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compact roofs and dielectric coating- not needed? (1 Viewer)

pat mitchel

Well-known member
Forgive my ignorance in the small roof binos category, but the use of dielectric coatings does not seem to be common on compact roof binos. Is there a reason for that or simply economics? Regards, Pat
 
The images will be out of phase without the coatings.

To me it just means a cheaper glass, but I may be wrong.

“Cheaper” as in corners cut.
 
Are we taking about p-coatings or mirror?
My 20 year old Canon 8x32 WP is missing the p-coatings I think (at least according to the "polarized 3D-glasses test". They are still great binos and very sharp. But they do have excellent AR coatings on the lenses.
In older binos I can't really tell if they're less bright because of the coatings of the prisms or lenses. Probably both but the difference to old porros isn't that big. It doesn't seem to influence sharpness all that much. More contrast.
On modern roofs I'd definitely expect both - dielectric mirrors and p-coatings. Everything else is too cheap to use.
That being said - the old NVD EDF 7x40 is still considered a great bino even without p-coatings.
But for magnification on the lower end, like 6-8x, it's probably not all that visible.
 
We are talking about the coatings which correct the out-of-phase images in S-P roof prisms, no matter what magical name the manufacturer may choose to give them.
 
The reason I ask the question is that when you go up to the mag X size (8x32) roof prism bino's, there's several example of 8x32 that have dielectric coatings (in place of silver I asume) starting at around 180-200 US dollars where none of the 8x25 except the Swarovski (swarobrite?) that I can see lists dielectric coating- since the coating themselves seems to be a selling point I can only guess that they don't have them if they don't list them. Just looking for an expalanation as to why it might be so. Thanks, Pat
 
The dielectric coating has nothing to do with phase correction and was a big upgrade over the older silvered mirror surfaces bringing an upgrade in light transmission for a brighter image.
On higher end binoculars it’s become the standard.
 
The dielectric coating or another mirror coating (silver or aluminium) is applied on that prism surface of a Schmidt-Pechan prism on which a light beam is entering and no perfect reflection occurs, so it is a correction coating.
That is something else as phase coatings.
Gijs van Ginkel
 
Yeah, but the phase coatings are dielectric too. Therefore if someone mentions dielectric coatings, it's not at all clear which ones.
AFAIK - weren't phase coatings always dielectric even while mirror coatings were still silver? I think I have read something along those lines.
 
I'm referring specifically to the coatings that are doing the reflection in place of the silver (or aluminum in earlier roofs) coats that provide the reflection. Better??? Again, they use them in 180 dollar US 8x30's, why aren't dielectric coatings used on a mid priced compact? Pat
 
The dielectric coating has nothing to do with phase correction and was a big upgrade over the older silvered mirror surfaces bringing an upgrade in light transmission for a brighter image.
On higher end binoculars it’s become the standard.
The p-coating is a dielectric coating, too. Also - dielectric mirror coatings are not that much of an upgrade. For example all the Fujinon KFs or the respective Sightron/Kenko models which were still made a little while back have silver coatings and the difference in brightness is not as great as one might imagine when comparing them to similar models with dielectric coatings.
A direct comparison between the newest Kenko DHIII Ultraview and the DHII would be interesting. Especially an exact number for the transmission (assuming the rest of the coatings is the same which is not very likely).
 
I'm referring specifically to the coatings that are doing the reflection in place of the silver (or aluminum in earlier roofs) coats that provide the reflection. Better??? Again, they use them in 180 dollar US 8x30's, why aren't dielectric coatings used on a mid priced compact? Pat
Price probably. The dielectric ones need at least 25 layers or even more.
But the mentioned models above are still pretty good.
I compared at length the Fuji KF 10x42 to the Svbony SV202 (dielectric coatings) - about the same price. The Fuji might be slightly less bright but CA in the Svbony is worse despite ED-glass.
So I think all else being equal - sure dielectric is better. But all else is never equal so direct comparisons of different models are still helpful. I have no problem with silver coatings.
Even some of my old roofs with silver or maybe even aluminum coatings and without any p-coatings are often quite good. Sure, not compared to the latest and greatest maybe but perfectly usable.
 
Hi Philipp; Understand I'm not being critical of silver or aluminum just trying to frame the fact that dielectric coating for reflection seems to be the latest/greatest (marketing) that is supposed to improve the optics and seem curiously absent for compacts when it's applied to most of the other classes of roof prism binos. Was thinking that the market for a compact might be small in comparison to the 8x30 and up, that it's not worth the costs. Regards, Pat
 
the use of dielectric coatings does not seem to be common on compact roof binos. Is there a reason for that or simply economics?
Doesn't it? According to Leica both the Trinovid and Ultravid compacts have HDC (transmission multicoating), P40 (phase), HLS (dielectric mirror), and AquaDura (hydrophobic) coatings. So I expect you'd have to go fairly cheap to not find it.
 
Doesn't it? According to Leica both the Trinovid and Ultravid compacts have HDC (transmission multicoating), P40 (phase), HLS (dielectric mirror), and AquaDura (hydrophobic) coatings. So I expect you'd have to go fairly cheap to not find it.
And my 7x21 Curios are damn bright, I have no idea what coatings they have, but they sure pass the eye test.
 
Hi Philipp; Understand I'm not being critical of silver or aluminum just trying to frame the fact that dielectric coating for reflection seems to be the latest/greatest (marketing) that is supposed to improve the optics and seem curiously absent for compacts when it's applied to most of the other classes of roof prism binos.
I'm aware.
But what type of compacts are we talking about? Are there any high-quality ones in lower price brackets?
I have looked through a made in Japan Kowa BD 8x25 -- it was pretty good but I cannot find any info about the mirror coating. It's around 250€.
The only compact I'd be interested in is the Swaro Curio or Lux HR 8x25 by DDoptics (no longer made but still easy to be found online) -- and both have dielectric coatings.
My Fujinon KF 10x42 is probably the only relatively modern roof prism model that I have with silver coatings. It is really good and in daylight I don't really notice much loss of brightness.
But in case of those small compacts like 8x25 or something along those specifications, I think I'd want was much brightness as possible.
I don't think I will buy any silver coated roofs that are recent releases, if there even are any. It's no longer up to date even though there might be not that much difference in brightness.
 
OK to simplify- entry level compacts- fair enough or should I be more specific? There's entry level 8x30 with both types (phase and reflective dielectric coatings, why not the compacts. Pat
 
There are two completely different types of layers:
1 layer that must be applied on the mirror surface of the roof Schmidt Pechan prism. It can be aluminum, silver or dielectric. The transition from silver to dielectric is a bonus, but it is not as spectacular as the one from aluminum to silver!
2 the phase correction layer that are applied to one surface on the prisms, gives the binoculars a higher contrast. Binoculars that do not have this layer have a low contrast, having a major impact on the optical quality

So those compact binoculars in question, if they have phase correction coating and at least silver reflectivity coating, they can be very good optically
 
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Binoculars that do not have this layer have a low contrast, having a major impact on the optical quality
The effect is not "major" though. If it was, there would be a much bigger difference between old porros and old roofs than there actually is as everybody can confirm who compares a porro from the 70's with a roof from the 70's of otherwise comparable quality and price.
I have a number of older roofs with no p-coating and even one relatively "modern" one which is actually one of my favourites -- the Canon 8x32WP (20 years old however). It is razor sharp and you will see no "reduction of contrast" compared to a 8x32 porro from that time.
So the effect of the p-coating is far less obvious than for example improved anti-reflective coatings on the lenses. Those do make a difference. P-coatings not so much, especially at lower magnifications like 6-8x.
Edit: just did a little comparison between an old 8x30 roof to my Zeiss Jena 8x30 and a Japanese made 8x30 wide angle.
The optical differences are minimal when it comes to resolution or sharpness.
IMG_20230310_111255.jpg

Photobombed by my feet in lovely white socks in plastic slippers. Do I look like a proper German or what :lol:?
 
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