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Eyepiece camera

 
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mcfluffin



Joined: 01 Sep 2011
Posts: 9

PostPosted: Tue Sep 13, 2011 11:21 pm    Post subject: Eyepiece camera Reply with quote

Hey all,
I'm not sure if this is more equipment related or general technique, so I'll start here. In short this is the issue I'm having:
-I get halfway decent images using AmScope MD1800 camera on dissection microscope through eypiece
-I get poor images that I can't seem to focus using through eyepiece on Olympus BHMJ based micrscope w/ Neo SPlan objectives (https://picasaweb.google.com/lh/photo/suEbmHEJ2KYQbbaxlMKgZg?feat=directlink)
Do I absolutely need a trinocular or similar adapter or is there something I could try before shelling out more cash?

I'm looking for some pointers on the advantages of using dedicated camera observation tube (ie no binocular or trinocular head but instead a camera adapter), a trinocular observation tube, vs eyepiece camera combined with a binocular observation tube. I suppose the first is best quality since you wouldn't have any divergence from the eyepieces. The second seems most convenient for everyday use and seems to be what most microscopes use. An eyepiece camera seems to have the advantage of being convenient if you don't have a trinocular system. Do these application comparisons sound sound correct?

I have an AmScope MD1800 camera through an eyepiece since I don't yet have any "real" camera adapter. While I'm not terribly impressed with this camera, it yields much better images on my dissecting microscope vs my metallurgical even at low zoom. I think that the camera is meant for this sort of set-up though and so wasn't expecting this. I am trying to use it on an infinity corrected system which is a little different than most of the systems that it was designed to work with. However, I was under the impression that the viewing tube focuses the light such that it wouldn't be an issue.

One other thing that I noticed is that on my first metallurgical microscope I was able to use a point and shoot camera on the eyepiece with good results (http://uvicrec.blogspot.com/2011/01/metalurgical-microscope-cnc.html). However, the focus distance to the lens is much smaller with this microscope and so it doesn't really work out. For example, I can't zoom in at all to get rid of the eyepiece ring. To be fair though I tried this with a new camera that has a much larger lens and so it might be related to that.

I'll try to provide some reference images but I figure if someone has some initial pointers they might not be needed. Please let me know if you need any more details. Any help is much appreciated and thanks for taking the time to read this!

EDIT:
I very carefully took a series of pictures and found the issue. It turns out that it was actually that when I would step away from the microscope (after releasing any hold on it) to hit the picture key on the laptop the floor shifted enough to cause a focus shift! I thought I remember having difficulty focusing it at all, but I didn't take any picture to prove that. Perhaps something else was mis-aligned that is better now. This issue only showed up with the USB camera since I didn't move for the point and shoot. I My boom stand is somewhat crude, I's suspect it could have something to do with that. In any case, the pictures are now at a usable focus level and to answer my question it looks like no, I don't need to buy another adapter if I don't want to, although it would still be nice to have.

I took some images for comparison, so here's a few in case someone is interested. Objective is Olympus Neo SPlan 20X and WK 10X/20L eyepiece for the point and shoot. I have two illuminators and took pictures with both to see how the image quality compared. Of course, there are a lot of variables here since things got bumped around from me changing equipment and lighting levels, but it gives a rough idea. I think I still need to work on adjusting the lighting some more but its getting better.

Polarizing illuminator, AmScope MD1800:


Polarizing illuminator, Casio EX-FC150:


BF/DF illuminator (brightfield), AmScope MD1800:


BF/DF illuminator (brightfield), Casio EX-FC150:


I also have a darkfield Casio/Amscope image pair. The sample didn't move much between the Amscope pictures so they make a nice comparison.
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Charles Krebs



Joined: 01 Aug 2006
Posts: 5805
Location: Issaquah, WA USA

PostPosted: Mon Sep 26, 2011 1:02 pm    Post subject: Reply with quote

Quote:
I am trying to use it on an infinity corrected system which is a little different than most of the systems that it was designed to work with. However, I was under the impression that the viewing tube focuses the light such that it wouldn't be an issue.
By the time the image reaches the eyepiece (or an eyepiece camera) there is really no difference. The infinity/finite optical differences take place in another location in the optical "train".

Quote:
To be fair though I tried this with a new camera that has a much larger lens and so it might be related to that.
That's likely the problem. The higher the "eyepoint" of the microscope eyepiece the better, but the camera lens is generally the limiting factor. Certain "point-and-shoots" have small lenses (physical size) with modest zoom ratios. The entrance pupil of the lens is relatively close to the front surface. These can often work well. "Point-and-shoots" with larger lenses (often greater zoom ranges as well) tend to result in vignetting since the entrance pupil is too far back "into" the lens.

Thoughts from your added "edit"....
It is always best, if possible, to arrange your set-up so that any "flex" in a component such as a table top (or as you have discovered, floor) can't alter the objective-subject distance AT ALL. Since the cameras you are using impart no vibration when an image is taken (as can be the case with a SLR type camera) you can try to set things up so that, even if the microscope stand and subject stand are different units, they rest on a common, very rigid (non-flexing) base. (I don't always practice what I preach Wink , so when I use an arrangement where the microscope stand and subject stand are different units I am extremely cautious that my arms or hands never contact or rest on the (wooden) table surface. It can be quite amazing how an imperceptible "flex" that occurs on the table surface by, say, resting a hand onto it after focusing, can change the subject to objective distance sufficiently to ruin the microscope focus.
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