photo tube for my Nachet NS400 ?

[ker2x]

Hi,

for more info about the microscope, see here : viewtopic.php?f=5&t=14536
and here : http://chicheret.free.fr/Microcosmos/Microscope.html

Here is the info I gathered and for which I'm 98% sure :
- The microscope have Infinity objective with RMS thread
- The tube length is 200mm
- The Trinocular port is C-Mount

For now I use a low quality eyepiece camera.
I want to use a proper camera (DSLR, video camera, or specialized camera).

I don't know the purpose of a tube, especially on an infinity corrected system. Perhaps it have a lens in it ?
What kind of accessory do I need to screw on the Trinocular port ?

Thank you

[apochronaut]

The first thing you need to do is make a determination of just how your head is configured.. There is an optic that is required in the head of infinity corrected systems called a telan lens or a telecentric lens, which focuses the infinity ray bundle. It also usually performs subtle aberration corrections . There must be one but it can be in differing locations, depending on the design.
Usually, it is in the bottom of the head and affects both the visual eyepieces and the photo tube but in one system I know of at least, that lens is in duplicate, with one up inside the head and another in the photo tube.
Check and make sure that lens is acting on the photo tube in your system.

[ker2x]

The first thing you need to do is make a determination of just how your head is configured.. There is an optic that is required in the head of infinity corrected systems called a telan lens or a telecentric lens, which focuses the infinity ray bundle. It also usually performs subtle aberration corrections . There must be one but it can be in differing locations, depending on the design.
Usually, it is in the bottom of the head and affects both the visual eyepieces and the photo tube but in one system I know of at least, that lens is in duplicate, with one up inside the head and another in the photo tube.
Check and make sure that lens is acting on the photo tube in your system.

Thank you, I'm not sure if the output is infinite or focused.hard to tell on the schematic alone. I'll try to find a way to check

[apochronaut]

Based on that schematic it has a rather complex system that seems to break the job of the telan lens into segments. I sure hope all of those first surface mirrors and doublets are in good shape. Be very careful cleaning the mirrors, they will scratch easily. In diascopic mode there are 4 first surface mirrors and at least 2 beam splitters.
There are also 4 doublets along the optical pathay before the binocular beamsplitter. The first two are a mirror image relay system to converge then diverge the infinity bundle in order to extend it' s practical length. The last two seem to be telecentric doublets per se, with the the role split into two parts it would seem. By the time the image passes through the photo tube beamsplitter , it has only been through one of the telan lenses so whatever the job of that second doublet is : it doesn't affect the photo tube. I would think it likely that the original photo tube accessories include a version of that second telan lens built in or a whole other photo optic that includes it's function.
What I would do in your case, once you have the basic binocular system working satisfactorily is make a temporary mock up of a tube out of cardboard tubes or plastic pipe and try out one of your eyepieces as a photo optic. Start there to get a rough idea of distances and corrections. It may be a simple case of finding a correct eyepiece to provide the needed extra corrections for field flatness or lateral ca. Likely most of the work is being accomplished in the first telecentric optic.

[ker2x]

Thank you,

i forgot to mention, I don't have the light module at the top (for reflected light), I only have the one for the transmitted light at the bottom.
it doesn't really change my photo tube problem of course.

I still can't figure out what kind of mount it is
Also, I'm pretty sure the previous owner put a camera directly on the output port, without tube or lens. (considering he glued some plastic canon mount on it)
Dunno if it worked however ^^

Diameter is around 3.4cm

[ker2x]

using a sheet of white paper :
I determined that I have a clear in-focus projection of the sample at a 16cm distance from the Trinocular mount.
The distance vary greatly with the focusing. but if I want both the eyepiece and the camera in focus at the same time, it appears to be 16cm