September Solar Challenge

[rsfoto]

Hi,

Just a side information which maybe could play a role

https://www.colourblindawareness.org/colour-blindness/

8.3% of men are colourblind while 0.5% of women are ...

[Montana]

Very interesting indeed Rainer, I didn't know anything about the blue-purple thing as in this quote "Being ‘red/green colour blind’ means people with it can easily confuse any colours which have some red or green as part of the whole colour. So someone with red/green colour blindness is likely to confuse blue and purple because they can’t ‘see’ the red element of the colour purple. See the example of pink, purple and blue pen cases above to understand this effect."
Maybe I should have asked the question about colour blindness as well. It also says those taking certain medications or with diabetes can also see colours differently. It is a fascinating subject.

Alexandra

[torsinadoc]

Very interesting indeed Rainer, I didn't know anything about the blue-purple thing as in this quote "Being ‘red/green colour blind’ means people with it can easily confuse any colours which have some red or green as part of the whole colour. So someone with red/green colour blindness is likely to confuse blue and purple because they can’t ‘see’ the red element of the colour purple. See the example of pink, purple and blue pen cases above to understand this effect."
Maybe I should have asked the question about colour blindness as well. It also says those taking certain medications or with diabetes can also see colours differently. It is a fascinating subject.

Alexandra

I’m red green color blind

[nicspenceryork]

Following my post in this thread about being able to see CaK features with my right eye without my glasses but not being able to see these features with glasses, I wrote to Vision Express to learn more and here is their reply…
‘Calcium-K telescopes allow you to image the Sun in the blue light of calcium (393.4 nm), however blue coating on your spectacle lenses (Hoya Blue Control) blocks wavelengths in the range of 420-460 nm. So it looks like this particular lens coating is out of the range of 393.4 nm, therefore it will likely stop you seeing what you need to see through the calcium filter. 
If you had a blue coating from a different manufacturer that might not be the case as not all lenses display similar transmissions of blue light and different manufacturers do not agree as to what percentage of blue light should be reflected or transmitted. Usually it is agreed that blue coating on the lenses should cut the wavelengths in the range between 420 and 460 nm.’
A little confused by this (as 393.4 isn’t within the range of 420-460) I asked a learned friend about it, who suggest that they might have omitted an all important ‘and below’ from the sentence.
Thought some of you might find this interesting. So, if you wear glasses and can’t see the CaK features, take them off and try again!
Nic