lens properties: ED, HD, Dielectric Coating, Multi Coating (1 Viewer)

[hexalite2k5]

Hey guys,

I am looking to buy my first pair of binoculars and I have roughly 200$ to spend. Around this price level I found a few interesting alternatives:
Bushnell Legend Ultra HD, Vortex Diamondback, Zen-ray ZRS HD, Zen-ray Vista, Nikon Prostaff 7.

Reading the specs I am left a bit confused by the description of the lens characteristics. For example, there's ED (extra-low dispersion) glass on the Legend , HD glass on the ZRS and Legend, and the ZRS also has Dielectric Coating. And another term mentioned is "multi-coated".

Which of these features should I care more about, and which are not very important? Which ones do you guys care more about?

Thanks a lot

 

[FrankD]

HD is a marketing term often referring to high definition images. It isn't really a glass type. ED glass is as you referenced it above. It helps to reduce color fringing on high contrast objects so you get a cleaner and sharper view...assuming the rest of the binocular is designed to take advantage of it.

Coated, fully coated, multicoated and fully multicoated all refer to how much anti reflective coatings are applied to all of the glass surfaces. Fully multicoated is typically the highest grade.

Dielectric coating is a special coating only applied to the prism in roof prism binoculars. You won't find it in porro prism models. It typically offers the highest level of reflectivity and therefore the brightest and sharpest images in a roof prism model. The next grade below that is silver prism coating followed by aluminum.

 

[Troubador]

HD is a marketing term often referring to high definition images. It isn't really a glass type. ED glass is as you referenced it above. It helps to reduce color fringing on high contrast objects so you get a cleaner and sharper view...assuming the rest of the binocular is designed to take advantage of it.

Coated, fully coated, multicoated and fully multicoated all refer to how much anti reflective coatings are applied to all of the glass surfaces. Fully multicoated is typically the highest grade.

Dielectric coating is a special coating only applied to the prism in roof prism binoculars. You won't find it in porro prism models. It typically offers the highest level of reflectivity and therefore the brightest and sharpest images in a roof prism model. The next grade below that is silver prism coating followed by aluminum.

Frank gives a great summary.

'HD' is appearing all over the place just like 'Turbo' did about 20 years ago. It may represent a quality increase or it may not; best ignore it.

Whatever such terms are attached to the bins you like the look of, try before you buy is the only real test.

Lee

 

[Chosun Juan]

Hexalite, a couple of points to add to what Frank has already said.

The HD designation is by and large a marketing term which trades on the hoopla surrounding the 720p, and 1080p standards for display devices (like TV's). However, it can also be used to indicate 'High Density' glass, which is meant to offer improved performance.

I don't think there's any water-tight agreement within the industry on it's usage, so it can mean anything from 'pure marketing fluff', to 'higher quality / transmitting glass', to 'low, or even extra-low dispersion glass', and probably anything in-between. Not all 'HD' glass is ED glass.

To add to the complexity, not all ED glass is created equal - there are several grades. The better grades of ED glass cost more - there are no free lunches in binoworld! ED glass is used to minimise CA (Chromatic Abberation) - basically the colours don't all line up to where their supposed to, causing colour fringing of various colours and severity. This affects each individual differently, and some people are not bothered by it at all.

Dielectric roof prism coatings offer around 99% reflectivity, versus around 90%+ for the other types. You should note that a porro prism (those old military style, looking binoculars) offer 100% reflectivity, since it's all done with internal geometry and negligible losses - there are many fans of porros, especially at these lower price points, to give more brightness bang for the buck - just make sure they are modern production designs, with the latest fully multi-coated lenses.

The losses on the prisms, add to the losses on the other lenses, to give the overall transmission ratio (generally ~85% for budget stuff -> 95% on the best $2k+ 'alpha' stuff). There is some debate around here as to how much additional brightness can be detected by the human eye - some feel its 3%, some 6%, or more.

The other consideration is age - if younger, you'll gain much benefit from the 8x42 size. It's easier to use, brighter, and you'll see more stuff, more of the time.

I, like many here, like brightness (dielectrics, or porro) AND minimised CA (ED glass). eg. Zen-Ray 8x43 ED3, roughly double your budget. You could spend well over $2k on relatively, marginally better than that 'alpha' bins - the law of diminishing returns. You have to choose what looks best for you. Good luck!


Chosun :gh:

 

[FrankD]

Good follow up posts.

Sorry for being so succinct yesterday but I was typing on my Iphone.

To answer your last question, here is what I would look for....

Assuming roof prism model:

Fully Multicoated
Bak-4 prisms
Phase Corrected (or phase coated)
Wateproof

That would be the bare minimum. ED glass in the objective lens and specifics in terms of the roof coating (aluminum, silver, dielectric) are a bit of a bonus. As Chosun listed above the ideal situation would be ED glass objectives and dielectric coatings on the prisms in addition to all of the bare minimum requirements I listed above. Having said that you may be surprised by bins that that don't have either ED glass or dielectric prism coatings in their design. The Sightron SII Blue Sky series comes to mind in this case as they have neither and yet the optical performance is several times the level of their cost. The key in that case, I believe, is that the rest of the optical design was so well thought out that it didn't necessarily need ED glass or dielectric coatings to produce optically excellent images.

If you go the porro prism route then preferred features would be:

Bak-4 prisms
Fully Multicoated
Waterproof

I say this in the general sense as there are always exceptions to the rules. I have owned several Bk7 porro binoculars that had images just as sharp and color-filled as their Bak-4 counterparts. If you read some of the more technical threads then you can find explanations for this. I have also owned several porro prism models that weren't fully multicoated. Though the image has less contrast than the fully multicoated models I haven't really found much else different optically. A case in point would be my Nikon 7x35 wide field model...circa mid-1980s. Excellent optical performance in all areas except for contrast. Even the importance of waterproofing can be often debated. Two of the most highly acclaimed porros available, the Nikon SE and EII, are not waterproof but folks still tend to buy them quite regularly.

Hope this helps.

 

[ceasar]

Succinct and well explained. I'm giving this thread a 5 rating!:t:

Bob

 

[hexalite2k5]

Thank you for taking your time to post such detailed explanations guys. I really appreciate it. I'm still a bit torn between Zen-Ray Vista, ZRS HD and the Sightron S II Blue Sky. But since I can't really test them in person and I have never bought a pair before I guess that's a bit expected. As a novice user do you think I will notice any difference in quality between these? Does a more experienced user notice differences or I'm likely to find people pretty much equally divided between these models?

 

[FrankD]

I think you would notice ths slight differences if someone was standing next to you and pointed them out. Otherwise I think you would find them entirely comparable optically.

 

[eitanaltman]

If you can afford $200 I would scratch the cheaper Vista off the list and make your decision between the ZRS HD, Diamdback and the Sightron.

I've owned both the Vista 8x42 and the Sightron 8x32 and the Sightron is clearly ahead optically, plus its significantly more compact. The Diamondback is similar to the Vista but has a wider FOV and nicer ergos (better focus knob and eyecups) plus you get the Vortex warranty.

The ZRS HD 8x42 is a great value if you want a full size 42mm aperture bin, it's still relatively compact for a 42mm (under 23oz) and by all accounts delivers terrific optics.

Basically, to piggyback on Frank's post, within this group of contenders the optics are so close that only the nitpickers on this site would be likely to find differences. Other factors -- price, size, weight, ergonomics, warranty -- are going to be greater differentiators than optics.