TWISTING FACTS ABOUT CAF2 FLUORITE APOs

[Ales - iStar Optical]

After reading some of the recent ads posted by the world's leading manufaturer of telescopes, I really could not just smile and forget about it... below text is what is publicaly written about new 'Fluorite' APOs made by this company. I will leave name of the product and name of the company out, it is actually not important. what is important (at least to me) are a totally misleading facts used to manipulate with buyers' mind. To call a fluorite enriched glass a Fluoro-APO is on edge.. but still acceptable (with grinding teeth). But to call this glass a pure Fluorite CaF2 is beyond any bounderies of a fair business strategy. I am not saying that this company is telling flat out lies about this product and material used. Im not saying that they are making thousands to believe that they are buying a true CaF2 Fluorite APO triplet.. and instead getting a Fluorite enriched glass FPL51 or FPL53, which is 7x less expensive compared to a pure CaF2 Fluorite material. Im not saying that going on and on about CaF2 Fluorite element and than at the end of the story just mention FPL type of glass is a deliberate manipulation with customers mind. Im just saying that this is not right and such company does not need to lower their standards to such level of misperception. Hey, if they put a true CaF2 in their APO and advertize it as pure Fluorite.. fine with me.. more power to them. But to call the scope a CaF2 Fluorite APO.. and actually sell fluorite glass triplet is below all reasonable standards, in my own eyes.. and I simply had to share this here.. with you guys. Read below and see for your self how easy is to play with someone's (customer's) mind.........believe me, Im not taking any pleasure in writing this. It may bacfire badly, may hurt our own business.. but Im not type of person who would simply stand by and do nothing... sentenses in parenthesis (..) were added by me.

The XYZ-Comany ED APO optical design assures virtual elimination of secondary, residual “false color" normally present in 2-element achromatic lens designs using Crown and Flint glass. XYZ-Comany APO refractors utilize a second lens element made from the mineral fluorite instead of Flint glass. Fluorite, CaF2, is a halide with unique properties and a hardness of only four (this is a true fact indeed, this is why we make our Phantom line fo scopes). It is an exotic and difficult material to fabricate into a lens (also a very true statement as Istar has plenty of experience by now, producing a true CaF2 Fluorite lenses). Hence the cost of manufacturing a fluorite lens is quite high compared to a Flint lens element, for instance (absolutely a true fact.. I wish we could produce them for less but it is simply not possible, .. and one kilo of this material cost nearly 2000 dollars and you end up trashing many CaF2 lenses during the prodcution process...).

Why fluorite? Fluorite’s molecular properties have several distinct advantages. First, it has superior dispersion characteristics compared to pure silica-based glass. (again.. absolutely true IF we are taling about CaF2 material) It functions as a high-index lens with very low dispersion. We use the term ED to signify “Extra-low Dispersion". Fluorite also corrects well for spherical aberration (again, absolutely true facts about CaF2 pure Fluorite material grown in the lab, costing arm and leg and very difficult to fabricate).

(and now you are for a BIG surprize....) XYZ-Comany utilizes only the very finest available fluorite lens, FPL-53. (Those of you who do not know what FPL-53 is... this is a fluorite enriched GLASS... very FAR from a pure CaF2 Fluorite which is used in our Phantom, selected Takahashi scopes, selected TEC scopes and a very FEW others).

I dont think I have to ad anything else to this story. But you should really read carefuly and think twice before you jump into your next purchase of so called Fluorite APO... only selected few produce them as stated and Im proud to say that Istar is one of them...
respectfully,
Ales

[borispider]

Tnx for the info. I know nothing about glass fab. but I'm glad to know
iStar doesn't skimp on their glass.

[Watcher3]

Ales. This is the ISTAR Scope Club! You can mention the other company here. I think it's despicable that in a sea of scope companies that sell FPL equivalent scopes, that someone would intentionally mislead the uninformed (read new) customer. This, to me is akin to the department store refractors made of plastic that promise 600x with Hubble images on the box, only worse. They're going after the MONEY that more informed astronomers would spend elsewhere. While the scopes may be good any way, they should not get a pass on pumping up their perceived value in this manner.

Still thinking an ISTAR 140mm F/7 fluorite doublet would be ideal for a quality scope that can be used for travel and good for visual on a CG-5 mount. Especially if you can price it for anything under a TEC 140 triplet.

[Ales - iStar Optical]

Yeah.. I know, I know. But still, name of that manufacturer is not important. Important is for people to get WELL educated and read the SMALL print, before they buy their next Fluorite APO. This company is not the only one using such tacticts and in reality... being THEIR size, they really dont need to tell such "stories" to fellow amateur astronomers. They simply want to pass a lower grade optics (material wise if nothing else...) for the best there is.. and brag about their lower price compared to competition. It is very easy since FPL53 glass cost fraction compared to mineral Fluorite CaF2....One simple comparison: one compnay produces a race car with a nice small block 8 cylinder engine with 400 HP.. exactly as it should be. The next guy produces a similar car but they put a 1,6 liter 4 cylindere 90 HP ngine into their car and they go on and on about how their car look exactly the same as the competitors'. And than they price their lazy sports car 15 percent below the 400HP competitions' model. Well.. which one would you buy.. if you dont read the small print and if you dont know anything about horse powers and number of cylinders.. you may buy the cheaper car.. but than beware! Never get into a serious race with the guy who paid for what his car is realyl worth..... should I ad anything else? Don't think so,
cheers,
Ales

[Ales - iStar Optical]

Apr 22, 2012 8:45:12 GMT -5 borispider said:

Tnx for the info. I know nothing about glass fab. but I'm glad to know
iStar doesn't skimp on their glass.

This is one of the reasons why you should know exactly what you are buying. You have automatically assumed that CaF2 is a special type of glass... well, this is exactly the type of assumption those other manufacturers are counting on.. and to lure you into believing that you are getting the real thing. CaF2 is NOT glass.. it is a mineral Calcium Fluorite grown in a highly specialized labs into large crystals (just like other synthetic gemstones) and than, such crystal is precisely sliced, formed and fabricated into finished lenses. In a finished objective lens / lens assembly, the CaF2 (pure mineral Fluorite) is typically positioned in between two special crown glass lenses. Optical performance of such triplet is considered the very best a modern optics can offer. Maybe in the future some other material will replace existing CaF2 mineral Fluorite and the optical performance may be even better. but such material is not yet on the market.. as of 2012 it does not exists... and frankly, optical performance of CaF2 triplet is textbook perfect. If designed properly, such lens is free of all aberrations including the chromatic aberration.
be well and please stay in touch,
cheers,
Ales

[bn1777]

Hey Guys , if your Fluorite scopes ( I have 2 Takahashi Fluorites so , do know what it can deliver ) are as good as my garden viarity 127mm f/8 crown and flint ACHRO , YES ! I will buy Istars Flourites . I have looked at Taks 6 inch Flourites and the price scares me away every time .
Thanks Ales .
Brian.

[counterweight]

OK... i just must ask. I was under the impression that FPL53 (or whatever this is about) is a 'doped' glass which is technically a liquid, where pure CaF2 is a crytalline formation? Or is pure (or near pure) CaF2 also a 'glass'? I notice a distinct difference in my FS-128 and TEC 160ED when looking at colors like in Alberio for instance, the CaF2 Tak 128 doublet the colors seem 'richer'. Just my impression, but a consistent one when it comes to visual impression between those two scopes only (I am trying to avoid any type of generalization). My TEC 160ED f/8 is NOT a CaF2 scope, but it sure delivers the goods.

OK so my statement has 2 parts, one a question about just what a pure CaF2 lens is in a scientific sense (here I think a toggle) and then my 'impression' the difference in performance between well made optics. Hope that makes sense.

[counterweight]

OK, reading second and a bit more carefully time I see Ales has answered all -

Just wanting to add that i think Ales point that 'well designed' trumps all. It's not just lens material, it's the "who" behind how the lens assy is prescribed and produced that really matters... well it all does, but i think the "who" should also amtter, at least that is why I am here...