Connecting a DSLR to phototube

[KingsleyJ]

Greetings fellow microscopists,

I recently acquired a Nikon Eclipse Si (infinity corrected) microscope [trinocular head F2), and I'm eager to delve into the world of capturing awe-inspiring images. However, I've encountered a bit of a quandary when it comes to establishing a connection between my DSLR camera and the phototube. I'm hoping that the seasoned experts in this forum can provide some guidance and insights to help me kickstart my microscopy photography journey.

While I've conducted preliminary research and tried various methods, I've yet to successfully link my DSLR to the phototube. My camera of choice is a Canon 90D [APS-C], so compatibility concerns should hopefully not be an issue.

I have tried mounting an "Olympus Photomicro Adapter L" to it (with a standard eyepiece as projection), but cannot get anywhere close to parfocality and when focus is obtained the image quality seems to suffer. Any guidance on this would be much appreciated - I am open to spending money on adapters, projection eyepieces, etc.

Thank you.


Cheers

[Scarodactyl]

I am not familiar with that particular head. For Nikons usually you can direct project onto aps-c with no intervening optics, though itnis much easier with a mirrorless camera. With a dslr you typically have to remove some tubes and adapt it directly to the top of the head. It lets you take advantage of the full rated image circle of your objectives and a bit more while avoiding additional aberrations from extra optics. But that may be harder with some heads.

[Pau]

Detailed pictures of your phototube could help, is the tube (blue arrow) ended in C-mount thread camera mount or the camera mount itself (red arrow) removable?
.

If doable direct projection suggested by Scarodactyl could be the best option. If you are restricted to C-mount there are some adapters that would allow mounting a DSLR, but it's better to wait your answers.

[KingsleyJ]

Thank you for the quick replies!

In response to Pau, the C mount (red arrow) is removable, but the whole tube (blue arrow) is not.

Attached are some pictures of the phototube:

[Pau]

Thanks for the answers.
I assume that the lens shown in the first picture is placed deep in the tube, isn't it?

What I don't like is the 0.55X phototube "magnification" (in fact reduction). This is convenient for C-mount small sensor cameras but very low for APSC, so if as you say the tube is not removable you need lenses for increasing magnification on sensor up to about 1.6X.

- My 1st option:
Nikon made some adapters called "Coolpix MDC lens" that have a C-mount female at the lower end and (in most models) M28X0.75 male thread at the other side.
They are basically good quality high eyepoint 10X eyepieces meant to work coupled to a camera lens focused to infinite in what we call an afocal setup*
The idea is:
MDC lens + 28mm to camera lens filter thread adapter ring(s) + camera lens (70-80mm)
The formula to calculate the relay magnification of afocal systems is:
(eyepiece magnification) X (camera lens FL) /250
so you would get: [0.55 X 10 (MDC) X 70 (camera lens)]/250 = 1.54X
The possible issue is the camera lens because it must have the entrance pupil not too recessed, and I'm not able to recommend a well proven one for this function.

Disclaimer: I've not tested this combo, I have an MDC lens but I only have used it in place of a stereo microscope eyepiece with 40 or 50mm lenses)

Other options:
There are third party adapters from different makers that could do, although some ones are very expensive while other are of unclear quality

* info on afocal: viewtopic.php?p=99265#p99265

- MDC lenses for peanuts: https://www.gamesnicer.xyz/detail/3-Nik ... upmuv.html (no info about the seller, at Ebay it can be bought for higher although reasonable prices)

- Expensive adapters: https://www.lmscope.com/
https://www.lmscope.com/en/lmscope_out2 ... mit=Search
https://www.lmscope.com/en/LM_Adapter_f ... 5x_en.html

Of course you have of course other alternatives
- buy a dedicated small sensor C-mount camera
- Remove the trinocular head and place the camera over the microscope frame with a 200mm lens (more useful for "macro style" work with low magnification objectives
- change the trino head for a model with no reduction and that can be adapted with DSLR for direct projection or more standard adapters
-or...

[KingsleyJ]

Pau, thank you for the insight into this - I will look into afocal. Though not ideal, it definitely seems like a viable option.

I have considered just purchasing a C mount “microscope” camera, but my main concern is the image quality of those devices. I previously owned such microscope camera (couple years back) and found the colour accuracy and fidelity to be terrible; wondering if things have changed now?

Any recommendations would be helpful

Thanks

[Pau]

Two more further questions,
- Does the removable C-mount part have any built-in lens?
- What's the inner diameter and depth of the phototube smooth cylinder part? (without the C-mount part)

(if they match with other more standard Nikon phototubes, an alternative setup with T-BPA or V-T tube and a projective Pl or PLI eyepiece could be made)

[KingsleyJ]

The removable C mount part does not have any lens - it just a metal connector.


Currently I do not have a way to accurately measure the diameter and depth of the phototube - I can make do with a ruler for now.

Attached are some pictures:

[Pau]

Note these are approximate - measured by ruler

This is enough precision, T-BPA and V-T tubes are designed for 38mm ports, so they don't fit.

[KingsleyJ]

I am okay with spending money to make it work - I'm looking into a configuration with the C-TT trinocular head, but can't seem to find more info on the dimensions.

[Pau]

I am okay with spending money to make it work - I'm looking into a configuration with the C-TT trinocular head, but can't seem to find more info on the dimensions.

Take a look at: https://www.optics-pro.com/Produktdownl ... ere_EN.pdf page 29

AFAIK, C-TT has the 38mm port and no reduction, so you can attempt direct projection placing the camera mount very close to the phototube end (easier with a mirrorless) or you can couple the T-BPA or V-T tube, a photoeyepiece PLI 2X and an adapter tube of approximately a bit more than 120mm like
https://www.ebay.com/itm/364098712409?h ... R9KJiLWwYQ

[KingsleyJ]

From my understanding the PLI eyepiece sits inside the T-BPA tube? I’ve found that the 2x ones are quite rare, so 2.5x with some FOV lost is acceptable for the time being.

Also, what is the purpose of the 120mm tube?

Thanks

[Pau]

From my understanding the PLI eyepiece sits inside the T-BPA tube? I’ve found that the 2x ones are quite rare, so 2.5x with some FOV lost is acceptable for the time being.

Yes, it does
The 2X is much less frequent, although I own both and this one was the less expensive, just good luck.

Also, what is the purpose of the 120mm tube?

It's am empty tube with 42mm lower diameter and the camera mount at the upper one, it places the image emerging from the projetive photoeyepiece on the sensor at the right height. You can replace it with custom adapters, extension tubes, bellows....
Take a look at viewtopic.php?p=267532#p267532
(now the total distance I use is a bit longer, about 123.4mm in my last tests, and some components have changed)

Anyway, again, if you buy the head first try direct projection, I've done it with good success coupling a Canon EOS to the Nikon SMZ1000 port and other members also to other Nikon microscopes. Unfortunately the image circle of my AZ100 is too small.

With a forum search like the following one you will find relevant info on both options:
search.php?keywords=Nikon+E600+direct&t ... mit=Search

[KingsleyJ]

Thanks, will update when I get the equipment.