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Building a LARGE fixed reflector/ observatory


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Hello all -

My Dad is a retired chartered engineer and lives in the highlands of Scotland. He has lots of tools and time at his disposal as well as 60 years engineering experience and a passing interest in astronomy and the heavens.

Today I got round to thinking about helping him to construct a large fixed scope on his land? I have seen various things about such projects on line but if anyone on here can advise/ direct me to info it would be appreciated so I start off on the right foot. :)

In the mean time I will be trawling gooooogle for info.

I'm thinking we could start construction by late summer and photographing/ blogging on the way.

Any ideas/ info would be greatly welcome.

Thanks in advance,


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Lots of experience on this forum but, to start with, how LARGE do you mean (10", 20"....)?

Around 20" I think depending on how long the focal length would have to be.

I am a complete novice at the moment so please escuse my ignorance (This idea came into my head about an hour ago) but how long would the tube need to be for 20"?


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A 20" f4 would be 70-80" long, and you would need to grind the mirror to a maximum depth of 0.3128"

Thanks for this. 80" is not too long for the place we have in mind. I was thinking of buying mirrors but they seem very pricey.

More research is needed. I may have a word with Orion optics down the road and see what they can supply.

Thanks for your help.


Edited by mylatestwhim
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Sounds like a fun project, but If you really want to build it yourself -- I'd suggest you start off with something smaller as a prototype. Unless you have someone with experience you can call on (in person), there will be a lot of mistakes to make while you learn, and at 20-inch and up, those could get expensive/frustrating. You'll build a better large scope if you have experience of building a smaller one first.

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:) I priced up mirrors last night :eek:

I'm thinking 16" could give a better balance between affordability and performance.

I do like the idea of a camera as we are thinking of modifying and existing building to house the observatory so space is not a problem for a monitor etc.

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We indend to create the observatory within this existing barn by modifying the roof and creating a raised platform and removable section of roof.

This will give an elevated position and allow good views to the south, missing the hills, and west, missing the trees as well as excellent views to the North and East.


The location is somewhere highlighted red.


Images: google maps

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