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Message: <blockquote data-quote="typo" data-source="post: 3419727" data-attributes="member: 83808">I think I might have used "sparkle" and "clarity" perhaps a handful of times when I'm trying to communicate that the combination of test conditions and the properties of the binocular have combined to produce really exceptional view quality to my eyes. I couldn't honestly say exactly what those contributing elements were, or even if anyone else would share the same experience.  It's certainly not something I would associate with a brand or even a model. I recall a Nikon EDG 7x42, a particular Swaro ELSV 8x32, a Vortex Razor HD 10x50, the Kite Bonelli 2.0 8x42 and one that will surprise many, a Vanguard Endeavour EDII 8x42. I still have that Vanguard and it really does give a clear example of why test conditions are a crucial element of the experience. More obviously than some of the others mentioned the view experience can swing from exceptional to something more ordinary as the light changes.I know, or very strongly suspect, that those samples had excellent effective resolution, better than average for an alpha. The contrast was excellent, but it might surprise some, the CA and even colour neutrality were not necessarily anything special. I suspect the transmission profile was part of the story though. It seems to me that high transmission or even profile flatness from 450 to 600nm are not particularly important for this experience. The swings in ambient light colour temperature massively overwhelm small differences in this region. Instead, I got a sense I could see the full colour spectrum from 380nm to 750nm wheras many seem severely curtailed to my eyes. That has to be the product of illumination and transmission.Very much a guess but I think for  "sparkle" and "clarity" you need the effective resolution, contrast and transmission to be right, but you also need the luck of having the right light conditions. However we all have different eyesight and perceptive abilities and I could't say if anyone elese would have shared the same experience.To address the second part of Jeremy's post that sharpness and brightness amongst other properties can be compared. Make no mistake, these are perceptions which frequently have very little to do with either effective resolution or luminance as far as I can judge.In normal use, few users have the eyesight to get close to the effective resolution limit of most binoculars. Those with 20/10 will bet closer than those with 20/20. However, our brains interpret optimal "sharpness" at much lower spacial frequencies in the 20/50 to 20/120 range. Higher contrast, (and I would include colour contrast), in this frequency range may well be judged 'sharp' Those who do photography will know that increasing 'sharpness' setting on their cameras will increase contrast at the expense of detail. I suspect the majority of comments here on "sharpness" are related to low frequency contrast and not resolution, contrary to what many think.Our eyes, or more correctly, our brains, are very bad at estimating light levels (luminance). We might be able to 'see' over a trillion fold range but we are very poor at discriminating small changes. It doesnt help that the pupil diameter of our eyes constantly oscillate causing a fluctuation of around 50% in retinal luminance at fairly high frequency. Replicating the way that most would compare binoculars, most people I tested couldn't spot a 30% difference in transmission. Even with my more practiced eye I could barely beat 10% in regular daylight. In fairly extreme test conditions I could get below 5% but that's not something I would generally be able do at a store or birding show.We are quite good at comparing colours and regularly relate that to climatic conditions. I've long susppected that most 'brightness' comments are related to colour bias in the transmission spectrum. I put a very weak blue filter in front of the objective of an otherwise fairly neutral binocular. According to manufacturers data it had a 90% transmission in the blue and about 75% in the green through to red. Everyone I tried it on immediately said the blue filter side was 'brighter' even though the average transmission was over 20% lower. We generally perceive bluer as brighter. This is particularly in some light conditions.To sort of summarise, sparkle, clarity, brightness and sharpness are all perceptions which seem 'real' to the user but normally cannot be readily related to the optical properties of the binocular and probably not to other users. They will normally be entirely subjective, extrememly dependant on the light conditions at the time of the test and are potentially very misleading.I'm not suggesting anyone should stop using these terms, but a better awareness of some of the factors that lead to those perceptions can't do any harm and may lead to more useful reviews.Cheers,David</blockquote>

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