At last – some good dark field views on the Zeiss IM microscope. In particular, the 4x bright field objective provided excellent dark field views when used with Phase 2 annulus on standard condenser. I also purchased some dark field filters from ebay (these fit into the Zeiss’ condenser filter holder but are really annulae of different sizes). The ones I purchased did not work BUT when I stuck either a penny or five pence piece on middle to increase size of central obstruction the views improved – particularly with the 4x objective the one penny annulus in the filter holder gave good dark field views.
The first photographs below give the same field in bright field and dark field using both of the above means (different photos) and then the photos below that are various views using dark field today. All photos are of water from Stowe Pool in Lichfield collected today.
Photos of same field from sample Stowe Pool pond water in bright field and dark field – using either Phase 2 annulus on condenser or one penny annulus in filter holder on condenser (below):
Other dark field images of pond water from Stowe Pool collected today in Zeiss IM microscope (below):