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03-01-2012, 07:52 PM   #1
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Problem Reds

I can't seem to get consistent results on reds from my K5...sometimes I think I have it figured out with various settings and then it goes all wrong anyhow. I spent an hour on PBase looking at male Cardinals and trying to determine if this was camera specific or just the K5? Although I did find some nicely done reds on Cardinals, the vast majority were blown out in areas or just plain wrong in hue. I couldn't see where any camera was better than any other camera....I thought some of the best were from the K20D and K7...and I do recall that I thought my K20D was pretty decent with reds.

Anyone else have any comments on this, any problems beyond "normal"? Even when I open a Raw Cardinal it is almost impossible to correct the tint, and blown reds are almost always present...sometimes a lot , sometimes a little, but always present.

Here are three I shot this evening (I have dozens of Cardinals in my yard, so I shoot them often) None of them are really accurate in color, although I worked hard to try and get them right. Another problem is that Cardinals are all differerent shades of red...making it even harder to adjust settings for accuracy.

Females are somewhat easier...less red.
[IMG] [/IMG]

This was a flaming red...blown reds galore!
[IMG] [/IMG]

This is the most natural of the three...he was several different shades of red, and I desaturated considerably to tone down the brightest shades.
[IMG] [/IMG]

I have also observed that the brighter they are the more the reds are likely to "smear and just become red globs, even if you slightly underexpose. Like I stated, I couldn't find any other camera that was consistently better.....is ther something about reds and digital that just don't mix well?

Regards!

03-01-2012, 08:06 PM   #2
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Hey Rupert,

Reds are tricky with the sensors. I've shot cardinals which took tons of PP to salvage because of the 'bleeding' and smearing. Other times, they've come out beautifully. That's through and *ist ds2, k10 and k7. I haven't tried birds with the k5 yet...kind of got out of them...but I expect the k5 would have a similar reaction.

I don't know what settings you're using, but if I remeber correctly, I lowered the contrast and saturation in-camera and shot raw to mitigate the risk.

What settings are you using? Including aRGB or sRGB?
03-01-2012, 09:43 PM   #3
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sRGB...usually decrease the saturation and contrast if shooting reds, but that doesn't always work either. Getting close seems to help, since it keeps more detail in the shot....I always shoot Raw+.
In looking at PBase Cardinals, I thought the Nikons did better, then I realized it was just that there were more of them...in proportion, none of the cameras seemed to be immune to the bleeding and blowout of reds.
I do think my K20D did reds better, but will need to give it a test alongside my K5 to be certain.

Regards
03-02-2012, 12:10 AM   #4
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I have the feeling that DA limiteds have more precise colour reproduction. Try the Da 70 ltd.

03-02-2012, 03:40 AM   #5
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Hi Ruprt

Looking at your sampling here I must say there does not appear to be much wrong with the reds on my monitor. The do not look optimal but are not bad just the same. However, I can't say because I do not know these birds. Looking at the EXIF's I see that all of them were taken under Auto White Balance settings. Since The K-5 Auto White is usually pretty good it would have been better to post some "untouched" sample pics to see what the problem is.

As it stands at the moment because of your PP work it is hard to say or see what your complaint is. I think your manipulated images, as far as the reds are concerned, are not too bad. I certainly do not see any of the red burn out you are complaining about.

Now I am not familiar with Cardinals so I can't say what looks right/wrong but your PP work has certainly effected the red rendering. As usual I have taken the time and "put my words where my eyes are" (which often gets me in to big trouble) and have created some corrections. This time however I have only applied the stock standard colour correction functions provided by several programs. Simply only a one click correction. No further input. So please no arguing as to which picture looks better I only wanted to see how a colour cast correction would effect the red in your pics. As you can see the reds have changed quite a bit and the corrected images differ very little. Now you tell me which of the birds look closer to reality. I have no idea.

For interest sake I include a shot with a lot of red in it which I shot with the K-5 in the south of France last year. I think the red behaves pretty well here with the light shining through the fabric. What do you think ?

Greetings

Last edited by Schraubstock; 09-16-2012 at 05:31 PM.
03-02-2012, 10:08 AM   #6
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Yes I complaint about that too last year when I did fielshockey and all red socks where blown out. Underexpose is the way to trick this and to use Hi-light expansion.

https://www.pentaxforums.com/forums/pentax-k-5-forum/160410-red-channel-overload.html
03-02-2012, 03:33 PM   #7
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QuoteOriginally posted by Schraubstock Quote
Hi Ruprt

Looking at your sampling here I must say there does not appear to be much wrong with the reds on my monitor. The do not look optimal but are not bad just the same. However, I can't say because I do not know these birds. Looking at the EXIF's I see that all of them were taken under Auto White Balance settings. Since The K-5 Auto White is usually pretty good it would have been better to post some "untouched" sample pics to see what the problem is.

As it stands at the moment because of your PP work it is hard to say or see what your complaint is. I think your manipulated images, as far as the reds are concerned, are not too bad. I certainly do not see any of the red burn out you are complaining about.

Now I am not familiar with Cardinals so I can't say what looks right/wrong but your PP work has certainly effected the red rendering. As usual I have taken the time and "put my words where my eyes are" (which often gets me in to big trouble) and have created some corrections. This time however I have only applied the stock standard colour correction functions provided by several programs. Simply only a one click correction. No further input. So please no arguing as to which picture looks better I only wanted to see how a colour cast correction would effect the red in your pics. As you can see the reds have changed quite a bit and the corrected images differ very little. Now you tell me which of the birds look closer to reality. I have no idea.

For interest sake I include a shot with a lot of red in it which I shot with the K-5 in the south of France last year. I think the red behaves pretty well here with the light shining through the fabric. What do you think ?

Greetings
I think the Photoshop Auto is the closest, but some detail is lost due to the loss of exposure in parts of the bird. Hard to tell at these small sizes though? I guess Cardinals are not a good example, due to their widely varying coloration....some fire engine red...some more orange...and some in-between or even mixed. At any rate, I don't blame the K5...it seems a universal problem when encountering reds for most any camera.
Regards & Thanks!
03-02-2012, 03:35 PM   #8
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Ron....I agree that it is the best solution I have found too, but it still doesn't always work, and the hue is often still wrong. Still, it is the best chance at getting it right...or closer!
Regards & Thanks!

03-02-2012, 07:24 PM   #9
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First, I love the Cardinal shots. They look just like they do in my backyard whenever they appear.

My K20D rarely smears reds, but it seems to love to do it with Bougainvilea flowers. I have a Canon that routinely smears reds. I think it is a universal problem from what I have read. I THINK I solved it last summer when shooting red cars by setting up my camera to display an RGB Histogram so that I can watch for overexposure in the red channel. Then I recover in post if needs be. It seems to work.

I don't have a K5, so I can't speak to that camera's performance in the red channel.

Hope this helps somewhat.
03-03-2012, 02:17 PM   #10
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Is this not potentially a problem with all Bayer sensors? After all, there are much more green filters than either blue or red. I've never understood the discrepancy, and would really appreciate if someone could explain why.

David
03-03-2012, 03:07 PM   #11
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I always understood that because the human eye is most sensitive to green light you want the measurement across an image to be the most accurate in that wavelength. So in the interpolation algorithm the Bayer filter provides double the information in green levels.
03-03-2012, 03:19 PM   #12
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I haven't had too many cardinal opportunities but some of my red flower macro's have been horrible. Those were with the K10D, not the K5 as I just got mine in the fall and we will still be living in the B&W world of winter until May. I've also had issues with yellow getting blown out. I can usually get them looking ok in PP but they really aren't quite the same. I think this may be more of an issue with digital sensors in general.
03-03-2012, 03:31 PM   #13
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Not saying it is perfect...it isn't......but my little X10 seems to get the colors more right than any camera I have used before......could be the EXR sensor, I don't know, but it does nicely on all colors most of the time. Of course, it is not too good at wildlife, just too short a range.......and anyhow, Otis hates it!
Regards!
03-03-2012, 04:04 PM   #14
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QuoteOriginally posted by Col Quote
I always understood that because the human eye is most sensitive to green light you want the measurement across an image to be the most accurate in that wavelength. So in the interpolation algorithm the Bayer filter provides double the information in green levels.
Thank you - I have no way of telling if you are correct, but that is by far the most reasonable answer I have seen.

David
04-07-2012, 07:06 PM   #15
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I just learned of the red sensitivity today while doing some test shots with my new-ish K-5. Red flowers in normal exposures almost completely blown out...too little dynamic range to salvage in camera raw. I posted a new thread on it, since I hadn't seen this one.
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