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Old 20-12-2020, 01:04 PM
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mura_gadi (Steve)
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ATM refractor

Hello,

Can anyone recommend books or websites etc that might help me with learning how to make a refractor telescope.



Thanks in advance
Steve
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Old 20-12-2020, 04:20 PM
Stefan Buda
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If you starting optical work from scratch, then making a small telescope mirror first is highly recommended. Once you complete that, you will know how to make a refractor too.
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Old 20-12-2020, 04:41 PM
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Merlin66 (Ken)
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Steve,
Do you mean assembling a refractor from a commercial objective lens, commercial focuser etc?
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Old 20-12-2020, 06:07 PM
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mura_gadi (Steve)
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Sorry from scratch

Hello

I recently acquired a lot of pyrex glass precut at 4-6" discs amongst other bits. The refractor idea has some appeal as it removes the costs of cutting and coating my Dob project glass for which I have a large slab of soda glass.

I am happy to rely on ED ep's to see what results I can get without special coatings on the glass to start with.

I thought I might be able to learn some glass grinding skills via a refractor with the blanks I have, then try the Dob project.


Steve
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Old 20-12-2020, 07:02 PM
phomer (Paul)
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Quote:
Originally Posted by mura_gadi View Post
Hello

I recently acquired a lot of pyrex glass precut at 4-6" discs amongst other bits. The refractor idea has some appeal as it removes the costs of cutting and coating my Dob project glass for which I have a large slab of soda glass.

I am happy to rely on ED ep's to see what results I can get without special coatings on the glass to start with.

I thought I might be able to learn some glass grinding skills via a refractor with the blanks I have, then try the Dob project.


Steve

Steve,


This is not a trivial exercise and although I am not an expert you will need at least two types of glass with different refractive indexes and they will need to be of optical quality. A mirror avoids those complications.


Paul
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Old 20-12-2020, 07:38 PM
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mura_gadi (Steve)
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ty all, I have found most things are unlabled. I will just revert to making a 6" newt for planets for now from one of the pieces of pyrex. Use the slower F# number to make my life easy.


Thanks'
All
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Old 20-12-2020, 10:17 PM
Saturnine (Jeff)
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Hi

As phomer pointed out, you need 2 types of glass to make an achromat, or ED lens, that have different refractive indices. There was a book published by Willmann-Bell who have recently ceased publishing, unfortunately.

https://www.willbell.com/tm/refractor-telescope.htm

I don't think that Pyrex was a suitable glass for one element of a refractor objective. Much easier to buy an objective if you wanted to make a refractor but the price of achros' these days make it more worthwhile buying a complete ota. Unless of course you are like me and just like making your own anyway with commercially available lens and other bits.
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Old 21-12-2020, 07:33 AM
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Merlin66 (Ken)
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https://www.telescope-optics.net/refractor.htm


This series of notes contain a wealth of knowledge.
Well worth flicking through......
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