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jrbarnett
Eyepiece Hooligan
Reged: 02/28/06
Posts: 4346
Loc: Petaluma, CA
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After six happy years of ownership the day has come. My FS-78's heretofore-untouched objective needs a bath. Before tugging on and/or twisting on the dew shade, I figured I would ask here.
How does one remove the dew shade on a Takahashi FS-78?
Thanks!
- Jim
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"I do not know what I may appear to the world; but to myself I seem to have been only like a boy playing on the seashore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me."
- Sir Issac Newton
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Theodore Mattas
super member
Reged: 11/12/04
Posts: 101
Loc: Thessaloniki, Greece
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You don't!
I faced the same problem with my old FS-102 (the one with non retractable dew shield) when cleaning time came and did the job without removing the dew shield.
I think that if you try to "force" things you will damage the dew shield, so since your model is not the retractable version you do absolutely nothing!
Teo
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Takahashi TOA-130S
Zeiss Abbe II ortho set
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edif300
member
Reged: 02/24/07
Posts: 30
Loc: Basque Country
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Hi,
You can remove the dew shield by unscrewing it:
unscrewed dew shield
Regards,
Iņaki
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Astroargazkigintza
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Erik Bakker
professor emeritus
Reged: 08/10/06
Posts: 532
Loc: Haren, The Netherlands, Europe
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Hi Jim,
When I clean my fluorites, I unscrew the dewcap and then unscrew the lenscell from the tube. Same should work for your FS 78. Afther that, you have a package that iis easy to clean gently and perfectly. No collimation or other isssues afterwards, just extremely clean and transparent optics. Be gentle though, both while unscrewing and while cleaning your optics.
Clear skies,
Erik
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Visual astronomer, main instruments:
Fully mounted Questar 7 P-BB
Celestron C 102F f/8.8 fluorite
Vixen FL 70S f/8 fluorite
Celestron C 55F f/8 fluorite
Sets of Zeiss, TeleVue and Brandon eyepieces
Zeiss 7x50 Marine B/GA
Zeiss TM german equatorial
Gitzo 224 with Manfrotto 501 fluid head
Unitron alt-az mount
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jrbarnett
Eyepiece Hooligan
Reged: 02/28/06
Posts: 4346
Loc: Petaluma, CA
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Thanks Teo.
I know Thessaloniki well. In 1985 I worked one summer on a wheat farm near Thessaloniki. I really loved Greece. I bet Thessaloniki has changed a lot since 1985 though.
Regards,
Jim
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"I do not know what I may appear to the world; but to myself I seem to have been only like a boy playing on the seashore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me."
- Sir Issac Newton
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jrbarnett
Eyepiece Hooligan
Reged: 02/28/06
Posts: 4346
Loc: Petaluma, CA
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Thanks Erik and Inaki.
Mine is the blue band style like the FS-102 in Inaki's photo.
I'm pretty sure the interior (focuser side) glass surface is clean. I have lots of dew spots and some contaminants on the front facing surface though, so I'll probably leave the cell attached. I was thinking I would lock it down on the teegul mount, and clean the front surface that way.
I haven't decided what I'll use to clean it though.
Regards,
Jim
--------------------
"I do not know what I may appear to the world; but to myself I seem to have been only like a boy playing on the seashore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me."
- Sir Issac Newton
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Erik Bakker
professor emeritus
Reged: 08/10/06
Posts: 532
Loc: Haren, The Netherlands, Europe
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Quote:
Thanks Erik and Inaki.
Mine is the blue band style like the FS-102 in Inaki's photo.
I'm pretty sure the interior (focuser side) glass surface is clean. I have lots of dew spots and some contaminants on the front facing surface though, so I'll probably leave the cell attached. I was thinking I would lock it down on the teegul mount, and clean the front surface that way.
I haven't decided what I'll use to clean it though.
Regards,
Jim
Hi Jim,
I use pure alcohol (96%, highest grade) (like Opticon, a professional optics firm that makes high-end optics for the major observatoties and created their legendary 10" SCT many years ago). It works very well on the fluorite doublets (even the fluorite element) Just be gentle in applying the alcohol. Check with the Astro-Physics and TeleVue, they have good instructions on cleaning on their sites.
Unscrewing the dewcap is not a matter of brute force, because that will slightly deform the dewcap, making it feel like glued-on. So have someone hold the tube with cell for you, then gently turn the dewcap counterclockwise with 2 hands. Make sure you apply rotational force to the dewcap and don't squeeze the dewcap. The slightest squeezing will lock the dewshield in place. This deformation only lasts while you apply squeezing forces, after that it returns to it's original round shape.
Clear skies,
Erik
--------------------
Visual astronomer, main instruments:
Fully mounted Questar 7 P-BB
Celestron C 102F f/8.8 fluorite
Vixen FL 70S f/8 fluorite
Celestron C 55F f/8 fluorite
Sets of Zeiss, TeleVue and Brandon eyepieces
Zeiss 7x50 Marine B/GA
Zeiss TM german equatorial
Gitzo 224 with Manfrotto 501 fluid head
Unitron alt-az mount
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Theodore Mattas
super member
Reged: 11/12/04
Posts: 101
Loc: Thessaloniki, Greece
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Use Baader's "Optical Wonder".
Absolutely amazing product..when you finish, the lens will look as if it was never cleaned, as if it is brand new.
Roland Christen at Astro-physics uses this fluid!
Teo
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Takahashi TOA-130S
Zeiss Abbe II ortho set
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