Slider for Motic BA310

[smollerthings]

Hi All,

So I bought a used Motic BA310. I wanted an ergonomic trinocular scope. And it is pretty nice, very comfortable to use.
The condenser doesn't have a swing filter holder. There is a slot in the In the middle of the condenser for sliders. Mine only came in with a dummy slider I taped to be able to hold my own filters, which is not ideal:


The Motic sliders are pretty pricey for what they are. See the darkfield slider.

https://moticeurope.com/en/darkfield-slider-4x-40x.html

Furthermore, I want to be able to put other filters of my own creation in there. Anyone has the measurements of the official slider they can share? I would like to model them and 3D print. Something like this:

Screenshot 2021-11-03 173923.png (104.03 KiB) Viewed 6291 times

Thanks!

[BramHuntingNematodes]

Ain't you got the dummy slider? Apply the verniers to it

[dtsh]

I'm sure you probably already know, but typical filters are 32mm in diameter and the thickest ones I have are 2.1mm thick

[smollerthings]

Ain't you got the dummy slider? Apply the verniers to it

I was wondering if the dummy is the same as the real ones (size of the hole, tolerance on the sides)

I'm sure you probably already know, but typical filters are 32mm in diameter and the thickest ones I have are 2.1mm thick

.

The dummy's hole is only 27 mm diameter

[Saul]

https://www.ebay.com/itm/265148287832

[david_b]

I have the Motic slider in your link.
I may be doing something wrong, but I'm not that impressed. When the slider 'clicks' into place, the darkfield effect is barely noticeable. I have to move the slider out of its 'correct' position to see any effect, and then the contrast is not what I hoped for.
However, as this is my first experiment with darkfield I have nothing to compare it to and could well be user error.

[smollerthings]

https://www.ebay.com/itm/265148287832

Thanks Saul, I have a 3D printer so I need to make use of it to amortize the sunk cost

I may be doing something wrong, but I'm not that impressed. When the slider 'clicks' into place, the darkfield effect is barely noticeable. I have to move the slider out of its 'correct' position to see any effect, and then the contrast is not what I hoped for.

What do you mean by the effect is barely noticeable? Do you mean the background is not dark but grey? At what magnification do you work at? Those condensers will do dark field until 20x well, 40x sometimes and won't do anything above. Have you centered your condenser?

[david_b]

What do you mean by the effect is barely noticeable? Do you mean the background is not dark but grey? At what magnification do you work at? Those condensers will do dark field until 20x well, 40x sometimes and won't do anything above. Have you centered your condenser?

I mean that when the slider is clicked in to its proper position I can't see anything at all with 10x objective - completely dark even with the brightness turned up to max.
The condenser is centred and I am getting a good brightfield view.
When I move the slider out of its correct position I see a kind of oblique lighting effect but not darkfield.
The Motic slider has two adjustment screws and playing with these doesn't help.
The slider is well made and would be worth the money if. only I could get it to work!

[Alexander]

I mean that when the slider is clicked in to its proper position I can't see anything at all with 10x objective - completely dark even with the brightness turned up to max.
The condenser is centred and I am getting a good brightfield view.
When I move the slider out of its correct position I see a kind of oblique lighting effect but not darkfield.
The Motic slider has two adjustment screws and playing with these doesn't help.
The slider is well made and would be worth the money if. only I could get it to work!

Darkfield is very sensible for condenser position. Did you try to move the condenser up and down using its focus dial?

[smollerthings]

Yes, check your condenser is at top position. You can also take out the eye piece and look into the tube to see what is happening at the condenser filter level.

[david_b]

Thanks both,
The condenser was set up for kohler illumination but I have raised the condenser to the top (it was almost at the top anyway).
The video starts with the slider at its brightfield stop, then I move the slider to the darkfield position, when the image is completely lost (black) then graually move it around and then back out to brightfield (sorry it's very boring!)
The slider says it suits 10-40x and this is 10x.
Thanks again for your help

https://youtu.be/nTpQtaigzRQ

[smollerthings]

Hi David,

So this is my understanding: Darkfield relies on light that hits the objects not from below but from the sides. So it doesn't really work for prepared slides that are perfectly flat. Things need to be 3 dimensional (I use it for pond life).

Also, you need to fully open the condenser's iris.

[david_b]

Hi David,

So this is my understanding: Darkfield relies on light that hits the objects not from below but from the sides. So it doesn't really work for prepared slides that are perfectly flat. Things need to be 3 dimensional (I use it for pond life).

Also, you need to fully open the condenser's iris.

Ok I think I have it working better now, I will experiment some more, thanks again for the tips.
I realise I forgot to answer your original question - the diameter of the apertures in the Motic holder are smaller than the blank: 22mm
Do you need any other measurements?

[smollerthings]

You are welcome and thanks for the info, what is the height of the slider? The center hole is only 22mm? Interesting...

[david_b]

You are welcome and thanks for the info, what is the height of the slider? The center hole is only 22mm? Interesting...

Hope this helps...

[Alexander]

Thanks both,
The condenser was set up for kohler illumination but I have raised the condenser to the top (it was almost at the top anyway).
The video starts with the slider at its brightfield stop, then I move the slider to the darkfield position, when the image is completely lost (black) then graually move it around and then back out to brightfield (sorry it's very boring!)
The slider says it suits 10-40x and this is 10x.
Thanks again for your help

https://youtu.be/nTpQtaigzRQ

Your video clearly shows that the annulus is de-centered. Darkness comes from left.

[smollerthings]

Hope this helps...

Awesome, may I bother you with the inner and outer diameters of the darkfield stop light hole?

[david_b]

Awesome, may I bother you with the inner and outer diameters of the darkfield stop light hole?

22mm & 28mm. The stop is 26.5mm (there's a very fine piece of wire holding it in place)

I'm getting more of a darkfield effect now but I'm seeing an unwanted circular patch of yellow colour. The condenser is at the top and moving it down makes the effect worse (larger & darker). I tried a different stop but the effect is the same.

edit: I tried some 3D printed darkfield and oblique stops I bought from the US ages ago and never used and no yellow patch.

[smollerthings]

Thanks, I am a little bit confused so I made a drawing:

DF.jpg (45.13 KiB) Viewed 6040 times

If I understand well, r1=11mm, I couldn't figure out r2 r3 and r4 from your previous message.

I also have the central orange light issue but it goes away when I up the condenser to the max. You opened the condenser iris to the max right?

Strange that the 3d printed filters work better than the official one!!!

[david_b]

Thanks, I am a little bit confused so I made a drawing:
DF.jpg
If I understand well, r1=11mm, I couldn't figure out r2 r3 and r4 from your previous message.

I also have the central orange light issue but it goes away when I up the condenser to the max. You opened the condenser iris to the max right?

Strange that the 3d printed filters work better than the official one!!!

Sorry for the confusion.

For the slider:
Inner diameter = 22mm (your r1 = 11mm)
Outer diameter = 28mm

For the patch:
r2 = 9mm
r3 = 11mm
r4 = 13.25mm

There is a bevel on the patch which engages the fine wire spring so the patch is held under tension against the 2x adjustment screws. Thickness of the Motic patch is 4mm.





Here are images showing the yellow cast when using the Motic patch, vs. the 3D printed patch. I can move the yellow area around by manipulating the adjustment screws but can't get rid of it. Condenser is wide open and all the way to the top (moving the condenser down or closing the iris makes things worse).

I remember now why I gave up with darkfield!

[smollerthings]

Thanks a ton.

Does this yellow patch occur on all magnifications? Do you get proper darkfield for 40x?

My intuition is that they made r2 large enough for the 40x to work and that it is too big for proper lighting for the lower magnifications. Maybe the solution is to use a lower r2 for lower magnification and the Motic one for higher magnifications? I am speculating here...