimen, first one brightfield with the iris closed (probably around NA 0.8, took no note of it) and the corresponding DICTHR (oiled) image. Brightfield really isn't doing too bad ;-).
Remember (as a humbling thought), the Victoreans showed it all before.
Best wishes, René
ps, I do always use this condense immersed, but with water. This is possibly the last time oiling it, it really isn't worth the hassle.
