Not Macro but interesting

[mawyatt]

Not Macro but cool anyway!!

https://www.dpreview.com/news/5581907920/watch-a-mirror-led-razor-and-a-camera-make-the-invisible-visible

Best,

Mike

[ChrisR]

It is.
I'm not clear right now, why it needs to be a curved mirror.
(He states it's parabolic, then spherical.)
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Chris R

[rjlittlefield]

I believe the curved mirror is used to produced collimated illumination. See the discussion at https://en.wikipedia.org/wiki/Schlieren_photography .

--Rik

[ChrisR]

Hmm, I see, I think, thanks. Something like the mirror in a flight simulator :
https://en.wikipedia.org/wiki/Collimated_light#Collimated_displays_in_flight_simulators

I wonder if a large (magnifier)fresnel lens over a plane mirror would work, instead of the concave mirror.
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Chris R

[rjlittlefield]

Certainly seems like that could be made to work, though I strongly suspect the rings of the Fresnel lens would be painfully obvious.

By the way, there's a bunch of YouTube videos about Schlieren photography. See https://www.youtube.com/watch?v=IZ0bYi9UFv8 for a good how-to-do-it video.

--Rik