DIY DF Filter

Do you have any microscopy questions, which you are afraid to ask? This is your place.
Post Reply
Message
Author
Metrophage
Posts: 22
Joined: Sat Sep 03, 2016 4:20 pm

DIY DF Filter

#1 Post by Metrophage » Thu Sep 22, 2016 7:46 am

Can anyone give me some tips about making a simple Darkfield filter. I tried following the instructions from http://www.microbehunter.com/how-to-mak ... lters/here and [url=https://www.youtube.com/watch?v=taKfysZ-LNY]. I used a large zip lock bag and cut them into circles the size of the blue filter the scope came with and stacked about a dozen cuts with a black circle drawn in the middle with a sharpie. Images attached.

Any advice for my next attempt? Different size patch stop, different material, is the filter even in the right place?
Attachments
IMG_1425.png
IMG_1425.png (312.04 KiB) Viewed 1891 times
IMG_1424.png
IMG_1424.png (297.48 KiB) Viewed 1891 times
IMG_1421.png
IMG_1421.png (310.57 KiB) Viewed 1891 times

User avatar
Oliver
Posts: 187
Joined: Sat Oct 11, 2014 12:57 pm
Location: Austria
Contact:

Re: DIY DF Filter

#2 Post by Oliver » Thu Sep 22, 2016 8:00 am

Hello,

The following link has a table (towards middle of article) with recommended circle size for the different objectives:
http://www.olympusmicro.com/primer/tech ... field.html

recommendations:
1. It is much easier to print the circles on overhead foil as it is much stiffer. You can also change the color for Rheinberg illumination if you have a color printer.
2. Cut out a black disk of cardboard and glue it into the center of a round piece of plastic from a clear CD cover or plastic petri dish or clear plastic packaging tray for fruits (they are all stiff). Careful: filter might heat up in the microscope light, so check if the plastic is temperature stable. Alternatively you can use a glass cutter to cut a microscope slide and then stick black cardboard into its center. The slide does not have to fill the whole filter holder, it only serves as a holder for the black cardboard.
3. Do NOT use reflective material (aluminium foil etc) as your DF filter, even if it blocks light the best. The reflective material acts as a mirror and will throw back the light to the lamp, which may overheat. You can paint the foil black or sandwich it between black paper, if the cardboard alone still allows some light to go through, but do not place a shiny reflective metal foil into the filter. Less of a problem if you have LEDs, as the light is cold.

Oliver.
Image Oliver Kim - http://www.microbehunter.com - Microscopes: Olympus CH40 - Olympus CH-A - Breukhoven BMS student microscope - Euromex stereo - uSCOPE MXII

User avatar
75RR
Posts: 7501
Joined: Sun Oct 12, 2014 2:34 am
Location: Estepona, Spain

Re: DIY DF Filter

#3 Post by 75RR » Thu Sep 22, 2016 11:00 am

Here is a link to some templates: viewtopic.php?f=12&t=134
Zeiss Standard WL (somewhat fashion challenged) & Wild M8
Olympus E-P2 (Micro Four Thirds Camera)

Metrophage
Posts: 22
Joined: Sat Sep 03, 2016 4:20 pm

Re: DIY DF Filter

#4 Post by Metrophage » Thu Sep 22, 2016 11:49 am

Great! Thanks a lot guys. I'll get those printed and give it a try.

Metrophage
Posts: 22
Joined: Sat Sep 03, 2016 4:20 pm

Re: DIY DF Filter

#5 Post by Metrophage » Sat Sep 24, 2016 3:45 pm

Just a quick follow up and another question. Firstly, huge thank you to Oliver and especially 75RR for those templates. I got them printed at an office supply shop and after a bit of tweaking with condenser heights and various sizes I'm getting *amazing* results. DF has opened up new and hugely fascinating viewing experience for me. It's particularly good at making out cilia and how it effects particulates during movement and feeding.

My question is about the gradient strips on the templates. What is their purpose and how do I use them?


Thanks again guys.

User avatar
Oliver
Posts: 187
Joined: Sat Oct 11, 2014 12:57 pm
Location: Austria
Contact:

Re: DIY DF Filter

#6 Post by Oliver » Sat Sep 24, 2016 5:04 pm

about the gradient strips: click the link above (from 75RR) where you downloaded the templates. In the thread further down, there are links that explain their use.
Oliver
Image Oliver Kim - http://www.microbehunter.com - Microscopes: Olympus CH40 - Olympus CH-A - Breukhoven BMS student microscope - Euromex stereo - uSCOPE MXII

Post Reply