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152 mm triplet refractor

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#1 Cascade Alpacas

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Posted 26 October 2021 - 11:53 AM

I have a 152 mm achromat, can you replace  the lens with a triplet lens?

 



#2 fftulip

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Posted 26 October 2021 - 12:18 PM

Yes you can replace an achromat objective with a triplet.  It's easiest to do if the lens cells are the same diameter.  When I replaced my achromat with a triplet I needed shim the new cell to fit the tube - not recommended if you don't have mechanical skills.  Also the focal length should be nearly the same, otherwise you may need to shorten or lengthen the light path, also possibly modify any baffles.  Of course after the change, you will have to collimate everything.  So while it's possible it's not an easy task.


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#3 Cascade Alpacas

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Posted 26 October 2021 - 06:11 PM

Thanks. I'm a machinist and  I work with carbon fiber and molds. This should not be to hard. Would you know where I could find a 152 mm triplet lens? Thanks



#4 Steve Cox

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Posted 26 October 2021 - 06:55 PM

I was going to recommend istar-optical.com, but I just looked, and the only triplet lenses they sell now are 140mm and 170mm, and both are at a price point you'd be better off just buying a whole new scope.



#5 ris242

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Posted 26 October 2021 - 07:14 PM

Thanks. I'm a machinist and  I work with carbon fiber and molds. This should not be to hard. Would you know where I could find a 152 mm triplet lens? Thanks

APM Germany - 152mm f/7.9

 

9.91 lbs


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#6 Westseen

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Posted 30 October 2021 - 11:10 AM

APM Germany - 152mm f/7.9

 

9.91 lbs

The APM 152 doublet is f/7.9 & 2.5 kg or 5.5 lbs.  So if the weight seems too much...

 

It would be nice if we could buy a ~150mm oil spaced triplet.  That would be much lighter.

 

User ThomasM meantions here:

https://www.cloudyni...telescope-r3059

160mm, triplet, oil spaced, f/6.5, weight = 3.5 kg (7.7 lbs)      ... just ctrl f "3,5"

 

I asked CFF if they were willing to sell just the lens, but Catalin said no at this time.


Edited by Westseen, 30 October 2021 - 11:12 AM.



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