MicrobeHunter.com Microscopy Forum

Some pictures of my self made filter slides. The first one shows the polarization filter, consisting of one rectangular slide fitting ito the slit under the eyepiece block and a round one (piece of polarizing foil glued over a hole, drilled in a petri dish lid), fitting nicely over the field lens and can be rotated. Also on the first photograph a PVC filter holder for dark field and oblique illumination pads (pads ordered from ebay). Second photograph shows this filter holder glued to the condenser with two sided tape.

A very nice solution Jan!

This is the filter-holder for the Leitz, they occasionally come up on e-bay, holds 2 'lollipop' filters.
Handy little thing, fixes onto condenser's bottom.

John B.

Thank you for the image. Maybe I run into one on ebay, now that I know what I should be looking for.

End of the day the 3D-printed dark field filters arrived and I put one in my filter slide. Beautiful sight, but after several minutes I saw smoke coming out of the filter slide and the plastic filter was melting. Didn't know the temperature under the condensor would get that high. Maybe I do something wrong.

Are the horizontal dark/light patters in the image below interference lines? Sometimes I can see the light shimmering. What could be the cause and (how) can it be avoided?

Is there a LED light in the microscope or perhaps in the room?

I'm getting real bad horizontal banding issues in my images taken with the eyepiece camera, if there is much clear background in the image.

In order to use this little gadget effectively, I will need to use smooth direct current to power the illumination lamp in the microscope.

Is there a LED light in the microscope or perhaps in the room?

No, there's neither a LED light in the room nor in the lamp house of the microscope. I think it has something to do with the camera, because I don't see it when observing by eye.

In order to use this little gadget effectively, I will need to use smooth direct current to power the illumination lamp in the microscope.

Will that solve the problem?

janvangastel wrote:

Is there a LED light in the microscope or perhaps in the room?

No, there's neither a LED light in the room nor in the lamp house of the microscope. I think it has something to do with the camera, because I don't see it when observing by eye.

In order to use this little gadget effectively, I will need to use smooth direct current to power the illumination lamp in the microscope.

Will that solve the problem?

Yes, it will solve the banding problem. I tested it by using the eyepiece camera to take a picture through an antique monocular microscope using an incandescent lamp on AC house current for light source. The banding was even worse than images taken through the AO 4 Series microscope.

Then used a battery LED lantern to provide a temporary light source for the monocular microscope. No banding at all. The batteries provide smooth DC, of course.

I have equipment on hand to run the 4 Series microscope on smooth DC current. It's a brute force, crude, 19th century solution, but those are what I like. I will post the details when I make the conversion so everyone here can have a good laugh.

This is a problem I see also, even with my Schott electronic 1500 KL fiber-optic light-source which runs a 150W halogen bulb on 14.5V I think.
With my Orthoplan and it's 50-70W halogen bulb turned to about 10V it doesn't occur at all, even with the eyepiece USB camera.

The rolling shutter of CMOS cameras is the source of the problem as it exposes the sensor in a 'rolling' vertical strip, not all-at-once (so-called global shutter)...

There's a HUGE amount re this problem online, just search for something like 'barring on CMOS camera images'.

I use a variable ND filter with my Orthoplan, allowing the bulb to be at max and using the filter to control light intensity - works like a charm and no colour shifting either.

My advice would be to get one of these, as mentioned in one of my earlier posts,



It's placed above the light-port and works beautifully, allowing your bulb to be set at nearly full, where it shouldn't cause barring....

This is the one I use as seen in the image above... John B.

As an aside, I had trouble understanding rolling shutters until I watched this excellent video:

https://www.youtube.com/watch?v=dNVtMmLlnoE

PS: I'm a Smarter Every Day fan, this guy has a ton a great stuff.

Thanks a lot. I have read some information and seen some video's today about the rolling shutter and I understand what's going on. I am going to me such a filter.

HiJ Jan, there's a very fortunate bonus with the variable filter that will delight you I think, as it did me!

Used to control illumination level of course it's perfect - but, when used for polarisation, yes, with the top polarised (linear) filter in the slide-in-out holder above the Orthoplan's nosepiece not only is the illumination able to be set, but if you turn the whole variable filter, i.e. both of it's rotating layers as one, still set for your preferred illumination level, you will find that polarisation will be able to be used, right to extinction (with a totally dark background and only the polarised material 'shining' through)!!

If you need brighter polarisation in terms of how brightly the polarised material, say crystals within plant tissue for example, 'shines' just turn the filter (one layer only) as for adjusting brightness without polarisation - the whole thing brightens, but as you again turn the whole assembly to bring back your polarisation level of extinction, you'll find that the shining polarised material is brighter/darker!

I use this variable filter exclusively now on my Orthoplan, both for illumination intensity AND for polarisation when I pull-out the holder to move the polarised filter (analyser) over the nosepiece.

This is the piece of linear polarising sheet cut to make an analyser for the Orthoplan's filter-holder - that slides in above the nosepiece. Into the slot it goes, In normal brightfield use the holder is pushed in, For use as a polariser-analyser the holder is pulled out to move the filter into place, Here's a quick video of use of the variable ND filter to control light intensity on my Orthoplan, the lamp is left on full and needs no adjustment. Also in the video I show use of the ND filter as the bottom filter (i.e. that over the light-port which is turned for extinction adjustment) for polarisation - also it still works for intensity - turn one of the two filter's layers for intensity, turn the whole thing for degree of extinction.... A very handy thing indeed, costing me about £9 from e-bay a couple of years back now.
Remember - linear filters must be used.



John B.