Alpha Spectacles (1 Viewer)

[birdrousta]

Would contact lenses work?

I think there is a firm making bespoke binoculars, Maven??, that might go to minus 10 dioptres.

The Minolta 8x23 AF autofocus binocular I think goes to minus 12 dioptres. I have this but have plus correction.

Maven is willing to go out to 12 D. I have a set of 8 diopter B2s coming next week. The option isn't available as a canned choice in the web form; I would call them ahead of time to discuss it, and also add something in the "notes" on your order form referencing the diopter correction needed and who you spoke with about the order.

Someone with a 10 D correction is going to need to use their eyeglasses a lot of the time, but once you're able to stand still and are more-or-less oriented, being able to get rid of them might let a bino with substantial overfocus be useful - that's how I'm using them, and it's a part of why I'm using the eyeglass lariats, so I can easily get them out of the way without losing them.

 

[matthew_]

Interesting Matthew.
Is the difficulty due to the 10 dioptres?
My optometrist gets it exactly right so I think there are good U.K. labs.
Near distance IPD differs from far distance IPD.
There are a few optometrists here who might advise.
My optometrist also corrects for prism in different ways.

P.S.
I think the near and far IPD may differ by 3mm or 4mm.
Is this the problem?

I know near distance IPD differs from far distance IPD. What I was saying was that if my far distance IPD was 62mm.. they couldn't fabricate one that is 62mm.. the laboratory would always produce one that is not 62mm.. it could become 64mm or even 60mm.. this was due to the lens making machine moving while the lens were grinded. I actually talked to the fabricators themselves and they said there was always errors or tolerances because of the low cost of their machines. How do I know it's not 62mm.. because I independent tested it myself using a lensometer. Another thing. If you will let the optical store you ordered it from test it. They will always doctor the result and lying to you that it's 62mm when it was not. This is why I want to try online lens maker.. I couldn't travel far because I'm in a wheelchair. So online is my only option.. it could be an online fabricator in Germany or the United States. Does anyone know of such in the US? I can easily order one there and have it shipped to me quickly. I know freight forwarders in the US who can ship it in 3 days to me. I have prescription written and ready to present it any online store which I have searched for already for 10 years but not sure which made a good one with accurate IPD as ordered. Thank you.

 

[perterra]

You got you're work cut out for you. I can offer no help here because you have gone over my head.

I will say, a good optician will not lie to you. But it may be very hard to differentiate between a good optician and one who will lie. I have used these guys for shooting glasses and feel they knew what they were doing. It might not hurt to make a phone call though there has to be someone similar closer to you.

http://www.texasshootersoptical.com/about-us.aspx

Good luck and let us know the outcome, because I am interested in hearing it.

 

[matthew_]

You got you're work cut out for you. I can offer no help here because you have gone over my head.

I will say, a good optician will not lie to you. But it may be very hard to differentiate between a good optician and one who will lie. I have used these guys for shooting glasses and feel they knew what they were doing. It might not hurt to make a phone call though there has to be someone similar closer to you.

http://www.texasshootersoptical.com/about-us.aspx

Good luck and let us know the outcome, because I am interested in hearing it.

This is what is going on. When I told the optometrist why the lens was not exactly 62mm IPD but 60mm.. He would say the optical labs have tolerances or allowances and our eyes can adjust. But I'm so sensitive I got eyestrain if it's not exactly 62mm IPD. So I actually argued with the 3 optometrists and quarreled with one because he said 2mm difference is really part of the optical labs tolerances.. this is because if I returned the spectacles to them.. they couldn't return it to the labs.

But I heard that very accurate labs could produce a spectacle of exactly 62mm IPD. This is what I couldn't find in over 30 years (I'm 45 years old). This is what I'm looking for. If you remember or encounter any online fabrication lab with accuracy and good competence. Please let me know.

 

[perterra]

This is what is going on. When I told the optometrist why the lens was not exactly 62mm IPD but 60mm.. He would say the optical labs have tolerances or allowances and our eyes can adjust. But I'm so sensitive I got eyestrain if it's not exactly 62mm IPD. So I actually argued with the 3 optometrists and quarreled with one because he said 2mm difference is really part of the optical labs tolerances.. this is because if I returned the spectacles to them.. they couldn't return it to the labs.

But I heard that very accurate labs could produce a spectacle of exactly 62mm IPD. This is what I couldn't find in over 30 years (I'm 45 years old). This is what I'm looking for. If you remember or encounter any online fabrication lab with accuracy and good competence. Please let me know.

I will ask around, if I get any info I will for sure let you know.

 

[matthew_]

After I found a lab anywhere in the world that can fabricate accurate IPDs in the spectacles. I'll have it fully multi-coated (99% transmission) like in the Leica Ultravid that would produce the sparkle.. (what is your estimate of typical transmission percentage of typical spectacles?) I read in this forum too that multi-coatings have certain transmission spectra.. how about in spectacles.. what is the typical transmission spectra? Is there a green cast like in the Zeiss SF I read in another thread?

Getting an alpha spectacle is in preparation for possibly getting the alpha Leica Ultravid which looks very nice compared to the very bucky Zeiss SF.

 

[matthew_]

To elaborate above. I am trying to understand why my present spectacles can degrade image contrast of any binoculars I tried turning mid range models into low end units (or alphas into mid range). Reading the many threads going on about it right now. Multicoatings for different wavelengths of light seemed to be required to get the full visible light spectra. If you only allow a certain window of it.. then the image contrast would be degraded. For typical spectacles.. what are the wavelengths the multicoatings were optimized for? Is it green light? Could my poor spectacles result from some missing multicoatings for certain wavelengths? Or is this overthinking and binocular multicoatings concepts couldn't be applied to spectacles. And the reasons for it? I avoid wearing contact lens because it can dry my eyes so would like a full multicoated spectacles with HT multicoatings (or Swarotop or whatever is the equivalent in spectacles for the premium multicoatings which is?)

 

[looksharp65]

I have nearsightedness with minus 10 diopters. I visited 4 optometrist/opticians. Although the prescription was correct. They couldn't get a lab that could accurately center the lens in the frames. For example If my IPD is 62. They would make lens that were 59 or 65 or worse. So I have 7 eyeglasses in my drawer that are not being used because of wrong horizontal and vertical IPDs. They explained the lens machine could move while rotating hence the error. I have tried it the past 10 years and already got tired of searching for labs that could make the right IPD. Therefore I'm looking for a specialized online laboratory that can make at least the IPD right. I can let my optometrist do the prescription in the sheet. Then send it to Zeiss (what else there?) for accurate fabrication. My optometrists don't have access to such labs.

Matthew,

I'm an optician/optometrist and I'm astonished with what you tell us here.
The spectacles with the faulty IPD's should never have left the shop.
If your prescription is -10 D and the mounting error is 0.2 cm, the resulting prism effect will be 2 prism diopters. That is way out of tolerances.
For horizontal prism effects, the tolerance is 0.50 prism diopters and for vertical, no more than 0.25 prism diopters is acceptable.
To put it frankly, they screwed you and sold you substandard products.
Furthermore, their explanation is intolerable. While it is true that edging high-power, high-index lenses is most demanding and errors occur, that's no excuse for leaving you with an unusable pair of spectacles.
If they don't know how to avoid the errors, for example by edging test lenses of similar power to find out if tweaks have to be made, they should swallow the pride and send the frame to the lens manufacturer so they can deliver a faultless product.

It is indeed more difficult to handle lenses of strong powers. Not only because of the above-mentioned edging and centration issues, but also because the frame may not always rest in the intended position, and small adjustments of the frame can induce significant prism effects and discomfort.
I and my colleagues agree that if the highly ametropic spectacle wearers weren't so uncomplaing, making spectacles for them would be a nightmarish and next to impossible task.

There are occasions, and they are not very rare, when the correction of each eye individually will be useless because of the two lenses's individual distortion pattern, magnification/minification and prism effects occuring with oblique gaze directions. Another special case is convergence anomalies, where progressive lenses of standard parameters will fail, but highly tailored versions may be usable.

I regret your previous experiences with spectacle purchases, but do hope you will realise that buying them online won't ensure success.
On the contrary, my view is that buying spectacles online means a step down in quality and more or less a lottery.
Your eyes deserve the best, so try to find a vendor with a solid reputation of being able to handle challenging prescriptions and (not least) with a solid complaint handling policy.

//L

 

[Binastro]

Thank you so much looksharp65.

I hope that Matthew can get satisfactory glasses.

I don't think differences with multicoating on two surfaces is that critical?
Maybe the plastics used or glass introduce shifts themselves?

I am lucky to have a very good optometrist and have used multicoated standard plastics for years on my glasses.
Now I have an annual check.

 

[matthew_]

Matthew,

I'm an optician/optometrist and I'm astonished with what you tell us here.
The spectacles with the faulty IPD's should never have left the shop.
If your prescription is -10 D and the mounting error is 0.2 cm, the resulting prism effect will be 2 prism diopters. That is way out of tolerances.
For horizontal prism effects, the tolerance is 0.50 prism diopters and for vertical, no more than 0.25 prism diopters is acceptable.
To put it frankly, they screwed you and sold you substandard products.
Furthermore, their explanation is intolerable. While it is true that edging high-power, high-index lenses is most demanding and errors occur, that's no excuse for leaving you with an unusable pair of spectacles.
If they don't know how to avoid the errors, for example by edging test lenses of similar power to find out if tweaks have to be made, they should swallow the pride and send the frame to the lens manufacturer so they can deliver a faultless product.

It is indeed more difficult to handle lenses of strong powers. Not only because of the above-mentioned edging and centration issues, but also because the frame may not always rest in the intended position, and small adjustments of the frame can induce significant prism effects and discomfort.
I and my colleagues agree that if the highly ametropic spectacle wearers weren't so uncomplaing, making spectacles for them would be a nightmarish and next to impossible task.

There are occasions, and they are not very rare, when the correction of each eye individually will be useless because of the two lenses's individual distortion pattern, magnification/minification and prism effects occuring with oblique gaze directions. Another special case is convergence anomalies, where progressive lenses of standard parameters will fail, but highly tailored versions may be usable.

I regret your previous experiences with spectacle purchases, but do hope you will realise that buying them online won't ensure success.
On the contrary, my view is that buying spectacles online means a step down in quality and more or less a lottery.
Your eyes deserve the best, so try to find a vendor with a solid reputation of being able to handle challenging prescriptions and (not least) with a solid complaint handling policy.

//L

Thank you for sharing. I will try to travel farther and look for other optical stores later this week.

Not only will I look for spectacles with correct IPDs. I will make sure the multicoatings will be properly done. When you look at objective lens of binoculars.. you can see deep red or deep green or even blue. But when I put my hands on the back of my spectacles and looked at the front.. the multicoatings were only very very light and didn't look deep green. If each surface has 4% reflectivity without multicoatings.. you get 8% loss of light in spectacles with 2 sides. But transmission is not the main problem.. you will also have lights reflected back to the eyepieces lowering image contrast. Do you know the percentage of light loss in spectacles? I don't think it is 0.02% for each side which Swarovski claimed in their Swarotop. I guess mine has maybe 2.5% light loss because of very light coatings. Furthermore.. do you know the transmission spectra (I learned this jardon reading other threads by a poster called Gijs) of spectacles? If it is optimized for green light and suppressing other spectra (blue and red).. this can interact with the binocular spectra resulting in loss of contrast. So with the 95% transmission Zeiss HT, it will be lower to 90% transmission with spectacles.. furthermore, the 5% loss light would return to the eyepieces forming ghosts or lowering image contrast.

Lastly. Plastic lens by itself is not as clear as glass lens. Do you know why?

Thank you very much.

 

[perterra]

Thank you for sharing. I will try to travel farther and look for other optical stores later this week.

Not only will I look for spectacles with correct IPDs. I will make sure the multicoatings will be properly done. When you look at objective lens of binoculars.. you can see deep red or deep green or even blue. But when I put my hands on the back of my spectacles and looked at the front.. the multicoatings were only very very light and didn't look deep green. If each surface has 4% reflectivity without multicoatings.. you get 8% loss of light in spectacles with 2 sides. But transmission is not the main problem.. you will also have lights reflected back to the eyepieces lowering image contrast. Do you know the percentage of light loss in spectacles? I don't think it is 0.02% for each side which Swarovski claimed in their Swarotop. I guess mine has maybe 2.5% light loss because of very light coatings. Furthermore.. do you know the transmission spectra (I learned this jardon reading other threads by a poster called Gijs) of spectacles? If it is optimized for green light and suppressing other spectra (blue and red).. this can interact with the binocular spectra resulting in loss of contrast. So with the 95% transmission Zeiss HT, it will be lower to 90% transmission with spectacles.. furthermore, the 5% loss light would return to the eyepieces forming ghosts or lowering image contrast.

Lastly. Plastic lens by itself is not as clear as glass lens. Do you know why?

Thank you very much.

I've never seen any color on my eye glasses, and the high definition lens seems just as clear as glass

 

[Binastro]

Dear Matthew,
I don't think actual colour is the main point.
My plastic regular glasses are all quite a deep green.
I use 6 different glasses regularly, having little accommodation.
I would think 0.5% per surface likely, giving 1% loss.
However, when greasy who knows?
When binocular eyepieces greasy, who knows?
I think that in practice good multicoated glasses will be fine.
Some of the more exotic plastics turn out worse than regular plastic.

Much more important is that you get glasses you can use.

 

[Binastro]

Rev. Dawes was very shortsighted and did not recognise people.
He had very fine eyesight.

A friend similarly has very fine sight.

 

[looksharp65]

Thank you for sharing. I will try to travel farther and look for other optical stores later this week.

Not only will I look for spectacles with correct IPDs. I will make sure the multicoatings will be properly done. When you look at objective lens of binoculars.. you can see deep red or deep green or even blue. But when I put my hands on the back of my spectacles and looked at the front.. the multicoatings were only very very light and didn't look deep green. If each surface has 4% reflectivity without multicoatings.. you get 8% loss of light in spectacles with 2 sides. But transmission is not the main problem.. you will also have lights reflected back to the eyepieces lowering image contrast. Do you know the percentage of light loss in spectacles? I don't think it is 0.02% for each side which Swarovski claimed in their Swarotop. I guess mine has maybe 2.5% light loss because of very light coatings. Furthermore.. do you know the transmission spectra (I learned this jardon reading other threads by a poster called Gijs) of spectacles? If it is optimized for green light and suppressing other spectra (blue and red).. this can interact with the binocular spectra resulting in loss of contrast. So with the 95% transmission Zeiss HT, it will be lower to 90% transmission with spectacles.. furthermore, the 5% loss light would return to the eyepieces forming ghosts or lowering image contrast.

Lastly. Plastic lens by itself is not as clear as glass lens. Do you know why?

Thank you very much.

First, allow me to doubt the 0.02% reflection rate of the Swarotop. The figure seems highly unlikely to me. Unfortunately I don't have access to any numbers, but I recall learning that a high-grade multicoating has 99.8% transmission, which means that a finished lens has 0.998^2, e.g. 99.6% transmission.
Although the light reflected from the surfaces may appear to have a distinct colour, and this wavelength is subtracted from the beam pencil going through the lens, it does very little to change the perceived colour bias as long as it's only two surfaces. Frankly, it is totally negligible. The residual reflection is made to keep within a very narrow wavelength range but maybe not quite monochromatic.
Thus it may seem fairly bright although the actual light loss is kept at a low level.
But since it's green light they're reflecting, they are not optimized for maximum green light transmission, they are optimized for everything else but green.

You also ask why mineral (silicate) lenses are "clearer", which is the better question. The transparency of the lenses will decidedly affect your perceived view much more than the properties of the multicoatings.

With your spectacle powers, the only reasonable high-index plastic lens is 1.74, and the high refractive index is reached by adding various substances to the polymer mix.
These chemicals reduce the transmission rate, and the finished lenses may look like they are tinted, especially on photos.
The high-index mineral lenses (1.7 and 1.8 at least) don't appear as brownish as the plastic, but I wouldn't bet on that. Things develop rapidly and the plastic lenses generally get better while the mineral lenses don't develop.
The transmission rates are available from the lens manufacturers and the optician should be able to provide them.
Best-case scenario is if transmission diagrams are available.

//L

 

[matthew_]

First, allow me to doubt the 0.02% reflection rate of the Swarotop. The figure seems highly unlikely to me. Unfortunately I don't have access to any numbers, but I recall learning that a high-grade multicoating has 99.8% transmission, which means that a finished lens has 0.998^2, e.g. 99.6% transmission.
Although the light reflected from the surfaces may appear to have a distinct colour, and this wavelength is subtracted from the beam pencil going through the lens, it does very little to change the perceived colour bias as long as it's only two surfaces. Frankly, it is totally negligible. The residual reflection is made to keep within a very narrow wavelength range but maybe not quite monochromatic.
Thus it may seem fairly bright although the actual light loss is kept at a low level.
But since it's green light they're reflecting, they are not optimized for maximum green light transmission, they are optimized for everything else but green.

Poorly applied multicoatings in spectacles can cause more light scatter causing loss of contrast. But is it perceivable (to what degree)? Whatever. I'd have the best multicoatings in my next spectacles. What brand is the tested standard? If we have Swarotop in binoculars. What is the best trademark in spectacles (like Alcontop)? I want one where we can find transmission characteristics or actual percentage of light loss and/or transmission.

You also ask why mineral (silicate) lenses are "clearer", which is the better question. The transparency of the lenses will decidedly affect your perceived view much more than the properties of the multicoatings.

With your spectacle powers, the only reasonable high-index plastic lens is 1.74, and the high refractive index is reached by adding various substances to the polymer mix.
These chemicals reduce the transmission rate, and the finished lenses may look like they are tinted, especially on photos.
The high-index mineral lenses (1.7 and 1.8 at least) don't appear as brownish as the plastic, but I wouldn't bet on that. Things develop rapidly and the plastic lenses generally get better while the mineral lenses don't develop.
The transmission rates are available from the lens manufacturers and the optician should be able to provide them.
Best-case scenario is if transmission diagrams are available.

//L

What do you meant by "Things develop rapidly and the plastic lenses generally get better while the mineral lenses don't develop." What "develop"? Did you mean plastic lenses technology are still being developed while glasses are no longer being developed? So different brands of plastic lens have different clarity??

About you statement "high refractive index is reached by adding various substances to the polymer mix." I tested my plastic and glass spectacles on all binoculars I can get a handle on. The plastic significantly degrade the contrast. When tested on a Sightron. It's like the Sightron became just Tasco, the loss of contrast even produce lost of details especially in tiny details. The glass lens only affect it very little (which may be related to non-optimum multicoatings perhaps or inherent in the glass.. do they add something equivalent to polymer mix in glasses too?).

I wonder if higher diopter (and thicker lens) would produce worse image. Is it right to say that the thicker is the plastic lens, the worse is the effect? If anyone has been using plastic lens here with diopters more than -5.0 or +5.0. Try to aim your binoculars on close up object then switch to focus bare eyes by turning the focusing knob past infinity and compare this to one using your eyeglasses.. you'd be amazed at the difference! If you'd notice this after spending years on the top Alphas.. all those sparkle would be missed all those times you didn't realize the plastic spectacles degrade the views and contrast of small details like the feather texture of birds.

If there is one here who has -8.0 myopia and you don't notice any significant loss of image contrast in any bino using your plastic spectacles.. Please let me know the brand and where you have it fabricated. The reason I prefer plastic is glass spectacles are just so heavy especially -8.0 diopters!

Thank you.

 

[Binastro]

Matthew,
I am no expert, but I think that your problems are mainly with the poor lab and poor opticians.
Glass can be better, maybe, but hopefully looksharp65 can say whether good plastic technology can equal glass at minus 8 to minus 10 dioptres.
High index materials are more difficult to make and handle, and in some cases degrade and tarnish almost instantly, if not immediately hard coated and edge blackened. (Very high end lenses).

 

[looksharp65]

Poorly applied multicoatings in spectacles can cause more light scatter causing loss of contrast. But is it perceivable (to what degree)? Whatever. I'd have the best multicoatings in my next spectacles. What brand is the tested standard? If we have Swarotop in binoculars. What is the best trademark in spectacles (like Alcontop)? I want one where we can find transmission characteristics or actual percentage of light loss and/or transmission.

The top brands always compete at the highest possible level, and there is not one single brand that stands out. I'd guess that the German brands Zeiss and Rodenstock can provide transmission characteristics, but that might be true for other brands as well.
Any smear, dust or raindrop/fog will reduce the contrast a lot more than the difference between the best and the worst multicoating.
When I'm at it, this reminds me about the fogging problem caused by breathing. The image loses contrast significantly and the colour bias turns towards brownish like an old Jena Notarem roof or worse.

It might be intriguing to learn that the devices used for applying the multicoatings are exactly the same regardless of the brand names of the lenses and coatings. This does not mean that the coatings are identical, since the preparation steps may differ, the lens materials differ and the machines are set to different settings for every individual brand.
Even within the brands, fine-tuning may be performed to achieve the desired result.

What do you meant by "Things develop rapidly and the plastic lenses generally get better while the mineral lenses don't develop." What "develop"? Did you mean plastic lenses technology are still being developed while glasses are no longer being developed? So different brands of plastic lens have different clarity??

That's exactly what I meant.

About you statement "high refractive index is reached by adding various substances to the polymer mix." I tested my plastic and glass spectacles on all binoculars I can get a handle on. The plastic significantly degrade the contrast. When tested on a Sightron. It's like the Sightron became just Tasco, the loss of contrast even produce lost of details especially in tiny details. The glass lens only affect it very little (which may be related to non-optimum multicoatings perhaps or inherent in the glass.. do they add something equivalent to polymer mix in glasses too?).

I wonder if higher diopter (and thicker lens) would produce worse image. Is it right to say that the thicker is the plastic lens, the worse is the effect? If anyone has been using plastic lens here with diopters more than -5.0 or +5.0. Try to aim your binoculars on close up object then switch to focus bare eyes by turning the focusing knob past infinity and compare this to one using your eyeglasses.. you'd be amazed at the difference! If you'd notice this after spending years on the top Alphas.. all those sparkle would be missed all those times you didn't realize the plastic spectacles degrade the views and contrast of small details like the feather texture of birds.

If there is one here who has -8.0 myopia and you don't notice any significant loss of image contrast in any bino using your plastic spectacles.. Please let me know the brand and where you have it fabricated. The reason I prefer plastic is glass spectacles are just so heavy especially -8.0 diopters!

Thank you.

In general, I for safety reasons never advocate using mineral lenses.
Dropping and breaking them may lead to a personal disaster.
But this does not preclude the possibility to have one pair of mineral lens spectacles, dedicated for use with binoculars.

Remember what I wrote about the plastic's reduced transparency?
If you consider the difference in edge thickness vs. central thickness, you understand that the periphery of the lens will be darker than the centre.
Furthermore, and this is true for both plastic and mineral lenses, their Abbe number is more or less low compared to standard lens materials.
As a result, they can produce significant chromatic aberration which degrades the image quality. I'm thinking that your plastic lenses have a low Abbe number and your mineral lenses a higher.

//L

 

[birdrousta]

If there is one here who has -8.0 myopia and you don't notice any significant loss of image contrast in any bino using your plastic spectacles.. Please let me know the brand and where you have it fabricated. The reason I prefer plastic is glass spectacles are just so heavy especially -8.0 diopters!

Thank you.

I'm not at 8 diopters, but I do notice a significantly better image when I don't wear my eyeglasses, and have noticed it for years. I drove microscopes professionally for a time, and the first thing anyone who wore glasses did when using one was to take off our eyeglasses. This was true for folks with hard-line, glass bifocals like the fellow who ran the lab as well as the students who worked there.

Of course, the environment near a microscope is very predictable, the environment near binoculars is not.

UPS dropped a box off at the house this afternoon with a set of Maven B2s with 8 diopters of overfocus. The astronomy weather forecast for tonight is pretty good, and with luck I'll be able to get out with the dogs in daylight on a ridge for a time as well.

I think the contrast issue you describe has a second source, in addition to the additional layer of glass or plastic - it's holding the binoculars farther from your eyes, and as a result, light from either side degrades the image and in particular the contrast.

In your place, I would think about looking for binoculars that can accomodate a lot of overfocus. Maven will do up to 12 D of overfocus.

There are folks here who have written to Leica and asked that their binoculars have additional focus past infinity added to compensate for nearsightedness, and Leica has made that adjustment for free. I don't know if Zeiss or Swaro or Nikon would or wouldn't do the same, but you could certainly ask your dealer to ask on your behalf.

If you find a pair of binoculars you really like and are not concerned about the warranty, you might be able to find someone locally who can make the change for you.

One way to do it, perhaps the simplest way, is apparently to move the oculars somewhat closer to the objective lenses. (Hopefully someone can correct me if I am not understanding that, and can explain what the tradeoffs involved are?)

But I do hope you're also able to find a way to get your glasses made properly for you. I am wearing a new-ish set of glasses and will be heading back to the optometrist soon to have them look to be sure the center of the curve is correct for my IPD - your notes on glasses with the correction not properly centered are making me wonder if that's why I'm having a longer adjustment period with these than I normally do.

 

[matthew_]

I'm not at 8 diopters, but I do notice a significantly better image when I don't wear my eyeglasses, and have noticed it for years. I drove microscopes professionally for a time, and the first thing anyone who wore glasses did when using one was to take off our eyeglasses. This was true for folks with hard-line, glass bifocals like the fellow who ran the lab as well as the students who worked there.

Of course, the environment near a microscope is very predictable, the environment near binoculars is not.

UPS dropped a box off at the house this afternoon with a set of Maven B2s with 8 diopters of overfocus. The astronomy weather forecast for tonight is pretty good, and with luck I'll be able to get out with the dogs in daylight on a ridge for a time as well.

I think the contrast issue you describe has a second source, in addition to the additional layer of glass or plastic - it's holding the binoculars farther from your eyes, and as a result, light from either side degrades the image and in particular the contrast.

In your place, I would think about looking for binoculars that can accomodate a lot of overfocus. Maven will do up to 12 D of overfocus.

There are folks here who have written to Leica and asked that their binoculars have additional focus past infinity added to compensate for nearsightedness, and Leica has made that adjustment for free. I don't know if Zeiss or Swaro or Nikon would or wouldn't do the same, but you could certainly ask your dealer to ask on your behalf.

If you find a pair of binoculars you really like and are not concerned about the warranty, you might be able to find someone locally who can make the change for you.

One way to do it, perhaps the simplest way, is apparently to move the oculars somewhat closer to the objective lenses. (Hopefully someone can correct me if I am not understanding that, and can explain what the tradeoffs involved are?)

But I do hope you're also able to find a way to get your glasses made properly for you. I am wearing a new-ish set of glasses and will be heading back to the optometrist soon to have them look to be sure the center of the curve is correct for my IPD - your notes on glasses with the correction not properly centered are making me wonder if that's why I'm having a longer adjustment period with these than I normally do.

Do all standard Maven B2s have 12 diopter pass infinity (i'm talking about negative diopter or nearsightedly because farsightedness would have opposite focus knob directions)? What other central focus binoculars have this extra reaches past infinity?

About having your IPD checked. My experience was that if you have it checked by the original optometrist/optician. He would doctor the result (marking the lens area wrong) and tell you the IPD is perfect (this is because he couldn't return it to the labs since most labs have 2mm tolerances). So what I did was bring it to any other optical stores to have it checked. And all the time I'd have accurate results of the exact IPD (which is wrong all the time).

 

[matthew_]

The top brands always compete at the highest possible level, and there is not one single brand that stands out. I'd guess that the German brands Zeiss and Rodenstock can provide transmission characteristics, but that might be true for other brands as well.
Any smear, dust or raindrop/fog will reduce the contrast a lot more than the difference between the best and the worst multicoating.
When I'm at it, this reminds me about the fogging problem caused by breathing. The image loses contrast significantly and the colour bias turns towards brownish like an old Jena Notarem roof or worse.

It might be intriguing to learn that the devices used for applying the multicoatings are exactly the same regardless of the brand names of the lenses and coatings. This does not mean that the coatings are identical, since the preparation steps may differ, the lens materials differ and the machines are set to different settings for every individual brand.
Even within the brands, fine-tuning may be performed to achieve the desired result.




That's exactly what I meant.



In general, I for safety reasons never advocate using mineral lenses.
Dropping and breaking them may lead to a personal disaster.
But this does not preclude the possibility to have one pair of mineral lens spectacles, dedicated for use with binoculars.

Remember what I wrote about the plastic's reduced transparency?
If you consider the difference in edge thickness vs. central thickness, you understand that the periphery of the lens will be darker than the centre.
Furthermore, and this is true for both plastic and mineral lenses, their Abbe number is more or less low compared to standard lens materials.
As a result, they can produce significant chromatic aberration which degrades the image quality. I'm thinking that your plastic lenses have a low Abbe number and your mineral lenses a higher.

//L

In your statement "Furthermore, and this is true for both plastic and mineral lenses, their Abbe number is more or less low compared to standard lens materials.". You meant the glasses used in spectacles were not standard lens material but mineral lens? I thought the glasses used in binoculars and spectacles are the same.. are they not? Where to find spectacles that use the same lens material as binoculars?