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Old Thursday 14th April 2011, 21:28   #51
wingersheek
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Hello, Again,
Please, Would Someone Explain And Compare The Similarities / Differences Between The Zeiss Classic 7x42 ( Bgat ? ) And The Newer Zeiss Victory 7x42 Fl ?

Thanks.
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Old Friday 15th April 2011, 01:57   #52
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Folks - Interesting reading on the Internet about what lead in optics does to CA. Go read. John
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Old Friday 15th April 2011, 06:17   #53
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John,
Can you pin it down a little closer?
Bob
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Old Friday 15th April 2011, 16:06   #54
brocknroller
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John,
Can you pin it down a little closer?
Bob
Bob,

This has been discredited by the experts, but since you asked....here's one of the Ohara's reports I mentioned earlier that "lead" me to suspect that lead-free glass caused greater CA.

NOTE that the lead and lead-free glass being compared in this report have the same refractive index and Abbe numbers and yet still show differences in CA (greater in the lead free glass).

This had been the crux of counterarguments - because lead-free glass and lead glass have the same Abbe number, they are equal in all respects including CA control. According Ohara, that is not the case with all lead free optical glass. The first example is in the extreme end of the spectrum and though important for microscopy is probably not relevant for sports optics. The second example refers to "wide wavelength ranges".

I did download a more relevant Ohara report that dealt differences in the entire spectrum, and which stated that after a number of failed attempts at finding the right combination of lead substitutes, Ohara was able to make lead-free glass "nearly as good" as its high grade lead optical glass, but I also lost that document in a fatal computer crash. I don't have time to look for it now, but I will try to find it later.

Here are some quotes to that effect:

"To illustrate the difference in anomalous dispersion of lead-containing glass material and lead-free glass with the same refractive index and Abbe’s number, the differences between the glass materials BPH5 and S-NBH5 manufactured by OHARA INC. are described below. The refractive index and Abbe’s number of the lead-free glass material S-NBH5 are the same as that of the lead-containing glass material BPH5. The anomalous dispersion (Δθg,F, Δθi,g) of S-NBH5, which is important for correcting the chromatic aberration in the short wavelength region, is half or less than that of BPH5. Therefore, it will be impossible to design an Apochromat objective lens unless lead-containing glass material such as BPH5 is used."

Another example:

"In another example, the difference between the lead-containing glass material LAM7 and lead-free glass material S-LAM7 manufactured by OHARA INC. is described below. Although the refractive index and Abbe’s number of both glass materials are the same, the sign of anomalous dispersion (ΔθC,t), which is important for correcting the chromatic aberration in the near-infrared region, is different. Therefore, S-LAM7 cannot be used as a substitute for LAM7 to manufacture objective lenses that can correct chromatic aberration in wide wavelength ranges up to the near-infrared region. It is impossible to design a near-infrared objective lens unless lead-containing glass material is used."

Brock
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Old Friday 15th April 2011, 18:57   #55
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Brock,
You are starting to sound like a scientist, I am worried about you!

I get the idea I think: The Abbe number is defined across the bright part of the visible, from C to F I think (486 to 656 nm), so two glasses could have the same Abbe number, but still behave differently outside that range.

So, what color are the fringes that you see? To me, lateral color fringes usually look purple on one side and yellow green on the other (which I think is characteristic of secondary spectrum, and may give a clue to the fringes's origin). Yellow and green are in the middle of the visible, so I don't see how your argument pertains to them. I suspect the purple is a mixture of red and blue, at the ends of the visible, perhaps enough outside the CF band that your argument has some validity.

The link looks very interesting, I will read it when I get time. Thanks.
Ron

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Old Friday 15th April 2011, 19:36   #56
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Thanks Brock, Ron and Henry.
I'll have to re read this closely a couple more times though.
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Old Friday 15th April 2011, 23:47   #57
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To answer Ron, the color fringing that I see is reddish purple on one side, yellow green on the other. Only kind I see.

I like Henry's suggestion that the uptick in CA reports in modern non-ED bins is due to the change in internal focus compound objectives.

If it weren't for the fact that I've also compared porros of the same design where the newer versions had more CA (though still less than the roofs), and if I hadn't also read similar reports about other "udpated" porros, I'd gladly jump aboard the compound objective = > CA bandwagon, because in general, I see more CA in modern roofs than I do in modern porros of the same configuration.

Not that also seeing more CA in newer porros negates the compound objective = > CA idea. It's just that it's beginning to appear from the other points that have been discussed earlier such as more awareness of CA, more birders, older birder population, etc. that rather than there being a "Lone Gunman," there could be multiple "shooters" conspiring together to create that CA uptick.

None-the-less, to beat the dead horse one more time...

I found another Ohara report that sheds some (color fringed) light on the lead vs. unleaded gas, er... I mean glass differences.

One interesting comment that amused me was this:

'In flint glasses, lead oxide plays a vital role in producing a negative anomalous partial dispersion. The B2O3-PbO system such as encountered in Ohara’s glass types BPH8, BPH5, BPM51 shows significant negative anomalous partial dispersion. However, since it is thought that the characteristic of showing negative anomalous partial dispersion with high dispersion is a unique property of B2O3-PbO system,1 it has been difficult up until now to eliminate lead oxide."

Translating into the vernacular, it means that their own presuppositions about what was possible delayed the development of lead free glass. Though I would bet that government regulations to "get the lead out" caused them to open their eyes and take another look.

What they found at first confirmed their suspicions...

"The lead-free flint glasses, for example the glass system SiO2-TiO2, showed the opposite behavior - positive anomalous partial dispersion (> CA). As environmentally friendly optical flint glasses having negative anomalous partial dispersion, the glass system SiO2-GeO2-Ta2O5 was
introduced."

The power of three was the charm except for its economic and physical limits....

"This [lead free] flint glass however is economically disadvantageous because, in order to achieve the desired negative anomalous partial dispersion, it required a large amount of GeO2 (germanium dioxide) and Ta2O5 (tantalum pentoxide), materials which are very expensive. In addition, this glass is difficult to melt and
therefore, it is hard to obtain material homogeneity."

Nobium to the Rescue

"In niobium containing glass systems, Ohara found that the SiO2-Nb2O5-ZrO2 system [Quartz+Niobium pentoxide+Zirconium dioxide] for Ohara’s glass types S-NBH8, S-NBH5, S-NBM51 has negative anomalous partial dispersion.

"These glasses attained almost the same values for θg,F as conventional lead containing flint glasses as shown in Table I.

Niobium oxide is effective for increasing the negative anomalous partial dispersion property of the flint glasses if the amount of niobium oxide is above 20%. As
a result, niobium oxide plays a vital role in environmental friendly glass having negative anomalous partial dispersion."

Hallelujah! Are we there yet? Not quite...

Problem of Niobium Oxide Containing Environmentally Friendly Optical Glasses

"Whether a melt of specific composition vitrifies or crystallizes depends on the composition and
the cooling rate.... As Figure 6 shows, lead oxide has an unusual characteristic such that the glass forming
tendency of even binary PbO-SiO2 system leads to lead oxide content of more than 60 wt%. So it is possible for lead containing glasses to achieve a very high refractive index."

The plot (and coating) thickens...

Give me Lead or Give me Jaundice

"However, niobium oxide has a narrower glass-forming region than lead oxide does. It shows that the
glasses tend to crystallize stronger when the content of niobium oxide is more than 40 wt%. In order to prevent the crystallization for niobium containing glasses with high refractive index, it is necessary to adjust the refractive index by using additional elements like titanium oxide....

(and another "however")....

However, since titanium oxide has the fundamental absorption in the range of the near ultraviolet, the absorption limit moves toward longer wavelength compared with lead containing glass as shown in Figure 7. This makes the glass slightly yellowish. Some extra
attention in material selection is required just in case the optical system is designed for use at the short wavelength part of the visible range."

and so on, the reports shows the "Long and Winding Road" (da da) that leads to the door of finding the right combination punches that KO'd lead glass (or "almost").

I've attached the entire document, complete with equations, abbe numbers, and all sorts of delightful technical information for those who like that sort of stuff.

But for those who don't, let's skip to the conclusion....

"Niobium oxide plays an important role as one of the components that are substituted for lead
oxide. Niobium oxide containing glasses are effective in attaining almost [there's that word again] the same relative partial dispersion values as conventional lead containing glasses....

"In the optical industry, the development of lead free products has become such an important
consideration that it is also part of the marketing strategy.[We are "cool" because we make Ecobins].
As a result, the demand for niobium oxide has doubled over the past ten years."

[The paper isn't dated but since lead free glass wasn't introduced until the late 1990s, I'm guessing this was written sometime in the past few years.]

"Future development of optical materials with special characteristics is desirable to accompany cost reductions including those in manufacturing methods and higher performance optical system design."

Given that Schott and other glass makers very likely went through this same trial and error process (assuming no corporate espionage was going on), I have to wonder if that R & D initially added some cost to the alphas and Nikon HGLs even though lead free glass has now trickled down to entry level optics?

Or if the cost of having to properly dispose of the lead and the safety concerns related to workers making lead glass offset the costs?

Regardless of the cause(s), if you see more CA in lead free glass bins of either porro or roof design, and it bothers you, there are ED/HD/FL/L glass bins available for the sensitive and discriminate birder at various price points. So no worries.

And there are always old porros and pre-internal focus roofs for sale....

http://cgi.ebay.com/Zeiss-Classic-8x...item2562ea5f7a

To be safe, carry a freezer baggie with you in case there's a downpour. But if the baggie's from China, make sure it doesn't have any lead.

Brock
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Old Saturday 16th April 2011, 01:05   #58
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Brock:

Nice work, and and a nice evaluation of the mfr. of glass through the years. I have
read through the Ohara piece, and unless you are a half scientist, it is a nice read and
does refer how hard it is hard to get better glass without the lead. It seems that for
using microscopes, color "does really matter", when doing a diagnosis for the color
of an object, and when time for treatment is critical.

I do not find any mention of ED, HD or fluorite added to the story, so I suppose that
has been the way to just shortcut and add the factors to get the better color correction.

I am thinking the term Ecoglass, is just another politically correct wording that has
become popular. I think there is lead still being used in some optic elements, to get things to work well for many of the makers, and that is why many here will not know about those things. I have only seen Nikon proclaiming the use of lead free "Ecoglass",
what about the rest?

Jerry
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Old Saturday 16th April 2011, 02:26   #59
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Brock,

Would you mind deleting your quote of my post. I deleted it, but evidently not quickly enough. I don't have time to participate in this discussion now.

Henry
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Old Saturday 16th April 2011, 03:23   #60
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Originally Posted by NDhunter View Post
Brock:

Nice work, and and a nice evaluation of the mfr. of glass through the years. I have
read through the Ohara piece, and unless you are a half scientist, it is a nice read and
does refer how hard it is hard to get better glass without the lead. It seems that for
using microscopes, color "does really matter", when doing a diagnosis for the color
of an object, and when time for treatment is critical.

I do not find any mention of ED, HD or fluorite added to the story, so I suppose that
has been the way to just shortcut and add the factors to get the better color correction.

I am thinking the term Ecoglass, is just another politically correct wording that has
become popular. I think there is lead still being used in some optic elements, to get things to work well for many of the makers, and that is why many here will not know about those things. I have only seen Nikon proclaiming the use of lead free "Ecoglass",
what about the rest?

Jerry
Jerry,

I was surprised to see all the optical and physical qualities they needed to get right with lead free glass besides "negative anomalous partial dispersion," and how as they solved one problem, another cropped up that they had to solve. It turned out to be a major undertaking even for opticians who know optics 100 squared better than we do.

You saw this ad, but for others who haven't, I think it's worth posting a link to an auction ad for a "rare glass" 8x32 SE that originally opened with a starting bin of $1,650. When some BF members saw this ad, they must have thought I wrote it! But he's far more "evangelical" than I am about the superiority of lead glass.

He also purports to know exactly when Nikon switched to lead free glass in the 8x32 and 10x42 SEs.

My favorite all time bin is the 8x30 EII, which has "EcoGlass". More CA than I'd like in high contrast situations, but it as Henry mentioned, it is a rather short bin, after all (at least w/out the added prostheses :-).

There was also an 8x30 E in near mint condition for sale recently, which if I were flush, I would have bought to compare.

Here's the ad of a true believer (or at least a good BSer who tried to drive up the price of these old 501 SEs :-)! Pay particular attention to the third paragraph about its optical properties.

http://cgi.ebay.com/ws/eBayISAPI.dll...K%3AMEWAX%3AIT

Brock
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Old Saturday 16th April 2011, 12:55   #61
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Jerry,


My favorite all time bin is the 8x30 EII, which has "EcoGlass". More CA than I'd like in high contrast situations, but it as Henry mentioned, it is a rather short bin, after all (at least w/out the added prostheses :-).

There was also an 8x30 E in near mint condition for sale recently, which if I were flush, I would have bought to compare.

Here's the ad of a true believer (or at least a good BSer who tried to drive up the price of these old 501 SEs :-)! Pay particular attention to the third paragraph about its optical properties.

http://cgi.ebay.com/ws/eBayISAPI.dll...K%3AMEWAX%3AIT

Brock
Brock,

I guess I'm going to have to take some time for a quick pot shot.

I'll repeat - I found that the EII with eco-glass shows no more lateral color in a controlled test than an E with leaded glass. Same thing for longitudinal CA between the two, even with the magnification boosted to 64x. The objectives of the E and EII are identical (same focal length, same objective cell) and when they are interchanged nothing about CA changes in either binocular.

I had already seen that ebay ad when a local birder called me all excited to bid on the "rare glass" binocular. I encourage everyone to read the ad just to see how wayward these kinds of speculations can become once they go viral. That seller has been drinking at more than one internet Koolaid stand. There is always "evidence" and the less the evidence is understood by the reader the better. Trying to debunk these things is as hopeless as taking on Bigfoot, the Chupacabra and Barack Obama's fake birth certificate put together.

Henry
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Old Saturday 16th April 2011, 14:44   #62
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I feel I've entered Thomas Pynchon's Lot 49, with Brock playing Oedipa Maas and making Pascal's Wager on lead.
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Old Saturday 16th April 2011, 14:56   #63
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Here's the ad of a true believer (or at least a good BSer who tried to drive up the price of these old 501 SEs :-)! Pay particular attention to the third paragraph about its optical properties.
BSer? Isn't that garbage quoted directly from posts on Birdforum?
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Old Saturday 16th April 2011, 16:39   #64
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Brock,

I guess I'm going to have to take some time for a quick pot shot.

I'll repeat - I found that the EII with eco-glass shows no more lateral color in a controlled test than an E with leaded glass. Same thing for longitudinal CA between the two, even with the magnification boosted to 64x. The objectives of the E and EII are identical (same focal length, same objective cell) and when they are interchanged nothing about CA changes in either binocular.

I had already seen that ebay ad when a local birder called me all excited to bid on the "rare glass" binocular. I encourage everyone to read the ad just to see how wayward these kinds of speculations can become once they go viral. That seller has been drinking at more than one internet Koolaid stand. There is always "evidence" and the less the evidence is understood by the reader the better. Trying to debunk these things is as hopeless as taking on Bigfoot, the Chupacabra and Barack Obama's fake birth certificate put together.

Henry
Henry,

I suppose you don't believe in the Loch Ness monster, either, do you? :-)

Take potshots at that ebayer 64 times if you'd like, I lampooned him myself, if you read my post carefully. I posted link that for "entertainment purposes only".

Although I did email him to find out how he knows that the 8x32 SE only had lead glass for two years and the 10x42 SE for three. I haven't been able to get the changeover dates/serial #s from Nikon despite much arm twisting.

I can't confirm or deny the lack of difference in levels of CA you found btwn the 8x30 E and 8x30 EII since I've never compared them.

I don't know if 64x is the magic number where all see the same thing through a pair of binoculars, because the last element in the optical train are still our eyes and brains. Consider the differences that users have reported in CA in the 16x70 Fuji FMT 1 & 2. That's twice the magnification that most birders use.

I've learned from reading wildly varying reports about various optical characteristics such as edge sharpness, pincushion, rolling ball, close focus distances, and even chromatic aberration, that what one person sees through a bin is not necessarily what others do through the same bin.

If you posted side by side photos of the E and EII showing what you saw through these two bins, and the photos confirmed your results, then I'd believe it.

I'll also repeat -I found that the 505xxx 8x32 SE shows more lateral color in a field test than the 501xxx 8x32 SE. Whether or not this difference would hold up at 64x, I don't know and it wouldn't matter anyhow, because I'm not using a 64x booster in the field. I have to live with what I see at 8x.

Unlike your ebayer buddy, I don't know if the 505 contains lead or lead free glass, but I do know that the 501 has lead glass. I also don't know if Ohara or whoever supplies Nikon's glass released lead free glass before it was optimized through trial and error testing and if that ended up in the 505.

Since the 550 8x32 SE was introduced in 2007-2008, and Nikon completed its transition to lead free glass in 2002, the 550 for sure has lead free glass, as does the 050 10x42 SE. So those would be the appropriate models to compare with older versions to test the differences in glass.

The SE doesn't have a compound internal focus objective, so I don't know what factor or factors explains the difference I see between the two SEs I've owned. The CA in the 505 isn't terrible by any means, but after using the 501 for years and not seeing any CA except at the edge of the field, I was surprised to see CA closer to the center in the 505 in high contrast situations.

Granted my eyes had changed over the 10 years since buying the two samples, but I compared them side by side. But knowing what I do now about the subjectivity of CA, I wouldn't take my own observations as gospel unless I was able to reproduce them in a photographic test.

What I do like better about the 505 is the greater color saturation. With the 8x30 EII, I get even better color saturation than the SE, but also more CA. The 8x30's image also looks brighter than the 8x32 SE's.

Similarly, the 10x42 LXL's image looked brighter than the 10x42 LX, and the LXL also showed more CA.

Since you discredited the lead free glass = > CA theory, when Ed came up with his > light transmission = > CA, it seemed plausible, because it agreed with what I was seeing through bins. But then you shot down that theory in 60 seconds.

So the only "theory" left (quotes because you said that you didn't have enough data to call it a theory) is your roof internal focus compound objective = > CA.

I see more CA in modern roofs than I do modern porros, so that seems plausible. But then again, so did the lead free glass and greater light transmission theories at the time. :-)

The only problem is that it explains the higher CA in roofs, not porros. Perhaps that's good enough since most of the binoculars made today are roofs.

I notice that Tero is conspicuously absent in this debate. How does his famous quote go? Someone else used it in his signature, something like... binoculars are two tubes, just look through them.

Well, if it weren't raining, I would be outside just looking through those two tubes rather than debating these matters of grave international importance. :-)

Henry, thanks for having patience with me and being a "guinea pig" for me and others who came up with alternative theories of CA. You're the best!

Brock, the Skeptic
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Old Saturday 16th April 2011, 18:53   #65
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I don't know if 64x is the magic number where all see the same thing through a pair of binoculars, because the last element in the optical train are still our eyes and brains.
You don't use a scope yourself on a regular basis, do you? Because if you did you'd know that high magnifications show CA (and other optical defects) far more easily and far more clearly than low magnifications. Compare, for instance, the Leica Apo-Televid 77 to the Leica Televid 77 at 20x and at 60x, or the Nikon EDIII to the Nikon III. At 20x there is a small (but visible) difference, at 60x it's *very* obvious. So obvious in fact, that even people not susceptible to CA will notice the differences immediately. You'd have to be color-blind not to notice the differences.

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I'll also repeat -I found that the 505xxx 8x32 SE shows more lateral color in a field test than the 501xxx 8x32 SE. Whether or not this difference would hold up at 64x, I don't know and it wouldn't matter anyhow, because I'm not using a 64x booster in the field. I have to live with what I see at 8x.
If tests of two pairs of binoculars using a booster don't show any difference, that proves there *is* no difference. A booster - assuming it's itself reasonably well-corrected, which can be checked quite easily if you have access to a high quality astronomical scope - just magnifies the aberations of a binocular or scope. A booster thus allows you to examine the optical defects of a binocular or a scope in far more detail than just using the binocular or scope as intended.

Now, supposing there really *is* a difference between the two 8x32's you compared, there's one alternative explanation not mentioned before - that one of them is a cherry and the other a lemon. I personally wouldn't discount that possibility, given the differences one occasionally finds between the two barrels even of alpha binoculars.

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Old Saturday 16th April 2011, 20:05   #66
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Henry,

I suppose you don't believe in the Loch Ness monster, either, do you? :-)

Take potshots at that ebayer 64 times if you'd like, I lampooned him myself, if you read my post carefully. I posted link that for "entertainment purposes only".

Although I did email him to find out how he knows that the 8x32 SE only had lead glass for two years and the 10x42 SE for three. I haven't been able to get the changeover dates/serial #s from Nikon despite much arm twisting.

I can't confirm or deny the lack of difference in levels of CA you found btwn the 8x30 E and 8x30 EII since I've never compared them.

I don't know if 64x is the magic number where all see the same thing through a pair of binoculars, because the last element in the optical train are still our eyes and brains. Consider the differences that users have reported in CA in the 16x70 Fuji FMT 1 & 2. That's twice the magnification that most birders use.

I've learned from reading wildly varying reports about various optical characteristics such as edge sharpness, pincushion, rolling ball, close focus distances, and even chromatic aberration, that what one person sees through a bin is not necessarily what others do through the same bin.

If you posted side by side photos of the E and EII showing what you saw through these two bins, and the photos confirmed your results, then I'd believe it.

I'll also repeat -I found that the 505xxx 8x32 SE shows more lateral color in a field test than the 501xxx 8x32 SE. Whether or not this difference would hold up at 64x, I don't know and it wouldn't matter anyhow, because I'm not using a 64x booster in the field. I have to live with what I see at 8x.

Unlike your ebayer buddy, I don't know if the 505 contains lead or lead free glass, but I do know that the 501 has lead glass. I also don't know if Ohara or whoever supplies Nikon's glass released lead free glass before it was optimized through trial and error testing and if that ended up in the 505.

Since the 550 8x32 SE was introduced in 2007-2008, and Nikon completed its transition to lead free glass in 2002, the 550 for sure has lead free glass, as does the 050 10x42 SE. So those would be the appropriate models to compare with older versions to test the differences in glass.

The SE doesn't have a compound internal focus objective, so I don't know what factor or factors explains the difference I see between the two SEs I've owned. The CA in the 505 isn't terrible by any means, but after using the 501 for years and not seeing any CA except at the edge of the field, I was surprised to see CA closer to the center in the 505 in high contrast situations.

Granted my eyes had changed over the 10 years since buying the two samples, but I compared them side by side. But knowing what I do now about the subjectivity of CA, I wouldn't take my own observations as gospel unless I was able to reproduce them in a photographic test.

What I do like better about the 505 is the greater color saturation. With the 8x30 EII, I get even better color saturation than the SE, but also more CA. The 8x30's image also looks brighter than the 8x32 SE's.

Similarly, the 10x42 LXL's image looked brighter than the 10x42 LX, and the LXL also showed more CA.

Since you discredited the lead free glass = > CA theory, when Ed came up with his > light transmission = > CA, it seemed plausible, because it agreed with what I was seeing through bins. But then you shot down that theory in 60 seconds.

So the only "theory" left (quotes because you said that you didn't have enough data to call it a theory) is your roof internal focus compound objective = > CA.

I see more CA in modern roofs than I do modern porros, so that seems plausible. But then again, so did the lead free glass and greater light transmission theories at the time. :-)

The only problem is that it explains the higher CA in roofs, not porros. Perhaps that's good enough since most of the binoculars made today are roofs.

I notice that Tero is conspicuously absent in this debate. How does his famous quote go? Someone else used it in his signature, something like... binoculars are two tubes, just look through them.

Well, if it weren't raining, I would be outside just looking through those two tubes rather than debating these matters of grave international importance. :-)

Henry, thanks for having patience with me and being a "guinea pig" for me and others who came up with alternative theories of CA. You're the best!

Brock, the Skeptic
Brock,

I hate to say this, but I don't think you've been reading previous posts very carefully. Henry did not shoot down Ed's theory in 60 seconds. My conjecture assumes that coatings are different but CA is the same. So, he wasn't even shooting at it. We are talking about entirely different concepts, either of which may prove to be valid or invalid.

Exactly what are you asserting?

It seems you are saying that binoculars made with eco-friendly glass have more CA than those made with leaded glass. Correct me if I'm wrong, but this appears to be based entirely on your personal observations of seeing more fringing in an eco-friendly model than a leaded model.

But I don't recall your test conditions or know how rigorous your methods were. To be credible, the two specimens would at least have been tripod mounted, set to the identical IPD, and subject to the same test-stimulus observing conditions. Preferably you would not know which binocular was being used, and you would be required to provide a relevant quantifiable dependent measure. Henry essentially does all these things, so I have no difficulty accepting his reports. Whether every observer would report the same absolute amount of CA is unknown, but it's hard for me to believe that other observers would see a difference when he didn't. Human's are outstanding difference detectors.

Let me summarize it this way. Whatever one's beliefs, if they rise to the level of a testable hypothesis the results should be replicable and reliable. BTW, a true skeptic is first skeptical of himself.

Ed
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Old Saturday 16th April 2011, 22:39   #67
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Bob - I was just trying to follow the discussion about CA issues and trying to separate the lead versus nonlead connections, so I googled up Wikipedia on the subject and found out that lead in optical glass enhances the focusing of light in doublets, for example, reducing the amount of CA which occurs. Also found out that chrystal glass containers which include some lead in there composition can actually contribute to lead poisoning if wine, for example, is stored because the lead in the glass leeches out into liquids. John
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Old Sunday 17th April 2011, 07:19   #68
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... Also found out that chrystal glass containers which include some lead in there composition can actually contribute to lead poisoning if wine, for example, is stored because the lead in the glass leeches out into liquids. John
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Old Sunday 17th April 2011, 12:16   #69
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Enjoyed the thumbnail. Norm Jackson. It is time for some levity in this thread. John
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Old Thursday 21st April 2011, 17:53   #70
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To Wingersheek, enjoy your binoculars because they are very good. Regarding the glass used in Nikon SE binoculars, do we have credible evidence that there was in fact any change made over the years? I don't give much credence to anything in Nikon's advertising copy. Remember the "Special Performance (SP) glass" in the 7x50 Prostar (an excellent binocular for its intended purpose but the "SP glass" part means absolutely nothing in reality)? Could Nikon have been using "Eco-Glass™" from the start of SE production and just applied a trendy name to it when they ran out of other fluff to write?
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Old Thursday 21st April 2011, 19:32   #71
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You don't use a scope yourself on a regular basis, do you? Because if you did you'd know that high magnifications show CA (and other optical defects) far more easily and far more clearly than low magnifications. Compare, for instance, the Leica Apo-Televid 77 to the Leica Televid 77 at 20x and at 60x, or the Nikon EDIII to the Nikon III. At 20x there is a small (but visible) difference, at 60x it's *very* obvious. So obvious in fact, that even people not susceptible to CA will notice the differences immediately. You'd have to be color-blind not to notice the differences.



If tests of two pairs of binoculars using a booster don't show any difference, that proves there *is* no difference. A booster - assuming it's itself reasonably well-corrected, which can be checked quite easily if you have access to a high quality astronomical scope - just magnifies the aberations of a binocular or scope. A booster thus allows you to examine the optical defects of a binocular or a scope in far more detail than just using the binocular or scope as intended.

Now, supposing there really *is* a difference between the two 8x32's you compared, there's one alternative explanation not mentioned before - that one of them is a cherry and the other a lemon. I personally wouldn't discount that possibility, given the differences one occasionally finds between the two barrels even of alpha binoculars.

Hermann
Hermann,

As far as I know, no-one has tested these two binoculars side by side at 64x or even with a 3x booster. But even if they did and they turned out to be the same in regard to levels of CA, that's not what I see, so something else could be afoot.

I have owned four Nikon SEs and tried a total of eight - two 8x32s, three 10x42s, and three 12x50s. The only sample variation other than CA (and even that is slight except in the 12x50s) that I found was in one 12x50 SE, which had a close focus of 16' rather than 24'.

The SE series is remarkable in its consistency. Either that or I've been really lucky.

I'd be very surprised if there was some defect in the 505 that makes it show slightly more CA than the 501.

Brock
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Old Thursday 21st April 2011, 19:52   #72
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Brock,

I hate to say this, but I don't think you've been reading previous posts very carefully. Henry did not shoot down Ed's theory in 60 seconds. My conjecture assumes that coatings are different but CA is the same. So, he wasn't even shooting at it. We are talking about entirely different concepts, either of which may prove to be valid or invalid.

Exactly what are you asserting?

It seems you are saying that binoculars made with eco-friendly glass have more CA than those made with leaded glass. Correct me if I'm wrong, but this appears to be based entirely on your personal observations of seeing more fringing in an eco-friendly model than a leaded model.

But I don't recall your test conditions or know how rigorous your methods were. To be credible, the two specimens would at least have been tripod mounted, set to the identical IPD, and subject to the same test-stimulus observing conditions. Preferably you would not know which binocular was being used, and you would be required to provide a relevant quantifiable dependent measure. Henry essentially does all these things, so I have no difficulty accepting his reports. Whether every observer would report the same absolute amount of CA is unknown, but it's hard for me to believe that other observers would see a difference when he didn't. Human's are outstanding difference detectors.

Let me summarize it this way. Whatever one's beliefs, if they rise to the level of a testable hypothesis the results should be replicable and reliable. BTW, a true skeptic is first skeptical of himself.

Ed
Ed,

I'm pretty sure you said that > light transmission = > CA. This was when you first presented this theory when we were discussing CA in lead vs. lead free glass, and you presented your theory as an alternative explanation for the increased CA in modern bins. I will have to dig out that post, probably not easy since it's buried in some thread with an unrelated title, but I will look for it.

So when Henry didn't find more CA in the FMC 8x30 EII than he did in the MC 8x30 E, that seemed to discredit your hypothesis since the FMC version would have greater light transmission.

Anyway, I'm done with nitpicking CA, particularly with the SEs, which aren't bad at all compared to some of the roofs I've tried, except the 12x50 SE, which shows a very noticeable amount of CA in high contrast situations, but it is 12x, after all.

I'm going to try to desensitize my eyes to CA, if that's possible. If you can condition your brain to see CA (by testing bins for CA), perhaps it also works the other way around, though I have my doubts in my case. Too pig-headed to trick my brain.

OTOH, I forget where I put my keys, so maybe I can forget where I saw CA. :-)

Brock
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Old Friday 22nd April 2011, 03:19   #73
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Bob,

This has been discredited by the experts, but since you asked....here's one of the Ohara's reports I mentioned earlier that "lead" me to suspect that lead-free glass caused greater CA.

NOTE that the lead and lead-free glass being compared in this report have the same refractive index and Abbe numbers and yet still show differences in CA (greater in the lead free glass).

This had been the crux of counterarguments - because lead-free glass and lead glass have the same Abbe number, they are equal in all respects including CA control. According Ohara, that is not the case with all lead free optical glass. The first example is in the extreme end of the spectrum and though important for microscopy is probably not relevant for sports optics. The second example refers to "wide wavelength ranges".

I did download a more relevant Ohara report that dealt differences in the entire spectrum, and which stated that after a number of failed attempts at finding the right combination of lead substitutes, Ohara was able to make lead-free glass "nearly as good" as its high grade lead optical glass, but I also lost that document in a fatal computer crash. I don't have time to look for it now, but I will try to find it later.

Here are some quotes to that effect:

"To illustrate the difference in anomalous dispersion of lead-containing glass material and lead-free glass with the same refractive index and Abbe’s number, the differences between the glass materials BPH5 and S-NBH5 manufactured by OHARA INC. are described below. The refractive index and Abbe’s number of the lead-free glass material S-NBH5 are the same as that of the lead-containing glass material BPH5. The anomalous dispersion (Δθg,F, Δθi,g) of S-NBH5, which is important for correcting the chromatic aberration in the short wavelength region, is half or less than that of BPH5. Therefore, it will be impossible to design an Apochromat objective lens unless lead-containing glass material such as BPH5 is used."

Another example:

"In another example, the difference between the lead-containing glass material LAM7 and lead-free glass material S-LAM7 manufactured by OHARA INC. is described below. Although the refractive index and Abbe’s number of both glass materials are the same, the sign of anomalous dispersion (ΔθC,t), which is important for correcting the chromatic aberration in the near-infrared region, is different. Therefore, S-LAM7 cannot be used as a substitute for LAM7 to manufacture objective lenses that can correct chromatic aberration in wide wavelength ranges up to the near-infrared region. It is impossible to design a near-infrared objective lens unless lead-containing glass material is used."

Brock
Jeeeeeesuz Brock! I pronounce you the new "MR. OPTICS". You should get that published in an Optics Journal! I didn't understand a word you said. WHEW! I am going to put you right up there with Henry and Dr.EDZ. Have you have been taking them smart pills again?

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Old Friday 22nd April 2011, 09:47   #74
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Heavy, Dude...
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Old Friday 22nd April 2011, 14:42   #75
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