What Do You Think About This?

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Refractordude
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What Do You Think About This?

#1

Post by Refractordude »


He is getting more mag by decreasing the aperture and increasing the focal ratio. Left Click the image.
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John Baars Netherlands
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Re: What Do You Think About This?

#2

Post by John Baars »


He is describing a side effect as if it were a main effect.
By masking the aperture he decreases the effects of external seeing. No wonder he sees planets and very close double stars better.
As a matter of fact he decreases the contrast (a small, hardly noticable percentage) by having a relatively bigger central obstruction, but the gain in details as a result of the better seeing wins apparently.

Observing more details in an amateur 4 inch f/15 achromat compared to a 4 inch f/5 achromat is quite obvious though.
Refractors in frequency of use : *SW Evostar 120ED F/7.5 (all round ), * Vixen 102ED F/9 (vintage), both on Vixen GPDX.
GrabnGo on Alt/AZ : *SW Startravel 102 F/5 refractor( widefield, Sun, push-to), *OMC140 Maksutov F/14.3 ( planets).
Most used Eyepieces: *Panoptic 24, *Morpheus 14, *Leica ASPH zoom, *Zeiss barlow, *Pentax XO5.
Commonly used bino's : *Jena 10X50 , * Canon 10X30 IS, *Swarovski Habicht 7X42, * Celestron 15X70, *Kasai 2.3X40
Rijswijk Public Observatory: * Astro-Physics Starfire 130 f/8, * 6 inch Newton, * C9.25, * Meade 14 inch LX600 ACF, *Lunt.
Amateur astronomer since 1970.
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