• Welcome to BirdForum, the internet's largest birding community with thousands of members from all over the world. The forums are dedicated to wild birds, birding, binoculars and equipment and all that goes with it.

    Please register for an account to take part in the discussions in the forum, post your pictures in the gallery and more.
Where premium quality meets exceptional value. ZEISS Conquest HDX.

Higher transmission in the 12X42 than the 10X52 😳🤔🤷🏻‍♂️ (1 Viewer)

SuperDuty

SuperDuty

Well-known member
United States
Funnily enough, I've read this on the small screen of my smartphone and, before opening the image that John A Roberts has posted, by just looking at the miniature pic, both graphs appeared to be one and the same, with that characteristic dip in the middle that Holger Merlitz has pointed out (which speaks about the consistency in the production methods by the manufacturer, doesn't it?). After opening the image, I can see there is an ever so slightly decrease in percentage, that can be very well due to the logical margin of error that any test has... or even a slight difference in performance between units/batches, or a combination of both. Well, yes, I guess there could also be a difference in the optical design/materials to justify. Anyway, I don't find it so surprising.
 
Shouldn’t a 10X52 be noticeably brighter than a 12X42, both having similar lenses and coatings ? Maybe not, my understanding of such things is admittedly very limited.
 
Hello,

regarding the original question: Please note, that transmission (= light that goes through the optics) isnt the same as percieved brightness.
If the iris of the human eye is the same or larger than the exit- pupille of the binocular (so no light is lost in the observers eye), than the binocular with the larger exit-pupille appears brighter.

Extreme example:
A 10 x 40 with 90% transmission will appear brighter than a 10 x 25 with 90% transmission, if the observes iris opens up to 4 mm.
Only if the observers iris open up to 2,5 mm, then the binocular with the higher transmission appears brighter.

I have read somewhere that differences about 3 % can be seen in direct comparison (?).
And that a larger exit pupille/larger objektiv diameter dwarfes differences in transmission (with decent quality devices), mentioned elsewhere by Holger Merlitz.

I hope thats understandable.
 
I have seen that often, that for instance a 25mm has more measured transmission than say a 50mm, when the stated transmission should be the same.
Don't know why that is. Maybe the length of the binoculars?
 
Holger Merlitz said:
Why is there, in both curves, a dip at ~520nm - has anybody a clue what is going on here?

Cheers,
Holger
Click to expand...
Coatings?
In an Edmund Optics catalogue there is a graph showing reflection of nine different coatings optimized for various wavelength ranges from UV, visible through to IR.
There's little to be seen on the trace for the visible light multicoating (350-700 nm), which remains below 0,5% in this range, but the traces for UV-visible (250-700 nm) and visible to near IR (400-1000 nm) both show mild peaks in reflectivity around 520 nm.

Regards,
John

PS:- Anti-Reflection (AR) Coatings Scroll down.
 
Last edited:
ReinierB said:
I have seen that often, that for instance a 25mm has more measured transmission than say a 50mm, when the stated transmission should be the same.
Don't know why that is. Maybe the length of the binoculars?
Click to expand...
I have seen that smaller apertures tend to have fewer lenses (for instance swaro cl Vs nl pure), thus having potentially higher transmission, but a smaller FOV.
 
Holger Merlitz said:
Why is there, in both curves, a dip at ~520nm - has anybody a clue what is going on here?

Cheers,
Holger
Click to expand...

I'm guessing it is something to do with prism treatment or glass coating because that notch is present on all NL and EL to a similar degree. I sometimes wonder if that lift at the blue end makes these otherwise excellent binoculars give a slight blue/cold sheen to the image. It's particularly easy to see on the sea or in grey shadows.
 
Nikon publishes light transmission values for its binoculars and the larger the objective the greater the light transmission provided. Clarity and contrast are a different matter. I get more image contrast and detail with a higher quality binocular and more with 10x over a 8x of the same brand and model.

For bird identification the two key attributes for me are image magnification and contrast to see the details.
 
Good grief, some basic matter:
-1- transmission is the amount of light passing through glass or another medium. The level of transmission depends on the optical pathlenght light has to cross and the optical clarity/purity of the glass components .
-2- brightness is more a psychological concept based on a combination of (a) the amount of light and (b) the color composition of that light..
Since this was and is coming back over and over I have written a review paper to clarify the discussion about it. It is entitled : Color vision, brightness, resolution and contrast in binocular images"", a review of published data , may 2013, 30 pages. It is published on the WEB site of House of Outdoor.
A larger objective does not yield a higher light transmission (the optical path lenght does not decrease ) but can deliver a brighter image depending on quality of the optical glass.
Gijs van Ginkel
 
Gijs van Ginkel said:
Good grief, some basic matter:
-1- transmission is the amount of light passing through glass or another medium. The level of transmission depends on the optical pathlenght light has to cross and the optical clarity/purity of the glass components .
-2- brightness is more a psychological concept based on a combination of (a) the amount of light and (b) the color composition of that light..
Since this was and is coming back over and over I have written a review paper to clarify the discussion about it. It is entitled : Color vision, brightness, resolution and contrast in binocular images"", a review of published data , may 2013, 30 pages. It is published on the WEB site of House of Outdoor.
A larger objective does not yield a higher light transmission (the optical path lenght does not decrease ) but can deliver a brighter image depending on quality of the optical glass.
Gijs van Ginkel
Click to expand...
Thank you, thank you, thank you.

It’s better when you say it.

So many threads, and so many “discussions” …….
 

Similar threads

D
Allbinos review of NL Pure 10x52. Beats the Nikon WX 10x50!
Replies
3
Views
887
Owlbarred
Owlbarred
John A Roberts
Vortex Razor UHD 8x32 - Allbinos Review
Replies
1
Views
490
yarrellii
yarrellii
yarrellii
Allbinos review of the Vortex Razor HD 8x42
2
Replies
26
Views
3K
Scott98
S
John A Roberts
Allbinos Canon 12x36 IS III Review
Replies
12
Views
3K
jcpjung
jcpjung
John A Roberts
Full Allbinos review of the NL 12x42
2 3
Replies
52
Views
11K
dries1
dries1

Users who are viewing this thread

Total: 2 (members: 0, guests: 2)
Back
Top