Filter Holder Modification. (Darkfield Oblique)

Here you can discuss DIY adaptations to the microscope.
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Roldorf
Posts: 493
Joined: Tue Apr 23, 2019 6:58 pm
Location: Northern Germany

Filter Holder Modification. (Darkfield Oblique)

#1 Post by Roldorf » Sat Aug 17, 2019 11:47 am

I have found that my filter holder is a little difficult to use (to put it mildly). It involves removing the filter holder from underneath the condenser inserting the filter then fiddling it back into the condenser. A solution was required!!
I decided that a swing out filter holder would be the best, so with the materials I had at hand (some 5mm white perspex and a steel rule) I measured the bottom of the condenser and started to cut out some pieces.
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I eventually ended up with this cobbled together holder:-

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The holder swings out so you can change filters, the one you see is a dark-field that I had made when i first got the scope.

Unfortunately the perspex transmitted far too much light and scattered it all over the place.
This was solved with the help of a black permanent marker late this morning which I used to 'paint over' the parts that were transmitting the light, an inelegant but quick and workable solution.
That solved the problem of the scattered light but I wasn't achieving dark-field. A slight mis-measurement meant that the filter holder (what could I have expected using a 500mm steel rule and a three meter tape) didn't quite go far enough in to properly centralize the stop.

Re-drilling the position of the screw for the swivel made the difference, however it went a little 'too' far, necessitating a little to and fro with the new holder.

Great things are discovered by accident. I noticed that this to and fro also gave me oblique illumination and although I don't get dark-field at 40x and 60x, I do get oblique at those objective's.

The next pictures are some quick and 'dirty' images of those results.
No editing other than the added text in Photoshop, just as they came from the camera.

10x
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40x

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60x

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The final mounting looks like this (showing the holder part way slid in).


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Location: Northern Germany

Unknown Brand: Optika SFX 91: Bresser Science Infinity: Canon 4000d
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tgss
Posts: 125
Joined: Wed Jan 25, 2017 3:48 am
Location: Ontario, Canada

Re: Filter Holder Modification. (Darkfield Oblique)

#2 Post by tgss » Sat Aug 17, 2019 5:57 pm

Good job Alan... actually very good job considering the vast array of tooling you had at your disposal :lol: And as you have shown, you never know what little bonus (oblique) fate will bring your way if you only try!
Tom W.

SarahC
Posts: 4
Joined: Tue Apr 07, 2020 11:01 am

Re: Filter Holder Modification. (Darkfield Oblique)

#3 Post by SarahC » Wed Apr 08, 2020 3:59 am

That was a good edit!

I wonder if you could offer your services anywhere online for that kind of mod for the microscope model you have?

Roldorf
Posts: 493
Joined: Tue Apr 23, 2019 6:58 pm
Location: Northern Germany

Re: Filter Holder Modification. (Darkfield Oblique)

#4 Post by Roldorf » Wed Apr 08, 2020 9:47 am

Hi SarahC, thanks for the compliment. I will have to get out the tools again this year and make a nicer filter holder, the first one was just a proof of concept even though I have used it on a regular basis since I made it, it is a little frustrating to have to fiddle with it every time. Some thinner material (black) and a little more care in the construction is called for this time. I will post version II when complete.
If anyone has created a holder it would be nice to see the results here.
Alan
Location: Northern Germany

Unknown Brand: Optika SFX 91: Bresser Science Infinity: Canon 4000d
ImageImage

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