I made a Schlieren setup with my telescope, camera and aluminium foil

[soundwave]

Hi all!
Long time since I've posted on the forums. Looks like an upgraded system. Nice

I just wanted to share something that I think is extremely awesome! 
I didn't know exactly where to post this... I thought maybe in science, but it's also photography... I dunno.

First of all... What is Schlieren Photography?
From Wikipedia: "Schlieren photography is a visual process that is used to photograph the flow of fluids of varying density"... In this case -- Air.

I watched this great tutorial on YouTube on how to make a homemade Schlieren setup, and it's pretty simple.
Unlike the tutorial, which uses a razor blade and a circuit-board for the LED, I just used a bit of aluminium foil and a phone's LED. 

This is what it looks like professionally: 

 

This is what it looks like with my setup - It's me lighting a lighter.
My full video (better quality) can be seen here: https://www.youtube.com/watch?v=6BulKfpf35A

The dark circle in middle is, of course, the secondary mirror's holder.
I placed my hand near the opening of the main tube.

 

Quick setup explanation and simplifications:

• I placed my extended telescope at one end of the room, and the camera setup at the the opposite end of the room (it's not a big room).
• I used aluminium foil instead of a razor blade.
• I used the phone's LED (uncovered) instead of a circuit-board LED.
• Otherwise, I just followed the linked tutorial.

 

Here is a crappy schematic of the setup:

 

Here is the camera setup:

 

So when the sky is cloudy, here's something you can try out

I think it's absolutely amazing.
Not "first-time-seeing-Saturn" amazing, but pretty spectacular and interesting! 

 

Have fun!

- itai -

[Peter Drew]

When the sky IS clear you can demonstrate a similar effect by defocusing a star and then hold your hand in front of the telescope, you will see the heat plumes rising from your hand.

[saac]

That is indeed cool, thanks for showing that,  You should be able to get a full unobstructed view by removing the secondary: one for cloudy nights perhaps. Would be interesting to see what a filament lamp produces as you vary the voltage across it, probably need to carefully remove the glass bulb around it first to get the best effect.

 

Jim

[Jim78154]

That is fantastic. Is there a practical use for it as well?

[soundwave]

Yes, according to Wikipedia:

A typical application in gas dynamics is the study of shock waves in ballistics and supersonic or hypersonic vehicles. Flows caused by heating, physical absorption or chemical reactions can be visualized.
Thus, schlieren photography can be used in many engineering problems such as heat transfer, leak detection, study of boundary layer detachment, and characterization of optics.

[beamer3.6m]

Could you not use a normal mirror as I'm not sure what the telescope is doing?

[soundwave]

I needed a parabolic (or spherical) mirror, and that's the only one I had

[Soupy]

Loving this... Now I know what to do on an outreach event when it's cloudy!

Its exactly like a knife edge test used to test mirrors!