5D MARK II: PROBLEMS WITH REDS

[d_qb]

<p>May be a dumb question to some.<br>

Recently I purchased a 5D Mark II. Have spent some time shooting it in low light and noticed that red areas appear to be blown-out. Areas of red blotches appear in the blown-out cases.<br>

The problem appears to be worse as the ISO amps up: that is, worse at 1600 ISO than at 100ISO.<br>

I have been shooting at 6000K as I did previously with the 5D model.<br>

I started noticing the problem also with the 5D: for example shooting directly into the sun at sunrise, or shooting bushfire images. A red ring appears around the sun, or areas of red from the bushfire blows out.<br>

The blotching is different to blow-out areas (the latter caused due to overexposure).<br>

Would gratefully appreciate any assistance, both with respect to:</p>

 

<ol>

<li>Possible causes of the problem; and,</li>

<li>Solutions to rectify images (outside of re-touching, etc.) that have already been captured.</li>

</ol>

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<p> </p><div></div>

[d_qb]

<p>I should add here that the problems are apparent in both the Raw AND JPEG files.</p>

<p>The above, while a low res JPEG, highlights the problem: it's as if a tin of paint has been spilt over the image ( in this case, randomly around the sun).</p>

[PuppyDigs]

<p>All my EOS bodies easily blow the red channel when banging the HL up against the right side of the brightness histogram. I've noticed it with my 50D, 40D and 5D, especially with red flowers. However, I found an easy solution: use the RGB histogram and set exposure according to the red channel. I normally only need to back off -1/3 stop EC, sometimes -2/3, to keep it from going ape shit.</p>

<p>If you use DPP, realize also the red channel may be perfectly fine in normal or neutral pic styles but blow out in landscape pic style (landscape really pumps the red 'n blue channels). In other words, the RAW file is fine but the rendering to TIFF or JPEG is blown. You might consider using neutral pic style as a starting point and tweak parameters to taste without hosing your red channel..</p>

[d_qb]

<p>Many thanks for that: very helpful.</p>

<p>For these files I've already shot is there any easy solution to rectify them or are they buggered? For example, can I make any simple adjustments in DPP or PS to sort the problem?</p>

[johnlakkas]

<p>I am not sure if that's the cause but in the picture you uploaded it's quite not possible not to clip and burn highlights. In the big ring arround the sun the red channel probably clips first then the green clips as the sun appears full saturated yellow then the blue clips as well and the image gets white. Maybe you should try to underexpose and overexpose it in the raw development or try the hdr so you have every channel detail.</p>

[des adams]

<p>Nice image.</p>

[hawkman]

<p>Hugh,<br>

If you can provide a magnified crop of the artifact is I may be able to tell what it is.<br>

Also, try converting the RAW file with DPP (don't use ACR/LR) with all NR setting (both sliders) set to zero and see if the artifact remains. </p>

[johnlakkas]

<p>If you want to better this shot what I consider the best is to try ajusting the curves when you develop the raw so you can smooth out the highlights if clipping is in the raw, if not then lower the contrast/saturation and develop so it can look more natural. Hope I helped.</p>

[g dan mitchell]

<p>It is easy for a channel to blow out on DSLRs when that color is very intense in your scene. There are a number of situations in which one learns to "watch out." It can happen to the red channel when shooting flowers, and it can even happen to the green channel with foliage. With artificial lighting, anything is possible.</p>

<p>It is a good idea to look at the version of the histogram that shows all three color channels, and to watch very carefully for the black highlight indicator - and when you are working with colors that are intense in one channel it isn't a bad idea to underexpose a bit.</p>

<p>Sometimes you can rescue such images in post by playing around with color balance and saturation and perhaps curves/brightness.</p>

<p>Dan</p>

[frank kennedy]

<p>I suggest you use the temperature slider in DPP and back it down a little. It's my understanding that 6000K is the color temperature for cloudy days. The temperature is less for sunny days. I don't remember the numbers but I read about it in the camera manual. I don't have a manual here now. </p>

<p>My pictures get warmer as I increase the color temperature, cooler as I decrease.</p>

[photos of hans koot]

<p>puppy face is right, as an addition: I noticed the same with theatre shots with red or blue lights. My explanation is that if you look at the bayer pattern of the sensor you see the reds only cover one quarter of the sensor. When you shoot nearly pure red and blown out or near blown out youre camera is having hard times to get it right. I am interested in other opinions about this theorie.</p>

[d_qb]

<p>Thank you to all for your answers. Has been a terrific learning experience.<br>

Managed to sort the issue out (thanks Puppy Face): primarily by neutralising the Picture Style.<br>

In some cases I pulled back the saturation.<br>

Fortunately, the images were not buggered after all. Always learning in this game.<br>

Cheers,</p>