What Does a Blue Lens Do in Binoculars
#1 
Posted 02 February 2005 - 07:13 PM
I'm looking to buy a pair of moderately priced binoculars (for stargazing of course), and I need some help. Does the color of the lens (amber, purkle, etc) affect astronomy viewing, and if so, what should I go for?
Right now, I'd like to find a pair under the $70 price point. Any help would be great. 
#2
Posted 02 February 2005 - 07:41 PM
Color of the lens coating isn't as important as it being non reflective and transparent. When you look at the front lens (objective lens) you should easily see inside the binocular.
For astronomy I would stay away from those highly reflective red coated lenses.
Rich
#3
Posted 02 February 2005 - 07:45 PM
Any recommendations? Amazon and telescope.com has good prices, from what I've seen.
#4
Posted 02 February 2005 - 08:05 PM
I haven't checked out the $70 binoculars recently. If you can, find a store where you can hold them and look through them. When you put them up to your eyes they should feel easy to look through. If your eyes feel like they are having to work when looking through the binocular you will not enjoy using that binocular. If the store is nice and their prices are not too high it would be good to buy from that store. It's great to have a store where you can try different binoculars and those stores need our support.
Getting binoculars via mail order or from the net is ok if you know exactly what you want.
Rich
#5 Guest_**DONOTDELETE**_*
Posted 02 February 2005 - 08:24 PM
The color of the objective lens IS important from the stand point of knowing what it is. A faint greenish-purple color is commonly what one should see and if you should look directly at a lens, a good anti-reflection coating will not allow you to see features on your face very well, if at all.
Those red ruby colored binoculars are junk.
#6
Posted 02 February 2005 - 08:35 PM
The color of the objective lens IS important from the stand point of knowing what it is. A faint greenish-purple color is commonly what one should see and if you should look directly at a lens, a good anti-reflection coating will not allow you to see features on your face very well, if at all.
Those red ruby colored binoculars are junk.
Per Roland Christen you can make a coating have almost any tint you want depending on how thick you make it.
My new Zeiss 10x42 FL has objectives with coatings that look slightly pink.
The color is not important, it is the coatings performance that is important.
Rich
#7 Guest_**DONOTDELETE**_*
Posted 02 February 2005 - 09:25 PM
Of course coating performance is important. I think that is obvious.
The color observed is determined by more than just the thickness. It is that, the choice of coating material, the material upon which the coating is applied, the angle of incidence of the light. So yes, obviously, one could tweak any of those parameters and get any color reflected back.
BUT, for astronomy applications you are typically not going to see an AR coating that looks red, orange, or pink...any of the colors that have a longer wavelength than green to purple. The reflected coating color is indicative of the wavelengths that are of interest. So, from that standpoint, the color IS important.
#8
Posted 02 February 2005 - 09:34 PM
I have narrowed it to a Nikon Action 10x50 (violet tint) and a
Bushnell Legacy 10x50 (almost no tint)
Opinions on which is better?
#9
Posted 02 February 2005 - 09:53 PM
Of course coating performance is important. I think that is obvious.
The color observed is determined by more than just the thickness. It is that, the choice of coating material, the material upon which the coating is applied, the angle of incidence of the light. So yes, obviously, one could tweak any of those parameters and get any color reflected back.
BUT, for astronomy applications you are typically not going to see an AR coating that looks red, orange, or pink...any of the colors that have a longer wavelength than green to purple. The reflected coating color is indicative of the wavelengths that are of interest. So, from that standpoint, the color IS important.
My Zeiss 10x42 FL is one of my best astro binoculars.
Why would you prefer to have a green and shorter wave length reflection? Our eyes are most sensitive in yellow/green. Why would you want to reflect it away, even a little?
There is virtually no red in the night sky that is bright enough for us to see, at least not with the collecting capacity of hand held binoculars.
Rich
#10 Guest_**DONOTDELETE**_*
Posted 02 February 2005 - 09:54 PM
Which AR coating is better? The ~1% reflected residual color, or "bloom" as it is sometimes called, in no way tells you the quality of the coating. It can give the characteristics of the coating. The faint green-ish bloom is common for modern broadband coatings. So, no one can say which is better based on that.
If you are asking which binocular is flat out better, then that is something else. If so, you should start another thread asking people for their opinion. I don't have much experience with the "smaller" binoculars, but others would help you.
Also, I suggest checking out the "mini-review" section of the forum. You might find either one, or both, of those binoculars listed. And in the "best of" section there are several links about lens coatings. I hope that helps.
#11
Posted 03 February 2005 - 06:16 AM
If you are considering Nikon Action, I would urge you to consider Nikon Action Extreme. Many report it is better. The AE still sells for $139 at Adorama. Last I looked shipping was free.
edz
#12
Posted 03 February 2005 - 06:30 AM
The color I see in coatings is more indicative of the chemical compostion of the coating material than anything else. It is true that improperly applied coatings can take on a deep green appearance due to improper thickness of application and hence these can become no more effective than properly applied single coatings. So keep this in mind, cheap improperly applied multicoatings, while they can be a selling point because that is what people want to hear, may not be as effective as single coated MgF. All of this information can be found in the "Best Of" links.
I've seen single coated MgF which always looks blue, or can sometimes almost seem to be clear or not there. And I've seen multi-coatings that have a green/purple tint, a purple/pink tint, a purple/amber tint, a green/purple/blue tint, plain green tint, a faint purple tint and a simple slight amber. They are all designed to operate within a designated range of wavelength. Each differs very slightly in it's peaks, but most all operate over the same wavelength range. Their purpose being to prevent reflection and improve transmission, I think any particular % light relected at any specific wavelength would be imperceptible.
Ruby colored coatings are not anti-reflective coatings. In fact, you will notice that ruby colored coatings actually reflect more light than anything else. They actually reduce light transmission.
edz
#13 Guest_**DONOTDELETE**_*
Posted 03 February 2005 - 07:32 AM
I might not have stated it clearly, but that is what I meant about the ruby colored binoculars. The highly reflective red coloring is there to look "cool". Nothing more, hence my description as "junk".
I think any particular % light relected at any wavelength would be imperceptible.
But we DO see a characteristic faint green-ish & purple reflected and MgFl2 is a colorless material. Some percentage of the incident light around 530-550 nm is being reflected back and can be seen. If you were to plot reflection vs. wavelength you would see a small peak around that wavelength region. This is typical for uniform 1/4 wavelength thick broadband multicoating of MgFl2 on the usual objective glass material.
#14
Posted 03 February 2005 - 01:23 PM
Just checked some of my binoculars for coating color.
Celestron 9x63 Ultima = greenish
Nikon 12x50 SE = greenish
Leica 12x50 BA = lighter greenish
Swarovski 8.5x42 = pinkish or maybe you would call it purple
Zeiss 10x42 FL = same as Swarovski but a little lighter in color (less saturation).
I don't worry about the color of the coating but how well I can see through the coating.
Rich
#15
Posted 03 February 2005 - 01:37 PM
Nikon 12x50 SE = greenish
Rich
I see the 12x50 SE as faint green with a very strong presence of purple/blue
The Pentax PCF III 12x50 is one example I have that is purple bordering on pink. If you hold it at the right angle you can see a faint green.
My Pentax PCF V 16x60 is an example of pure green coatings. They are highly reflective and the diminished performance of the binocular in relation to others near its size supports the my contention of improperly applied coatings being less effective.
edz
#16 Guest_**DONOTDELETE**_*
Posted 03 February 2005 - 01:46 PM
It is interesting that you mention "...at the right angle...". As we all know, the angle of incidence will naturally affect the reflected perceived color. Some coating materials are more susceptible to this than others. One of the reasons why MgFl2 is so popular for AR coatings is that it is relatively less dependent on the incident angle compared to other materials.
#17
Posted 03 February 2005 - 01:47 PM
Nikon 12x50 SE = greenish
Rich
I see the 12x50 SE as faint green with a very strong presence of purple/blueThe Pentax PCF III 12x50 is one example I have that is purple bordering on pink. If you hold it at the right angle you can see a faint green.
My Pentax PCF V 16x60 is an example of pure green coatings. They are highly reflective and the diminished performance of the binocular in relation to others near its size supports the my contention of improperly applied coatings being less effective.
edz
Hi Ed,
I was looking at the objectives of my binoculars at about the same angle, nearly straight into the binocular. At that angle my Nikon 12x50SE has a light green or greenish yellow color. If I hold them so that I'm well to the side, off axis, so that I'm not seeing much into the binocular, the color is purple. I don't think light hiting the objective at that angle would be seen through the eyepiece.
Rich
#18 Guest_**DONOTDELETE**_*
Posted 03 February 2005 - 02:01 PM
EdZ would know best, but I think the light incident on the objectives at your shallow angle Rich does not enter the EPs. The transmitted light is simply absorbed in the barrel wall or is scattered around inside the barrel in some way.
#19
Posted 03 February 2005 - 02:06 PM
EdZ would know best, but I think the light incident on the objectives at your shallow angle Rich does not enter the EPs. The transmitted light is simply absorbed in the barrel wall or is scattered around inside the barrel in some way.
I agree. I could only see an inch or two down the inside of the barrel. Not close to seeing the prism.
Rich
#20
Posted 09 February 2005 - 06:38 PM
Does Color Matter? Yep!
Yellow = head cold
clear = pneumonia
Brownish Red = Bronchitis
Folks can build a religion out of talking about the color of anti-reflective coatings. However, here is the bottom line:
When you go from simple magneseum fluoride coatings to multi-coatings, you gain 9-14 percentage points in light transmission--all else being equal. When you get into that realm, there is not a set of eyes on the planet that can tell the difference. Any REAL difference is going to be in glass types, blackening, and baffling.
Just a thought,
Bill
Source: https://www.cloudynights.com/topic/22049-does-color-matter/
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