Brightness, resolution and contrast are all separate things from color rendition in optics. A good example is that in high end optics, Leica and Nikon are considered to be color neutral, while Swarovski used to be known for offering a "warmer" or more color tinted view. All make optics that are supreme in terms of resolution. People's perceptions about how this coloration of the image affects resolution and contrast tend to vary widely with the individual, but when folks are really comparing these ideas as separate concepts, they can generally be seen as completly separate issues. Brightness, is largely a function of obj. diameter and magnification, coupled with coatings.
For what it's worth, if you're looking for color neutral views, you might look at various models of binoculars from brands such as Minox and *some* Nikon and even Swift Audubon.
Actually, Qiao Chen, I've got a better idea for you. Rather than have us describe all the possible bins that are colorfree or colorful, why don't you tell us what size bins you want and what you want them for? There's a surprising amount of owner experience to be had on this forum if you ask the right questions.
Ed & Kevin,
You guys might get a kick out of this. I concur with Kevin about Russian binox. Anyway, after trying a ridiculous number of various bins, one of the sets that I keep is a set of 7x50 Tentos Russian binox. They were made in the USSR back when that was still possible. They are ridiculously heavy and bulky and tint everything quite yellow. But, get this: when it's dawn or dust or flat out night, and I want to differentiate Bambi from the trees around her, these jumbo Soviet glasses will do it in a way that only the previous Steiner Night Hunters in 7x50 could do it. The Tentos cost me $40 on Astromart, whereas I sold the Steiners at an extreme loss for 10x that amount. And the Tentos are center focus, whereas the Steiners were indiv. focus. I've never seen a set of 7x50s that were as bulky or weighed as much. And I've never seen another set of binox that were the equivalent of looking through those "Blue Blocker" sunglasses that were all the rage a decade ago, but for what these Tentos are, they are somewhat amusing. Still, there's something about the coatings or the optics on them that means that Jupiter is a blob, while the stars are contrasty pin points. I've had similar experience with 2 other Russian binox in different sizes. They're simply weird!