Checking pinching in day time?

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turboscrew
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Checking pinching in day time?

#1

Post by turboscrew »


Are there any good ways to check mirror pinching in day time?
In my case, artificial star is not an option, because 300 mm (12") F/4 needs quite a distance.
According to @SkyHiker 's wonderful work on the subject, my distance to artificial star should be 200 meters at which the artificial star size should be 374 um max. (Dawes limit).

BTW, I really think that the SkyHiker's work should be there in the articles.
- Juha

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Telescope: OrionOptics XV12, Mount: CEM120, Tri-pier 360 and alternative dobson mount.
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Ruud
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Re: Checking pinching in day time?

#2

Post by Ruud »


A distant raindrop hanging from a leaf on a bright day, lensing the Sun, might do the job.
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Lady Fraktor Slovakia
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Re: Checking pinching in day time?

#3

Post by Lady Fraktor »


As long as you left a slight expansion space between the mirror and holders there should be no pinching.
See Far Sticks: Antares Elita 103/1575, AOM FLT 105/1000, Bresser BV 127/1200, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS100/1000, Vixen SD115s/885
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Re: Checking pinching in day time?

#4

Post by turboscrew »


At least I didn't notice any pinching. (Thanks for the advice back then @Lady Fraktor.)
- Juha

Senior Embedded SW Designer
Telescope: OrionOptics XV12, Mount: CEM120, Tri-pier 360 and alternative dobson mount.
Grab 'n go: Omegon AC 102/660 on AZ-3 mount
Eyepieces: 26 mm Omegon SWAN 70°, 15 mm TV Plössl, 12.5 mm Baader Morpheus, 10 mm TV Delos, 6 mm Baader Classic Ortho, 5 mm TV DeLite, 4 mm and 3 mm TV Radians
Cameras: ZWO ASI 294MM Pro, Omegon veLOX 178C
OAG: TS-Optics TSOAG09, ZWO EFW 7 x 36 mm, ZWO filter sets: LRGB and Ha/OIII/SII
Explore Scientific HR 2" coma corrector, Meade x3 1.25" Barlow, TV PowerMate 4x 2"
Some filters (#80A, ND-96, ND-09, Astronomik UHC)
Laptop: Acer Enduro Urban N3 semi-rugged, Windows 11
LAT 61° 28' 10.9" N, Bortle 5

I don't suffer from insanity. I'm enjoying every minute of it.

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