Further searching on Raspberry Pi NoIR filters. If DuckDuckGo doesn’t give me good results, why don’t I try Google?
20161222/Google raspberry pi noir camera filters
Indeed, I’m getting some actual results now!
20161222/https://tinkererblog.wordpress.com/2016/03/08/raspberry-pi-noir-with-ir-cut-switch/
Only $3! Much better than my previous $15 find!
20161222/https://www.aliexpress.com/item/CCTV-IP-module-dedicated-IR-CUT/32323006210.html
20161222/https://www.raspberrypi.org/forums/viewtopic.php?f=37&t=96997&p=673996#p673996
UPDATE 2019-11-28: The AliExpress link is no longer valid, the manufacturer discontinued the item.
Oh, so this is the story behind the included blue gel filter that comes with the Raspberry Pi NoIR camera.
20161222/https://publiclab.org/notes/warren/10-29-2013/raspberry-pi-infrared-camera-ships-with-public-lab-s-infragram-filter
Here is an instructable that recommends tweaking the focus on the Raspberry Pi Camera by breaking the glue. Also, it comments that the IR illuminators are probably designed for security cameras, thus taking 12 V rather than 5 V.
20161222/http://www.instructables.com/id/Raspberry-Pi-Birdbox-Camera/step2/Install-the-Pi-NoIR-Camera-Board/
20161222/http://www.instructables.com/id/Raspberry-Pi-Birdbox-Camera/step3/Adjust-the-Focal-Length-of-the-camera/
20161222/http://www.instructables.com/id/Raspberry-Pi-Birdbox-Camera/step4/Attach-the-Infrared-LEDs/
Oh, Thingiverse! Interesting, here. Well, we have a design here that also recommends the use of placing a zoon and manual-focus lens in front of the Raspberry Pi NoIR camera.
20161222/http://www.thingiverse.com/thing:819269
JJJ TODO LINK UPDATE!