132 replies to this topic

[peleuba]

Assuming gkevinw heard what he though he heard perhaps Roland’s thinking on the subject has evolved. It would be interesting to hear Roland’s first person thoughts on this.

 

Indeed.  You should ask him.

[Polyphemos]

It is not about the stars, it is all about star #1 that created us, it took a billion years. ….

 

bessy.jpg

https://www.research...le-400-700.ppm 

 

 

Our acuity in green has also been explained by the need to evaluate vegetation as a food source. No doubt green vegetation is a response to the terrestrial solar spectrum as well, making for overlapping causes and dependencies, but then there are other variables to consider as well.

[Yuri]

Hi Yuri - I assume you mean red and blue lasers for the interferometer.  Wouldn't you also need the reference sphere (within the interferometer) nulled in whatever wavelength you nulled the optics?  In other words, if normal production scopes are nulled in green you test with a green laser using reference spheres that were nulled in green.   If this is the case, it becomes quite expensive just to make a few one-off scopes having to purchase (or make) new reference spheres. 

 

Hi Paul,
The reference sphere (ethalon) is a reflective element and works for all wavelengths, it does not need to be "nulled". But it must be a very high quality part (1/20 PV), it tested 656 nm at full aperture of 28mm.
Pictured are two laser lights passing through a single mode opto-fiber.
Switching takes a couple of minutes.
But I do not use the red one for our optics, it is there for fun only.

 

 

 

[Polyphemos]

Indeed.  You should ask him.

I don’t think I have the requisite access like some others I know. Left up to me we’re stuck with the information we have and I’m not comfortable we have the important parts.

Edited by Polyphemos, 20 April 2025 - 09:08 PM.

[ABQJeff]

While that has been consensus on CN for quite some time and obviously Yuri agrees.  I do find it interesting that Roland is noted above saying that Yellow makes more sense than Green.  Personally, I don't think it really matters so long as the optics are made to a high standard, as there are scopes nulled in Green, Red, and Yellow, that pass the visual acuity tests with flying colors.

Yellow 570nm vs Green 550nm, they are both legitimate.  Both in middle of 400nm - 700nm, both corresponding close to peak sensitivity because of how our eyes evolved.  Yellow is more suitable for terrestrial and bright views (like Moon and planets under light pollution) (color vision), green for dark adapted eyes.  Nulling to either would mean red and blue aren’t terrible.

[PKDfan]

FWIW: i took an extended multi month journey throughout North western North America up to the Beaufort sea through Alaska onto the Manitoba border and B.C. Alberta Saskatchewan Washington Idaho Montana Oregon & experienced 7weeks of 24hour sun and as a precaution against excess UV wore BluBlockers that of course cutoff Blues and i can relay that there are literally thousands of shades of green that popped with subtle nuances of both green & yellow.

Sight i think is weighted towards finding the greenest or Ripest vegetation which indicates a rich potential food source while yellow helps reveal the ripeness of 'the fruits' therein. Wheat a good example.


I find this discussion very intetesting so added my perspective of Why green could be so crucial to discern well.


CSS
Lance

[ABQJeff]

It is not about the stars, it is all about star #1 that created us, it took a billion years. The spectral sensitivity of our eyes coincides with maximum spectral intensity of the Sun. We are all "children" of the Sun. It developed our vision accordingly, and the vision of most animals (see  Bessy's eyes attached)¹.
If the nearest star was of different spectral class with intensity shifted to red, for example, then our vision would be optimized for red-infra-red (like a vision of some snakes), it also would be of lower resolution.
If the Earth was orbiting around a blue star like Vega, then we all would be "vegans"   but do not expect a better vision - short wavelength (UV) would be partially blocked by the cornea and eye lens, and could damage the eye (cataracts, etc.).

 

I might be mistaken somehow, count the above as Easter day fantasy and correct me, well, "nobody's perfect”

 

¹ Cat's vision, BTW, is of two colors blue-green, no red cones. They for sure would avoid telescopes nulled in RED.

 

bessy.jpg

Completely agree.  My comment on red stars was that truly pure red stars that we see are few.  OP started with argument since most stars we observe have a large red component shouldn’t we null in red.  Sure a red compnent, but the blue-green-yellow of constellation and Open Cluster stars we pick up more in our eyes and dominate what we see, same for sunlight reflected off Jupiter, terrestrial viewing etc.

 

Anyway, per your comment on cats, that is tied to them being night vision/low light optimized for rods (permanently shifted to blue-green).  Which is exactly why I have to have my refractors nulled in green.  My observing partner would be quite upset and immediately detect that the scope was out of sorts with her blue-green sensitivity.

 

[Psion]

A great telescope should have excellent correction from red 630nm to green 530nm (i.e. Strehl ~0.97). Blue can have a worse correction e.g. Strehl 0.80.