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nytecam
Postmaster


Reged: 08/20/05
Posts: 9841
Loc: London UK
ETX-70 OTA stripdown new
      #2010728 - 11/26/07 05:11 PM Attachment (157 downloads)

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

Attachment

--------------------
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
Re: ETX-70 OTA stripdown new [Re: nytecam]
      #2010730 - 11/26/07 05:13 PM Attachment (117 downloads)

tailpiece

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nytecam
Postmaster


Reged: 08/20/05
Posts: 9841
Loc: London UK
Re: ETX-70 OTA stripdown new [Re: nytecam]
      #2010731 - 11/26/07 05:14 PM Attachment (103 downloads)

tailpiece #2

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nytecam
Postmaster


Reged: 08/20/05
Posts: 9841
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Re: ETX-70 OTA stripdown new [Re: nytecam]
      #2010735 - 11/26/07 05:15 PM Attachment (90 downloads)

rear photo/erector port

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nytecam
Postmaster


Reged: 08/20/05
Posts: 9841
Loc: London UK
Re: ETX-70 OTA stripdown new [Re: nytecam]
      #2010739 - 11/26/07 05:16 PM Attachment (97 downloads)

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
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Reged: 08/20/05
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Re: ETX-70 OTA stripdown new [Re: nytecam]
      #2010742 - 11/26/07 05:17 PM Attachment (98 downloads)

rear tube /focusing rod

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Rainbow
professor emeritus


Reged: 08/27/04
Posts: 662
Loc: Norfolk, UK
Re: ETX-70 OTA stripdown new [Re: nytecam]
      #2011750 - 11/27/07 06:12 AM

Nice pics - very useful - send them to Mike Weasner

That isn't a cemented doublet is it?

--------------------
Meade ETX 90 UHTC, 497 Autostar, 884 tripod, right angle finder.

CALIBRATE MOTORS and TRAIN DRIVES!



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nytecam
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Reged: 08/20/05
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Loc: London UK
Re: ETX-70 OTA stripdown new [Re: Rainbow]
      #2011919 - 11/27/07 09:39 AM Attachment (87 downloads)

Hi Rainbow
Quote:

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

Attachment

--------------------
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




Post Extras: Print Post   Remind Me!   Notify Moderator  
Rainbow
professor emeritus


Reged: 08/27/04
Posts: 662
Loc: Norfolk, UK
Re: ETX-70 OTA stripdown new [Re: nytecam]
      #2012140 - 11/27/07 11:43 AM

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

--------------------
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
Re: ETX-70 OTA stripdown new [Re: Rainbow]
      #2013729 - 11/27/07 11:58 PM

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.
----
Dave


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nytecam
Postmaster


Reged: 08/20/05
Posts: 9841
Loc: London UK
Re: ETX-70 OTA stripdown [Re: David Castillo]
      #2013928 - 11/28/07 03:18 AM

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

--------------------
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




Post Extras: Print Post   Remind Me!   Notify Moderator  
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