There was a thread on the German microscopy forum that described third party objectives that work with the old/original DIC equipment from Zeiss (https://www.mikroskopie-forum.de/index. ... ic=43653.0). Some of you may may be familiar this thread, but for those who haven’t seen it I wanted to share my experience with one of the objectives that was mentioned in the thread. This is the Leitz NPL-Fluotar 50X, NA 1.0 oil objective and is used with a 160 mm tube length Zeiss microscope. The old/original Zeiss DIC equipment is shown in the photo below and was used on a Zeiss Photomicroscope III.
I obtained this objective and here are some of my observations. This objective is nearly parfocal with other Zeiss objectives that I use. I have used it with oil (Cargille Type A) and because it has a slightly longer working distance than my 100X oil objective I have found it easier to work with. Since the NA of the objective is 1.00, I have not oiled the condenser to the slide. The images produced with this objective are really impressive. Some examples are shown below. Photos were taken with a Canon 1300D camera using flash.
Phacus (from a floating coverslip). Note the striations on the pellicle of the cell.
Characium, a stalked alga. The disk that attaches to the filamentous alga strand is a reddish brown color
Nuclearia, a small amoeba with filopodia. The nucleus with its nucleolus and an ingested diatom can be seen.
Tim