Mirrors issue?

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flord.lord
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Mirrors issue?

#1

Post by flord.lord »


Hi,

Today I attempted to collimate my new telescope. The result can be seen in the photo.

The primary mirror is perfectly within the FOV (all the adjusting clips are visible, and the secondary and vanes are bang on in the middle of the primary..

However, this whole "reflection" is not centered ON the actual mirror. (The photo doesn't do it justice, it's not that bad).

Is this an issue?

Thanks.
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IMG_20200730_204859.jpg
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5.1" SkyWatcher Explorer 130M EQ-2
4" SkyWatcher Heritage 100P Mini Dob

Greater London - Bortle 8
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goldstar
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Re: Mirrors issue?

#2

Post by goldstar »


Looks like the secondary is too far up the tube and needs to be moved closer to the primary.
It may be missing some of the light cone otherwise.
Loosen the secondary central screw and wind in the three adjustment screws to bring it down further.
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flord.lord
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Re: Mirrors issue?

#3

Post by flord.lord »


goldstar wrote: Thu Jul 30, 2020 9:20 pm Looks like the secondary is too far up the tube and needs to be moved closer to the primary.
It may be missing some of the light cone otherwise.
Loosen the secondary central screw and wind in the three adjustment screws to bring it down further.
[mention]goldstar[/mention] Great, I see now. Is it a necessary fix though? I tested last night on the moon, which was nice and sharp, and Vega, which came to a point.

I just don't want to mess if I don't have to.
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Re: Mirrors issue?

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Post by SkyHiker »


... Henk. :D Telescopes: GSO 12" Astrograph, "Comet Hunter" MN152, ES ED127CF, ES ED80, WO Redcat51, Z12, AT6RC, Celestron Skymaster 20x80, Mounts and tripod: Losmandy G11S with OnStep, AVX, Tiltall, Cameras: ASI2600MC, ASI2600MM, ASI120 mini, Fuji X-a1, Canon XSi, T6, ELPH 100HS, DIY: OnStep controller, Pi4b/power rig, Afocal adapter, Foldable Dob base, Az/Alt Dob setting circles, Accessories: ZWO 36 mm filter wheel, TV Paracorr 2, Baader MPCC Mk III, ES FF, SSAG, QHY OAG-M, EAF electronic focuser, Plossls, Barlows, Telrad, Laser collimators (Seben LK1, Z12, Howie Glatter), Cheshire, 2 Orion RACIs 8x50, Software: KStars-Ekos, DSS, PHD2, Nebulosity, Photo Gallery, Gimp, CHDK, Computers:Pi4b, 2x running KStars/Ekos, Toshiba Satellite 17", Website:Henk's astro images
flord.lord
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Re: Mirrors issue?

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Post by flord.lord »


SkyHiker wrote: Fri Jul 31, 2020 12:06 pm No it's normal, see https://www.catseyecollimation.com/pensack.pdf
[mention]SkyHiker[/mention]
Reassuring...but what about the fact that I can see the optical tube through the collimation cap...I have a feeling this isn't natural?
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Re: Mirrors issue?

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Post by OzEclipse »


If you can see the whole mirror, and more, from the centre of field, it means 100% illumination of the field at the centre. if there is an offset, you may get some asymmetric vignetting towards the field edge. If you're getting good results, use it for a while, look for vignetting and decide if you need to 'fix' it.
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