Colour rendition

Regarding color differences with Sigma...

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Hypothesis 1: Sigma glass is optimized for sharpness, not color rendition. This has been my going theory, until this morning. This isn't well understood by most folks, but different glass does have different color rendition. Even Canon is known to produce some glass with varying color transmission.

Hypothesis 2: Metering and Canon Standard picture profile results are somewhat impaired on third party glass... Canon Auto, which often chooses standard, (is in these three samples btw, I checked by toggling between the two), in turn prioritizes parts of the image with a proprietary selection criteria based off lighting, and may not produce the same results on lenses without correction data, namely third party glass. Likewise, I’ve found third party glass without correction data, leads to off-results particularly with evaluative metering. Spot or center weighted priority are a good mitigation for this, but are spot or center weighted thus not taking the entire scene into account. This leads to uneven results where parts of the image essentially blow out the highlights as the camera (mis)interprets uncorrected vignette as dark areas which center or spot ignore/give less weight, at the expense of not metering the whole scene. Then there is always good ol exposure compensation; I do recommend keeping it in the back of your head when shooting non-Canon glass in particular.

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Some important reading regarding Canon picture profiles aka JPEG profiles:

https://global.canon/en/imaging/picturestyle/style/faithful.html

"It is the feature of the Faithful style that color change is few by the deference of the light. In the examples, though the “Standard” is more vivid reproduction, at the part where strong light is hit, the “Faithful” maintains the color taste near the actual subjects."

https://www.canon.com.hk/cpx/en/technical/pa_New_Picture_Style_and_Sharpness_parameters_for_Ultra_High_Resolution.html

The default [Saturation] of “Fine Detail” is similar to “Standard” but the default [Contrast] is set lower than “Standard”. “Fine Detail” has Sharpness’s [Fineness] and [Threshold] both set to the minimum of [1], so even thin and low contrast edges can be sharpened to produce an image emphasizing fine edges and patterns. Unlike “Neutral” and “Faithful”, “Fine Detail” is intended for images that will be used straight from the camera, without post-processing (however we suggest you to take RAW images to enjoy the maximum post-processing flexibility).

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Fine detail, may be a good mitigation for color rendition since it has a traditional Canon saturation profile, but, not prioritized based off metering data. Also, although not described, Fine detail has a different highlight curve preserving more highlight data preventing blowouts... Note the curve on the right end has a different, curve. Auto, is using Standard in this case which I confirmed by toggling to Standard and nothing was changed.

So going with theory #2 for a minute, Fine detail would partially correct for the metering differences by preventing some blowout, and, giving less weight to metering data for color and contrast shifts... I might agree btw.

Original, reprocessed from RAW

Fine Detail used

Fine Detail, with 4-2-4 sharpness, +0.5 Contrast (to match standard). I found a whole stop of added contrast was a bit too much here, by my taste.

Original / SOOC

Fine Detail

Fine detail, 4-2-4, +1 Contrast

Original / SOOC

Fine Detail

Fine Detail, 4-2-4, +1 Contrast

I do prefer the Fine detail with 4-2-4 sharpness and added contrast (to match Standard, without being Standard); there is more of a Canon "feel" to the images. I was aware of the implications of lack of correctional data on metering and was ready to shift exposure comp or metering type, but, hadn't stopped to consider JPEG engine shifts, till today. There may be something to door #2 as alot of Canon's secret sauce is in fact, the secret sauce.

BTW, this can be done in-camera with customizing picture style, using Fine Detail, and adding +1 contrast, and adjusting Sharpness to 4-2-4. Lightroom not needed. It's an improvement in my book.

I may have been wrong about Theory #1... Most of Sigma's handiwork has been when bolted on a Sony body, which are not known for stellar SOOC JPEG rendition. Coupled to a Canon, Canon isn't throwing any weight (pun intended) to helping third party glass work well on it's platform because they want to sell their glass. A bit of help, does seem to be in order and some tweaking Fine Detail closes a good part of the gap I feel.

The differences seem subtle, until you're making changes in DPP4 you can see the detail recovered on my bearded dragon's head, my daughters left cheek, and the added contrast to my son's hair, the pink shifts in my daughters face, etc. Call me picky, but a little here a little there, adds up. This may be a theory (#2), but I feel it has teeth to it reviewing the impacts and the more Canon-esque rendition it imparts. It may be Sigma glass is comparable in color transition, but, is hampered by Canon's lack of embrace to third party glass like Sony has, maybe.

Folks will say color differences between platforms are small deal, till they're not. I'll say the differences here are small, but, the output from the adjusted workflow is more true to Canon, in my eyes. Canon's perceptual quality optimized "Standard" picture profile appears to be replicable with some success with modification to Fine Detail for third party glass is the moral here, and, it may explain a missing part of the equation here why third party glass lacks the oomph, on Canons...