Image shifting while focusing on Stereoscope Olympus SZH10

[NicoVB]

Hi all,

I have a problem while focusing on a Stereoscope Oly SHZ10.
My photo camera OMD E M 1 is connected with the L-adapter and NKF 2.5 photo objective.
I use my camera on tethered live view mode on my pc in Olympus Capture.


I encounter following problems:
1. I think i lack an enormous amount of sharpness, when i look throught the eyepieces, the image is razor sharp, but on my camera i lack a lot. (I think...)

Here are a few examples, no stack, just one shot straight from the camera, without post processing.





2. When i use the fine focus, the sample moves while focussing.
Same here, it does not happen when i look through the eyepieces, but it is very noticeable in the camera.

Here is little video to see the effect, i just turn the focus on the scope, nothing else. What causes this?

https://youtu.be/qpHqcNrGZaY

Can you help me improve my pictures?

[Charles Krebs]

Question #2 first. This is normal on a stereo scope. The camera sees one side of the stereo view. Look through the scope viewing binoculars and close one eye. You will find that as you refocus, the image will shift just as you see in your camera. This is why some are willing to forego the stereo view and use a "macroscope" which provides a straight shot through the optics to the camera.

The answer to your first question is a little more involved. I'll give what I believe to be the "issue" and you might not like the answer. (I could be wrong here but I've seen it quite a few times before, and faced it myself with my Nikon SMZ800.)

Usually, stereo scopes strike a compromise between DOF, long working distances and resolution. They tend to go in the direction of greater DOF and working distances because those are the features needed most for their intended jobs. As a result you will find that the numerical apertures (NA) are typical modest to small for the magnifications provided. The SZH10 is a great stereo, but typical of the breed, the NA is quite modest. You don't say what objective you have, but, for example, the 1X Plan Apo has a NA of 0.087. (And in a stereo that maximum NA is usually only realized in the camera when the scope is set to maximum magnification. At lower magnification setting the actual NA in use is considerably lower!)

So with that scope and the 1X, the magnifications sent to the trinocular tube will be from 0.7X to 7X. You then "feed" it through the 2.5X NFK into the camera. So the camera would see magnifications from 1.75X to 17.5X. I have no idea what the "used" NA is at the lower magnifications (it will be less than the full 0.087), but at 17.5X (in camera) the used NA would be 0.087. Now consider the NA of a typical microscope objective in that range... a basic 10X would typically be 0.25-0.28, a basic 20X would typically be about 0.40. So the resolution would be less than 1/3 that of a typical microscope objective. (But you have hugely more working distance and hugely more DOF when viewing... there is that "compromise").

To make things even tougher, the 2.5X is really made to be used with a 24x36mm sensor (35mm or "full-frame). Using it with a MFT sized sensor magnifies the final image even more than it should be.

Bottom line... most stereos have limited maximum NAs, which limit their resolution and useful magnification (especially for photography). You have no real way of knowing what the actual "in use" NA is except at a full magnification, where it is likely at the lens' max NA. Despite this, if you want to achieve the best results possible you should try to keep any additional magnification into the camera as low as possible. This is much easier said than done, since most of the optics manufacturers made were either for larger film sizes (35mm and up) or for smaller video (and now digital) formats. Users of APS-C and MFT often have a tough time getting an appropriate magnification into the camera.

[NicoVB]

Charles, great explanation on what causes all this.
I have indeed the DF Planapo 1x on it.

Your explanation really made it clear what happens and why i don't get the expected results. I really miss experience and knowledge, but i'll get there , every small step at a time.

So this is a great examination scope, but the photography options are limited, now i see. To bad, because i love the working space.
But that's ok, i have some more scopes to play with .

I'll try to experiment a bit with a Fujifilm 3d camera on the eyepieces, could give some unexpected results.

[Pau]

Of course I 100% agree with all that Charles says, but would like to add two more (secondary) points:

- In principle the NFK photoeyepieces are to be used with Olympus microscopes like the BH2 whose objectives need image corrections at the eyepiece while most stereos (not totally sure about yours) don't need these corrections, so they will induce aberrations in the opposite sense. Maybe they are not visible with a small sensor camera but with a bigger sensor will be.

- Directional light like the used in many stereos doesn't allow to use the full objective aperture, even more with highly reflective subjects. Evenly diffused illumination could improve the image to some extent.

For m4/3 you could look for a 1X C mount adapter if available (avoid cheap chinese ones) to capture a wider field. Image sharpness (not actual resolution) will improve just because the field will be wider and it will not be so highly affected by empty magnification.

[Alan Wood]

Pau

Olympus specifies the NFK photo eyepieces for the SZH (and for the cheaper stereos like the SZ4045).

I do not know if the optics in these stereomicroscopes are designed to be used with compensating photo eyepieces, or if Olympus just didn't bother to make non-compensating ones.

The PE photo eyepieces for the BX microscopes are non-compensating, but they cannot be used in the stereomicroscopes because their diameter is too large.

Alan Wood

[Pau]

Alan, thanks for pointing it, Charles did the same by PM.

This is why I said ..."while most stereos (not totally sure about yours) don't need these corrections" without having the model manual at hand

Is it the same situation with other Olympus stereos?

[Alan Wood]

Pau

I have never seen a statement from Olympus about the eyepiece requirements of their stereomicroscopes.

At the Quekett Microscopical Club, we sometimes use Olympus eyepieces in other stereomicroscopes with no problems, so I suspect that the viewing eyepieces are non-compensating.

There are lenses in the camera adapters, so possibly these un-correct the image so that the NFK photo eyepieces can correct it.

Photographs taken through my SZ4045 with an NFK 2.5x photo eyepiece are not great, but they don't show colour fringes.

Alan Wood

[Pau]

There are lenses in the camera adapters, so possibly these un-correct the image so that the NFK photo eyepieces can correct it.

Interesting (and weird) situation Thanks for posting the info.

You can determine if an eyepiece is compensating or not just looking at the image field limit with a white background: compensating type show a more or less prominent orange-yellow halo while non compensating do not show halo or just slightly blue

From: Davidson and Abramowitz. OPTICAL MICROSCOPY.
Simple eyepieces such as the Ramsden and Huygenian (and their
more highly corrected counterparts) will appear to have a
blue ring around the edge of the eyepiece diaphragm when
viewed through the microscope or held up to a light
source. In contrast, more highly corrected compensating
eyepieces with have a yellow-red-orange ring around the
diaphragm under the same circumstances. Modern noncompensating
eyepieces are fully corrected and show no
color. Most of the modern microscopes have all
corrections done in the objectives themselves or have a
final correction in the tube lens. Such microscopes do
not need compensating eyepieces.

[NicoVB]

I used the same NFK 2.5x on my BHB scope now, and i receive much better results!!
Like you said, a stereoscope is a big difference.




I used a SI Apo40/1.00F.
I know the lightning and all is not good, just testing the NFK...