Pollen hunter project–III- Investigating pollen size with a scale

I was displaying my pollen slides to kids around my place and one of them, all of 5 years, who measures everything with a scale asked , “How small are they?”. I mumbled my way through deftly, ignoring the question but it rang for a while in my head after. Measurement is an integral part of science and this was one aspect that I had conveniently ignored through this project. Could I create a digital scale that I could use over and over. I pulled out a stage micrometer that I had bought some time back. These cost about $11 on amazon, and their smallest division is 0.01 mm or 10 microns and they have a 100 divisions in total (Figure 1A). I have a Google phone that I measured has 4x digital zoom (Figure 1B).


 scale-unmag  scale-comp

Figure 1A and 1B

For all my pollen pictures, I mostly use the 140x optical zoom and the 4x digital zoom, or on rare occasions the 400x optical zoom with a 4x digital zoom.  This mean that if I create a template picture of the stage micrometer at these optical and digital magnifications, I shall have a scale that I can superimpose (using google picasa) and get an approximate size of the pollen or any object of study. First I needed to have pictures of the slide micrometer.

Optical magnification No Digital zoom 4x Digital zoom
140x 140x-nozoom 140x-4x
400x  400x-umag  400x-4x

As long as I use the same digital and optical zoom on my sample and capture pictures with my Google phone, I can superimpose any picture with these scales using google picasa and measure distances knowing that each division is 10 microns.  Wow this is exciting. I cant wait to wake up and tell the 5 year old that I know the size of the pollen. A few measurements of the different objects I have seen with the foldscope follow. If you see a logical error in my reasoning, let me know.

Object and calculated measurement Image
Spruce pollen – 50 microns spruce-size
Magnolia pollen – 40 microns magnolia-scale
Black locust pollen- 30 microns blacklocust-scale
Trichomes 120-170 microns tric-scale
Male spider mite – ~110 microns mitescale
Honey-suckle pollen at 400x- 50 microns honey-scale


5 Comments Add yours

  1. Manu Prakash says:

    @laksiyer: This is a breakthrough. Specially with all the inkjet printers around – we could calibrate with something I can print as the smallest dot on a transparency.. I think I will try the printing – but also see if I can overlay them in real time; so the digital zoom is integrated.

    Such a wonderful post. Thanks for inspiring. Everyone everyday 🙂


  2. Niramay Gogate says:

    I was thinking that if we could overlap the scale physically with our slide, it would be better. It would be helpful even for videos

  3. Manu Prakash says:

    @Nirmay: I will try that. But it has to be in the same plane as the sample (so upside down) since we don’t have a conjugate plane to put objects in (like a classical compound setup). @Laksiyer inspired me to make it work..


  4. laksiyer says:

    @Manu: Adding a scale to the foldscope will be super. I hope the Transparency printing goes well. Keep us posted.

  5. Saad Bhamla says:

    @Laks: The following statement is on-point with my experience…

    “I was displaying my pollen slides to kids around my place and one of them, all of 5 years, who measures everything with a scale asked , “How small are they?”. ”

    I had the same experience two days ago and had been thinking on the back-burner about the size. You’re post clarified everything up very nicely!!

    Thank you!

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