Leica Trinovid 10x50 BA (1 Viewer)

[CloseFocus]

Let's suppose you wear sunglasses because it's very bright outside: Which image is better - that provided by a pair of binoculars with low contrast or one with high contrast?



You believe everything manufacturers claim in their brochures? Gijs van Ginkel's analysis showed that Fuji's claim is plainly wrong.



Not really, as the improvement isn't just an increase in brightness, but rather improvements in contrast and colour balance.

Hermann

I think you are both right. One of the ways contrast is degraded by poor optics is for the optical images to overlap, due to CA and just plain lousy optics. So a good binocular will provide better contrast simply by providing a cleaner image. But there are filters that will dim the image, but will also improve the contrast, such as yellow filters on a rainy day, or polarized filters on bright days. Every fisherman knows you can see fish in the water better with polarized glasses. Amateur astronomers have OIII filters that only allow a narrow band of light emitted by oxygen atoms to pass through. These significantly reduce the brightness of the image, but vastly improve the visibility of subtle features in nebulas.

 

[ronh]

Gijs,
I can hardly doubt your measurement of the Fujinon 10x50, because when I voiced my surprise some time ago you were thorough enough to repeat the measurement, which agreed with your first.

I'm just pointing out that that measurement is at odds with many people's impressions from using that model (look over on Cloudy Nights forum to see what a following it has) and with at least one measurement, in the Allbinos review which reported its transmission as 94.9%
http://www.allbinos.com/61-binoculars_review-Fujinon_FMTR-SX_10x50.html

Of course, none of that makes your measurement wrong. All I can figure is, you must have gotten a defective one. It must happen sometimes. Thanks again for all your work, which is a real contribution to our common interest.
Ron


James,
You will see from Henry's yellowed parchment from the Dead Sea Scrolls that Fujinon patented the electron beam coating deposition process, which is still the state of the art for evaporating the substance to be deposited as far as I know. This suggests that Fujinon was rather serious about it. Why other binoculars frequently measure less than 95%, well, there are all kind of excuses that might be made for that, none of which impugn Fujinon, in my opinion.
Ron

 

[Gijs van Ginkel]

Ron, post 42,
Thank you for your kind words. If I have some time, I will try to measure another Fujinon sample, to see what values we find then. If it is done I will report it.
Gijs

 

[Omid]

Improved transmission across a wide spectrum also improves contrast and colour reproduction.

I think you are both right. One of the ways contrast is degraded by poor optics is for the optical images to overlap, due to CA and just plain lousy optics. So a good binocular will provide better contrast simply by providing a cleaner image.

Yes, contrast is enhanced by better optics (less color aberration, less stray light). Here is a simple example that explains how much better coating can enhance contrast:

Imagine looking at a chess board (simple black and with pattern) using a binoculars with 90% transmission and very little other aberrations. Of the 10% light which is lost, some of it is absorbed by the glasses or the interior body of the binoculars. Some is also reflected back towards the front. Some part (say 2%) might get to the exist pupil after multiple reflections at lens surfaces. This is the part that is distributed over the actual image and reduces the contrast.

Lets assume that the original chessboard has a contrast of 100% (white areas= 100, Black areas = 0). Our binocular will reduce the brightness of the white areas to 90 (due to its transmission factor) and might increase the brightness of the black are to 2 (due to stray light). So, now we get a contrast ratio of (90 -2)/90= 97%.

Now lets increase the transmission to 95% by improving the coatings. This might reduce the stray light component that reaches the exit pupil to 1%. With this binocular we get a contrast of (95 -1)/95= 99%

So, improving transmission by improving coatings DOES increase theoretical contrast. But the improvement is very small and barely matters. Note that the human eye can detect a luminance range of 10 to the power 14, or one hundred trillion (100,000,000,000,000) to 1 (about 46.5 f-stops)!!! Since the eye dynamically adjust to such huge ranges of luminance, it is not very sensitive to a few percent change in intensity.

In addition, by selectively attenuating certain wavelength, the eye "sees" much better contrast in various natural scenes such as a sunny beach or cloudy day or .. as pointed out by CloseFocus. Increasing transmission in all frequencies is only a theoretical performance criterion, our eyes don't necessarily want that

 

[radiotools]

50 and 56mm

I agree with Hermann about this. A 50mm aperture delivers about 42% more light to the eye than a 42mm aperture. The differences in transmission among modern binoculars are a small fraction of that.

Also help to easily line up eye pupils to the binoculars large exit pupils, I have tried side up side with my Zeiss 10X40B TP and 8X56B TP , with the 10X40 I could not see anyhing in the dark at 9.00 PM , with the 7X50 and 8X56 it was possible to see in the bushes any movement B

 

[radiotools]

50 and 56mm



Also help to easily line up eye pupils to the binoculars large exit pupils, I have tried side up side with my Zeiss 10X40B TP and 8X56B TP , with the 10X40 I could not see anyhing in the dark at 9.00 PM , with the 7X50 and 8X56 it was possible to see in the bushes any movement B

That is 100 % correct, I checked with my Leica 8X50 BA , Zeiss 7X50 B T Marine and Zeiss 8X56 Night Owl vs Leica 8X42 and 10X42 HD , the 42mm showed poor performance at dusk , I could see the trees in the forest with the large diameter glasses
For daylight use the 42mm are great and light to carry about