Almost totally blown red channel...

[TME]

Hi,

I've been experiencing this for some time now... decided to post and see if it's a sensor issue that needs fixing or my technique that needs fixing...

I have been trying to photograph red roses for some time now (or in fact anything red) and I usually have to junk my shots cos the red channel gets almost completely blown.

I took some today of some red roses in a restaurant with mixed warm lighting... I include a shot with flash and one without... the detail captured is ridiculously bad... compared to the detail of the surrounding bits in the image...

Is my sensor giving way? Or my technique crap? I don't have this issue shooting flowers (or anything else) of different colours...

7D, 17-35mm f/8, ISO400, centre-weighted metering, centre AF spot sensor, 5600HS(D), bounced with LightSphere.






Thanks!

[eow]

it look really bad...my pns can easily resolved such red colour..
the red does look severely clipped

[Rashkae]

Wasn't this a known issue of the 7D?

[LittleWolf]

Originally Posted by TME I have been trying to photograph red roses for some time now (or in fact anything red) and I usually have to junk my shots cos the red channel gets almost completely blown.

A clipping channel most likely means you're overexposing. There's also a possibility that the camera sensor records the image just fine, but it exceeds the gamut of the output colour space. (In this case, recording raw sensor data would help.)

E.g., in sRGB, a "pure red" cannot be brighter than about 21% (assuming "white"=100%). (For blue, it's even worse at about 7%, green saturates at about 72%.) In other words, saturated colours cannot be very bright.

[godzilla60]

i am not sure if this helps but for my A100, it happens when i set to "vivid"........but i seldom take pics of red roses so i did not change the setting...

[Watchman64]

I experienced the same with red flowers. Custom WB and setting to Adobe renders a more accurate color compared to Vivid.

[TME]

Originally Posted by Rashkae Wasn't this a known issue of the 7D?

Yupe it's a known issue... but not this bad right? I never really noticed this issue... I looked back at my archives and found that all my roses I shot in the past were done with the 7 and not the 7D... it's a bit way off to have the red channel completely blown...

[TME]

Originally Posted by LittleWolf A clipping channel most likely means you're overexposing. There's also a possibility that the camera sensor records the image just fine, but it exceeds the gamut of the output colour space. (In this case, recording raw sensor data would help.) E.g., in sRGB, a "pure red" cannot be brighter than about 21% (assuming "white"=100%). (For blue, it's even worse at about 7%, green saturates at about 72%.) In other words, saturated colours cannot be very bright.

Did you check the histogram? I deliberately allowed the camera to expose properly... all other channels are not blown, only the red...

I'm not quite sure about what you mean about out of colour gamut... usually out of gamut means that the colour is unnatural... it simply gets replaced by the nearest colour (depending on the algo used in the camera), it does not cause the details in a wide area of colour to blow completely... and it's usually very fine detail that is lost... here, even the major details which can be easily resolved by a simple PnS camera are totally blown...

[ninelives]

TME, are you shooting jpg or raw? check your camera setting ( creative style). and also your awb.

[TME]

Originally Posted by ninelives TME, are you shooting jpg or raw? check your camera setting ( creative style). and also your awb.

Bro I'm using the 7D... only sharpening +1, the rest of the settings all set to default... I am using AWB all of the time except for mixed lighting. Regardless of the WB I use, even with flash outdoors, there is a red cast... I think it's inherent in the sensor... and the red channel is always blown... surprising a deep pink is ok... only fire-engine red, wine red, and every shade in between, the details are blown...

[simranjits]

What is your meter reading for the rose when you do spot metering?

[TME]

Originally Posted by simranjits What is your meter reading for the rose when you do spot metering?

I did try centre-weighted, pattern or matrix and spot metering for another photo that I shot in Austria this June... but not for this photo... in all three cases, in Austria, the reds were totally blown. I was shooting red roses again... in fact the histogram shows that all other colours are actually underexposed while the red is totally off the scale... don't know why either... haiz...

The following two shots are close-ups and with +0.5 EV and you can still see the veins in the flower petals at 100%. Photobucket's max size is 1024*768 but I can see the details on in PS at 100%. Outdoors, Vienna, 8-9am, summer (June), sun behind me.




The following are shot with 0 EV compensation. Again the red channel is totally blown... no idea why. Pattern metering, centre AF sensor. Outdoors, Vienna, 4-5pm, summer (June), sun behind me.




This is the only shot where there is some semblance of detail on the red petals.
Outdoors, Vienna, 11am - 12noon, summer (June), sun in front of me but shooting in the shade.


You will notice that in all cases, the details around the flowers are captured and can be seen... duh!