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Re: Absolute highest magnification for a C11?

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  • Frank
    Not arguing the demographic Bryan but floaters aren t necessarily an indicator of age. Many are embryonic and present almost from conception.
    Message 1 of 20 , Jun 29, 2011
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      Not arguing the demographic Bryan but floaters aren't necessarily an indicator of age. Many are embryonic and present almost from conception. http://en.wikipedia.org/wiki/Floater

      I didn't know that until my last eye check (56 yo male) and the Doc pointed some floaters out in the retinal image he had just taken...Optomap images are so much better than dilating drops and a manual inspection with a retinoscope(?) by the way.

      So I said, "Damn old age anyway!" and he said, "Nah, just leftover bits of egg whites". We all have them, amateur astronomy just presents the opportunity to _see_ them.

      Then I asked about trying to erase them with a laser and he said, no, that would be like shooting orbital space junk with missiles. It would just turn big pieces into more annoying little pieces.

      cheers,

      Frank D

      --- In sct-user@yahoogroups.com, "Worsel" <bryancashion@...> wrote:
      >
      > LOL
      >
      > This tells us something about the demographics of our hobby.
      >
      > Bryan
      >
      > --- In sct-user@yahoogroups.com, John Mahony <jmmahony@> wrote:
      > >
      > > During a night of very good seeing at our local star party last year, we came up
      > > with a new definition of "very good seeing". It's when you can crank the
      > > magnification up to the point where the floaters in your eye are more annoying
      > > than the turbulence.
      > >
      > > -John
      > >
      > >
      > >
      > >
      > > ----- Original Message ----
      > > > From: William Hamblen <wrhamblen@>
      > > >
      > > > With very small exit pupils your eye has a great depth of focus and
      > > > defects in the eye, including floaters, irregularities in the cornea or
      > > > crystalline lens, and so-on become all too visible. A lot of people
      > > > find that annoying. With larger exit pupils those distractions are less
      > > > visible. Greatest acuity of vision usually is with exit pupils a little
      > > > less than 1 mm.
      > > >
      > > > Bud
      > > >
      > > > On 06/26/2011 07:36 PM, Worsel wrote:
      > > > > Chris Lord's article on eyepieces is an educational read on its own.
      > > > >
      > > > > http://www.howardastro.org/documents/evolution_of_eyepieces.pdf
      > > > >
      > > > > He states that, all other things being optimum, there are upper and lower
      > > >limits on an eyepiece focal length, dependent on the scope focal ratio (page
      > > >15). Upper limit occurs because the iris opening of the eye itself stops down
      > > >the eyepiece. Lower limit occurs because of diffraction. This results in a
      > > >corresponding upper and lower limit on scope magnification for a given scope
      > > >f/.
      > > > >
      > > > > For an F/10, the lower limit would be 5 mm. If the SCT is an 11 inch, then
      > > >the corresponding limiting mag is 2800 / 5 = 560x.
      > > > >
      > > > > Now, I have tried (and I suspect that many of the forum have as well) going
      > > >to 700x or higher (e.g. a TV 3-6 mm zoom at 4 mm in a 11 inch SCT = 700x) just
      > > >because I can. I can see things in the eyepiece and they are BIG, but I'm not
      > > >enthralled with the distortion (of course, I have crummy AND old eyes to begin
      > > >with). This has occurred even on nights with 8 or 9 out of 10 seeing.
      > > > >
      > > > > Bryan
      > > > >
      > > > >
      > > > >
      > > > > ------------------------------------
      > > > >
      > > > > Visit the sct-user home page at:
      > > > >
      > > > >
      > > > >
      > > > > http://skywatch.brainiac.com/SCThpYahoo! Groups Links
      > > > >
      > > > >
      > > > >
      > > > >
      > > >
      > > >
      > > >
      > > > ------------------------------------
      > > >
      > > > Visit the sct-user home page at:
      > > >
      > > >
      > > >
      > > > http://skywatch.brainiac.com/SCThpYahoo! Groups Links
      > > >
      > > >
      > > >
      > > >
      > >
      >
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