Public Lab Research note


This is part of a series on community-microscope-tests.

Community Microscope Initial Evaluation

by MaggPi |

Read more: publiclab.org/n/16369


This post is an initial evaluation of the community microscope (with USB webcam- reverse lens).

See: https://publiclab.org/notes/bronwen/05-07-2018/community-microscope-assembly-instructions

https://publiclab.org/notes/bronwen/05-07-2018/microscope-webcam-conversion

Components: -Camera: USB 2.0 webcam with reverse lens -Image: Microscope Camera Calibration Slide (Minimum division: 0.01mm (10 um)) -Computer: Raspberry Pi -Software: fswebcam for picture with matplotlib for annotation

My resolution estimate (for the USB 2.0 webcam and reverse lens) is approximately 100 pixels for every 50 microns or 2 pixels /micron. Please double check and recommend alternate ways to state/measure resolution!!

Note that this is a first review and it's possible that different techniques or materials may provide different results.

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some technical details on the usb camera

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calibration webcam raspberry-pi camera gsoc microscope pi-camera resolution soc gsoc-2018 soc-2018 community-microscope pi-microscope

series:community-microscope-tests


8 Comments

Hi, @MaggPi - i loved your longer report-in - want to upload all of that analysis here too? Thank you so much, really good improvements you've suggested in there!

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Or in a separate note, either way?

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@warren, Post is updated with complete eval. Note that this is a first review and it's possible that different techniques or materials may provide different results.


This is fantastic. Thanks so much -- how is your project going, by the way?

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Good so far. @warren Working on โ€˜cycleโ€™ programs that show different processing effects. Believe that understanding processing modes could be useful for both spectral imaging and microscope applications. This link, https://youtu.be/XEn5Nd_W7rA , shows a Raspberry Pi V2 visible camera (with picamera software) processing effects demo. Some quality is washed out by the time it is uploaded to youtube but most effects are still visible. The demo also only changes one image setting at a time, I assume some effects would be more visible if multiple settings were changed.

The video demonstrates brightness, contrast, AWB (Automatic White Balance), Image effects and exposure processing modes. Image is displayed at default settings between modes for comparison. Over 40 different settings are displayed and the video length is 5:11 minutes. More info: https://projects.raspberrypi.org/en/projects/getting-started-with-picamera

The camera configuration uses an image from another posting ( https://publiclab.org/notes/MaggPi/05-11-2018/raspberry-pi-noir-close-up-imaging ) but added a resolution chart to compare with

@amirberagain, https://publiclab.org/notes/amirberAgain/05-23-2018/use-of-a-5-bill-for-microscope-calibration

The hardest part was learning how to handle Raspberry Piโ€™s video format h264. I tried converting the video to MP4 and AVI, but the youtube resolution was bad. Eventually I was able to upload h264 and got HD!

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Oh wow this is awesome. Deserves its own post! I love your setup and it's a great video!


Also love your microscope improvement suggestions! Especially:

  • moving bolts far out to edges
  • washcloth! Amazing idea - simple and affordable!
  • seeing the 8 megapixel noted on the camera -- haha not quite ๐Ÿ˜„

Your onion and leaf photos are great! Very good detail on the leaf cells. Did you stain them at all?

I'm hoping to photograph some chlorophyll at some point. Like in the opening shots of the Infragram video - (which i found online) https://www.kickstarter.com/projects/publiclab/infragram-the-infrared-photography-project

Anyways i'd also love to see a comparison between the webcam and the Raspberry Pi cameras. Great work, again!

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I don't know how did I miss this great post! A few pointers which are worthwhile noting: * whenever you feel like you are missing something mechanical just look for it in Thingiverse! for example, see https://www.thingiverse.com/tag:Microscope/ * For anything that has to do with color, I like the CameraTrax 24 color card (14$ on Amazon)https://www.amazon.com/CameraTrax-24ColorCard-2x3-White-Balance-Guidebook/dp/B004QXU8VI * In your leaf images the blue channel looked like it has some vignetting (the center is brighter than the edges).

Looking forward to see much more!


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