nytecam
Postmaster
Reged: 08/20/05
Posts: 9841
Loc: London UK
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These pics may be of interest showing my piggybacked ETX-70 OTA stripdown and disassembly [4 allen-key screws + 2 Philips screws] for cleaning [mostly OG + flip mirror] and tweaking and later reassembly. 
PS - this is NOT my new ETX-70 kit 
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Nytecam 51N 0.1W
Meade 30cm LX200+C8+Ha+CaK PSTs+spectrographs
SX M9+Lodestar-C CCDs/Canon 300D DSLR
My Meade astrograph-colour deepsky
My supernova discovery
My dome build/spectroscopes/DSO images/Lodestar colour images & videos
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nytecam
Postmaster
Reged: 08/20/05
Posts: 9841
Loc: London UK
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tailpiece
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nytecam
Postmaster
Reged: 08/20/05
Posts: 9841
Loc: London UK
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tailpiece #2
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nytecam
Postmaster
Reged: 08/20/05
Posts: 9841
Loc: London UK
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rear photo/erector port
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nytecam
Postmaster
Reged: 08/20/05
Posts: 9841
Loc: London UK
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OG + retaining ring. The broader edged [bottom negative] lens element seats into the lens cell within the telescope tube with the positive top element surface exposed externally.
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nytecam
Postmaster
Reged: 08/20/05
Posts: 9841
Loc: London UK
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rear tube /focusing rod
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Rainbow
professor emeritus
Reged: 08/27/04
Posts: 662
Loc: Norfolk, UK
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Nice pics - very useful - send them to Mike Weasner
That isn't a cemented doublet is it?
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Meade ETX 90 UHTC, 497 Autostar, 884 tripod, right angle finder.
CALIBRATE MOTORS and TRAIN DRIVES!
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nytecam
Postmaster
Reged: 08/20/05
Posts: 9841
Loc: London UK
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Hi RainbowQuote:
Nice pics - very useful - send them to Mike Weasner. That isn't a cemented doublet is it?
It is cemented and so is a second and John Carruthers' 80mm ETX OG
Here's the reverse of retaining ring - note the three raised 'pads' at 120 degree intervals contacting the OG edge - and [right] OG in place. A simple 'keyway' [two projecting screwheads precisely 3-inches apart] in a small section of plywood was devised to apply equal anticlockwise pressure across the retaining ring to release the OG Overall the ETX is a very neat design 
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Nytecam 51N 0.1W
Meade 30cm LX200+C8+Ha+CaK PSTs+spectrographs
SX M9+Lodestar-C CCDs/Canon 300D DSLR
My Meade astrograph-colour deepsky
My supernova discovery
My dome build/spectroscopes/DSO images/Lodestar colour images & videos
|
Rainbow
professor emeritus
Reged: 08/27/04
Posts: 662
Loc: Norfolk, UK
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Strange, the ETX 70 that I saw dismantled was not cemented - although that was a factory 'refurb'.
I guess the design evolves slightly with time
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Meade ETX 90 UHTC, 497 Autostar, 884 tripod, right angle finder.
CALIBRATE MOTORS and TRAIN DRIVES!
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David Castillo
Pooh-Bah
Reged: 09/09/06
Posts: 1398
Loc: Carmel Valley, Ca
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Nytecam,
Nice shots. I hope you take the time to Blacken the edges on the objectives with a Sharpie marker and give those baffles a shot of Krylon ultra- flat black to get rid of tons of off-access light in the OTA. You might also hit the edges of the diagonal with that sharpie while you've got it handy. If you are feeling real lucky , put some pieces of adhesive backed flocking on the sides of the diagonal housing. I think you will be doing back flips when you see how much boost in contrast it makes.
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Dave
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nytecam
Postmaster
Reged: 08/20/05
Posts: 9841
Loc: London UK
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Quote:
I hope you take the time to Blacken the edges on the objectives with a Sharpie marker.......Dave
Thanks David - I saw your post [elsewhere] and will bear it in mind. It seems the weak point of most cheaper telescopes to ignore simple baffling to remove extraneous light and I have a roll of self-adhesive black 'flock' paper that I've used down the years for this purpose.
The unblackened lens edge on Meade rear erector prism containing a Barlow [with my new ETX-70 kit] is a shocker and pining for a black marker pen 
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Nytecam 51N 0.1W
Meade 30cm LX200+C8+Ha+CaK PSTs+spectrographs
SX M9+Lodestar-C CCDs/Canon 300D DSLR
My Meade astrograph-colour deepsky
My supernova discovery
My dome build/spectroscopes/DSO images/Lodestar colour images & videos
|
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