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ED vs SD - Worth It?

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#26 edwincjones

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Posted 19 October 2019 - 04:36 AM

In many areas and aspects of wordly goods, it has long been the case that relatively highly increased premiums are paid for relatively minor "improvements".

 

Often, around 50% of the "top offering" price can buy around 90% the quality of a similar product.

 

Whether or not that extra 10% of product quality is worth that extra 50%  price will always be open to debate, but generally speaking, "the best" more often than not is, by definition, "the best" money can buy, and some people who can more comfortably afford "the best", choose to do so.

 

Kenny

 

From an economic standpoint it is usually not worth it,

and many, maybe most of us cannot tell the difference;

but if you are pushing the optics for that last degree of definition,

and can afford it, then maybe   question.gif

 

My argument to myself is the  eyes are getting older

and need all the help they can get

(probably false that optics will help)

but late at night when one is trying so hard...........

 

edj


Edited by edwincjones, 19 October 2019 - 04:47 AM.


#27 Jon Isaacs

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Posted 19 October 2019 - 06:14 AM

Since Keith, the OP, seems to be referring to APM's 82mm and 100mm BT offerings, ED and SD are the marketing terms they use in their website descriptions to differentiate the two levels of ED glass used. "ED" being FK61  and "SD" being either FPL53 or FCD100  depending on the model. For APM's purposes, "ED" means Abbe Vd ~81.5 and "SD" means Vd ~95.

 

So when you're reading Markus' APM site, the above terms apply.  I have no desire to see confusing marketing terms like SD/HD or whatever becoming any kind of standard one way or another. By now, most CN members interested in this stuff know there are the two tiers of ED glass.  Call them by their company designation and that works fine for me; why make it more confusing?  wink.gif

 

Rich

 

Rich:

 

I'm not if we're both on the same page or not. I say use the designations used by the glass manufacturer, this avoids possible confusion when generalizing as you did when discussing SD versus ED versus optical quality. 

 

What's confusing is that APMs distinctions are not generally accepted and should never be used in any other context. If I asked Roland Christen about SD glass versus ED glass, I think its very likely he would say they're the different names for the same thing.

 

I know a fair amount about the various glass types but reading this thread, I had to figure out that APM was using SD to mean FPL-53 class glass and ED to mean FPL-51 class glass when in fact, they're all  ED glasses by any normal definition. Someone reading this thread 5 years from now might not get that figured out.. 

 

Jon



#28 Jon Isaacs

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Posted 19 October 2019 - 06:23 AM

From an economic standpoint it is usually not worth it,

and many, maybe most of us cannot tell the difference;

but if you are pushing the optics for that last degree of definition,

and can afford it, then maybe   question.gif

 

My argument to myself is the  eyes are getting older

and need all the help they can get

(probably false that optics will help)

but late at night when one is trying so hard...........

 

edj

 

The older you get, the less sensitive your eyes are the the blue end of the spectrum so you're less sensitive to chromatic aberration..

 

But the older you get, the pickier you get... or at least the pickier I have gotten..

 

Still, if ibwere buying these binos, I'd go with the FPL-51 or even achromatic version, they would not be a close doubles/planetary instrument in my hands.

 

Jon


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#29 Gyna

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Posted 19 October 2019 - 01:30 PM

I rather have a ED with 1/6 wave then a SD with 1/3 wave optics.

 

I agree, at high magnification (137x) I can't see CA from objectives, but I start to see a loss of sharpness due to a mix of spherical aberration and 'poor' lens polishing. Anyway, the ED is still a great bino...

 

Marco


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