[newmikey]

These images indeed suffer from a blown-out red channel but also from focus that is badly off as well as camera movement caused by a shutterspeed that is too low. I'm by no means an accomplished concert shooter but I've tried my hand at a few now and then and will try to offer advice:

Let's tackle the red issue first:
Anvh's answer comes close to at least part of the story. You are dealing with lots of light in very severely restricted frequencies but the sensor does not "see" color at all - the Bayer filter eventually ends up "making' color out of a B&W image because of the color matrix overlaid onto the image. Every pixel in the eventual image is an averaging of that sensor location with the surrounding sensor locations. If that sensor location on the spot where the Bayer matrix has a red filter shows a quantity of light but the neighboring ones saw very little (they either have a green or blue filter holding back the red), those neighboring ones will have a tendency to end up red in the eventual image as well.

Second, your metering system was designed to convert everything into shades of grey as well, averaging out across the whole of the image or most of the image depending on the metering mode chosen. In a typical concert you actually expect the background to be dark and the performers well lit but the metering system does not "understand' that crucial piece of info. Even spot metering will not do here as it measures a small area only, again as B&W or better yet light&dark. Depending on whether that small area is over a face or over a piece of clothing, exposure may vary wildly. The "spot" can actually be quite a bit larger than what you see in the viewfinder, leading to issue like the ones with averaged metering above.

Third, in a concert environment, light tends to hit your metering system from two sides; not only through the lens but strong light sources behind you may cause lots of "leakage" through the viewfinder eyepiece causing the metering to get confused.

Reliable focus under concert lighting
The focussing system again relies on an average lighting situation where most of the lightrays are known to focus on the sensorplane more or less. However, we know that different colors are bent differently at every glass/air boundary dependent on the refractive index of the materials used. Under this lighting, the focus system can be fooled easily in thinking you are focusing while actually the overkill of one particular wavelength might mean a slight front- or back-focus. The SAFOX II in the K-5 (legacy model) is known to have issues under such light sources but frankly I'd expect any camera to exhibit this behaviour under these extreme conditions. The solution is to increase DOF by closing the aperture a bit, just enough to "catch" both the slight fron- as well as back-focus within the available DOF.

Camera movement
If you are shooting in Av modus, chances are your shutterspeed are dipping below the minimum required to sharply render based on subject distance, focal length and steadiness of hand or use of f.i. a monopod. Singers who bounce over the stage like balss in a pinball machine don't help any either. The solution is to choose your shutterspeeds wisely.

Total story
Putting all of this together it becomes obvious that actually only 2 modes of shooting are sensible: full Manual (M) or full auto ISO (TAv) where you constantly check your histogram and zoom in on the LCD to make sure you did alright and adjust where necessary. If using TAv it might even be necessary to dial in a few stops of underexposure to account for the dark background. In both modes, make sure your aperture is set to a sensible value to get at least a bit of DOF (use a calculator online to determine prior to the shoot) and your shutter speed is at least 1 divided by the focal length or faster (adjusted for any movement on the stage). I could be totally wrong but that is how I would approach the red light issue. If you shoot raw which I believe you did, whitebalance can be adjusted afterwards and it does not affect exposure at all.

[rzarector]

Thank you for the incredible post. So much detail. I have a hard time wrapping my head around the Color sensor stuff you wrote but I think I get the idea.

out of curiosity the shots you took here, what kind of metering did you use?

[Anvh]

I can write it down slightl simpler.

of the K5 sensor with 16 mega pixels.
4 mega pixels are red
8 mp are green
4 mp are blue

So if you shoot an image which is mostly red then the red pixels will do most of the work, the quality won't be like a 16mp photo but closer to a 4mp photo.


As for metering use manual.
Stage lighting can change quite rapidly and dramitcly so you metering can easily be fooled.
Some use spot metering on the faces for example but for those wide angle shots that isn't an option at all.
What i do is zoom in on the face or clothing take a metering by pressing the "green button" you will get an exposure that should be pretty close. You might want to adjust about a stop or so to get a perfect and then everytime the lighting change a lot (different song?) you start over again. You can get fast with this and get a good exposure within 5 seconds on manual mode.

[newmikey]

Thank you for the incredible post. So much detail. I have a hard time wrapping my head around the Color sensor stuff you wrote but I think I get the idea.

out of curiosity the shots you took here, what kind of metering did you use?

The EXIF info is visible if you click through to Flickr but the first two were spot-metered with a lot of exposure correction dialed in (-1.3 Ev) the other two were Center-weighted average again with a stop or more of exposure correction to avoid blown-out highlights and account for intentionally dark backgrounds.

ISO was on auto and ranged from ISO1250 to ISO3200 and I used apertures of between f5.6 and f8 on my 50-135mm/f2.8 to avoid refraction-based focus issues. Shutterspeeds were actually quite low (mostly half of the focal length used) but that is because I have a batterygrip and a very steady hand in shooting. (as long as I stay off the beers)

[nomadkng]

there's a reason most of your strip clubs use red lights... because when interacting with human flesh, a lot of imperfections and blemishes "disappear"

the use of red light is an intentional method of removing detail in most cases, so you're also fighting the lighting manager's plan

[rzarector]

Well folks I had some more success this time around. I took a lot of what you said into account and played around with my settings a whole bunch.

Rocking my K-01, The sigma 17-50 2.8, and the Pentax 55mm* 1.4. I primarily used my zoom as its much more flexible than the stiff 55. And its my new guy so its getting a lot of use. I love this lens, love love love it. anyway back to subject...

I stared in Manual mode and bracketed exposure a few times. Found that I got good results on reducing the Red with being a full stop down even a bit more, from 2.8. Sure things were a bit underexposed but I got much more detail and once editing in post the clarity improved even more. I reduced saturation a bit using radial filters in LR and some brush work.

The stage had uneven lighting and didn't change much so the lead singer was bathed in red most night and the rest of the band in blue. Weeeeeeeeeeeee!

I ended up playing with a number of modes throughout the night. Some Tv some Av really seeing what the camera did and boy were you all right. It appears the camera gets really confused with these harsh lights.

I even locked exposure for periods of time trying to lock in a good spot to get certain people but had more or less ok results. Still a pain to shoot these small clubs and venues with little to no light change. I need to get into some bigger venues with some better lights to play with. but you gotta learn to crawl before you learn to walk!

cannot thank you all enough for this help. your experience and help is priceless! much love!

PS: POLL QUESTION: On a networking card to hand out at shows, to link people to my stuff:

A> QR code?
B> website with tiny url?
C>Just your email dude?
D> QR and Tiny url?

thanks!

[rzarector]

Here was one from last night.

Attached Images

 

[narual]

only 2 modes of shooting are sensible: full Manual (M) or full auto ISO (TAv) where you constantly check your histogram and zoom in on the LCD to make sure you did alright and adjust where necessary. If using TAv it might even be necessary to dial in a few stops of underexposure to account for the dark background. In both modes, make sure your aperture is set to a sensible value to get at least a bit of DOF (use a calculator online to determine prior to the shoot) and your shutter speed is at least 1 divided by the focal length or faster (adjusted for any movement on the stage). I could be totally wrong but that is how I would approach the red light issue. If you shoot raw which I believe you did, whitebalance can be adjusted afterwards and it does not affect exposure at all.

This helped a ton. I think setting white balance at the beginning, not in post, made a *huge* difference though… it seemed to pick up skin tones much better and I didn't' end up with 800 featureless red faces. (But that could be because this place had better lighting than the last one. I think they were gelled lights instead of LEDs, too)