Fungus Gnat and a Microscope.

The previous post’s image turns out to be the nether regions of a male Dark-winged Fungus Gnat (Sciaridae), as identified on BuigGuide.

The photo is of a specimen I mounted in PVA in 2004. The image was taken through the photo-port of a microscope called Jenamed 2, manufactured in the former East Germany, by Carl Zeiss, Jena. I originally purchased this microscope over 17 years ago, as damaged surplus from a medical lab here in Edmonton. The damaged part was the microscope stage, which had a complicated system of wire, pulleys and ball bearing glides which I have been unable to fully repair, but otherwise the ‘scope is in good condition with a full complement of undamaged objectives and eyepieces. I do want to make the most of this tool, even though there will be limitations  due to the lenses, which are planachromats rather than the better corrected planapochromats. I have learned a bit online, but there are still some questions I have about this microscope and how to make best use of it.

"Carl Zeiss Jenamed-2 with Olympus E-PM1 on homemade photo tube."

Carl Zeiss Jenamed-2 with Olympus E-PM1 on homemade photo tube.

First, the objectives and the markings on them:

Planachromat 5x/0.10 ∞/—A
Planachromat+ 10x/0.20  ∞/—A
Planachromat 40x/0.65   ∞/0.17—A
Planachromat Hi 50x/1.0   ∞/0—A
Planachromat Hi 100x/1.3   ∞/0—A

The 5x, 10x etc. indicates the magnification and the number after the first / is the numerical aperture. The ∞ indicates that they are infinity-corrected objectives, and must be used with a particular microscope with a lens in the tube. The HI indicates that they are Homogeneous Immersion objectives, where immersion oil should be placed at the interfaces between the objective front lens and the specimen slide and also between the front lens of the condenser and the underside of the specimen slide.¹.

The /– indicates that the low powered objectives can be used with or without a cover glass on the specimen. On the 50x and 100x, the 0— means (from a response on a web forum) that no cover glass should be used, and the 40x requires a 0.17 mm thick cover glass.

As for the A…

“An A means an objective without chromatic difference of magnification. This objective has to be used with an ocular without chromatic compensation.”

I haven’t quite wrapped my brain around that statement, considering that these are achromats that do not have full chromatic correction, however, the oculars are the original (GF-Pw 10x) wide field eyepieces so that should not be a concern.

So the outstanding questions are:

  1. what does the “+” on the Planachromat+ 10x mean?
  2. what does the “Pw” on the ocular mean?
  3. and would the original phototube (which I do not have) have had any corrective lenses?

Any information on these questions, or any other advice on how to get the most out of this microscope would be appreciated!



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