Transmission spectrum curve, neutral vs natural (1 Viewer)

[kimmik]

Two otherwise identical telescopes, but different transmission spectrum:



Spectrum 1 and 2 will have:

• Similar brightness
• 2 will have faint yellow/green tint
• 1 will be more neutral, but less colour accuracy, like fluorescent light (neutral but less natural)

Perhaps binoculars/telescopes should have a CRI rating like lightbulbs. Colour rendering index, out of 100. Leica and Nikon will top the chart I suspect.

Going further, there could be several separate colour ratings:
Colour temperature
Colour rendering index
Gamut
Colour uniformity across the FOV
Colour uniformity with pupil alignment changes

 

[fazalmajid]

How would 1 be neutral if it is missing nearly half the red spectrum (625-750nm)?

Now CRI (Ra) is notorious for being blind to deficiencies in red (R9) which is why there are better measures like CQS or TM-30 so yes, CRI would probably rate 1 as good even if it isn't.

Your graphs do resemble the transmission spectrum of the Swarovski NL Pure (1) vs. the EL SV (2):

https://www.houseofoutdoor.com/wp-content/uploads/2020/11/Test-new-Swarovski-NL-pure-8X42-and-Zeiss-Victory-SF-8x32-nov-2020.pdf

 

[kimmik]

How would 1 be neutral if it is missing nearly half the red spectrum (625-750nm)?

It takes only two complementary colours to achieve white, and red doesn’t even need to be present.

Eg orange plus blue, yellow plus purple.

The CRI would be horrible with this “white” light.

 

[Scott98]

Remember the human eye is much more sensitive to the green in the middle than the blue & red on the ends. Plants like the blue and red, our eyes are attuned to the green/yellow. So I would avoid the scope with the dip in the middle.