Lets play a game! Part 2 Can a doublet be apochromatic?
- John Baars
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Re: Lets play a game! Part 2 Can a doublet be apochromatic?
It seems that we do not have a comprehensive definition of apochromation. So then it becomes an approximation. I am very fond of Wolfgang Rohr's approach that measures how far apart the various focal points of the colors are. (so only the colors anyway) That means that many contemporary refractors fall within the limits of apochromatism. Even some doublets.
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.
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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Re: Lets play a game! Part 2 Can a doublet be apochromatic?
When I get this spun I like to look back at Galileo's Telescope,and what he did with it,it’s not the scope but the person behind it
- j.gardavsky
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Re: Lets play a game! Part 2 Can a doublet be apochromatic?
The apochromasie has been defined by Ernst Abbe in 1886 (I have the reprint).
When
a) Then 3 different wavelength come to a common focus
b) And for two different wavelengths the Strehl achieves its maximum value
You simply can't meet these requirements with just 2 lenses even if made of any exotic extraordinary dispersion glass materials, how much you ever might try.
(It is not as in the fun video on "Make The Right Angle Right").
This is the reason, why Zeiss and Lichtenknecker have switched from the Abbe's strict apochromasie requirement to the softer
And the ZEISS APOs have been actually designed as the
Best,
JG
Last edited by j.gardavsky on Tue Feb 16, 2021 6:56 pm, edited 1 time in total.
6" F/5 Sky-Watcher achro, 2" BBHS Star Diagonal, 2" zenith prism, 1.25" Takahashi prism
Leica 82mm APO Televid
Eyepieces: Docter UWA; Leica B WW and WW Asph. Zoom; Leica HC Plan S and L, monocentric; Pentax SMC XW, O-, XO; Tak MC O, Carl Zeiss B WW, and Pl, E-Pl, S-Pl, W-Pl;
Swarovski SW; Baader Symmetric Diascope Edition; Nikon NAV SW, ; TMB supermonocentric; Rodenstock; Vixen HR; TV Delos
Filters: Astrodon, Astronomik, Baader, Balzers, Zeiss West and East, Lumicon
Binoculars (7x42 up to 15x85): Docter Nobilem, Leica Ultravid, Nikon Astroluxe, Swarovski EL Swarovision; BA8 (Kunming Optical)
Leica 82mm APO Televid
Eyepieces: Docter UWA; Leica B WW and WW Asph. Zoom; Leica HC Plan S and L, monocentric; Pentax SMC XW, O-, XO; Tak MC O, Carl Zeiss B WW, and Pl, E-Pl, S-Pl, W-Pl;
Swarovski SW; Baader Symmetric Diascope Edition; Nikon NAV SW, ; TMB supermonocentric; Rodenstock; Vixen HR; TV Delos
Filters: Astrodon, Astronomik, Baader, Balzers, Zeiss West and East, Lumicon
Binoculars (7x42 up to 15x85): Docter Nobilem, Leica Ultravid, Nikon Astroluxe, Swarovski EL Swarovision; BA8 (Kunming Optical)
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Re: Lets play a game! Part 2 Can a doublet be apochromatic?
What JG said!
∞ Primary Scopes: #1: Celestron CPC1100 #2: 8" f/7.5 Dob #3: CR150HD f/8 6" frac
∞ AP Scopes: #1: TPO 6" f/9 RC #2: ES 102 f/7 APO #3: ES 80mm f/6 APO
∞ G&G Scopes: #1: Meade 102mm f/7.8 #2: Bresser 102mm f/4.5
∞ Guide Scopes: 70 & 80mm fracs -- The El Cheapo Bros.
∞ Mounts: iOptron CEM70AG, SW EQ6, Celestron AVX, SLT & GT (Alt-Az), Meade DS2000
∞ Cameras: #1: ZWO ASI294MC Pro #2: 662MC #3: 120MC, Canon T3i, Orion SSAG, WYZE Cam3
∞ Binos: 10X50,11X70,15X70, 25X100
∞ EPs: ES 2": 21mm 100° & 30mm 82° Pentax XW: 7, 10, 14, & 20mm 70°
Searching the skies since 1966. "I never met a scope I didn't want to keep."
∞ AP Scopes: #1: TPO 6" f/9 RC #2: ES 102 f/7 APO #3: ES 80mm f/6 APO
∞ G&G Scopes: #1: Meade 102mm f/7.8 #2: Bresser 102mm f/4.5
∞ Guide Scopes: 70 & 80mm fracs -- The El Cheapo Bros.
∞ Mounts: iOptron CEM70AG, SW EQ6, Celestron AVX, SLT & GT (Alt-Az), Meade DS2000
∞ Cameras: #1: ZWO ASI294MC Pro #2: 662MC #3: 120MC, Canon T3i, Orion SSAG, WYZE Cam3
∞ Binos: 10X50,11X70,15X70, 25X100
∞ EPs: ES 2": 21mm 100° & 30mm 82° Pentax XW: 7, 10, 14, & 20mm 70°
Searching the skies since 1966. "I never met a scope I didn't want to keep."
- John Baars
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Re: Lets play a game! Part 2 Can a doublet be apochromatic?
@j.gardavsky This is a very clear explanation, thanks!
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.
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.
- chartram
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Re: Lets play a game! Part 2 Can a doublet be apochromatic?
This is a great thread. Will probably need to read it through another 4-5 times before much of it makes sense to my caveman brain :-) I mean that as a sincere compliment to each and every person who has given a response!
I like the Stradivarius analogy given above. It seems like a lot of the key optical differences, especially between decent quality doublets and triplets will be transparent to the average enthusiast.
Mike
I like the Stradivarius analogy given above. It seems like a lot of the key optical differences, especially between decent quality doublets and triplets will be transparent to the average enthusiast.
Mike
Mike Chartrand
Scopes: WO Star 71 Gen-II (F/4.9), Astro-Tech AT115EDT (F/7), Celestron 8" Edge HD (F/10)
Cameras: ZWO ASI1600MM w/ Baader 1.25" LRGB & Narrowband Filters, ZWO ASI174MM mini, Starlight Xpress Lodestar X2
Mount: Skywatcher NEQ6 Pro
Guiding: Orion ST-80 (f/5) w/ADM MiniMax (side-by-side), ZWO OAG
Software: PHD2, Sequence Generator Pro, PixInsight
Dark Site Transportation System: 2020 Telluride SX
Scopes: WO Star 71 Gen-II (F/4.9), Astro-Tech AT115EDT (F/7), Celestron 8" Edge HD (F/10)
Cameras: ZWO ASI1600MM w/ Baader 1.25" LRGB & Narrowband Filters, ZWO ASI174MM mini, Starlight Xpress Lodestar X2
Mount: Skywatcher NEQ6 Pro
Guiding: Orion ST-80 (f/5) w/ADM MiniMax (side-by-side), ZWO OAG
Software: PHD2, Sequence Generator Pro, PixInsight
Dark Site Transportation System: 2020 Telluride SX
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