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05-27-2018, 06:38 AM   #1
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One way to avoid over-exposure with LED stage lights

This is to approximate the following: have separate ISO options for RAW and JPEG, such that we can protect highlights and leverage iso invariance, while being able to chimp to check focus and composition.

As background, the issue is that LED stage lights can overexpose just one channel. For example, magenta lights will make the camera over expose the red pixels (of the raw file). Last few concerts, I decided it's fine to trust AF, not really be able to chimp, but leverage iso invariance and avoid over exposure.

So for lighting that would have required iso 1600+, I set iso to 400. Overall, it was a successful approach, but for some pictures it was almost impossible to check on the backscreen (yet after +2-3EV in pp the results were fine).

Next time I'm planning to use one of the JPEG modes set to maximum brightness, I can sacrifice portrait mode for example, and get brighter previews. If only the slider allowed more drastic adjustments. I'm wondering if anyone else has tried this
Alternatively, the firmware could have a jpeg option to always show what the camera thinks is correct exposure, but keep the raw files at a set iso.


Last edited by aaacb; 05-27-2018 at 06:51 AM.
05-27-2018, 09:01 AM   #2
sbh
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If you have the K-1, you can also set the display brightness to maximum. This will show the preview image brighter than it really is.
(The bottom button on the 4-way-dial)


Your last sentence is interesting. Not that I would have a usecase for that, but still an interesting approach.
05-27-2018, 01:47 PM   #3
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QuoteOriginally posted by aaacb Quote
This is to approximate the following: have separate ISO options for RAW and JPEG, such that we can protect highlights and leverage iso invariance, while being able to chimp to check focus and composition.

As background, the issue is that LED stage lights can overexpose just one channel. For example, magenta lights will make the camera over expose the red pixels (of the raw file). Last few concerts, I decided it's fine to trust AF, not really be able to chimp, but leverage iso invariance and avoid over exposure.

So for lighting that would have required iso 1600+, I set iso to 400. Overall, it was a successful approach, but for some pictures it was almost impossible to check on the backscreen (yet after +2-3EV in pp the results were fine).

Next time I'm planning to use one of the JPEG modes set to maximum brightness, I can sacrifice portrait mode for example, and get brighter previews. If only the slider allowed more drastic adjustments. I'm wondering if anyone else has tried this
Alternatively, the firmware could have a jpeg option to always show what the camera thinks is correct exposure, but keep the raw files at a set iso.
I think it is a shame that we can't bracket shots based on Iso - that would solve the problem here.
You are dabbling with utilising Iso invariance - ideal for your situation.
Normally even 3 stops under and you can see the results enough to confirm focus etc.
Iso invariance - PentaxForums.com
05-27-2018, 02:23 PM   #4
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Another issue I've found is that just a few exposures of live bands under LED lighting were very under or over exposed. I couldn't understand it at first, but then I realised that LED stage lights change rapidly, and I was getting caught out by a lighting change just at the moment I took the photos; the camera had set the exposure (I presume) just as I pressed the shutter release, but by the time the shutter opened, the lights had changed.

05-27-2018, 03:16 PM   #5
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QuoteOriginally posted by sbh Quote
If you have the K-1,
Sounds like a useful function, but my k3ii doesn't have it. I could just set it from the menus.

QuoteOriginally posted by GUB Quote
Normally even 3 stops under and you can see the results enough to confirm focus etc.
True, but I still feel I have to squint a bit After testing at home, max brightness increase in the jpeg profile seems to help a bit.

---------- Post added 05-27-18 at 06:26 PM ----------

QuoteOriginally posted by Robot camera Quote
by the time the shutter opened, the lights had changed.
Speaking of changing lights: Once at a college basketball game, and it only happened once in all the photos I've ever taken, another photographer's off-camera flash fired exactly when I was taking my picture at 1/500+ shutter.
More on-topic: were these strobes, as in, rapidly flashing? I don't remember the last time a band had similar light patterns, but it's good to keep in mind.

Last edited by aaacb; 05-27-2018 at 03:26 PM.
05-27-2018, 04:29 PM   #6
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QuoteOriginally posted by Robot camera Quote
Another issue I've found is that just a few exposures of live bands under LED lighting were very under or over exposed. I couldn't understand it at first, but then I realised that LED stage lights change rapidly, and I was getting caught out by a lighting change just at the moment I took the photos; the camera had set the exposure (I presume) just as I pressed the shutter release, but by the time the shutter opened, the lights had changed.
Again if you are up in the Iso range then be brave and trust your cameras Iso invariance and shoot with the same shutter and aperture but base Iso (100). then all the variation ends up being differing degrees of push processing in editing. These shots were in a shocking environment of movement and very little ambient lighting. I pushed them at least 6 stops in PP. Lens was Revuenon 50mm 1.2 and I used it wide open at 1/30 on the K1.


And I would love to hear suggestions of varying settings for this situation. It would have been nice to stop down to f2 and it would have been great to be at 1/60 but I think the increased noise would detract. It was a procession that i had to move with so all were handheld - a monopod might have worked.
05-27-2018, 08:35 PM   #7
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QuoteOriginally posted by GUB Quote
I think it is a shame that we can't bracket shots based on Iso - that would solve the problem here.
I believe if you are shooting in TAv mode, and have exposure bracketing on, it will do exactly what you are describing.



QuoteOriginally posted by Robot camera Quote
Another issue I've found is that just a few exposures of live bands under LED lighting were very under or over exposed. I couldn't understand it at first, but then I realised that LED stage lights change rapidly, and I was getting caught out by a lighting change just at the moment I took the photos; the camera had set the exposure (I presume) just as I pressed the shutter release, but by the time the shutter opened, the lights had changed.
Am I wrong, or would this case be properly exposed if one were using an LX?
05-27-2018, 10:56 PM   #8
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QuoteOriginally posted by leekil Quote
I believe if you are shooting in TAv mode, and have exposure bracketing on, it will do exactly what you are describing.
Just tried it and yes but with a bit of a work around. for an image say correctly exposed at x shutter y aperture and Iso 1600 then firstly set exposure compensation to -4 stops and set 2 brackets one at +4 exposure. Seems to work but I would far rather be in M mode where I can insist on base Iso. But maybe I am being pedantic!

05-27-2018, 10:59 PM   #9
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QuoteOriginally posted by leekil Quote
Am I wrong, or would this case be properly exposed if one were using an LX?
Sorry for a dumb question but what is an LX ?
05-28-2018, 03:19 AM   #10
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QuoteOriginally posted by Robot camera Quote
Another issue I've found is that just a few exposures of live bands under LED lighting were very under or over exposed. I couldn't understand it at first, but then I realised that LED stage lights change rapidly, and I was getting caught out by a lighting change just at the moment I took the photos; the camera had set the exposure (I presume) just as I pressed the shutter release, but by the time the shutter opened, the lights had changed.
(My words)
I suppose that I would have opted for manual exposure had I realised at the time, but I generally don't chimp much, just an occasional check that all's generally well using the digital preview. I'll know better next time.
06-05-2018, 11:09 PM   #11
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QuoteOriginally posted by GUB Quote
Sorry for a dumb question but what is an LX ?
A Pentax LX film camera, it uses off-the-film TTL metering while the shutter was open so it could react to changes in lighting during the exposure.

Though whether or not it would be better in this case was not an entirely serious comment...
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