Re: [ATM] New site

[Aki Lötjönen <aki.lotjonen@phnet.fi>]

Hi Vlad,

Yes, you are absolutely right - why not Houghton?
Maybe because Houghton telescopes have been unknown and you have to pay 
for the lens material too. Also there is a lot of work to do with 5 
surfaces even if all are spherical and easy to make. To make  LH optics 
there are also a few new stages like de-wedging, trepanning and maybe 
edging compared to traditional mirror making. But all these are just 
new, interesting parts to learn - and quite easy ones.
I read somewhere that there might be problems with cooling of corrector 
lenses. I have now used my LH telescope for awhile and cannot report 
such a problem. Okay, my usage of LH is still quite limited.

Rgds,
Aki



vladimir sacek wrote:

>Hi Aki,
>
>Thank you. Obtaining Houghton aberration coefficients
>was pretty straight-forward from the general thin lens
>equations. It is really puzzling why this corrector type
>isn't more in use. I just added a simple prescription for the
>Houghton variation that is easiest of all correctors to make:
>a pair of two plano- lenses with equal curvatures (one positive,
>the other negative). In the Newtonian arrangement it has
>1/2 the coma of the Maksutov counterpart, and 1/3 the coma
>of the Schmidt-Newtonian. So - why not Houghton?
>
>Vlad
>
>
>----- Original Message ----- 
>From: <aki.lotjonen@phnet.fi>
>To: <atm@atmlist.net>
>Sent: Monday, July 17, 2006 5:12 AM
>Subject: Re: [ATM] New site
>
>
>Hi Vladimir,
>
>Very nice and interesting "put together" web-pages. I'm sure ppl find
>your pages very useful. I personally happily noticed that you also has
>a section for Houghton correctors.
>
>Regards,
>Aki Lötjönen
>
>  
>
>>For the reason that there were more important things to do,
>>I spent last couple of months putting together a site on the
>>subject of telescopes:
>>
>>http://www.telescope-optics.net
>>
>>
>>To some extent unavoidably repetitive, but also with some
>>interesting hard to find (on the Net) and original contents.
>>After several editing sessions, I still run into occasional
>>typos and incoherent thoughts. So, feel free to let me know
>>for what can be bettered - I'll be thankful for it.
>>
>>Vlad
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>>
>>    
>>
>
>
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