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05/09/2011 10:48:13 PM · #1 |
I'm going to be doing some shots soon which will include plasma and laser cutters. While, I've pretty much nailed down the shots I want to do, I haven't quite figured out how I'm going to meter the damn things.
I don't want to totally blow out the light source from the plasma or lasers, but I do want them to also cast a rim light on the worker that is operating them. I can meter the amount of light put off at the subject, ie meter the rim light, but I'm relatively sure the cutter would blow out. I'll be using strobes for key of the worker.
I can't stare at the things through the viewfinder, as they would burn my eyes out. I could go to Liveview, but I also can't be holding up the production line the machines are on for very long.
My first thought is to set my light meter up for a reflective reading, metered from about where I'll be shooting from and then meter my strobe output through an incident reading, get a good ratio and then shoot away, ofcourse probably using Liveview. I'd be working pretty much the same way I'd handle a sunset behind a subject.
I don't like doing shoots as an experiment. I want this to be a get in and get done. So, if anyone has a clue or experience with shooting welders or plasma or laser cutting equipment, I'd much appreciate it.
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05/09/2011 11:28:45 PM · #2 |
I"m thinking an incident reading isn't going to do you much for keeping such a small insanely bright source from blowing because you're not worried about light as it falls on the scene but the source itself. I'd say determine what the exposure is for that, pump your scene as close as you can by stopping way the hell down. Might need to use an ND to drop its exposure to something manageable, while still firing lights at full.
The whole idea is that you'll need to determine whatever your acceptable exposure for the cutters is, then fill the rest of the scene to match.
Just my guess though, never tried it myself.
ETA: I guess what I'm saying is that if you meter for it you're going to get an insane result of stops for the exposure since it's so damn bright alongside the comparatively dark surroundings.
Message edited by author 2011-05-09 23:36:29. |
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05/09/2011 11:34:45 PM · #3 |
If you have a flash meter I'd suggest at least trying to use it in "flash" mode and see if you can get a meter reading in it. That would be my attempt. Or you could fire a couple of shots in AV mode with them arcing during the shots. Figure out what to meter it to get the effect you want, then power your strobe up to match what you need on the worker.
Message edited by author 2011-05-09 23:35:20. |
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05/09/2011 11:36:49 PM · #4 |
It's about like shooting the sun in mid day, so if you can get the sun at midday plus the clouds that are right near it, that may give you a good benchmark to work from. It may be a good idea to use a serious ND filter. Welding lenses are generally about ND 10 to ND 12, cutting lenses are a little lighter like ND 8 or 9. You can look straight at the sun with an ND 12 welding lens and welding hood for a few seconds without causing damage, but it's still pretty bright.
Smoke may cause a problem, as it moves all around, and changes the light quite a lot as it moves between the camera and subject.
A cloth hood and live view might work ok, so you can see what you are getting as it is happening.
If any of those sparks hit your lens, it will stick to the glass, and will pull a plug of glass out if you try to get it off, so use a UV filter. A lot of the light from a plasma cutter or welder will be UV anyway.
Hope it works out nicely for you.
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05/10/2011 10:44:06 AM · #5 |
Thanks guys for the helpful tips. I found a friend that is willing to let me experiment with an arc welder, while not exactly the same, it should give me some insight into how to get the shots I want, without holding up production on the plasma and laser cutters too much. I'll also be headed to the shop to do a bit of other recon too.
Definitely thanks for the ND suggestions, believe it or not it's something I had not thought about. And I'll definitely use a UV filter, although I'm planning the shot with at least an 85mm focal length.
After some thought, I'm thinking that I'll use a strobe to create the rim light on the subject, rather than using the plasma light, so I'll have more control of each element.
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