I am starting to get prepared for the Great American Eclipse, and planning my shooting schedule. I have an ICE ND1000 neutral-density filter that I want to use for some video shots. This filter reduces the light by 10 stops (1024x attenuation). The problem is, there is no data available for the UV and IR transmittance (i.e. - the filter may reduce visible light by 1000x, but it might pas a lot of IR, which will affect the color of photos, and also might cause eye damage if it was used to look directly at the sun). So, I needed a way to test it’s IR-blocking abilities (UV wasn’t a concern, since normal camera lenses block UV effectively).
The first thing I did was to find my Gen-I night vision goggles. These are Russian-surplus binoculars, and are your basic IR-sensitive HV image intensifiers. I used a TV remote control as an IR source. The goggles could see the IR from the remote control quite clearly. I then put the remote control behind the ND1000 filter, and it almost completely blocked the IR. Good - that’s what I was expecting. But, an LED is near-IR (800 nm or so). The sun emits lots of IR that is longer than that, and I didn’t have any way to either generate it or detect it. What I really needed was an Integrating Bolometer, but I didn’t have one handy.
I did, however, have a hand.
I found a 2" magnifying glass, and went outside to my source of far-IR (the sun), and focused the sun onto the palm of my hand, and found that it was instantly too hot to tolerate.
Good.
Then, I put the filter in front of the lens, and tried the same thing. With the filter attenuating the sunlight, I could actually see the image of the sun on the palm of my hand, and I could focus it to a tiny point. But, even when focused as small as I could, I could not feel any heat. This told me that the total energy being transmitted through the filter was substantially attenuated. Whether it was more or less than 1024x, I don’t know, but at least it was clear that the filter wasn’t passing gobs of IR energy.
So, I feel confident in using this filter for the eclipse, and I’m happy that I finally got some use out of my degree in Physics.
Science for the win!
careful - you could be blinded by this science!
Science!
Good heavens, Miss Sakamoto, you’re beautiful!
You scienced the shit out of it.
I love weird science!
Careful, you are flirting with possible cerebral hyperplasia!
Just from an over-abundance of caution, I used a UV-LED flashlight and some fluorescent paper to test the filter’s UV transmission. It was even less than the IR - the paper didn’t fluoresce at all with the filter in the path of the light.
Nice effort! I will remember this method for the next time my integrating bolometer is in the shop.
Pffft. A real scientist would have used someone else’s hand.
And that is the difference.
Ha!
I once heard the following:
“The difference between a Scientist and a normal person is, if you tell a Scientist that there are 100 billion stars in the Milky Way he’ll believe you, but if he sees a sign that says “wet paint,” he’ll touch the surface to be sure.”
Science is just the description of reality. Anything real that you accomplish is through science, since there’s no way to affect reality except through real means.