Microscope adapter for Canon Eos 5D

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Gurkan
Posts: 25
Joined: Tue Dec 02, 2014 3:13 pm

Microscope adapter for Canon Eos 5D

Post by Gurkan »

Hi all!
I really need some begnner advise on this topic.
I recently purchased a Labomed CxL trinocular microscope for the purpose of doing some photomicrography.
At the same time I ordered a camera adapter that included a photo eyepiece, this was made by the same manufacturer,
Also a T2 adapter was purchased from another seller.
After som test shoots I was really dissapointed with the result; a lot of chromatic abberation and no real sharpness. I used a flash and turned down the condensor light to avoid motion blur.
Also the focal plane was different from what I could see through the eyepiece and what got captured on the camera sensor.
Does anyone know if there is a better solution with better optics?
I see a ton of different "adapters" out there but I don't really know what to consider.
I should mention that I have done a lot of macro photography and have 30 years experience of "ordinary" still photography.
Thank's in advance!

Pau
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Post by Pau »

Please post detailed pictures of the microscope photoport and the camera adapter (or at least links to the equipment if available)
Pau

Gurkan
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Joined: Tue Dec 02, 2014 3:13 pm

Post by Gurkan »

Thank's Pau!
I will take some shots of my equipment tonight. :D

Gurkan
Posts: 25
Joined: Tue Dec 02, 2014 3:13 pm

Post by Gurkan »

So, here are some snapshots of my stuff:

The Labomed CxL with the photo tube on top.

Image

The Photo tube.

Image

Photo port, 21mm inner diameter.

Image

The "photo eyepiece" that sits inside the tube.

Image

T2 adapter.

Image

Maby the reason the focal planes are offset due to the thick T2 adater?

Pau
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Post by Pau »

Your adapter uses the method known as eyepiece projection, a classic method but often not the best one with a visual type 10X eyepiece, but assuming that the equipment is matched because you bought it together, it must work decently.
First I must confess my lack of direct experience with this model. I'm sure that you've already considered some of the following points.

- The T2 adapter doesn't seem too thick, it is a standard (older T adapters are not parfocalised but T2 must be)
- First test your "photoeyepiece" in one visual tube and viceversa to find if it is any issue with it.
- Your phototube seems regulable in lenght and pretty long. Focus visually and try to parfocalise it changing the phototuble length without refocusing the microscope.
- Try to use your phototube as viewing tube. For photoprojection usually the eyepiece must be placed a bit higher of the parfocal visual position
- Check the position where the photoeyepiece sits inside the tube. Test if there is any alternative position
- About chromatic aberration, if it is much higher than with the visual eyepieces it sounds to me due to mismatch of optical corrections (my second point could allow to determine this). Some microscopes use objectives that need complementary corrections done at the eyepiece, so they need to use compensating eyepieces while others don't. You can easily determine if an eyepiece is compensating or not just looking through it to a well illuminated white field (even outside the microscope): compensating ones show an orangeish halo just at the image circle limit while no compensating ones doesn't show halo or just very slight and blueish. I would not be very surprised if your seller have mixed different kinds of eyepieces.

But some CA at the periphery is to be expected with achormat objectives and can be corrected in post processing. Sample images could allow to study it.

Of course there are other methods to couple the camera to the scope. Search at the forum for afocal.
Pau

Gurkan
Posts: 25
Joined: Tue Dec 02, 2014 3:13 pm

Post by Gurkan »

Tank's a million Pau for taking the time to help me get started!!

I have tried using the photo eyepiece in the "teachers tube" that came along with the microscope and it looks dine there, so I guess the there is nothing wrong with the optic quality.
Looking through the eyepiece against the bright computer screen, I can't see much of the halo you're describing, maby a tiny one if I really put in the effort, or maby it's just my imagination.
Also tried shifting the distance by sliding the tube the amount it can allow for it, no luck though.

Looking through the camera trying to focus is impossible, there is no way to get it sharp using that method. This makes me think that something really weird is going on with the compability of the opticts chain.

I will search for "afocal" to see if I can get any wiser :)

Thank's again!

Pau
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Post by Pau »

Gurkan, have you tried all the posibilities I'd proposed?
It's vey important to test visually (without camera) the eyepiece at the phototube to test both image quality and eyepiece position.

Ask for advice to the seller (but don't expect much)


I agree, the camera optical viewfinder is pretty useless at the microscope at least without a dedicated screen (not so rare in old film days but now inexistent). MUCH better to tether the camera to a computer via USB with the bundled software Canon Utility

Afocal works very well if you can put the eyepiece at the right height (parfocal with the viewing ones) and hold the camera/lens at the adequate position.
Pau

Gurkan
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Joined: Tue Dec 02, 2014 3:13 pm

Post by Gurkan »

Yes, I have tried all the things you suggested.
Wen looking through the eyepiece sitting in the tube, it looks ok.
So, something must be wrong with the distance between the eypiece and the camera sensor. I have tried shifting the tube but that doesn't seem to do the trick.
The dealer doesn't seem to know much about this unfortunately... :(

When looking for an afocal adapter, is there something particular to consider besides the port diameter (21mm in my case)?
/Gurkan

Charles Krebs
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Location: Issaquah, WA USA
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Post by Charles Krebs »

Gurkam,

Pau mentioned earlier:
- Try to use your phototube as viewing tube. For photoprojection usually the eyepiece must be placed a bit higher of the parfocal visual position
My suspicion is that is what you need to play around with. (Not sure why it is so far off if the set-up was provided by the manufacturer).

To be used for projection with the adapter shown, the eyepiece definitely needs to be elevated from the "viewing" height.

Consider the case when the eyepiece is placed in the trinocular tube, and visually (with your eye not the camera) the view through that eyepiece is in focus at the same time as the viewing binocular eyepieces. Let's just call this the "viewing" height or "base position".

If the eyepiece in the trinocular tube is raised about 5mm from the "base position" then the camera sensor needs to be about 125mm away from the eyepiece. If you raise the eyepiece about 10mm from the "base position" projection distance is reduced to about 62.5mm. (You can accomplish this by putting a small plastic collar or some tape around the top of the eyepiece).

Check out this page (Read intro then start at 1-B):
http://www.krebsmicro.com/parfocal/index.html

If you have the original 5D (no live view) you may need to run a few iterations of the procedures 1-B and 2-A. (Live view makes it much easier).
But you should be able to get things "parfocal" pretty quickly.

If you have the original 5D (no live view and thus no EFSC -electronic first shutter curtain) then remember you will need to adopt certain working procedures to minimize the effects of camera shutter vibration.

Gurkan
Posts: 25
Joined: Tue Dec 02, 2014 3:13 pm

Post by Gurkan »

Thank's Charles for the advice!
I will definitily play with this.
The links you provided have some seriously vital info on the matter, thank's a lot for providing them!

This will surely get me going.

Thank's Pau and Charles for being so generous to a neewbie!
/Gurkan

Gurkan
Posts: 25
Joined: Tue Dec 02, 2014 3:13 pm

Post by Gurkan »

Ok, so I have tried lifting the tube and that made it worse.
BUT removing the T2 adapter and positioning the camera by hand, looking through the EOS Utility I can find a perfekt sharpness spot!

So, conclusion; The T2 apdater is to thick.

So, now the next step is to find a T2 adapter that has the right thickness.
/Gurkan

Gurkan
Posts: 25
Joined: Tue Dec 02, 2014 3:13 pm

Post by Gurkan »

Just another small question:

Is 21mm inside diameter of the photo port a common standard size?

/Gurkan

Pau
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Post by Pau »

Hi Gurkan,
I've labeled your photoadapter with names I can guess adequate to understand better the problem, for exemple I'm not 100% sure of what are you referring as T mount adapter (hope this is OK):
Image

Correct me if wrong:
- As I said the T2 mount is a standard and it looks normal, even if it was too thick this could be easily corrected lowering a bit the upper tube
- I think that the photoeyepiece sits inside the adapters just at the lower tube upper end. Is it visually parfocal with the other eyepieces?. If yes, try placing it 5mm higher as Charles suggests. In that case try to focus the camera changing the heigh of the upper tube that clearly seems regulable just unlocking the knob.
- If the photoeyepiece is parfocal and the upper tube removable you have a good base to make an afocal setup

I don't think that 21mm is a standard diameter for photoports, usually they have standard eyepiece diameters (23mm or 30mm) or are clearly wider.
Pau

Gurkan
Posts: 25
Joined: Tue Dec 02, 2014 3:13 pm

Post by Gurkan »

Thank's for the illustration Pau!

Unfortunately the upper tube is not able to move downwards, there is a stop inside that prevents this.

The photo eyepiece is not parfocal with the viewing eyepieces, the focal plane is a bit "above".
The only conclusion I can make from this is that the image is projected just in front of the camera sensor. I have now tried to lift the eyepiece about 5mm and now I can actually get a pretty sharp picture, quite a lot of CA and not parfocal yet though.
Need to figure out the right distance.
I also found a T2 adapter that only builds 1 mm in height, I think that is a better choice than lifting the eyepiece.

Now I also need to figure out why the live view is so much darker than the actual exposure... :)

To bad that the photo ports isn't standardized. Just to be clear, it's the hole that goes into the microscope I mean, not where the photo eyepiece sits.

/Gurkan

Charles Krebs
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Joined: Tue Aug 01, 2006 8:02 pm
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Post by Charles Krebs »

Gurkan,

I really doubt the thickness of the T-mount has anything to do with your problem.
The photo eyepiece is not parfocal with the viewing eyepieces, the focal plane is a bit "above".
By this do you mean that the eyepiece needs to be "raised up" or "lowered" (even if it is not possible to do so with your adapter) to get it to focus simultaneously with the viewing eyepieces? It would be very helpful to know it it is possible at all to get the trinocular eyepiece to be visually in focus (by eye... not camera) at the same time as the viewing eyepieces.

To use the eyepiece you showed above as a projection lens, it is necessary to have it positioned higher (probably in the range of 5-10mm) than a "base" viewing location. (To use the afocal method it is necessary to get that eyepiece in a position in the trinocular tube so that it is in focus (by eye) simultaneously with the viewing eyepiece).

To use an eyepiece as a projective lens it is a bit of a "delicate dance" between eyepiece elevation and camera height. When the eyepiece height changes even a little, the camera height needs to be adjusted. The higher the eyepiece is elevated from the "base" viewing position, the lower the magnification into the camera body, and the closer the camera body must be to the eyepiece. Conversely, the less the eyepiece is elevated the higher the magnification and the farther away the camera must be positioned. It is very possible to position the eyepiece so that needed camera adjustment exceeds the what is possible in the adapter.

If I understand your earlier message it sounds like you had the adjustable tube (upper tube) as low (short) as possible, but it was necessary to remove the T-mount and position the camera even closer to get it in focus. Is this correct? If so, then it sounds like the eyepiece is positioned slightly too high. (However... if this is the case, and the eyepiece is positioned as low as the adapter allows, then you have a problem).

Otherwise it just takes a little adjusting of the eyepiece height followed by the appropriate adjustment of the camera height. As I said, it may take a few iterations to get it right.

The ideal positioning of eyepiece height and camera position will provide a magnification into the camera that is close to the "field" you see through the viewing eyepieces (that is... not cropped in too tightly into the field observed, but a magnification not so low that you get darkened, vignetted corners). If your set-up (adapter) has adequate adjustment range of eyepiece height and also camera height you can achieve this goal.
I also found a T2 adapter that only builds 1 mm in height, I think that is a better choice than lifting the eyepiece.
Keep in mind that the eyepiece needs to raised in order to make it project a real image into the camera body. But the actual "best" amount of elevation is the one that will provide the best magnification for the camera body used. For example, you would likely want higher magnification into a full frame (24x36mm sensor) body than you would want with a smaller sensor. So with the full frame body the eyepiece would be raised slightly less than with an APS sized (or smaller) sensor. (If viewing with 10X eyepieces most people typically like about a 2.5X magnification into a full-frame body and about a 1.6X magnification into an APS body).

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