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I'm filming TIG welding on Sony A7 III without a welding mask.

The best results with auto-focus and automatic exposure I was able to get are below - using PP10 HLG3 with Knee set to 75% slope -5 and exposure adjustment to -2 - as you see, highlights are still blown.

Is there any way I can preserve the highlights without using manual exposure? Many thanks.

DaVinci Resolve showing highlight clipping

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    \$\begingroup\$ Why the insistence on avoiding using manual exposure? It's the simplest and easiest way to get to where you want to be for such types of shots. Built-in metering, even "spot metering" mode, is not designed for such extremes in brightness in the same scene. Most cameras are programmed to allow a very small percentage of the frame to "blow out" in order to get some details in the rest of the frame. Also, follow the advice of others and protect yourself and your gear from the massive amount of UV and IR generated by TIG welding. \$\endgroup\$
    – Michael C
    Commented Aug 3, 2020 at 13:51
  • \$\begingroup\$ Michael, I'm both filming and welding so I'd like to minimize the camera setup time. With manual exposure one can't properly frame or focus until the welding is on. \$\endgroup\$ Commented Aug 3, 2020 at 21:18
  • \$\begingroup\$ Set up once for the non-welding segments and shoot them. Then setup once for the actual welding parts and shoot them. Then interleave them timewise in the editing room. That's how video production companies do it with various sets, actor combinations, props, costumes, etc. \$\endgroup\$
    – Michael C
    Commented Aug 4, 2020 at 14:02
  • \$\begingroup\$ Take care of your sensor. Take a look photo.stackexchange.com/questions/75285/… \$\endgroup\$
    – Rafael
    Commented Aug 4, 2020 at 16:15
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    \$\begingroup\$ @MaximKachurovskiy: there are loads of both plastics and dyes and semiconductors that will decay under hard UV light. That does not happen immediately. As your Bayer filter is decolorised, saturation of your pictures goes down, as plastic lens elements suffer, contrast goes down, as the sensor suffers, the amount of hot (that become saturated at longer exposures) and eventually dead pixels increases. IR may cause aperture blades to warp but is not the only danger. \$\endgroup\$
    – user94347
    Commented Aug 5, 2020 at 18:09

2 Answers 2

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Frankly, I'd at least use ND-filters certified for solar photography. Welding plasma is not fun: it emits a brutal amount of high energy UV light. I'd not trust the camera-internal filters to be able to deal with it gracefully. I've seen a guy who thought welding gloves were unnecessary and worked without them for some task. If you think you have seen bad sunburn, think again.

You don't want this shit to make it into your camera: it would probably wreak ruin on non-glass lenses and other parts possibly not 100% impervious to very hard UV light. You also want to definitely protect your eyes from exposure.

While you won't damage them using an electronic viewfinder, a DSLR with an optical viewfinder would be a different matter.

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    \$\begingroup\$ Forget the regular ND filter, use a solar filter that also attenuates UV and IR as well as visible light. \$\endgroup\$
    – Michael C
    Commented Aug 3, 2020 at 13:53
  • \$\begingroup\$ @Michael C: "certified for sun use" was supposed to mean that. I'll replace "sun use" with "solar photography" to make this clearer. \$\endgroup\$
    – user94347
    Commented Aug 3, 2020 at 16:11
  • \$\begingroup\$ Why not just properly call it a "solar filter"? \$\endgroup\$
    – Michael C
    Commented Aug 3, 2020 at 20:54
  • \$\begingroup\$ Yes, looks like the sensor was simply saturated in those areas and no amount of digital tweaking (picture profiles or exposure compensation) could help that. I only have 5-stop ND filter on hand and here's the best I could shoot: i.imgur.com/aSgi24a.jpg - looks like I need to get at least 10 or 12 as suggested by other answer. Thanks! \$\endgroup\$ Commented Aug 3, 2020 at 21:15
  • \$\begingroup\$ It doesn't matter how many stops of ND you use, if you allow the camera's meter to set exposure it will allow the very small, very bright area to overexpose in an attempt to properly set exposure for the rest of the frame. It will attempt to compensate using a wider aperture (iris), a longer exposure time (larger shutter angle), or higher ISO. \$\endgroup\$
    – Michael C
    Commented Aug 4, 2020 at 13:21
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  1. As suggested by the other answer: use a ND (Neutral Density) filter qualified for broad spectrum high intensity EM radiation, because TIG welding radiates a nasty amount of energy. I’d suggest a filter between 12 and 16 stops.
  2. If you really don’t want to manual expose, turn down the exposure compensation.

Note that the the dynamic range of your scene is huge. Don’t expect the darkest and the brightest parts to be visible at the same time!

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  • \$\begingroup\$ Right, my 5-stop ND filter didn't fully solve this: i.imgur.com/aSgi24a.jpg - but looks like exposure compensation actually can't fix this because the sensor is simply saturated in those areas. I got it at -3 anyways though. Thank you! \$\endgroup\$ Commented Aug 3, 2020 at 21:16

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