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Meade DS-90 Rehab Project

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29 replies to this topic

#26 jonalmada

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Posted 19 March 2019 - 02:32 AM

I managed to find a parted out DS-60 with a nice bag of hardware off Ebay that had everything I need - The bag of screws, bearings and such was all I needed, so I picked up just that to help rebuild the DS-90 and also a DS-114 reflector - It'll be a fun pair of rebuilds ;>) Will document it and share it with you guys ...


Edited by jonalmada, 19 March 2019 - 02:56 AM.


#27 zendata

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Posted 18 July 2020 - 10:44 PM

I am fixing up a previously unloved DS-90 and the two objective lenses (doublet) were out of the OTA. They are looking in pretty good shape, not scratched but I have no idea of the spacing between the lenses or the correct orientation for re-assembly. There is a very fine clear nylon washer that looks like a spacer of <1mm which I am assuming gives a small air gap between the doublet? Or is it a washer for the outer lens interface with the screw in retainer?

 

Can any one please let me know the correct original configuration and position of the two lenses?

 

Thanks


Edited by zendata, 19 July 2020 - 12:46 AM.


#28 oldtimer

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Posted 14 September 2020 - 12:19 PM

I am currently awaiting delivery of a DS 90. I have in my multi collection of notes and don't remember the source, that the Classic Fraunhofer design calls for lens spacing of no more than .1mm or .004 inch.  A 1mm spacer is too wide. I have corrected two scopes with these spacers by removing them and replacing them with three 2mmX2mm squares pieces of scocth tape.. Subsequect visual mages were much better.

 

Gary (oldtimer)


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#29 gnowellsct

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Posted 14 September 2020 - 03:33 PM

I have done a rehab on a 60mm Sears from the sixties, made in Japan deal.

 

In those days,maybe ten years ago, you could get a really nifty Crawmach focuser for this generation of scopes.  1.25 inch R&P.    You put it on the scope you think ahhh, success!  Crawmach disappeared from the business, it was brisk but maybe not profitable.

 

But the mount can't hold that much weight.  And I'm talking about BEFORE you put a real finder and an eyepiece, even like, an RKE 28mm instead of a .965 something or other, into the 1.25 inch diagonal.   I'm keeping it because I think some day i might get it some rings and throw it on a real mount.  

 

But you know.  That would be on the day when I decide to take out a 60mm Sears f/11 achromat instead of a CFF 92mm .  Or even a Vixen SD81s.   

 

These scopes have lessons to teach but the lessons are not always about how you can fix it up.  Very difficult to bring a 1965 VW up to the standards of even a simple Toyota Corolla today.  You need to build a whole new car.

 

Greg N


Edited by gnowellsct, 14 September 2020 - 03:34 PM.


#30 zendata

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Posted 14 September 2020 - 08:12 PM

Thanks for the advice Gary (oldtimer) 

 

I re-assembled it with the spacer in-between the doublet and it seems to work very well, but then so do the first pair of hi-fi speakers you ever hear no matter how good or bad they are. I am guessing the nylon ring is about .4mm in width - so one fine night soon I will do as you say when I have the chance for a bit of objective A/B testing (excuse the pun).

 

Graham




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