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Registered Member #4074
Joined: Mon Aug 29 2011, 06:58AM
Location: Australia
Posts: 335
I think the arcs are simply too bright for the camera, causing it to whiteout.
I've had some luck filming strong arcs through an electronic welding mask. I could get decent footage of a 5A arc using lens shade 9 (typically used for low-current TIG and stick welding). If the MOT arc is only <1A you might be able to use shade 3-5 filters for a little extra visibility.
I wonder if the IR/UV from a MOT arc is enough to permanently damage a camera? I've exposed my phone camera to dozens of bright arcs with no noticed effect, but could it potentially cause dead pixels or other damage in cheap cameras?
Registered Member #543
Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992
Why not use a cheap variable neutral density filter? These commonly cover ND2 - ND400, which is between 1 and 18 stops.
If it is still too bright at ND400, couple a fixed ND400, or ND1000, in series with the variable filter.
Once you have a good image of the arc, you can merge it with a picture of the gap taken under normal exposure conditions, to create a naturalistic effect.
Registered Member #15
Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068
That's because the dynamic range of the human eye is many times more than that of a camera.
For this reason, I always do the following for arc photos when using it for publications or professionally required applications such as product photos, brochures, etc...
1. Take an exposure of your background and coil. Use whatever exposure you want to get the brightness the way you want it.
2. Take your arc photos and expose for the arcs.
3. In photoshop, start with your background image as your base layer. Then add arc layers to the background. Use the LIGHTEN blend method. This will very nicely put the arcs into your background image. You can put 10s of arc images into a signal background and come out with a very high quality image. Much higher quality than if you simply left your camera shutter open for a minute or two.
And yes, you need to have the camera on a tripod for this.
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Why do high current Arcs recorded on video always look white with a colored outline
