Need help connecting a Nikon Coolpix L120 to a microscope

[jkexplorer]

I bought an OMAX microscope with a trinocular head, which also included a 5MP camera. The camera quality is not great, as I expected, but it is sufficient for now. I do have a stand-alone 14MP digital camera, a Nikon Coolpix L120, which I would like to use instead of the low-powered camera included with the microscope. I have watched videos on using cameras with microscopes, so I have a basic understanding of the process, but I need help to determine the specific adapters I need in my case.

My camera is all one piece. Since there is no removable lens, there is no way to attach an adapter to the inside of the lens area. I think I will need an adapter tube where the camera housing (60cm exterior diameter) sits inside the adapter (see attached image). I have found these on various websites, so I think I can handle that part.

The part I am unsure of is, once I have that adapter, what do I use to connect it to the trinocular photo tube? I assume I’ll need some kind of refocusing adapter (compensating ocular) which goes between the adapter tube and the photo tube, but I am not sure how to find the right one for my setup, or what other adapters I might need to sit between the adapter tube and the compensating ocular.

I realize there may be other parts or information needed for this setup, but if anyone has any experience with this kind of situation, I would be grateful for any information. Thank you.

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[MichaelG.]

Nice sketch !!

What you are wanting to do is ‘afocal’ imaging, and [for starters at least] just try putting one of the visual eyepieces into the tube.

A search of the site should find you plenty of information.

MichaelG.

[hans]

Have you tried holding the camera by hand and taking photos through the normal binocular eyepieces? That will check whether the entrance pupil of the camera's built-in zoom lens is close enough to the front glass surface to work with a normal eyepiece.

[Hobbyst46]

Have you tried holding the camera by hand and taking photos through the normal binocular eyepieces? That will check whether the entrance pupil of the camera's built-in zoom lens is close enough to the front glass surface to work with a normal eyepiece.

An important preliminary test, since the sensor of the coolpix is small, 1/2.3" - maybe about the same size of the sensor of the 5MP camera; so a small fraction of the FOV will be imaged, hence a reduction lens is perhaps needed, like 0.5X; yet afocal means using an eyepiece...(I might be wrong though).

[hans]

The camera lens together with a standard eyepiece can theoretically provide the necessary reduction. (The L120 lens is 4.5 mm at the wide end of the zoom range which gives 4.5 mm / (250 mm / 10) = 0.18X reduction going from the intermediate image to the sensor with a 10X eyepiece.) But even if the FOV is not limited by cropping due to magnification and sensor size it may still be limited by vignetting if the entrance pupil is too far inside the camera lens.

[jkexplorer]

Thank you all for your feedback. I took a picture from the camera directly through the eyepiece. The image was just a small fraction of what I could see with my own eyes, and it was difficult to get a good picture without a large bright spot. I turned the LED brightness down a little, and was able to get a better image. When I finally did get a picture, the quality was quite good. The color accuracy matched what I could see with my own eyes, so really the only issue overall is that I can only capture a small area. I tried all of the above without the eyepiece, and could not see anything. I am willing to spend whatever is necessary (within reason of course) to get this arrangement to work, but I'm afraid I'm so new to this that I don't even know the right questions to ask. It just seems like there should be some kind of optics which would sit between the photo tube and the lens of the camera so that the full image of the specimen can be visible at the scale I can normally see. I will experiment more with cardboard tubes to see if that helps with the lighting.

By the way, for the sketch, I took pictures of the actual parts, then used a photo editing tool with a de-gaussing filter to make them look like sketches. I thought it would help illustrate the details and make it easier on the eyes.

Thanks again!

[hans]

...so really the only issue overall is that I can only capture a small area.

Did you experiment with different zoom settings on the camera? And if the camera has a manual aperture mode, did you try with the aperture fully open? May not help much, many camera lenses, especially ones with large zoom ratio, have this problem.

I tried all of the above without the eyepiece, and could not see anything.

This is expected.

I am willing to spend whatever is necessary (within reason of course) to get this arrangement to work, but I'm afraid I'm so new to this that I don't even know the right questions to ask. It just seems like there should be some kind of optics which would sit between the photo tube and the lens of the camera so that the full image of the specimen can be visible at the scale I can normally see.

Some options for what are basically higher-eyepoint eyepieces are mentioned in the "Fixed-lens Cameras" section here:
http://krebsmicro.com/photomic1/photomic1.html

I have not looked into these much but my impression is that, given the age of your camera, the money may be better spent getting a different camera with lens that is compatible with the normal eyepieces or an interchangeable-lens camera that can be used with a relay lens like the one on your 5MP OMAX. Have you tried a smartphone camera? The L120 has a large lens with long telephoto zoom range but that is not useful on a microscope and the sensor is relatively small. A modern smartphone may be fairly close in performance.

[Hobbyst46]

I tried all of the above without the eyepiece, and could not see anything. I am willing to spend whatever is necessary (within reason of course) to get this arrangement to work, but I'm afraid I'm so new to this that I don't even know the right questions to ask. It just seems like there should be some kind of optics which would sit between the photo tube and the lens of the camera so that the full image of the specimen can be visible at the scale I can normally see.

Do not be discouraged ! A LOT of folks who try to install a camera on the microscope face exactly this challenge, especially with modes that are not really supported by the microscope makers.

[jkexplorer]

That was a very interesting article, though I may need to read it through a few more times . I tried with different zoom settings, and I think that with the right adapter tube (even considered making one out of black PVC) I may get a degree of success. I agree it may be easier/better to just get a dedicated but higher quality microscope camera system. They aren't terribly expensive, and that would allow me to focus (no pun intended) more on the specimens and less on the technical requirements of getting a picture of what I'm looking at. In any case, this has been a fruitful learning experience, and I appreciate the helpful responses from this community, so thank you again!

[Hobbyst46]

That was a very interesting article, though I may need to read it through a few more times . I tried with different zoom settings, and I think that with the right adapter tube (even considered making one out of black PVC) I may get a degree of success. I agree it may be easier/better to just get a dedicated but higher quality microscope camera system. They aren't terribly expensive, and that would allow me to focus (no pun intended) more on the specimens and less on the technical requirements of getting a picture of what I'm looking at. In any case, this has been a fruitful learning experience, and I appreciate the helpful responses from this community, so thank you again!

More comments - hopefully not nudging:
1. A "dedicated" camera is designed to be installed WITHOUT eyepiece. Olympus for example sells dedicated cameras that, in order to catch the full FOV, need a reduction lens (which they sell as option). BUT, these cameras produce good images on infinity-corrected microscopes, in which all corrections are accomplished by the objective and tube lens, so the eyepiece is not essential. On the OMAX scope it depends, if optics are different from the above mentioned, premium performance from an Olympus camera (or other high-quality brand camera) is not guaranteed. If OMAX sells a specific dedicated camera for your microscope, it may be worth trying, since it can be returned if not wanted.
2. About two years ago, installation of Canon DSLRs on Bresser microscopes, finite or infinite optics, with good results, was reported on the forum. Focal installation, without the camera lens, as far as I reckon.

[MichaelG.]

Just to stir things a little ... The old Coolpix 4500 https://www.dpreview.com/reviews/nikoncp4500 was commonly used with a Leitz Periplan eyepiece, to produce quite decent images [the eyecup thread screws straight into the filter thread]

I have an article on file somewhere ... will add a link when I locate it.

Honestly can’t foresee any great problem with using the L120 for basic imaging.

MichaelG.

.
Edit: Found it ... https://www.quekett.org/wp-content/uplo ... camera.pdf
20 years old, but still very informative.

[Scarodactyl]

A few of the bigger third party names in camera adapters have made ones for coolpix cameras, though not this model as far as I know. Martin had a few, including the MM99 and whatever this is: https://www.ebay.com/itm/Martin-MMC00L- ... 4140335873 and LMscope also made one (I got one with some other stuff a few months back but sold it).

[DonSchaeffer]

A 5 megapixel dedicated camera may be enough.
https://www.youtube.com/watch?v=2JhWaMFBm4I

[hans]

I tried with different zoom settings, and I think that with the right adapter tube (even considered making one out of black PVC) I may get a degree of success.

If you can get a reasonable field of view then the next thing to check is whether one of your normal eyepieces fits and is parfocal in the photo tube. (I am not familiar with the OMAX/AmScope type microscopes but I believe this is how the trinocular heads are designed to work?) To check parfocality, if you focus on something normally with a low power objective then without changing focus move an eyepiece into the photo tube, is the image in focus?

[jkexplorer]

It has been a while, but I wanted to give an update to my imaging issue. I ended up buying a 16MP microscope camera with an included 0.5 C-mount. The quality was a lot better than the 5MP camera I got with the microscope. For the most part my issue has been resolved. There's just one small, but annoying, problem. The focus is just slightly off from the camera (as displayed on the computer) to what I see through the eyepieces. For now, I just ignore what is on the screen until I can find what I'm looking for on the slide, then I look t the computer screen and carefully adjust the fine-focus knob until it looks good on the computer screen. I can live with it, but I feel like what I need to solve the issue is an adjustable-length photo tube. There is a silver metal piece (part of the photo tube, but not sure the exact name) which screws into the other heavier part of the photo tube (which screws into the microscope head). This metal piece can be raised by unscrewing it (which can make it about 1cm higher) to increase the focal distance, but cannot go any lower than it already is. I need it to go lower. Has anyone heard of such a thing? I tried doing a search, but can't find anything. Not a big deal, as the new camera is working great quality-wise. Oddly, the product manual has a name for everything except the two parts of the photo tube.

[Hobbyst46]

It has been a while, but I wanted to give an update to my imaging issue. I ended up buying a 16MP microscope camera with an included 0.5 C-mount. The quality was a lot better than the 5MP camera I got with the microscope. For the most part my issue has been resolved. There's just one small, but annoying, problem. The focus is just slightly off from the camera (as displayed on the computer) to what I see through the eyepieces. For now, I just ignore what is on the screen until I can find what I'm looking for on the slide, then I look t the computer screen and carefully adjust the fine-focus knob until it looks good on the computer screen. I can live with it, but I feel like what I need to solve the issue is an adjustable-length photo tube. There is a silver metal piece (part of the photo tube, but not sure the exact name) which screws into the other heavier part of the photo tube (which screws into the microscope head). This metal piece can be raised by unscrewing it (which can make it about 1cm higher) to increase the focal distance, but cannot go any lower than it already is. I need it to go lower. Has anyone heard of such a thing? I tried doing a search, but can't find anything. Not a big deal, as the new camera is working great quality-wise. Oddly, the product manual has a name for everything except the two parts of the photo tube.

Does the 5MP camera get exactly parfocal with the viewing eyepieces ? if so, it is a bit strange that the 16MP camera does not, given that so many unbranded eyepiece USB cameras look alike; perhaps one can switch the 0.5X lens tubes (the one on the 5MP and the other on the 16MP) ? otherwise the only solution seems to be shortening the silver metal tube, namely, lathe work...or 3D printing of a shorter tube. As I have learnt, parfocality is very important.

[75RR]

There is a silver metal piece (part of the photo tube, but not sure the exact name) which screws into the other heavier part of the photo tube (which screws into the microscope head). This metal piece can be raised by unscrewing it (which can make it about 1cm higher) to increase the focal distance, but cannot go any lower than it already is.

Photo?

[jkexplorer]

It's hard to compare the 5MP with the 16MP, for a couple reasons. First, the 5MP had such low quality, that it looked bad no matter how I adjusted the focus. Second, the new camera has software which can somehow provide a clarity value as I adjust the focus so I can focus as good as possible. I am adding some pictures of my particular setup. One image shows the parts of the photo tube I am referring to, the second shows what it looked like with the 5MP, and the third shows the 16MP with the C-mount. I agree with one of the comments that it's either lathe time, or 3D print time. I'm leaning toward the latter, but I have no 3D printer. (wah wah wahhhh) If someone knows what that silver piece is called, I'd appreciate knowing what that is; otherwise I'm just calling it "part A".

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Thanks again, everyone.

Jon

[75RR]

May sound a little drastic but if Part (a) can be removed then you could ask a local metal worker with a lathe to remove say 5mm from the top.

[hans]

In addition to tube length of the photo port there are at least two other things that could be off to cause this: position of the intermediate image relative to the top of the tube the camera/lens is inserted into (property of the camera/lens) and tube length going to the eyepieces. Some questions that might help narrow down the problem:

Do you need to refocus by a similar amount with an eyepiece in the photo tube instead of the camera?

If you focus looking through the binocular eyepieces then remove one and put the camera in its place do you still need to refocus by a similar amount?

Looking through the eyepieces only, how much do you need to refocus when switching among objectives? Then looking at the camera only when switching objectives, is more or less refocusing required than when looking through the eyepieces?

It looks like the head is the type where tube length needs to be adjusted manually when changing interpupillary distance? If that adjustment is not quite calibrated correctly on the head perhaps it would be acceptable to use it to match the binocular to the photo tube, assuming the required adjustment is not too large relative to the range available on the eye tubes?

[jkexplorer]

Great suggestions, Hans. I will try that.

I looked at the camera and the C-mount, but there are no adjustable parts I can find.

When I switch objectives, the amount of fine-refocusing is about the same between what I need for myself via the eyepieces, and what I need for the camera. It's a very small amount, but very noticeable.

Before introducing the camera into the scenario, I set the interpupillary distance to 63, and both dipoters to 63. When I do that, things look "correct" (again without the camera). Now, when I place the camera in the photo tube, and get the focus as good as possible (when viewing the image on the computer screen), I find that I have to adjust the diopters to the lowest setting, around 55. At those settings, the focus difference is a small as I can get it, but only the camera, or I, can have the correct focus through fine adjustment, but not both. I will try the suggestions you provided to find out where things start to get wonky, and also look into finding. someone with a lathe.

[hans]

A few other thoughts:

Did you buy the camera and lens preassembled together as a unit? Is it possible a C/CS mount spacer ring between the camera and lens is either missing, or present but not supposed to be there?

On some of my older C-mount cameras there is a non-obvious way to focus -- loosen set screw on the side with a hex key, then the ring the lens threads into, which is itself threaded into the body, can be screwed in or out.

Since the direction you need to go is further into the tube, you maybe could alternatively unscrew the lens from the camera a bit? Probably not a good long-term solution if you are sure the camera/lens combo is correctly matched and focused and binocular tube length is correct, but maybe acceptable if the adjustment required is small.

[jkexplorer]

The camera (blue part from the earlier picture) was one piece, then the C-mount was a separate piece. The C-mount screws into the camera. I looked and noticed a T5 Torx screw on the side of the camera lens/screw-in piece. I can unscrew that and remove the interior ring (or extend it slightly), but it will not go in any further. It seems like all the pieces in this puzzle can increase the focal length via an adjustment, but there's nothing to decrease it! Doh!

[hans]

Hmm, yeah what I said about unscrewing the lens was backwards, but it sounds like you already understood that. I don't have any other suggestions, but permanently shortening the tube may not be a good idea until the camera/lens are conclusively ruled out, otherwise you will have a problem in the future if you ever want to use a different camera setup.

[jkexplorer]

I'm still going to try your suggestions with the camera on the eyepiece port, but I expect I'll have to make my own custom adjustable part A. Hopefully that will work, and I can leave the original part untouched.

Thanks.

[jkexplorer]

Another update. I focused the eyepieces as I normally would, and the camera on the photo tube. From the software, it showed a clarity value of 52. The value does not have any units, as it is just a value made-up by the program, but the higher the better. I then removed an eyepiece, and placed the camera w/C-mount on that eyepiece port. It was still as out-of focus as before with the exact same clarity value of 52. I adjusted the fine-focus to get the best camera focus I could, and found that the best clarity value was 800. Based on how little I actually had to adjust the fine-focus (and holding a small ruler next to the stage), I'd say I only need to decrease the focal length by no more than one or two millimeters at most. So close, but so far away...

[hans]

Sounds like that pretty well rules out a binocular vs. photo tube mismatch. Another thought, to measure the required displacement more accurately, could you focus the camera in the photo port, then put and eyepiece in the photo port and see how far it is necessary to lift the eyepiece to get focus? I think that distance should be close to the distance you would need to further insert the camera going the other way.

[Hobbyst46]

Below are photos of my own eyepiece camera ("remote relative" of yours... . 5MP "digital camera" with C-mount and 0.5X reducing lens. Connected by screwing without any unscrewing to modify distances. When inserted into the bino eye tube of my (secondary, still under improvements) microscope, the 0.5X lens tube is fully inserted, until it stops at the yellow line. At that point the same sharpness is achieved by eye view and the camera. No need to shorten any tube.

I control the camera with either the Toupview software or the MICAM 2 software, both are downloadable and free. I set exposure time, white balance and other features. I did not notice a "clarity" or similar feature, the software allows to control the brightness of the image via the regular features.

In the photo below, please ignore the cellotape on the camera and the various artifacts in the diatoms image. It is only an illustration of the focus. Plain brightfield, 40X0.65 objective.

P.S. the external groove in the o.5X lens tube was perhaps designed to hold an o-ring for greater friction between the lens and eyepiece tube; I do not use it.

[MichaelG.]

Another update. I focused the eyepieces as I normally would, and the camera on the photo tube. From the software, it showed a clarity value of 52. The value does not have any units, as it is just a value made-up by the program, but the higher the better. I then removed an eyepiece, and placed the camera w/C-mount on that eyepiece port. It was still as out-of focus as before with the exact same clarity value of 52. I adjusted the fine-focus to get the best camera focus I could, and found that the best clarity value was 800. Based on how little I actually had to adjust the fine-focus (and holding a small ruler next to the stage), I'd say I only need to decrease the focal length by no more than one or two millimeters at most. So close, but so far away...

That sounds a very useful software feature ... presumably relating to contrast level [which varies with the accuracy of image focus]

Sounds like it’s time to get the hacksaw [or any more sophisticated cutting implement] at it
.... Unless, of course, there is a removable 5mm extension ring screwed into the camera !

https://www.ikegami.com/cb/products/pdf ... smount.pdf

MichaelG.

[jkexplorer]

Huzzah! I have achieved success! Hobbyst46, when you said that you removed the O-ring on your C-mount extension, I realized two things. First, I'm an idiot. Second, mine also has a rubber O-ring in the same position, for the purpose of stopping the part from descending too far into the photo tube. I removed it. Now that meant that the C-mount would go TOO far down, but that is ok, because part A can be unscrewed/raised by a large amount and still have a solid connection to part B. I focused using the eyepieces to where I considered it to be perfect focus, then began adjusting the height of part A until the image on the monitor looked good, and I was able to get the optimal clarity factor with all objectives. I have now achieved parfocal perfection.

Thanks to everyone who helped me solve this issue!!!

Jon