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12-01-2013, 01:26 PM   #1
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New K-3 owner-problem

Hello . just got the K-3 friday. upgraded from the samsung gx 20 .. it's really nice and cool .
i want your opinion on a problem . i shot a concert with the k-3 and some pictures have "burn" spots. the lens was pentax-f 50mm 1.7. i've uploaded 3 photos were you can see them . in the first photo it;s the blue patch on the guitarist nose. the spots also appears on hair and in the red photo you can see that it is half of the bass players face. this never happened to me with the gx20. i have shot in the same place with the same light but nothing like this. what do you think. does the k-3 have a problem or its from the lack of aa filter.. or maybe some settings.. all opinions are welcomed . thanks !

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12-01-2013, 01:42 PM   #2
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Those spots look like colored lights from their lighting set up hitting his nose, hair, face, etc. That is the way the camera rendered the hot spots. If you can't use flash to counterbalance some of the ambient light, I don't think you can avoid that.
12-01-2013, 01:46 PM   #3
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I got some of those recently with my K-01... so I dont think it is an AA filter issue. I think it is just overexposure.

What it seems to be when I look at my full res files is just an overexposure point of the BLUE or RED stage lights. So instead of a white blowout like you would get in the sun. You are seeing blue and red 'hot spots'. And they do not recover well. I have started shooting with EV comp set lower in stage settings now.

Also, I have noticed with my dslr cams, that the new LED lighting is tougher to PP and WB than the old PAR stage lights.

I got a nickel that says these stage lights are LED
12-01-2013, 01:49 PM   #4
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Welcome to LED lighting, plus JPEGs. You'll find this can happen with the K-x, K-5 and probably the K-3 too, by the look of it.

Have a look at this thread for a discussion of the issue and some guidance:

https://www.pentaxforums.com/forums/6-pentax-dslr-discussion/93809-modern-led...t=led+lighting

Shooting RAW helps, as may careful awareness of the white balance at the shoot (I take a grey card along to gigs and take a few shots of it when illuminated by some of the lighting to help with post-processing). The simplest solution is to post-process away the colour-cast by adjusting your RGB saturation for the problem colour.

12-01-2013, 01:52 PM   #5
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It's not a problem of a camera it's problem of LED color lights . Even Hollywood suffer from LEDs, see "Man in black 3"
12-01-2013, 03:52 PM   #6
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QuoteOriginally posted by burb Quote
in the first photo it;s the blue patch on the guitarist nose. the spots also appears on hair and in the red photo you can see that it is half of the bass players face. this never happened to me with the gx20.
Why would this be a problem with the K-3, and not the GX-20? Both use a CMOS sensor.
12-01-2013, 04:30 PM - 1 Like   #7
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QuoteOriginally posted by tomwil Quote
Both use a CMOS sensor.
Different sensor, different image engine, different metering sub-system, different processing algorithms, different spectral sensitivity - who knows.

It's a common problem, even for Nikons and Canon's - and I bet Samsungs too, sometimes.

Flickr: Discussing New lighting problem: LED stage lights in Lighting Essentials
'The stage lighting looked normal to the eye, but in my photos some specific areas would be hugely oversaturated with color, to the point that they would lose all detail and look "posterized." '
Lame Emitting Diodes: LED Lights Cause Problems for Digital Concert Photography - redfishingboat
Fight against LED stage lights: Pro Digital Talk Forum: Digital Photography Review

etc etc
12-01-2013, 05:17 PM - 2 Likes   #8
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LED stage lighting. Best you can do is shoot RAW and be very careful not to over expose any part of the photo. LED's have a very narrow color spectrum too which makes WB adjustment after the fact very difficult.

12-01-2013, 06:07 PM   #9
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QuoteOriginally posted by twitch Quote
which makes WB adjustment after the fact very difficult.
Indeed.
Even badly affected images can be rescued through WB tweaking and saturation adjustment, but it takes work. From the K-5:

Straight out of camera JPG:


DNG after some processing (could do better):
12-02-2013, 01:13 AM   #10
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thanks guys. that really helps. the photos are shot in DNG and converted to put on thread. with the gx20 i never got over iso 800, the lens was the same.. all i could think of was that the metering system was different , the aa filter was missing or the sensor was broken. but you are correct. those are led light and if you say it happens to other , i am at peace and i can go shoot

I am enjoying the K-3 so far. hope i can provide some picture and opinions soon.

i also noticed that the kit lens 18-55 has a plastic focus ring. maybe it"s not as durable as the old one but sure is lighter and faster in focus.. and quieter
12-02-2013, 01:15 AM   #11
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QuoteOriginally posted by rawr Quote
Indeed.
Even badly affected images can be rescued through WB tweaking and saturation adjustment, but it takes work. From the K-5:

Straight out of camera JPG:


DNG after some processing (could do better):
good job rawr with the processing. good to know it can be fixed
12-02-2013, 04:56 AM   #12
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QuoteOriginally posted by burb Quote
good job rawr with the processing. good to know it can be fixed
Thanks. Fixing is possible. However it can be a big nuisance, especially if you have a lot of photos to process. Compounding the problem, the LED's will often cycle colour quickly, so that a Lightroom develop setting for one photo (eg reduce saturation of magenta) wont work for another photo where green is the problem.
12-02-2013, 06:10 AM   #13
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The problem is probably in part created because the metering is performed before the spot lights up, or the strong lights/shadows trick the camera into overexposing these areas.
12-02-2013, 06:30 AM   #14
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QuoteOriginally posted by bdery Quote
in part
Only in part, I think, since it does mainly affect highlight areas. But with LED's as an illumination source there seem to be some specific technical problems that relate to how Bayer sensors handle very specific (too specific) colour wavelengths. (UnknownVT's thread linked above Modern LED Stage Lighting & photography problems examines the technical issue in detail).
12-02-2013, 06:47 AM   #15
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So the solution is to deliberately underexpose? Then recover the exposure in RAW? Could you just dial down a few steps of EV?
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