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4864Re: Questions On APO Strehl Ratio

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  • jimhp29401us
    Sep 2, 2002
      One other point. Perhaps you're right, but apochromatic refractors
      are very expensive per inch of aperture. There must be a reason. I
      believe they provide the best images inch for inch of any optical
      design. Now that's just my opinion and I won't be offended if anyone
      disagrees. Finally, I do believe if you pay Rolls Royce prices for a
      telescope you deserve Rolls Royce quality optics. Again, just my
      opinion. But, if I'm going to pay $20K for an 8" OTA I expect a lot
      and high, Very high, quality optics is definately part of it.


      > ----- Original Message -----
      > From: "garyjmo" <garyjm@v...>
      > To: <tmboptical@y...>
      > Sent: Sunday, September 01, 2002 9:57 PM
      > Subject: [tmboptical] Re: Questions On APO Strehl Ratio
      > > Rolland had presented a photo taken through a .95 and a .99
      > >strehl scope. The difference was noticable but
      > > I can see your point.
      > Gary,
      > Without looking at the site, whether they are simulated images
      (like on
      > Royce's site) or real, they represent (virtual) perfect images
      taken under
      > (virtual) perfect conditions. In practice, it will be very
      difficult to
      > duplicate that at the eyepiece. A .99 strehl intensity is more
      > for someone working at the very forefront of technology doing
      imaging, etc.,
      > where he is trying the very utmost limits of what is possible.
      There, even
      > the very smallest increment cannot be overlooked.
      > Here, you are living on a razors edge, where everything is
      > against you. Even a tiny amount of focusing error will do far more
      harm to
      > your image than a .95 strehl optic. Most people dream of (but
      > attain) having an optic as good as .95. Tom's telescopes represent
      the very
      > SOTA. Every one will give textbook perfect performance, and he
      guarantees a
      > minimum of .95. What does that say? Will you ever see a
      difference in the
      > image of a .95 and a .97 scope? I doubt it. One in a thousand
      claims he
      > can. And I suspect that only half of those are really sure of what
      > see.
      > WayneG
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