Eclipse camera adapter

[Elapid]

Recently I was fortunate to acquire a Nikon Eclipse Ni-U microscope. It has a trinocular head which has a long tube extending vertically about 15cm and having a Nikon camera adapter on the end. This allows me to attach my Nikon full frame sensor DSLR directly to the tube. With this arrangement the camera and microscope eyepieces are parfocal.
Sounds perfect, right? The problem is that the camera adapter has 2.5x magnification built in and Nikon doesn’t seem to make an adapter that doesn’t magnify. So this 2.5x magnification results in capturing only about half of the microscope field which I see in the eyepieces. I really want to image the majority of the objective field.
Now with other scopes I’ve owned I’ve attached my DSLR by removing the tubes on the trinocular head and finding a real image plane and then machining a simple aluminum adapter which puts the camera sensor exactly in the real image plane resulting in capture of the entire image plane on the sensor. The sensor and eyepieces are almost perfectly parfocal. Although the corners are vignetted, with a 45Mp sensor I can afford to crop out the corners and still have a 30Mp or so image.
I’d like to do the same thing with my Eclipse but I don’t know where the 2.5x magnifier is located and I’m reluctant to take the thing apart until I have a better idea what I’m doing. Does anyone have experience with this type of microscope imaging system? Perhaps there is a better way to do it?

[PeteM]

Pictures might help. That and the camera image format. I've had a few Eclipse heads, but none that sound like yours. The closest thing I've seen has a lens inside C-mount cameras.

With the ones I have there is a way to remove long sections (yours 150mm) with three setscrews along the side, unscrewing, or in some cases removing socket head screws down inside the tube that attach the head to the body.

Like you, I'll often use direct projection. For the Nikon E600, which should be similar, this ends up with a full frame camera flange quite close to the head. A 2.5x projection lens setup also works well with a full frame camera - not the 2x diagonal coverage you seem to be getting. Are you using 22mm FN eyepieces or the widest ones? A full frame, APS-C, or ??? sensor?

[Elapid]

I’ve done a few photos. The riser tube is 10cm not 15cm as I had guessed. Looking down into the tube I can see a lens about 1/3 of the way up from the bottom. It’s listed as a 2.5x adapter so I imagine that is the lens which provides the 2.5x. On the top of the tube is a Nikon Fx mounting ring and it connects to my Nikon electronic X-series camera using the adapter which allows use of the “old” Fx lenses on the newer electronic cameras. With the X-series cameras there is no need to worry about mirror lock-up or electronic front shutter curtain. At the base of the tube is a 90 degree mirror or prism which reflects the beam upwards into the tube. In one photo you can see that there are rubber plugs which must cover the set screws which would hold the tube on. It looks like there is a small amount of yellowish sealant.
So I’m thinking that there must be a virtual image plane where the tube lens is located and a real image plane where the sensor is. Correct?
If I remove the rubber plugs and the set screws I could probably remove the tube and lens. But would there likely be a real image plane just above the base? Could anything get knocked out of alignment just by taking the tube off? Or what if I put a 1.4x teleconverter on the camera and made an adapter so that it would rest where the tube lens is now? I’ve been hesitant to try to remove the tube out of concern it might not go back together properly. I’ve talked to the Nikon rep and he couldn’t find an answer so I guess I’m on my own.
Yes, I am using the 22 eyepieces. The camera sensor is 24x36mm.

[Scarodactyl]

I believe this head may not be suitable for direct projection, at least I remember a complaint on that front. I believe the entire angled assembly may detach at the back, with the default image going horizontal. Direct projection, especially onto a larger format, will probably be hindered by the extra mirrpr or prism in the light path whose edges may crop thr image.

[Elapid]

Ok, thanks. You’re right, the right angle assembly is a separate component and detaches from the head. However there are 3 rubber plugs at the base of the tube. I suppose I can remove the plugs and see if I find screws, then consider if I want to try to detach the tube. I know that if I want to buy the epi-fluorescence module it will attach to where the right angle assembly fits into the head.

[Scarodactyl]

It might be worth considering a different head entirely, though getting all the features in one can be a pain. This model has the ergo tilt, 23mm oculars but you can get good 10x/22s that work great, and can be modified for direct projection with its nice ultrawide tube lens, covering aps-c at least. But the mod is a bit annoying, requires a 3d printed part and it is not too hard to break it in a way that is hard to fix if one is incautious during the mod (ask how I know). It also has an erect image which I love but I know is annoying for people used to an inverted image.

[Elapid]

That’s a good thought, thanks. The scope is new enough that the dealer would probably do a swap for another head that would cost me little or nothing. I really like the ergonomics of this head, not just the tilt but also the in and out feature of the eyepieces. I’ll check with the dealer and see what he says. There is, of course, a Nikon camera system designed for this scope but it’s only 5Mp and costs really big bucks. I think it fits right onto the back of the right angle adapter and it might give a wider FOV.