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Issues Of Colour  
User currently offlinePsych From United Kingdom, joined Nov 2004, 3048 posts, RR: 58
Posted (7 months 3 weeks 12 hours ago) and read 3018 times:
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Regular readers to this and the 'Feedback' forum will be very familiar with discussions relating to colour - was it an accurate representation of the scene; is there a cast; is there a natural hue?

Looking through some images I recently took on a lovely morning at Manchester, I came across a stark example of the differences camera angle can make to the 'feel' of colour in an image. So I thought I would share them here and hope that those with greater expertise could give some little explanation re what is actually going on. This may even inform those debates about what constitutes 'accurate' colour in an edit.

Below you will see two images of a departing Airbus, taken a few seconds apart. The images are completely unedited apart from resizing for upload in the thread. For those familiar with the environment, I was standing looking in a north westerly direction, across Runway 23R, towards the Concorde hangar. The low sun at this time would have been roughly at my '5 o'clock', behind me. In the first image I am looking slightly to the right - I would say roughly at about 340 to 350 degrees:

To the right


In the next image I have tracked the aircraft as it passed to the left of perpendicular - roughly pointing 290 degrees, or thereabouts (just rough guesses here, to illustrate the point):

To the left


Both images are taken with the same camera settings, so that is not influencing anything. The differences are more apparent if you click on the images above, opening them outside of the thread in a separate window, and switch between them.

The very significant difference in hue (or cast, if you prefer) is solely to do with the angle of the subject relative to the sun. This is particularly apparent in the difference seen in the white fuselage (and, of course, the colour of the blue sky).

Is the frame to choose for uploading just a matter of taste, or is one more likely to be considered to 'have a cast'? They certainly have a different feel - one is 'warm' and the other 'cold'. Is one more likely to be rejected? If I have to significantly edit the colour in one (for me it would be the second one, with its notable blue look, as compared to the 'warmer' shot 'to the right') am I unnecessarily altering reality? Is there any colour issue that needs to be 'corrected'?

Food for thought, and hopefully debate.

All the best.

Paul

28 replies: All unread, showing first 25:
 
User currently offlineMcG1967 From UK - Scotland, joined Apr 2006, 506 posts, RR: 1
Reply 1, posted (7 months 3 weeks 11 hours ago) and read 2984 times:

Paul,

what were the white balance and metering settings?

I've also noticed that changing between Adobe Standard, Camera Faithful, Camera Neutral, Camera Portrait, Camera Landscape and Camera Standard settings in either Lightroom or Adobe Camera Raw in Photoshop can alter the colour and appearance of a shot.

Mark


User currently offlineSilver1SWA From United States of America, joined Mar 2004, 4761 posts, RR: 26
Reply 2, posted (7 months 3 weeks 11 hours ago) and read 2982 times:
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Paul,

Was your camera set to "Auto" white balance? If so, the difference is due to the camera calculating a different temp between shots. I get this a lot when in AWB.



ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
User currently offlinePsych From United Kingdom, joined Nov 2004, 3048 posts, RR: 58
Reply 3, posted (7 months 3 weeks 10 hours ago) and read 2968 times:
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Thanks Mark and Ryan.

Yes, the camera was set to AWB, which I assume is the setting for the majority of photographers in 'normal' daytime conditions. The other settings were f/8, which led to a shutter speed of 1/800th.

I'd be interested to understand more about what causes that significantly different 'calculation' in temperature when, effectively, the scene is so similar. As you say, Ryan, this often happens - I use AWB all the time generally. Usually I prefer the 'warm' feel that you get with a Canon photo.

These kind of issues highlight well the differences between RAW and JPEG photography where, with the former, adjusting the colour temperature in post-processing is possible.

Cheers.

Paul


User currently offlinemjgbtv From United States of America, joined Jan 2008, 801 posts, RR: 0
Reply 4, posted (7 months 3 weeks 10 hours ago) and read 2967 times:

Quoting Psych (Thread starter):
Is the frame to choose for uploading just a matter of taste, or is one more likely to be considered to 'have a cast'?

Interesting question. My instinct is to say 'whichever one looks most like your eye saw it', and I would probably use the sky as a reference for that since I'm sure the sky color did not really change that much from one angle to the other. However, given how much is going on inside the camera I wonder if one image is actually more representative of the live scene or not. Perhaps the most accurate rendering would have the sky color from one and the aircraft from the other. Unfortunately not the most helpful answer, I guess...


User currently offlineLH526 From Germany, joined Aug 2000, 2347 posts, RR: 14
Reply 5, posted (7 months 2 weeks 6 days 17 hours ago) and read 2864 times:
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AWB will change your white balance frame by frame and alter it accordingly. Just get a decent grey card, meter your WB and exposure with the grey card and you are set.


Trittst im Morgenrot daher, seh ich dich im Strahlenmeer ...
User currently offlineckw From UK - England, joined Aug 2010, 730 posts, RR: 16
Reply 6, posted (7 months 2 weeks 6 days 17 hours ago) and read 2862 times:

Its tricky stuff - colour temperature will vary according to the angle of the sun - the more extreme the angle, the warmer the colour temp (all else being equal). This is complicated by the fact that the light is reflecting at different angle off the aircraft, and the nature of the surface will have an effect on the look of the colour. Extreme examples of these can be seen in for example variations in rainbows or cars painted in pearl finishes.

AWB is tricky and may be performed in a number of ways - working with specular highlights, averaging colour of the image, assuming areas of white etc. more probably a combination of these, and of course with the manufacturer's own bias as to what makes a pleasing picture.

The human eye is also a problem - consider how good our own AWB is such that white pages appear to be white under nearly any lighting setup!

Add to this the paint itself - ever try to touch up a car with "white" paint? Is any paint "pure white"? In the case of the SAS, I think the fuselage is actually a light grey. Is it a neutral grey? I found a references which stated the colour is Pantone 9083 which translates to an RGB of 211/205/199 - definitely a bit warm ... however, this is also reflecting a blue sky, so would be somewhat neutralised.

I think the only way to get an accurate colour balance is to take a reading off a grey card using exactly the same light conditions as on the subject. No problem for a static model, but somewhat impractical for a moving subject (if you want more than one shot). But for aircraft remember that your subject is some distance from where your grey card will be. Reflected light from the ground and sky may be significantly different on the subject than the grey card. (and remember, your camera is always recording light reflected from the subject, not light falling on the subject).

Does it matter? If you are recording colours for reference purposes, then obviously yes (for example, to replicate a colour scheme for a model), though even then can we assume the paint was identical in every case? Some reading around suggests minor variations in colour depending where a re-spray is performed.

Personally I would go with "does it look right". Frankly, unless someone has access to colour chips and exact values of the colours can be determined which can then be reproduced through colour correction, then nobody is producing "accurate" colours - probably impossible anyway, as the spectrum available digitally falls far short of real world colors!


What you can do is look for obvious casts - so the probably "quite close to white" tail logo would be worth examining with a colour picker.


Cheers,

Colin



Colin K. Work, Pixstel
User currently offlineThierryd From Luxembourg, joined Dec 2005, 2068 posts, RR: 51
Reply 7, posted (7 months 2 weeks 6 days 15 hours ago) and read 2840 times:
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Hey Paul,

in addition to what the other guys said, from a screener's point of view both those images look acceptable to me (from a color perspective). The first one shows a light hue, if I may call it that, while the second one is neutral but, given the low sun angle, the photo is perfectly fine.

Cheers,

Thierry



"Go ahead...make my day"
User currently offlinePsych From United Kingdom, joined Nov 2004, 3048 posts, RR: 58
Reply 8, posted (7 months 2 weeks 5 days 10 hours ago) and read 2725 times:
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Thanks to all for your input.

I'd be very happy to read anything more 'technical' regarding how the angle makes a difference to the camera, if there's anyone who can oblige. The issue reminds me of how polarising filters darken the sky/affect the image differently when at particular angles to the sun.

To answer one point, my view is that the first of the photos in question - the one 'to the right' - is definitely a more accurate representation of the light as it was, which certainly didn't have the colder, blue aspect noted in the other one.

My experience at Manchester in a morning, with the sun behind, is that this is often something that happens when a series of photos are taken, from right to left (with the sun behind). It is as though they move to 'warm' to 'cold'.

Paul


User currently offlinevikkyvik From United States of America, joined Jul 2003, 9703 posts, RR: 27
Reply 9, posted (7 months 2 weeks 5 days 9 hours ago) and read 2715 times:
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Quoting Psych (Reply 8):
My experience at Manchester in a morning, with the sun behind, is that this is often something that happens when a series of photos are taken, from right to left (with the sun behind). It is as though they move to 'warm' to 'cold'.

Wouldn't surprise me. Depending on where the sun is, the sky can vary in color significantly, both with respect to horizontal angle and vertical angle of the shot. I'm guessing the camera's AWB takes that into account.

To me, it's similar to shooting in full auto or aperture priority mode, where the camera sets the exposure. I can get rather different exposures from the same series of shots (and hence, I shoot full manual).

I haven't used AWB in a long, long time (even when shooting in broad daylight). I try and set the white balance to represent what I see when I took the shot. Even with night shots, I'll usually set it to be approximately what I see, and then I'll re-white-balance in post to tone down the orange from sodium lighting, if necessary.

Anyway, I agree with Thierry, color looks fine in both screening-wise.



"Two and a Half Men" was filmed in front of a live ostrich.
User currently offlinespencer From United Kingdom, joined Apr 2004, 1635 posts, RR: 17
Reply 10, posted (7 months 2 weeks 2 days 8 hours ago) and read 2586 times:

No offence to your good self Paul, or anyone else for that matter; but when we're discussing acceptance criteria such as this then the fun for me has really gone in this hobby!! So very petty, it's unreal! A website, read this one if you like, is basically governing how we shoot. Sure, we as photogs decide whether we want to upload but c'mon man, it's getting stupid!
Spencer



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User currently offlinejid From Barbados, joined Dec 2004, 972 posts, RR: 32
Reply 11, posted (7 months 2 weeks 2 days 8 hours ago) and read 2581 times:

Quoting LH526 (Reply 5):
AWB will change your white balance frame by frame and alter it accordingly. Just get a decent grey card, meter your WB and exposure with the grey card and you are set.

no use at all in this situation LH526 as you can only set your WB to one particular angle. In this case just shoot in RAW and do your colour adjustment in post processing. But the question of representation is a good one, do you leave the shot 'as seen' or do you adjust your image to make it look more 'acceptable' ?

Jid



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User currently offlinePsych From United Kingdom, joined Nov 2004, 3048 posts, RR: 58
Reply 12, posted (7 months 2 weeks 2 days 7 hours ago) and read 2565 times:
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Hello Prof. Webb! All well I hope.

Spence - in defence of the thread, a key motivation was to understand a little more about the physics of why the colour is so notably different over a relatively small arc. Clearly something relating to angles of light and the 'brain' of the camera, altering the white balance.

I'm interested that both are considered okay for screening. To me that's a positive situation regarding some flexibility because, to my eye (and I was there), one looks right and the other looks wrong.

Cheers.

Paul


User currently offlinebaldwin8 From Canada, joined Aug 2007, 61 posts, RR: 0
Reply 13, posted (7 months 2 weeks 5 hours ago) and read 2411 times:
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Good reading in this thread. I've been working and photographing/scale modelling in military/civilian aviation all of my adult life and I can tell you their is no such thing as neutral. Maybe it is just the low sun angles way up here Canada, but colour casts are constantly changing. I've had a number of rejections recently for colour casting and contrast and just pulled a few from my upload queue and will just let the last few get screened and that will be enough for me. The editing has taken the fun out of the hobby for me.

User currently offlinesovietjet From Bulgaria, joined Mar 2003, 2550 posts, RR: 17
Reply 14, posted (7 months 2 weeks 3 hours ago) and read 2398 times:
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I agree with spencer, it seems like a very nitpicky subject we are talking about here. Yea there is a change in the color between the two shots. I have noticed it before in my shots too and I almost always use AWB. Doesn't really bother me, as I can "fix" it in RAW and even in JPEG although it is a bit harder. But in 99.9% of cases it is "close enough". Eventually in post processing removing a color cast is very easy. Gray cards? Seriously? Those would only work for one specific shot, say a side-on. Then your shots as the aircraft approaches and goes away from you will probably have the "wrong" white balance. I think in all the years I have been photographing at airports, bases, airshows, etc... I have seen maybe one person use a gray card. They are useful, but not for moving aviation IMHO.

User currently offlinetrvyyz From Canada, joined Oct 2004, 1369 posts, RR: 10
Reply 15, posted (7 months 1 week 5 days 6 hours ago) and read 2291 times:

You guys take this too seriously. For the OP to compare two shots, you should have set the WB to a constant (eg. preferably in kelvin or even daylight), then check for difference between two shots to say that the color changed. You cannot put on AWB and claim the lighting or color changed, there is more than one variable that could change. People who are obsessive about this can use the grey card, expo disc or custom white balance. Or simply use raw and render the temperature that you feel right either based on the actual scene or your taste. There is nothing wrong or right if done properly.

[Edited 2013-12-03 13:44:41]

User currently offlinePsych From United Kingdom, joined Nov 2004, 3048 posts, RR: 58
Reply 16, posted (7 months 1 week 5 days 5 hours ago) and read 2279 times:
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I'm fascinated with the way this discussion has been taken on different tracks, and the apparent irritability with different contributions.

To address the comments above, the thread is not about getting perfection from the point of view of white balance; it was to understand more what factors create the very apparent shift in the colour seen in the two examples. Basically it was about getting a physics lesson and understanding more about the way light and camera technology work. Then there are obvious potential links into discussions about colour casts, screening criteria etc, should the discussion have gone that way.

Nothing wrong with such a discussion on a Photography Discussion Forum.

Paul

[Edited 2013-12-03 14:24:14]

User currently offlineSilver1SWA From United States of America, joined Mar 2004, 4761 posts, RR: 26
Reply 17, posted (7 months 1 week 4 days 19 hours ago) and read 2246 times:
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Quoting trvyyz (Reply 15):

I agree that AWB had everything to do with the differences between the two shots. But to be fair to Paul, his question pokes at what happened between shots, taken at different angles relative to the sun, that caused the camera to evaluated a completely different result from one shot to the next. I think it's an interesting discussion.



ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
User currently offlineckw From UK - England, joined Aug 2010, 730 posts, RR: 16
Reply 18, posted (7 months 1 week 4 days 18 hours ago) and read 2244 times:

The question comes down to "what is right" - if there is a right! What do you expect from AWB? Do you want it to neutralise all colour casts - ie. always render a white surface as white? Then what about shots at sunset - would you expect an orange cast to be eliminated? Surely that looks wrong.

It is also important to consider that there is I think a difference between a choice of color temperature (which is pretty much confined to shifts from yellow to blue) and colour casts which might include any color.

I use AWB (as a starting point) and shoot RAW. In post I'll often select a white point to eliminate any colour casts, but having done that will often want to manually adjust the color temperature to warm or cool the shot to make it closer to how I remembered the scene - or make it simply more pleasing to my eye. I also think photography is more art than science.

Cheers,

Colin



Colin K. Work, Pixstel
User currently offlinePsych From United Kingdom, joined Nov 2004, 3048 posts, RR: 58
Reply 19, posted (7 months 1 week 4 days 14 hours ago) and read 2229 times:
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Quoting Silver1SWA (Reply 17):
But to be fair to Paul, his question pokes at what happened between shots, taken at different angles relative to the sun, that caused the camera to evaluated a completely different result from one shot to the next. I think it's an interesting discussion.

Thanks Ryan - perfectly put.

Colin - your knowledge on things photographic never ceases to impress me. I can feel myself wanting to ask you to describe the difference between 'hue' and 'cast', which has always been one of my bugbears.

Cheers.

Paul


User currently offlinetrvyyz From Canada, joined Oct 2004, 1369 posts, RR: 10
Reply 20, posted (7 months 1 week 4 days 13 hours ago) and read 2222 times:

Quoting Silver1SWA (Reply 17):
what happened between shots, taken at different angles relative to the sun, that caused the camera to evaluated a completely different result from one shot to the next.

the angle of incidence and angle of reflection have changed, even the amount of light hitting and reflecting would change. So, the exposure would also change and these caused the awb to jump more than it would need to compared to the temperature change (that also would have changed).
As Colin said, making white 'white' doesn't solve (like the custom WB) in all lighting conditions eg. golden hours. To get the color to what you'd need is raw (possibly in awb or even kelvin for jpg preview) and fine tuning in PP.



[Edited 2013-12-04 06:36:59]

User currently offlineckw From UK - England, joined Aug 2010, 730 posts, RR: 16
Reply 21, posted (7 months 1 week 4 days 2 hours ago) and read 2196 times:

Quoting Psych (Reply 19):
describe the difference between 'hue' and 'cast'

Well I'll give it a go - but I don't think I can directly compare 'hue' and 'cast'. Consider the following sentence:

"The setting sun caused a cast of an orange hue"

Basically a "hue" is a component of colour. Other components include lightness and saturation - you'll be familiar with the combination from any photo editing software - essentially, it's what makes colour coloured (or how the reflected light triggers the sensors in our eyes).

So everything we perceive as colour has a hue, including color casts. Important to note that the hue is determined by the reflection of light off the surface, and so is different to colour temperature.

A 'cast' can perhaps be defined (photographically) as a hue which affects the entire image - an extreme case would be sepia toning. It may be more visible in certain parts of the image (highlights for instance) but it is by definition uniform which means is can usually be easily corrected.

For completeness it is worth saying that colour temperature is in effect the colour of the light itself - technically it is a measure of energy. For most purposes, the colour temperature can be thought of as falling between cool (blueish) and warm (orangey).

So returning to cast, we may find an image has a greenish or cyan cast - we easily perceive this as "unnatural" so is undesireable. However, the warm glow caused by a sunset is also a cast - one we generally like.

What should we aim for? Some people use a grey card (or 18% reflectance card) to set white balance. This is fine, but note that it is using reflected light. So it is reflecting the colour of the light. It is only truly grey at midday when the sun has a colour temperature of 5500 - 6000K. What a grey card tells you is what grey looks like under a particular type of light - it may still result in a colour cast.

Of course if you use a grey card, and include it in a shot, you can use that grey card to set a colour filter in photoshop thereby removing the cast caused by the light itself.

The question is, should you do so? IMHO "neutralising" the colours of a dawn or dusk shot is no different to adding an orange filter to a daylight shot to simulate a sunset - I've no issues with doing that, but understand that the "neutralised" shot is just as inauthentic.

Of course real life photography gets more complex - the environment comes into the mix. Cloud cover can affect the colour temperature. If a white aircraft is parked on green grass, the undersides will look greenish (reflected light). Should this be corrected?

One thing to watch for is the difference between localised colour shifts caused by reflected light as opposed to an overall colour cast. The greenish effect mentioned above might catch the eye, but if you apply a general correction to this, you'll find the topsides and sky going too magenta. And sadly, our eyes are not scientific instruments - we respond differently to different colours - and this can vary with individuals. Personally I'm very sensitive to cyan casts, but much more tolerant of yellow casts.

Clear as mud right?  

As for screening - well ultimately objective criteria are being applied to a subjective area. Far from an ideal situation. In the "real world" photo editors don't give a damn about objectivity. The shot works or it doesn't. The best photo editors have a good eye and instincts, and trusts them. Anyone shooting professionally will have many times experienced utter bewilderment as to why their perfect shot wasn't used!

Cheers,

Colin



Colin K. Work, Pixstel
User currently offlinePsych From United Kingdom, joined Nov 2004, 3048 posts, RR: 58
Reply 22, posted (7 months 1 week 2 days 14 hours ago) and read 2116 times:
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Excellent stuff, Colin. Thanks so much for taking the time.

Can I use another example to get a little more clarification:

Here are two photos of one of my favourite airline schemes - favourite primarily because of the way it looks in the 'warm' light of a low sun (and by 'looks' I guess I mean the way the paintwork absorbs and reflects the ambient light).


View Large View Medium
Click here for bigger photo!

Photo © Paul Markman
View Large View Medium
Click here for bigger photo!

Photo © Paul Markman



I would argue that both these shots accurately portray the scene as it was when the photo was taken. So I believe neither photo has a 'colour cast'. Evidently they look very different indeed - all to do with the light, which differed primarily due to its angle in the sky. As we all know, a low sun results in warmer colours - and therefore 'hue', as I understand it - itself to do with angles of light; amount of atmosphere the light travels through; more scattering of the blue end wavelengths etc.

So does the 'warmer' shot have an orangey 'hue' but no colour cast? I think so. For me, the second SAS Airbus shot in the first post has a blue colour cast due to the AWB creating an image that did not accurately reflect the actual colour in the scene. That 'blue feel' was unrelated to atmosphere, lighting, or anything else in the actual environment at the time. Hence I would be happy to alter that in editing.

In essence, rightly or wrongly, in my head I have associated 'hue' with 'natural', and 'cast' with 'unnatural'. For some reason I don't think of warm sunsets as showing a cast because, in my mind, part of the definition of a cast is that it is unintended/unwanted. This may simply be my own lack of thorough understanding of the issues.

Cheers.

Paul


User currently offlinevikkyvik From United States of America, joined Jul 2003, 9703 posts, RR: 27
Reply 23, posted (7 months 1 week 2 days 3 hours ago) and read 2085 times:
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Quoting Psych (Reply 22):

In essence, rightly or wrongly, in my head I have associated 'hue' with 'natural', and 'cast' with 'unnatural'. For some reason I don't think of warm sunsets as showing a cast because, in my mind, part of the definition of a cast is that it is unintended/unwanted. This may simply be my own lack of thorough understanding of the issues.

Not sure that there's any difference between a naturally-occurring cast and an artificially introduced cast. After all, people may perceive them differently anyway.

I'd say this photo has a rather large color cast, but it's a pretty accurate reflection of the light at the time:


View Large View Medium
Click here for bigger photo!

Photo © Vik S




"Two and a Half Men" was filmed in front of a live ostrich.
User currently offlineckw From UK - England, joined Aug 2010, 730 posts, RR: 16
Reply 24, posted (7 months 1 week 1 day 8 hours ago) and read 2031 times:

A "cast" is technically any thing which alters the actual color of the subject. The cast may be caused by natural (low sun) or articificial means (postprocessing). A cast affects the whole image and is neither a good thing or a bad thing. If you know the subject is white, a cast is anything which deviates from white.

A "hue" is the color of the cast - so we can say this picture has a blue cast or an orange cast.

Confusion arises because in practice we tend to use "cast" in a negative sense. (You seldom hear a picture praised because of a pleasing orange cast).

I think in the case of the first Etihad shot there is definitely a warm "cast" - but because it is caused by the low sun, it is natural in appearance.

Cheers,

Colin



Colin K. Work, Pixstel
User currently offlineCaptainKramer From United Kingdom, joined Feb 2012, 225 posts, RR: 0
Reply 25, posted (6 months 3 weeks 4 days ago) and read 1766 times:

Hi Psych,

I just want to add that I think the biggest pitful of using AWB, especially in Jpeg is that the Camera is chasing a colour temperature setting that is determined in the factory, carried out in a room most likely and not outside in the real world. (I'm not certain it can be altered in the menu.) So the Camera is either adding or subtracting red or blue to make white appear white, but the white value might be optimized to shooting in Summer and not Winter, as the shot of the SAS plane with the blue sky seems particularly Cool in appearance.

It would be interesting to see how AWB performs Midday in Summer, especially to see how the Camera attempts to render white as white, with all things being equal.

I have experimented quite a bit with Colour Temperature settings during Winter time and have arrived at a Colour Temperature hovering around 6000 to 6400 Kelvin leaving shots with a slightly warmer feel to them, especially if shooting exclusively in Jpeg, when the sun has reached it's highest point during Winter on a clear, cloudless day.

I just want to add that the Sun always burns brightly in Space 24/7. It's the Atmosphere itself which plays a major role in rendering the Colour Temperature of Light. (The amount of light illuminating the scene can also have an effect on Saturation levels. Less light the higher the Colour Saturation, i.e a Blue Sky appears more saturated in Winter, conversely more light = less Colour Saturation, especially during Middays in Summer). So as the Sun sets the Colour temperature shifts towards the Red end of the Colour Spectrum, the light physically passes through more Atmosphere to reach its subject, often filled with man made particles/particulates, such as Pollution/Smog and naturally occurring particles such as Dust. In Summer high overhead at Midday the Sun physically passes through less Atmosphere so any particles suspended in the air will have less effect. (Unless your in LA where Smog can act like a giant Tobacco filter!).

Another influence on Colour Temperature is the Sky itself. The Sun is the main source or Key Light that illuminates the scene, but on a clear day the Blue Sky itself acts as a Fill Source, helping to fill in the subject i.e. a Plane with a Cool Bluish Colour Cast (especially in the shadows). In Winter the Sun also remains low on the Horizon creating a High Contrast situation. The shadows are generally darker making the Cool Blue Colour Cast less apparent, but in Summer can become more visible in certain low contrast situations.

Cheers Frank


User currently offlineCaptainKramer From United Kingdom, joined Feb 2012, 225 posts, RR: 0
Reply 26, posted (6 months 3 weeks 3 days 12 hours ago) and read 1721 times:

I also want to add one thing, regarding the departing SAS A320 and the use of AWB Mode.

In the first shot the Camera is pointing at a scene where the subject, in this case an SAS A320 departing at take off, has a cream coloured livery, it is not pure white, it appears warm. Also the sky in the background is not blue, but appears to be filtered through a light haze.

So the AWB goes to work, not knowing that the plane livery is not pure white, so subtracts the red bias present in the livery and adds blue to make an approximation of white. So by the time you take the second shot the AWB applies those values to the second shot, and that is why most likely the Hull of the SAS A320 now appears white. The background also has had the red subtracted, adding blue and as a result renders the sky a bluer tinge than was found in the first shot.


User currently offlineviv From Ireland, joined May 2005, 3142 posts, RR: 29
Reply 27, posted (6 months 3 weeks 3 days 11 hours ago) and read 1714 times:

What a very interesting discussion.

In brief, I have noticed the same phenomenon when shooting in the early morning with the low sun directly behind me and aircraft passing in front of me from left to right and getting closer to me until directly in front.

I am no expert and rarely use AWB, but it seems to me that reflection, refraction and angle must all play a part.

I will try a series of shots using a constant WB and then another series using AWB to see what happens.



Nikon D700, Nikkor 80-400, Fuji X Pro 1, Fujinon 35 f/1.4, Fujinon 18 f/2
User currently offlinePsych From United Kingdom, joined Nov 2004, 3048 posts, RR: 58
Reply 28, posted (6 months 3 weeks 3 days 4 hours ago) and read 1688 times:
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Thanks very much for the recent additions to my thread.

This all makes it more like the discussion I was hoping for at the outset - and the type of thread I enjoy reading on this Forum.

A very Happy Christmas to all.

Paul


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