Author Topic: Filming welding arc - filter necessary?  (Read 164 times)

gyppor

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Filming welding arc - filter necessary?
« on: October 28, 2018, 10:48:21 AM »
Hi Kron Tech,

If I want to film the arc from a stick welder, should I use a welding shade in front of the lens? I'm concerned the brightness and UV radiation might damage the sensor. I would have the shutter at a very small angle but I realize since it's an electronic shutter, the sensor will still be exposed to the intense UV light the whole time.

Thanks!

G

Nikon1

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Re: Filming welding arc - filter necessary?
« Reply #1 on: October 28, 2018, 10:53:49 AM »
I filmed An CNC- Plasma Cutter and an -Laser Cutter on my Nikon J5 @ 1200 fps Without any special Filter. I used an Standard Clear Glass filter which i guess is an UV-Filter used in Photography, but just to prevent the Front of My lens from Hot Metal Stuff, since i was super close.
You will need to use VERY short Exposure time For that, since it is Realy bright.
I used Like f22 or even f44 for the Plasma and an bit of an faster Apperture on the Laser.
Didnt kill the Sensor for me.
But i cant gurantee for your case...
« Last Edit: October 28, 2018, 10:58:06 AM by Nikon1 »

jasonfish

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Re: Filming welding arc - filter necessary?
« Reply #2 on: October 28, 2018, 02:30:04 PM »

Sael

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Re: Filming welding arc - filter necessary?
« Reply #3 on: October 28, 2018, 04:26:03 PM »
A nice short article on the dangers of photographing bright objects over on PetaPixel: https://petapixel.com/2017/09/01/photos-cameras-lenses-got-destroyed-solar-eclipse/

If the light source you are directly filming is bright enough to burn things with just a magnifying glass it's best to look into protection, especially if you're expecting to be looking at it for a long period of time. I'd also think the near infrared radiation would be more of a hazard to the lens and camera than UV. Modern lenses usually have UV blocking coatings, as well as the glass itself being not very transmissive to UV. Near infrared on the otherhand will pass through and while the bandpass filter in front of the sensor will reflect most of it, it will heat anything it shines on.

Regular photographic ND filters are not designed to block near infrared, and as such are not suitable for solar photography. For this reason I wouldn't recommend using them for photographing welding either. A solar filter might work if you want more true colours, but I can't say how well they would work. Welding lenses are made for looking at welding arcs and are thus probably the best choice protection wise.

Welding shades are cheap insurance against lens and sensor damage, and not terrible to have extra of if you've got welding equipment already. A no.7 or 8 shade should be fine, it's about a 9-10 stop reduction and thus is approximately equivalent of going from F/2 to F/45 - F/64, or going from 1000μs to 2μs - 1μs exposure. If this is too dark for your needs a no.6 lens is a whole 3 stops faster, or 1000μs down to ~20μs.

gyppor

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Re: Filming welding arc - filter necessary?
« Reply #4 on: October 29, 2018, 11:16:26 PM »
Thanks, looks like I'll use a welding shade. I was hoping to film without the greenish tint of welding shades but I'd rather save my sensor!

Sael

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Re: Filming welding arc - filter necessary?
« Reply #5 on: October 30, 2018, 03:39:38 PM »
The green tint can be removed with some colour correction, there are plenty of articles around describing how:

https://www.diyphotography.net/use-welding-glass-as-10-stops-nd-filter/

I might look into if it's possible to do it with the in-camera white balance...