Fluorite-based APO vs ED vs SuperED

[tom_mann1]

<p>P Mui - Thank you very much for taking the usual discussions of optics on photo.net up several levels!</p>

<p>Sincerely,</p>

<p>Tom M</p>

[arthuryeo]

<p>>What was the cost of the Zeiss superachromat lens?</p>

<p>I believe the last time I looked, it was several $thousands but looks like there's a wider range in eBay between $3500 - $11,000.<br>

http://shop.ebay.com/?_from=R40&_trksid=p3907.m38.l1313&_nkw=superachromat&_sacat=See-All-Categories</p>

 

[arthuryeo]

<p>I guess if one is so inclined, one can always get the Zeiss 350mm Superachromat and hook it up to a D3X or D1s using an adapter. But, I am not sure how that would work in terms a medium format lens matching the resolution for the 35mm format platform.</p>

<p>Any one did this before? I know I have done it for a 80mm Planar and 40mm Distagon.<br /></p>

 

[p_mui]

<p>It should work out fine. A "medium format" lens is just basically a lens with a larger light cone to cover the area of a 6x6, 6x7, etc. But I'd be willing to bet that the Zeiss on the D3x would produce some amazing images.<br>

The Takahashi that I was talking about covers almost the complete area of a 4x5 inch plate. So it can be considered a large format lens.</p>

[michael_oxford]

<blockquote>

<p>The Takahashi that I was talking about covers almost the complete area of a 4x5 inch plate. So it can be considered a large format lens.</p>

</blockquote>

<p><em>Don't even get me started ... </em></p>

<p>Anyone looking to donate a 4x5 Speed Graphic?</p>

[arthuryeo]

<p>Looks like only Canon has the ability to grow Fluorite crystals this large but that was so long ago. Doesn't Nikon and Takahashi have the ability to do that by now? If not, where does Takahashi get their supply of crystals?</p>

[arthuryeo]

<p>It also looks like the this new Zeiss scope is FL based.<br>

http://www.zeiss.com/c1256bcf0020be5f/Contents-Frame/b1b673e13a2591bd852576650052beea</p>

<p> </p>

[arthuryeo]

<p>Apparently, that new scope use some kind of ED variants. It's glass-based combined with FL --- not pure FL crystals.</p>

 

[arthuryeo]

<blockquote>

 

<p><em>As the saying goes, one fluorite glass element can be replaced by a few ED elements...</em><br>

What "saying"? Please cite a source.</p>

 

</blockquote>

<p>Here's the the source ...</p>

<p><a href="http://www.usa.canon.com/consumer/controller?act=CanonAdvantageTopicDtlAct&id=2641">Fluroite and UD Advantage</a></p>

[kelly_flanigan1]

<p>Having a more exotic glass type has always allowed a lens designer to use less elements; whether today; 50 years ago or 100 years ago; or 150 years ago.<br>

<br /> The cost per pound of glass of what is considered super exotic can be 1000 times more than plain Jane BK7; even more if one considers total finishing costs.<br>

<br /> Folks who have never worked in optics probably will never understand this. Heck go out an assemble a swing set with Home Depot steel 1/4-20 screws; then build another with solid gold screws and tubes.<br>

<br /> In a lay sense wondering how a better glass be used to reduce on element in a design is like being confused about how a grade 8 bolt might replace 2 stove bolts; or how a steel panel may replace a wood one and be thinner. :)<br>

<br /> If one studies a *glass map* of Refractive index versus dispersion; OVER TIME (centuries) ; one sees that it is always expanding.<br>

<br /> What was considered exotic in 1880 is less so in 1930; less so in 1950; less so in 1970. One sort of has a narrow main sequence of glass types as dots on the *glass map* in 1880 from n=1.5 /V75 to n=1.7 /V=30.<br>

Then about WW2 it got alot more types. A Glass that is in the 1970's Leica Noct is way off the sequence; ie n=1.9 v 40.<br>

<br /> Even glass in the WW2 Kodak Aero Ektar is way off the main sequence</p>

[p_mui]

<p>Arthur,<br>

Yes, the new FSQ106ED is based off the ED glass, FPL53 if I recall correctly. The older scope, the FSQ106N uses 2 crystalline fluorite elements. On high magnification viewing, or for that matter, any viewing, the fluorite model shows a bit more contrast due to the lack of scatter.<br>

Canon has it's own subsidiary company, Optron, which grows the fluorite crystals. Nikon probably won't go to fluorite since they're marketing ED glass heavily, and also fluorite crystals are much harder to work with. When a figure is being put on the fluorite, it's soft enough to "bound" and "rebound" as well as contract and expand due to friction of the polishing material. ED glass is much easier to work with in this aspect. <br>

I've looked through Zeiss and Leica spotting scopes and have been disappointed with their level of color correction. A very sensitive test is to put the view onto a tree branch a few hundred feet away. If it's an overcast (mostly white) background, you'll see a purple fringe outlining the tree branch. I'll look through the 85T FL when I get a chance. What worries me is that there are quite a few optical elements in the chain, something that will definitely rob the contrast, saturation, etc. Thanks for the link!<br>

Kelly - agreed on your observations. Better materials, with increased precision in manufacturing and detail work will make for a much better end result!<br>

One thing about the air spaced design, it's more tolerant of batch / melt data shifts, but it will still affect the end result. It gives the camera manufacturers a bit of slop to the glass, but not too much. <br>

As the melt data changes, you can either have the solid color correction, or keep the same focal length. NOT both. So, if they're designing a 600mm optic, they can keep the 600mm focal length, but the color correction will differ from the batch. Vice versa also - keep the same critical level of color correction, but the focal length will change from batches. In many cases, they'll keep the same focal length. Just way too much work into producing master test plates for each different batch of glass for the entire lens. Big "fudge" factor, especially if you consider some of the 17+ element designs.</p>

 

[l_s15]

<p>Very interesting discussion. Let me clarify the confusion that nikon can't make CaF2.<br>

Nikon has been making their own fluorite home grown crystals for years and still do:<br>

<a href="http://nikon.com/products/glass/index.htm">http://nikon.com/products/glass/index.htm</a><br>

This capability is inherited from their precision division which makes steppers (super high end optical devices) for semi conductor manufacturing and laser lithography for which nikon is one of the top names in the world. This application demands the most ultra precise optics and thus provides nikon with a lot of technology for their camera division. Canon makes steppers too but it is a smaller player in this field. As far as Nikon's usage in their photographic lenses, I recall notes of nikon camera lenses with CaF2, yet they stopped in favor of several varieties of ED and super ED glass as other manufacturers have.</p>

<p>As for why is CaF2 left out by nikon, the most likely explanation is simply that the benefits aren't worth the cost to their market audience. As P Mui stated "There's MUCH more to color correction than just saying "ED" or "fluorite"". Nikon's high end mass produced glass is rated just as highly as canon's and other mass produced competitors in terms of what matters: the images it produces. Color correction is just one of many factors in what delivers an image of the quality expected for the application. Compare any nikon to canon super telephoto lens review and nearly all get superb reviews where the most variation is within samples not between brands. Off course, you always have your fanatics on either side swearing on their mother's name for either brand and absolutely nothing will ever convince them otherwise. Yet that's another problem along the lines of stockholm syndrome.</p>

<p>Clearly if Nikon (and everybody else) felt that not using CaF2 was putting them at a disadvantage, they'd be using it. Leica, Zeiss, and others also make superb lenses w/o CaF2 that rival or surpass those with CaF2 in sharpness, resolution, contrast, CA control, etc. This is easily explained given no lens from these companies is 100% CaF2 elements, and the beauty of it is that it doesn't have be in order to create a perfectly outstanding lens for their market. Light must still get past a lot more non CaF2 materials and bend in odd ways before it reaches the final surface and optical design remains a huge factor. The quality and design of these materials is also of the outmost importance. All of this cannot be conveniently brushed aside. Many say "but while all being the same CaF2 is on top" are right...IF all being the same. But nothing is ever all the same thus it is a moot point.</p>

<p>Obviously, just like the best nikon or canon glass, with CaF2 or not, it simply does not stand a chance against even higher quality optics for special applications, in particual astronomy, which is in a leage of itself. But how can this be if CaF2 is made by god to be perfect? thus anything with it must be perfect too? Taking your facts out of a manufacturer's marketing claims is always an exercise in caution because they will ALWAYS paint the best while convinently neglecting anything that tells the full story.</p>

<p>Yet this practice will never go away because every company wants to stand out in some merit or another even if the overall significance of that merit could be called into question.</p>

<p>In summary, as I said, while it is undisputed that these "exotic" elments do help, you're still buying an assembled aparatus that performs as a whole and not just a piece of solid glass. This is why ultimately most people buy their optics based on the <strong>results</strong> for their application. Given these companies market to wedding, sport, landscape and studio photographers as their main core; it is not surprising that they don't stand to the scurtiny of astronomy and it is not at all surprising that they opt out of CaF2 and yet remain just as competitive.</p>

<p> </p>