filter to video liquid metal

kavanaa1

Hi
Im trying to capture hot liquid metal using a video camera. The brightness of the metal means that the images are unusable as it is impossible to see the liquid, all I get is white glow.
is there a filter I could put in front of the lens to shield the camera from the very bright light?

Thanks.

Prenderb

Something like a 10-stop neutral density filter? Or some welding glass?

zerohamster

If you use welding glass you will most likely get a very strong magenta cast on images/video but it is so much cheaper than a good ND filter (a 10 stop ND might suit you).
Also there is a massive amount of IR given off by molten metal so beware that it will heat up the sensor when looking at it for long periods of time with an ND filter on and a very short time without.

Zillah

zerohamster wrote: »

Also there is a massive amount of IR given off by molten metal so beware that it will heat up the sensor when looking at it for long periods of time with an ND filter on and a very short time without.

Hmm, I wonder what it would look like under an IR filter.

zerohamster

It would probably look somewhat similar to the colour version because it would be giving off intense light of the visual spectrum and IR+higher depending on the temperature of the metal but the "colder" spots in the molten metal would show up more in the IR spectrum in the surface as far as I know.


Im guessing IR would look like the opposite of a photo of someone with freckles in B+W compared to an IR shot of the same person (clear ghostly looking skin),
so the visual spectrum would be bright and clear and the IR should look somewhat freckled depending on the temperature of the metal (in relation to what wavelength the camera sensor is capable of capturing in the IR spectrum as they have IR blocking filters on them to replicate more the function of a human eye)

It would be interesting to see if it gave it a more spotted contasty look but again im just theorising so it might not capture the contrast between temperatures enough to look freckled.

Heebie

You might get some neat effects with a good near-IR filter like a Hoya R70? (I think that's what it's called.. I don't have mine to hand right this minute.)

zerohamster

Also I forgot to mention, if you are using a video camera that has a night mode that will shift the low pass filter (block IR light) out away from the sensor to pick up IR light in the dark. (a lot of consumer vid cams have a nightshot mode that do this and a small IR torch on the front)

This in combonation with a visible light blocking filter would work better than just the filter but of course the IR light would have to be bright or the camera wouldnt be able to expose correctly as it cant do long exposure like an still camera would be able to.