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Shooting Molten Metal


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#1 Markus Stone

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Posted 09 October 2017 - 09:37 PM

I have to shoot a Bronze casting next week for a small corporate gig. DSLR (5D Mk IV).

 

Obviously there will be a very large difference in exposure between the metal and the talent. My plan of attack is as follows;

 

  • I'll shoot HDR mode (I've tried playing with the CLog mode, but I can't see a clear benefit in dynamic range and it has a difficult to remove greenish colour cast). It will hopefully help a little anyway.
  • ND or variable density filter (watching out for the dreaded dark cross)? to try to retain longer shutter speeds. (will having such a bright source introduce internal filter reflections?)
  • Blast a snooted fresnel in there to try and bring up the exposure of the surfaces interacting with the metal a bit? Not sure what good it will do, I mean we're talking molten metal here and I imagine the surfaces are blackened with soot! (with the possible exception of the mould itself).
  • Radiant heat - can it hurt the lenses with thermal shock?
  • Two cameras mounted on a bar, one tight, exposed for the metal, one wide, exposing for the talent conducting the pour.

From memory shooting in a steel smelter years ago, you want the steel to be a bit over so it retains that 'hot' look.

 

Any other tips? Slo-mo?

 

Thanks

 

Markus


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#2 Giray Izcan

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Posted 10 October 2017 - 04:03 PM

I would over expose the molten metal within the limits of your camera where it appears maybe a bit lighter orange. Something burning like fire etc should be overexposed to give the feeling of hotness. I would light the talent with a soft light, and underexpose by a stop and a half.
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#3 Mark Kenfield

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Posted 10 October 2017 - 05:45 PM

I think you're on the right track Markus. I'd do the same thing I try to do when shooting fire/flames - fire as much ambient light at the subject as possible, so that you can expose for the hottest elements but still see surrounding surfaces.


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#4 Keith Walters

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Posted 10 October 2017 - 06:55 PM

You're may have the problem  that molten metal is going to emit a large amount of infrared, and ordinary filters won't block that.

I once tried to take still photos of molten copper droplets and got some weird-looking results because of this.

Eventually I knocked up an old-fashioned smoked glass filter by exposing a sheet of clear glass to a candle flame (same as you use for taking photos of the sun, but not as dark).

It was a bit uneven shading-wise but the exposure then came out a lot better.

The photo was done to disprove something that was claimed in an insurance scam, so in that case we didn't care too much about the overall image quality. I have made better quality filters using a kerosene lamp with the filter glass mounted about 3 feet above it, in a draught-free room.

My plan at that time was to show  that a carbon filter would solve the problems that people were having with Red cameras and IR contamination using ordinary ND filters, but I could never get hold of anyone with a Red camera willing to let me experiment with this :rolleyes:

 

Another job I had was to shoot high-speed video of a shipment of matches where the heads would sometimes shatter during the striking process, sending flaming sparks everywhere, and in one case setting off the entire box, resulting in burns (and, naturally, a lawsuit).
I initially did a quick test in my workshop, with the matches clamped in a vice, and just dragging the side of the matchbox across the head to ignite them. I produced some fantastic close-up slo-mo shots that showed the match heads exploding into a perfect little fireworks display, but then the main flame would flare up and completely obliterate the image.

So then I spent an hour or so setting up outside in the midday sun to reduce the contrast, and then spent a couple more hours fruitlessly trying to re-create my original shots. After countless attempts, mostly of the matches igniting perfectly with no sparking, or of the matches failing to ignite at all, or the heads breaking off and threatening to set fire to the piece of cloth I'd set up as a background, I ran out of matches and gave up.

But anyway, the client's lawyer was happy with my original shots, and he said if anything it looked more dramatic :D


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#5 Robert Hart

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Posted 11 October 2017 - 12:45 PM

If your cam is anywhere near the metal, a sacrificial clear or UV filter on the front of the lens to protect against sparks coming off and melting pits in your lens's front element would be worthwhile installing.


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