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Gerbera
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PostPosted: Tue Jan 31, 2023 12:15 am    Post subject: Gerbera Reply with quote
First one is Mamiya 120/4 at f/4 and second one is Canon FD 200/4 at f/4.
Different red rendition.
Minimal PP.






PostPosted: Tue Jan 31, 2023 5:51 am    Post subject: Reply with quote
Like 1 very nice!


PostPosted: Wed Feb 01, 2023 4:43 pm    Post subject: Reply with quote
Your comparison demonstrates clearly that Mamiya slightly oversaturates reds while Canon adds some blue/magenta (seen especially well in the background green of the leaves). Do you consider it to be the glass itself or the way each lens directs the AW of the camera?


PostPosted: Thu Feb 02, 2023 1:20 am    Post subject: Reply with quote
Red is a challenging color to render well. I find that many many lenses do a poor job of displaying the brilliant red colors of some of the rhododendron flowers in my yard.


PostPosted: Thu Feb 02, 2023 2:20 am    Post subject: Reply with quote
jamaeolus wrote:
Red is a challenging color to render well. I find that many many lenses do a poor job of displaying the brilliant red colors of some of the rhododendron flowers in my yard.


I agree with part of the above- especially where strong cross lighting is involved.
I have had faint pink wilted store bought roses render semi-dark lipstick red. Undiffused direct flash will do the same thing with some lenses.

Some of my older single coated lenses fall into the above category.
While the images may not have technically "correct" color rendering, the images can still be useful and pleasing.
It all depends on what is wanted out of the final image.

As for Canon glass having a different rendering, yes it does.
That is by no means a put-down of Canon glass- far from it.
Some of the imagery made on film with the FD era lenses is absolutely beautiful, at least in my experience.

When it comes to color accuracy of flowers, I've found moderate back-lighting to be a bit of an advantage, especially with older glass.

I hope to find out more on this in the coming spring when the flower boxes and planters come back out.

-D.S.


PostPosted: Thu Feb 02, 2023 1:31 pm    Post subject: Reply with quote
alex ph wrote:
Your comparison demonstrates clearly that Mamiya slightly oversaturates reds while Canon adds some blue/magenta (seen especially well in the background green of the leaves). Do you consider it to be the glass itself or the way each lens directs the AW of the camera?


I just said that is a different red rendition.
Mamiya is the closest to the actual color of the flower.
As for the blue/magenta tinge? It might be the polarizing filter???
Both lenses had polarizing filters: Mamiya - Hoya, Canon - B+W

I've always considered Mamiya having the closest to reality red rendintion when I did these kind of non accurate Very Happy comparisons.
And to quote jamaeolus red is a chalanging color to render properly and in my experience the most prone to burn.
Here is another Mamiya that is spot on with the colors:

Morning glory



PostPosted: Thu Feb 02, 2023 4:30 pm    Post subject: Reply with quote
Mamiya rendering is something warmish, like almost all my mamiya lenses for 35 mm.

My 55/1,8, 35/2,8, 135/2,8 and 85/2 8 (all SX) have warm rendering.


PostPosted: Thu Feb 02, 2023 6:45 pm    Post subject: Reply with quote
I always find it helpful to remember than many flowers - especially red and orange ones - are reflecting light far beyond the spectrum visible to the human eye.


PostPosted: Thu Feb 02, 2023 7:35 pm    Post subject: Reply with quote
jamaeolus wrote:
Red is a challenging color to render well. I find that many many lenses do a poor job of displaying the brilliant red colors of some of the rhododendron flowers in my yard.


Himself wrote:
red is a challenging color to render properly and in my experience the most prone to burn.


When talking about red flowers two things are important to remember:

1) In a Bayer sensor, only 25% of the pixels are red pixels
2) When taking images of a red flower, the green and blue channels often get nearly zero light

As a consequence (especially if the flower cover just a few % of the entire image) the red channel is completely overexposed. This overexposure combined with the low resolution of the red channel (only 6MP in a 24 MP camera!!) results in a inaccurate reproduction of such flowers.

The solution is very simple: Underexposure by 1-2 EV and careful conversion of the RAW data.

S

EDIT if you look at the channels seperatels (R, G, and B), you will see that tha Mamiya has very little information in the blue and green channles compared to the Canon. Thus the Canon shows much more details in the red flower than the Mamiya.


PostPosted: Thu Feb 02, 2023 8:06 pm    Post subject: Reply with quote
KEO wrote:
I always find it helpful to remember than many flowers - especially red and orange ones - are reflecting light far beyond the spectrum visible to the human eye.


+1 Like 1 Right -- the sensor responds to the "light far beyond the spectrum visible to the human eye."

stevemark wrote:
When talking about red flowers two things are important to remember:

1) In a Bayer sensor, only 25% of the pixels are red pixels
2) When taking images of a red flower, the green and blue channels often get nearly zero light

As a consequence (especially if the flower cover just a few % of the entire image) the red channel is completely overexposed. This overexposure combined with the low resolution of the red channel (only 6MP in a 24 MP camera!!) results in a inaccurate reproduction of such flowers.

The solution is very simple: Underexposure by 1-2 EV and careful conversion of the RAW data.

S

EDIT if you look at the channels separate (R, G, and B), you will see that the Mamiya has very little information in the blue and green channels compared to the Canon. Thus the Canon shows much more details in the red flower than the Mamiya.


+1 Like 1


PostPosted: Fri Feb 03, 2023 12:27 am    Post subject: Reply with quote
stevemark wrote:


1) In a Bayer sensor, only 25% of the pixels are red pixels



Quite the opposite of the human eye where the majority of cones are those that perceive the red wavelength.


PostPosted: Fri Feb 03, 2023 10:42 am    Post subject: Reply with quote
Himself wrote:
stevemark wrote:


1) In a Bayer sensor, only 25% of the pixels are red pixels



Quite the opposite of the human eye where the majority of cones are those that perceive the red wavelength.


Fortunately there are many reasons why you can't compare our eye's retinas to digital camera sensors Wink

And yes, red is a tricky colour for the common sensors. Stephan and I have had that discussion before, although in the end that turned out to be me failing to notice a PP issue with the Photoshop levels adjustment and conversion from AdobeRGB to sRGB profile, despite me having underexposed the original shot on purpose as Stephan suggested to do.

Hint: if you do a levels correction on an AdobeRGB shot before you convert from AdobeRGB to sRGB, make sure you double-check the red channel for saturation after the conversion. Even when the red channel is not saturated in AdobeRGB colour space after the levels correction, then converting to sRGB can oversaturate the red channel. In my experience when there is a danger of red channel saturation you are better off doing the AdobeRGB to sRGB conversion first, and then do a levels adjustment for exposure.

My colour space math isn't good enough to explain this (well, it's non-existent really), but I suspect this has to do with the AdobeRGB colour space having a much wider gamut in particularly the CIE green coordinates compared to the sRGB space. Conversion to the sRGB colour space then resulting in extra saturation in the red channel maybe has something to to with the chosen rendering intent and with white point compensation during this conversion.
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