Magenta looks scary for M240 with Summicron 35 ASPH

[adan]

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Have you ever tried to get Lavender flowers on film? Or even worse - Jacaranda trees.   Purple is the hardest colour to approximate in a photograph.

 

True, this.

 

Way back in the early 1980s, Kodak introduced E100N slide film with sensitivity curves specifically re-designed to improve rendering of purple and near-purples, in flowers and clothing.** When it came out, Kodak and the photo mags ran comparison pictures with E100N and Kodachrome (sadly, pre-Internet, and thus not archived), showing how much better E100N handled just such purplish colors. It all has to do with how the "dyes" or color-reflecting/emitting chemicals in flowers (and some clothing) reflect light - often in the wavelengths we can't see (infrared and ultraviolet). The M8's "purple" blues and blacks and grays were just the digital version of this problem.

 

http://www.askamathematician.com/2012/06/q-do-colors-exist/

______________

** particularlly some azo dyes - banned for health reasons later in the 1980s, thus making E100N less necessary, at least for fashion photographers.

[mjh]

Purple is the hardest colour to approximate in a photograph.

The problem with purple is that it is a hue without a corresponding wavelength. As far as physics is concerned, purple does not exist. While violet and red mark the ends of the visible spectrum, for eyes only able to discern three primaries, red, green, and blue, those extremes meet to form a colour circle, and where they meet there is purple – the hue that doesn’t exist.

 

Anyway, the issue with oversaturated reds hat little to do with specific cameras or lenses. It is an issue with the RGB colour space – any RGB colour space, be it sRGB, Adobe RGB, or any other. The primary colours red, green, and blue are the first to overexpose; cyan, magenta, and yellow are more robust. All you can do is to expose so that none of the three colour channels show clipping.

Edited June 17, 2018 by mjh

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[lct]

[...] Anyway, the issue with oversaturated reds hat little to do with specific cameras or lenses. [...]

 

How do you explain that reds clip so easily with the M240 and not with the CL or other cameras then?

[jaapv]

The problem with purple is that it is a hue without a corresponding wavelength. As far as physics is concerned, purple does not exist. While violet and red mark the ends of the visible spectrum, for eyes only able to discern three primaries, red, green, and blue, those extremes meet to form a colour circle, and where they meet there is purple – the hue that doesn’t exist.

 

Anyway, the issue with oversaturated reds hat little to do with specific cameras or lenses. It is an issue with the RGB colour space – any RGB colour space, be it sRGB, Adobe RGB, or any other. The primary colours red, green, and blue are the first to overexpose; cyan, magenta, and yellow are more robust. All you can do is to expose so that none of the three colour channels show clipping.

Surely, Michael, that is an oversimplification. Sure, a camera is an RGB device, but the choice of dyes in the Bayer filter will influence the colour rendering, Secondly, although the user interface of Lightroom and Photoshop is (largely) various RGB variants, the basic algorithms are LAB. LAB, by decoupling luminance from colour information, will make far more flexible colour control possible. I will and cannot go into the full implications, but suffice to say that one can work with colours that are either impossible or invisible in RGB colour spaces. What happens in the conversion from LAB to RGB (or other formats, for that matter)? Adobe knows, but I don't for sure.

 

Then we have the limited gamut of monitors and printers. sRGB is already getting obsolete, but Adobe RGB monitors are still only found in the high end and Prophoto screens are not yet realistically available on the market, as far as I am aware.

Printers can mostly handle Adobe RGB nowadays, but still suffer from the conversion to CMYK inks. Professional printers will have multiple ink cartridges to mitigate this problem, but many still manage on four - or even three.

And how many photographers have a fully colour-managed workflow? Digital colour is a mess, there is no way around it, I fear.

[Exodies]

How do you explain that reds clip so easily with the M240 and not with the CL or other cameras then?

Metering differences?

[jaapv]

Metering differences?

I would say not only that, but differences in the Bayer filter as well. The CL in my experience tends to exaggerate greens. And has a bias to expose to the left.

[mjh]

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Surely, Michael, that is an oversimplification. Sure, a camera is an RGB device, but the choice of dyes in the Bayer filter will influence the colour rendering, Secondly, although the user interface of Lightroom and Photoshop is (largely) various RGB variants, the basic algorithms are LAB.

Sure enough, but what the sensor delivers is RGB and even after converting from the sensor’s colour space to a standard colour space, the limitations inherent in any RGB colour space still persist.

 

Adobe RGB covers some highly saturated greens and blues that sRGB does not, and ProPhoto RGB features an even bigger gamut. Still another colour space won’t mitigate the problems with clipping in one of the three colour channels. Converting to Lab won’t solve these issues either. It’s just that Lab is bigger than any device-dependent colour space so raw development based on algorithms operating within the Lab domain won’t introduce any new limitations.

[jaapv]

I quite agree that the basic problem is clipping in the colour channels, as I posted from the beginning. The best way to avoid this issue is to expose a bit more to the left.

 

However, LAB is fundamentally different from RGB, as it separates luminosity from colour data.

It is quite possible to pull down the clipped magenta or green colour in the A channel, whilst maintaining brightness in the L channel, something that is quite impossible in any RGB space. And that helps when you have blown a colour highlight. It is not about the gamut in that case, but about colour intensity vs. brightness.

[Michael Geschlecht]

Hello Fabregaszy,

 

Welcome to the Forum.

 

There is a lot of good advice from many people here. To add to this:

 

Photos of some flowers contain colors that sometimes do not appear to be the same colors that those flowers are in life.

 

This is because, as Andy wrote in his Post #21 above: Certain flowers, as well as certain other things, sometimes reflect portions of the spectrum that digital sensors & films are sensitive to which are not visible to people. This invisible to us portion of the spectrum records as some color. Therefore adding to the exposure. Much like invisible to people Ultra Violet light was recorded on early black & white films. 

 

What this means is that SOMETIMES there will be a photo of a flower in which the flower"s color appears inaccurate. While the remainder of the photo is OK. This will tend to make the flower noticeably the wrong color. And therefore it will be harder to correct.

 

Best Regards,

 

Michael

[Gregm61]

 

You have handled the Reds wonderfully. Are you saying all you do, is avoid clipping and then fix the rest in Post?

 I would love to find a way where I'm not putting so much time into every shot.  Reds are a pain with the M240

Could you please give me more detail on your technique .......please?

 

 

If I am using the EVF I just watch the histogram and make sure the exposure does not "fall off" the right-hand side and let the shadow fall where they may. I can drag up shadows from the death on MP240 files, but highlight? Once they're clipped, they are clipped.

 

When not using the EVF and outside, in bright daylight and ISO 200, my exposures are typically 1/250 sec at f11 or any other reciprocal, allowing for up to 1.5 stops or maybe 2 if there's a lot of shadow detail. I just want to make certain I am as close as possible to the right-hand edge of the histogram without blowing over it.

 

A couple more from yesterday at the Arboretum where I was using the 35/1.4 FLE and 21mm f3.4 without the EVF..

 

 

 

 

 

Looking at these raw files in ACR before doing anything to them, you'd never think they would have amounted to anything, but I've learned my limits with these files and it's pretty much all on the highlights-end. I exposed to retain all highlight detail and processed for the shadows..these were very shadow-y in the mid-afternoon harshest light of the day. I didn't want to lose that look.

 

 

 

Edited July 1, 2018 by Gregm61

[fabregaszy]

Hi, all, here's some update:

 

1) For lens:

I switched to a 50 Summilux ASPH and with a B&W 846 filter, the red still looks a mess on camera LCD playback but better when import to Mac and shown on screen.

 

2) For RAW (DNG) converter:
I usually use Lightroom Classic CC for my DNG files. But recently I tried Capture One 11 with curiosity and was surprised that it could handle the color much better!
And for Lightroom Classic CC, turn down the exposure value may also help, but not as good as the Capture One result.

 

Here is a JPEG directly export from DNG using Capture One

 

Edited July 3, 2018 by fabregaszy

[fabregaszy]

I went a little further and trial with DXO PhotoLab and it performs even better, it almost the same as I saw with human eyes

 

And last the one by Lightroom (without adjust exposure)

 

What surprises me is that the JPEG output by camera body looks much similar with the Lightroom one, sad story.

Edited July 3, 2018 by fabregaszy