This is description of this part:
Leitz Wetzlar projection microscope eyepiece with 4x magnification
Manufacturer: Leitz Wetzlar (Germany)
Marking on the eyepiece: Proj. 4x
Magnification: 4x
Kind: projection eyepiece for photomicrography
Intended for: microscopes corrected for objectives with TL = 170 mm
Mounting diameter: 23.2 mm
Projection eyepieces are special microscope eyepieces used to project the microscopic image onto the sensor of a camera. Many microscope photo tubes and trinocular heads have a seat for a projection eyepiece.
Leitz projection eyepieces of this magnification carry several different markings. You will find "Proj.-Ok. H4x", "Proj.-Ok. P4X" and - as on the item offered here - simply "Proj. 4x". The letter H stands for the Huygens design. Leitz also made projection eyepieces of other magnifications, 2.5x among them, so the 4x version is not the only one in this family.
The eyepiece is intended for microscopes with a mechanical tube length of 170 mm. The older Leitz stands are corrected this way, Orthoplan, Ortholux, SM and SM-D among others. Later microscopes of this brand already work with a 160 mm tube. In Leitz optics of this generation part of the chromatic aberration correction is deliberately moved from the objective to the eyepiece, so matching an eyepiece to an objective is not merely a mechanical question here.
Despite its name, this eyepiece behaves differently from a typical projection eyepiece. It does not form a real image at a fixed distance, but projects the image to infinity - exactly like an ordinary viewing eyepiece. This makes it excellent for the afocal method, that is, photographing with a camera that keeps its own lens placed above the eyepiece. Leitz itself built its photographic adapters on precisely this method.
Leitz "Proj." eyepieces also found use outside microscopy. Eyepieces of this family were part of the microprojection attachments for the Leitz Prado and Pradovit projectors, which threw the image of a specimen onto a screen for a whole lecture room. If you are completing such an attachment, this is exactly the part.
Use in a microscope with a 160 mm tube length remains a matter of your own DIY modification. Mechanically the eyepiece fits any 23.2 mm seat, but the intermediate image is then formed in a different place, so focus and image scale will come out differently from what the manufacturer intended. There is, however, a route that gives a beautiful combination: into a microscope of another manufacturer you fit a Leitz Wetzlar objective computed for 170 mm, and this eyepiece above it. The optical path is then entirely Leitz - objective and eyepiece work as they were designed to, and only the stand remains foreign, a PZO or a Carl Zeiss Jena one for instance.
The "compatibility" section lists the microscope models this eyepiece can be used with, but that list is of course not complete. This projection eyepiece can be used with any microscope of any manufacturer, as long as it has a tube or another seat for an eyepiece of 23.2 mm diameter - subject to the difference between 160 and 170 mm tube length (I write about this above).
What is this part needed for?
- if your microscope has a photo tube or a trinocular head with a 23.2 mm seat and you want to take photographs using a projection eyepiece
- if you already have such an eyepiece, but it is damaged, scratched or has fungus on the lenses
- if you want to keep a projection eyepiece as a spare
- if you are completing a microprojection attachment for a Leitz Prado or Pradovit and the eyepiece is missing from it
- if you have an older Leitz microscope for a 170 mm tube and want to photograph the way the manufacturer intended
- if you need a compensating eyepiece for photomicrography, because your Leitz objectives leave part of the chromatic aberration correction to the eyepiece
- if you want to use this eyepiece in a microscope of another manufacturer together with a Leitz Wetzlar objective computed for 170 mm
- if you are trying out projection eyepieces of different magnifications to find the best one for your microscope and camera combination - and you want to test this one
- if you have neither a photo tube nor a trinocular head, but want to use the eyepiece for photomicrography through the eyepiece tube
