Looking for a cheap and cheerful IR light source

CitizenJoe

Roscolux 19 (x2)) Roscolux 83 (x1) Roscolux 90 (x1)

It's inferred above, but the gel option will NOT work with most LED lights [edited - sorry].

That said, the cheap amazon type options do work well. Just make sure that the wavelength of light output from the fixture matches the wavelength that your camera is looking for.

Cheers,

Hugh

thatmattrogers

@citizenjoe They're advertised as 850nm and I have an 850nm filter for the camera, so hopefully both companies are telling the truth.

fingers crossed on that one.

dbini

i have a few of those CCTV IR floodlights but they are quite difficult to work with. the IR is generally produced by an array of LEDs each with their own internal reflector, so the beam is difficult to focus, even with a custom barndoor system (I mounted mine inside wooden boxes).
I have used them to light a performer for tracking from an overhead camera (b/w industrial USB cam with an IR pass filter) but it is difficult to prevent spill onto the floor and the falloff is quite steep. I ended up using 3 or 4 small units to light a 4.5m circular stage area.

If you do try this kind of solution, remember to put some gaffa tape over the light sensor so that the unit thinks it's always nighttime.

i much prefer using combined lighting gels with a halogen profile, but its not very sustainable - the wider the beam, the closer the lamp to the gel, the quicker the gels burn out, even when running at 25% max brightness, so i have needed to use at least 4 lanterns to cover a stage.

in an ideal world, there would be an IR version of a COB LED profile lantern, but it's a very niche application, so i don't expect they would ever be easy to find.

Fred

@thatmattrogers

As al you really need is contrast you can also opt for lighting the floor and not the performer with IR. This does require that your visible lighting for the performer and anything else in your set has minimal IR (or better yet none) content.

You will also see a great improvement if you camera also blocks visible lighting using an IR pass filter. Not many IR cameras have this built in, but Midwest optics sell a variety of filters you can put over your camera lens.

Using these I have had good results getting solid reliable tracking of movement from above. Ie using cheap IR floods to light the floor and not the performer.

CitizenJoe

@fred said:

<p>@thatmattrogers</p><p> but Midwest optics sell a variety of filters you can put over your camera lens. </p>

This is what I use; Lee 87:

thatmattrogers

@fred absolutely, the plan is to use a Sony a5100 that has had its IR and UV cut filters removed from the sensor then add an 850nm filter onto the lens.

So in theory, if both the LED arrays and the photographic filter have both been sold with accurate information. I should get a very clean 850nm image.

Here's hoping.

thatmattrogers

@citizenjoe like I said above I'm ideally looking for a solution which doesn't rely heavily on in house fixtures, but it's good to have this info as a back up.

thatmattrogers

@dbini good to have a heads up from someone who has worked with LED floods, I'll be your thoughts on mind whilst I'm problem solving.

I won't have the same problem with exposure since I'm using a camera capable of manual exposure, but it's definitely worth putting on people's radar if they're using this fire reference later.

Fred

@citizenjoe yep, but these are not great for optical transparency for cameras.

https://midopt.com/filters/bp8...

These are made for moutning to cameras, so no leaks and wont distort the image either. Habign said that in a pinch the lee filter will do.

Also if there i the opposite availble - filters for lights that will block IR these will be useful for better isolation - so that your visible lighting does not mess with the IR lighting.

CitizenJoe

@fred said:

@citizenjoe yep, but these are not great for optical transparency for cameras.

True, but for what I use it for (tracking) it doesn't matter. They are a cheap and cheerful alternative!

Cheers,

Hugh