Homemade reflector has 3 images
- Phoenix22
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Homemade reflector has 3 images
I am new to telescopes. I made a simple reflector at home with a 15cm primary and a small circular mirror (available at your general store). Just to give an idea, my telescopes body is made out of a Pringles can.
I did all the calculations precisely and even collimated the scope. The result is that am getting a clear image but there are ghost images appearing to the left and right of the main image.
It may help to mention that the primary mirror is not parabolic.
Can you please help with what went wrong?
I did all the calculations precisely and even collimated the scope. The result is that am getting a clear image but there are ghost images appearing to the left and right of the main image.
It may help to mention that the primary mirror is not parabolic.
Can you please help with what went wrong?
- PapaFox
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Re: Homemade reflector has 3 images
saw this on the internet, is the inside of your pringles can black?
Some telescopes suffer from internal reflections inside their tubes, because the inside of the tube needs to be black.
Some telescopes suffer from internal reflections inside their tubes, because the inside of the tube needs to be black.
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- goldstar
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Re: Homemade reflector has 3 images
That small circular store bought mirror is certainly aluminum coated only on the back surface.
This causes multiple reflections from the uncoated front surface and anyway either surface will not be flat enough for astronomical purposes.
Secondary mirrors are coated only on the front surface which has been manufactured to high flatness and polish hence the higher cost.
This causes multiple reflections from the uncoated front surface and anyway either surface will not be flat enough for astronomical purposes.
Secondary mirrors are coated only on the front surface which has been manufactured to high flatness and polish hence the higher cost.
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Re: Homemade reflector has 3 images
Yes, any rear-coated mirror will produce multiple reflections. All mirrors made for household use are rear-coated for durability. All astronomical or optical mirrors are front-coated for clarity.
DSO AP: Orion 200mm f/4 Newtonian Astrograph; ATIK 383L+; EFW2 filter wheel; Astrodon Ha,Oiii,LRGB filters; KWIQ/QHY5 guide scope; Planetary AP: Celestron C-11; ZWO ASI120MC; Portable: Celestron C-8 on HEQ5 pro; C-90 on wedge; 20x80 binos; Etc: Canon 350D; Various EPs, etc. Obs: 8' Exploradome; iOptron CEM60 (pier); Helena Observatory (H2O) Astrobin
- Voyageur
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Re: Homemade reflector has 3 images
How did you fit a 15 cm primary mirror into a Pringles can? Must be some big Pringles out there that I don't know about!
Scopes: Vixen VMC200L, D=200mm, F=1950, f/9.75; Televue 2" Everbright diagonal. Coronado PST; AstroTech EDT 80mm, F=480, f/6.
Mounts: Vixen SXW/Starbook (original); Stellarvue M2C alt-az.
Eyepieces: Televue: 55mm Plossl, 22mm Panoptic, 17.3mm Delos, 13mm Nagler, c. 1980, 11mm Plossl, 7mm Nagler, 5mm Radian; Meade 15mm Super Plossl; VERNONSCOPE 2.4X BARLOW
Binoculars: Leica 8x32 Trinovids, circa 1997; Orion Megaview 20x80, Orion Paragon Plus mount.
Mounts: Vixen SXW/Starbook (original); Stellarvue M2C alt-az.
Eyepieces: Televue: 55mm Plossl, 22mm Panoptic, 17.3mm Delos, 13mm Nagler, c. 1980, 11mm Plossl, 7mm Nagler, 5mm Radian; Meade 15mm Super Plossl; VERNONSCOPE 2.4X BARLOW
Binoculars: Leica 8x32 Trinovids, circa 1997; Orion Megaview 20x80, Orion Paragon Plus mount.
- Lady Fraktor
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Re: Homemade reflector has 3 images
Congratulations on the DIY project, as has been said already the issue is with the second surface mirrors.
Other than the image ghosting can you get any decent views from it?
Other than the image ghosting can you get any decent views from it?
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EQ: TAL MT-1, Vixen SXP, AXJ, AXD
Az/Alt: AYO Digi II/ Argo Navis, Stellarvue M2C/ Argo Navis
Tripods: Berlebach Planet (2), Uni 28 Astro, Report 372, TAL factory maple, Vixen ASG-CB90, Vixen AXD-TR102
Diagonals: Astro-Physics, Baader Amici, Baader Herschel, iStar Blue, Stellarvue DX, Takahashi prism, TAL, Vixen flip mirror
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- Ylem
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Re: Homemade reflector has 3 images
Homemade stuff is definitely fun years ago some Boyscouts had a homemade Dob with a sonatube, must have been 12"
Clear Skies,
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- Phoenix22
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Re: Homemade reflector has 3 images
My mistake. Its focal length is 15 cm. It's of a radius of 20 mm. Hope this clears up your confusion on the Pringles can size
- Phoenix22
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- Phoenix22
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Re: Homemade reflector has 3 images
I have been having cloudy skies here for the past week (since the completion of the tube). Will definitely report the results once I get to see some clear night skies.Lady Fraktor wrote: ↑Sun Sep 29, 2019 4:28 pm Congratulations on the DIY project, as has been said already the issue is with the second surface mirrors.
Other than the image ghosting can you get any decent views from it?
- Phoenix22
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Re: Homemade reflector has 3 images
Thank you so much @KathyNS and @goldstar. This must be the cause of the abberation. Let me see if I can find any optical M2s of the same size.
Also, is it true that parabolic M2s are better or do circular ones work equally well?
Also, is it true that parabolic M2s are better or do circular ones work equally well?
- Voyageur
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Re: Homemade reflector has 3 images
Well, darn, I was hoping for some giant Pringles!
Seriously, it's pretty cool that you made a telescope. Lots of ideas here on how to perfect it. Good luck!
Scopes: Vixen VMC200L, D=200mm, F=1950, f/9.75; Televue 2" Everbright diagonal. Coronado PST; AstroTech EDT 80mm, F=480, f/6.
Mounts: Vixen SXW/Starbook (original); Stellarvue M2C alt-az.
Eyepieces: Televue: 55mm Plossl, 22mm Panoptic, 17.3mm Delos, 13mm Nagler, c. 1980, 11mm Plossl, 7mm Nagler, 5mm Radian; Meade 15mm Super Plossl; VERNONSCOPE 2.4X BARLOW
Binoculars: Leica 8x32 Trinovids, circa 1997; Orion Megaview 20x80, Orion Paragon Plus mount.
Mounts: Vixen SXW/Starbook (original); Stellarvue M2C alt-az.
Eyepieces: Televue: 55mm Plossl, 22mm Panoptic, 17.3mm Delos, 13mm Nagler, c. 1980, 11mm Plossl, 7mm Nagler, 5mm Radian; Meade 15mm Super Plossl; VERNONSCOPE 2.4X BARLOW
Binoculars: Leica 8x32 Trinovids, circa 1997; Orion Megaview 20x80, Orion Paragon Plus mount.
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Re: Homemade reflector has 3 images
Your focal ratio is
DSO AP: Orion 200mm f/4 Newtonian Astrograph; ATIK 383L+; EFW2 filter wheel; Astrodon Ha,Oiii,LRGB filters; KWIQ/QHY5 guide scope; Planetary AP: Celestron C-11; ZWO ASI120MC; Portable: Celestron C-8 on HEQ5 pro; C-90 on wedge; 20x80 binos; Etc: Canon 350D; Various EPs, etc. Obs: 8' Exploradome; iOptron CEM60 (pier); Helena Observatory (H2O) Astrobin
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