More contrast with ED scopes? (2 Viewers)

[Tringa45]

There is some clever people here that could help me with developments of my theory.

Theory is nothing if you lack the basic knowledge. We had more than enough of those during the pandemic.

Or you get abusive messages for daring to think out the box for one second.

I try to restrict personal criticism to PMs but since you have referenced it, here is the "abusive" content. Quote:

John,
After 3 months on the forum and posting several questions on basic knowledge you are now being argumentative and referring to your "experience".
I think that is a little presumptive.

John Unquote

I should, of course. have written presumptuous.

 

[beacon hill]

I see my creamy quote has come back a couple of times.
Although I do not have the optical knowledge as many here. (Have learnt some words I did not know existed.)
Am a dealership though. So hopefully I know just a little about bins.

With the tests I was mentioning, I simply got the ED and non ED version of exactly the same set of bins -
look at a nearby house with convenient white washed walls, and as the TV quiz show goes "say what you see"
Only research they need to use is what their eyes can see. No internet needed. What one customer can see, another may not.
But now I usually ask them to look at some lamp posts or if they are visiting, bright white swans against a
white back ground when comparing different specs.

 

[John goshawk]

Yes agreed. Today I did same test with opticron HD66 and HD66ED. Whites appear 'whiter' and darks darker.
Don't understand the science behind it fully.
I know that is heresy for many people on here.
But for others who trust there eyes (and other people's eyes!) it seems pretty obvious beacon hill is correct.
I have to admit the increase sharpness also helps considerably with contrast of the ED scope.

 

[Tringa45]

With the tests I was mentioning, I simply got the ED and non ED version of exactly the same set of bins -

Which were they? I'm not aware of any current binoculars available as ED and non-Ed versions, certainly not in the so-called "alpha" category.
The best way to test for colour neutrality is to point an eyepiece at a white sheet of paper in daylight and view through the objective.
You then have a direct comparison.

John

 

[Binastro]

Barr and Stroud Savannah binoculars are available with or without ED glass.

I think I have the 12x56 ED and an older 10x56 Non ED, so I cannot compare directly.

The older 10x56 was secondhand repaired, but still uneven focus of both halves.

The new 12x56 ED is fine.

There are probably other ED and non ED binoculars otherwise identical.

Not everyone uses £2,000 binoculars, where non ED is unlikely even if not stated.

Regards,
B.

 

[Binastro]

Actually, the whiteness of a binocular image is likely to depend on the chemical composition of the glass.

The WW2 Barr and Stroud binoculars used grey glass from best Scottish sand, which was the only sand available.

My two Bresser 15x60 binoculars have dirty grey images, probably from rubbish Chinese glass. With rather poor coatings the transmission is low.

Cerium?, I think was used to whiten glass, particularly glass containing thorium in camera lenses and a few astro eyepieces and rather many Kodak WW2 eyepieces.

So the reason ED glass may be whiter is just that it uses better quality whiter glass than the effects of chromatic aberration with fast optics.

Looking at a white sheet of paper often easily shows which lenses are whiter.

Looking at identical ED and non ED binoculars may not in fact give any definitive answers.

Regards,
B.

 

[beacon hill]

OK. Maybe mine and my customers eye sight needs testing.
You could say with 18 years as a dealership I have looked through
quite a lot of binocs (understatement of the year) so do know my stuff. Plus on a practical level with
no on-line research know how to explain with practical demos to buyers.
But will bow to those with more expert knowledge and lurk in the background on such topics.

All I can say finally on the topic with regards testing optics in general.
Regular get customers travelling 100+ mile round trips to visit us.
The response I get from these buyers who pick up sets of bins and look through
them, letting me explain as they go along is rather different and more appreciated then some responses here.

 

[John goshawk]

This 'discussion' is reminiscent of Charlton Heston in Planet of the Apes.
The self elected high priests are terrified of even discussing what can be seen with their naked eye - and become very aggressive, suspicious and hostile to anything that challenges their beliefs.
I didn't realise optics was a form of religion for some!
Happy Birdwatching!

 

[Tringa45]

The self elected high priests are terrified of even discussing what can be seen with their naked eye - and become very aggressive, suspicious and hostile to anything that challenges their beliefs.
I didn't realise optics was a form of religion for some!

Few things are more fallible than human perception but science is science (and religion is something completely different).
I have prefaced a few posts with "open to correction" and the more one learns, the more one becomes aware of one's own ignorance.
We all post nonsense from time to time. Even Henry has admitted to this, although I think that must have been about fifty years ago!
My latest piece of rubbish was last Sunday on another thread.
I'm reminded of a quote by Bertrand Russell:- "The fundamental cause of the trouble is that in the modern world the stupid are cocksure while the intelligent are full of doubt."

John

 

[henry link]

I think John is confusing the effects of uneven light transmission across the visible spectrum with the effects of uneven focus across the visible spectrum. The former causes an overall change in color balance from certain colors having weaker or stronger transmission compared to other colors, but that's unrelated to where different colors come to focus. The latter causes different colors to be brought to focus at different distances behind the objective lens, but that has no significant effect on overall color balance because the amount of light transmitted (focused and unfocused) remains the same for all colors.

A simple way to test the effect of CA on color balance is to rack the focus slightly back and forth while looking at a flat white target that fills the FOV. Look for color balance changes as different wavelengths go in and out of focus.

 

[Tringa45]

I think John is confusing the effects......

Missed a heartbeat there, Henry.
Remember Martin Pond, aka OPTIC_NUT, with whom you showed unending patience?
I fear we have a reincarnation here.

Regards,
John

 

[tenex]

Why you being so rude? Would you say that if you sat opposite me?

Of course. Yours was a perfectly fine question to ask, but trying to answer it yourself with concepts you don't understand is not useful. Why are you so ready to take offense?

I would still like to know how much of a difference there seems to be in overall contrast between the scope models discussed above, and why. Coatings are generally pretty good today even on mid-range instruments. But they're not always designed to maximize contrast, for example if intended for low-light use. So what might the manufacturers be thinking here?

 

[BoldenEagle]

I would still like to know how much of a difference there seems to be in overall contrast between the scope models discussed above, and why. Coatings are generally pretty good today even on mid-range instruments. But they're not always designed to maximize contrast, for example if intended for low-light use.

Don't know ED vs non-ED scopes but comparing Kowa Prominar 883 to Zeiss Victory Diascope 85FL reveals substantial difference in contrast: Kowa has clearly more contrasty image but very often Zeiss seems to reveal more details not only in low-light conditions but also in daylight when looking for example birds with black or dark feathering. It seems that at least in some conditions less contrast can indeed be useful. I guess it is a result from difference in lense coatings?

Regards, Juhani