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Cepheus Elf
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Reged: 08/01/10

Loc: Rainy, Cloudy Lancashire UK
Double Star Colours and Aperture new
      #5592413 - 12/28/12 10:33 AM

Hi Folks,

I have read a couple of independent authors who advise that large aperture scopes can be detrimental when observing colourful doubles as their light gathering power can bleach out the stars' colors and they recommend 4-6" scopes as the optimim aperture for observing bright colourful doubles.
My own observations over the last three years with scopes ranging from 3" to 12" do not agree with this view and I have to say that in every case (wide and close, bright and faint pairs), the colours of the doubles I observed were much more intense in the bigger aperture scopes - even the very bright pairs like Albireo. Just wondering if anyone else found aperture to be a an advantage when observing colourful doubles

All the bset and clear skies,
Mick


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Darren Drake
Carpal Tunnel
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Reged: 10/09/02

Loc: Chicagoland
Re: Double Star Colours and Aperture new [Re: Cepheus Elf]
      #5592469 - 12/28/12 11:08 AM

More aperture is definitely better for seeing colors. Sometimes it helps to defocus the image a little to spread out the colors instead of just seeing them concentrated into a point source.

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azure1961p
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Reged: 01/17/09

Loc: USA
Re: Double Star Colours and Aperture [Re: Darren Drake]
      #5593161 - 12/28/12 07:09 PM

I know what they are trying to say and unfortunately they didn't really say it. Yes when a star like Vega or Betelgeuse is seen thru a 20" scope it's terrifically bright but the orange leans more toward yellow as the reds are bleached out a bit. Now here's what they didn't finish saying: a larger scope sees MORE stars and puts color in stars a 6" might reveal as simply grey. So you see more color with more choices to pick from while the 4" list is comparatively short to the 20" for example. When you have that much light gathering power you aren't restricted to naked eye magnitudes and the multitude of stars now showing color is in another realm.

Pete


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Cepheus Elf
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Reged: 08/01/10

Loc: Rainy, Cloudy Lancashire UK
Re: Double Star Colours and Aperture new [Re: azure1961p]
      #5596417 - 12/30/12 03:48 PM

Thanks for your thoughts on this Darren and Pete.

Mick


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Rich (RLTYS)Moderator
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Reged: 12/18/04

Loc: New York (Long Island)
Re: Double Star Colours and Aperture new [Re: Cepheus Elf]
      #5599303 - 01/01/13 10:11 AM

I have observed a number of colorful doubles with my 10" refl. I then tried a 4" apature stop and could see no real difference in color. Admitedly my eyesight is not the best but this was my personal experience.

Rich (RLTYS)


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