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Re: [ATM] 32" Focal ratio
Be careful with the Wynne corrector, should you head in that direction. It requires very accurate lens making skills. Several surfaces are quite steep and should have their radii of curvature accurate to 0.1% or better. Spacing tolerances are tight and there is not much room for centering or tilt errors. A challenge for a skilled optician.
-- Dave
-----Original Message-----
From: Ukyo Chen <ukyochen888@hotmail.com>
To: polaraligned@optonline.net; atm@atmlist.net
Sent: Tue, 02 Aug 2005 15:09:29 +0000
Subject: Re: [ATM] 32" Focal ratio
Hi Scott and ATMers,
My design with wynne corrector have a fixed 45 degree diagonal and,
a. Not need to change anything to both for visual and photo.
b. Only 20% diameter obstruction;
c. Corrector only use BK7 glass, which is the most cheap and popular optical glass.
d. Only use 1 6" diagonal mirror.
e. coma free!
Is it better than your design? Wouldn't you think about it?
Best Regards,
Ukyo Chen
>From: polaraligned <polaraligned@optonline.net>
>To: Ukyo Chen <ukyochen888@hotmail.com>
>Subject: Re: [ATM] 32" Focal ratio
>Date: Tue, 02 Aug 2005 07:26:32 -0400
>
>Thank you,
>I appreciate your time. The system is to be folded
>with a 12" flat. The obstruction ratio will be about
>38%. You can see a rendering of the scope in here:
>http://photobucket.com/albums/v223/polaraligned/25%20inch%20scope/
>The camera lies between the primary and the flat secondary.
>My thoughts of using a longer focal ratio are for less coma to deal
>with and also easier collimation. I will be using a removable
>3rd diagonal mirror for visual use, when not imaging.
>
>Thanks for your help,
>Scott
>
>
>
>
>----- Original Message ----- From: "Ukyo Chen" <ukyochen888@hotmail.com>
>To: <polaraligned@optonline.net>; <aplanatic@aol.com>; <atm@atmlist.net>
>Sent: Monday, August 01, 2005 10:03 PM
>Subject: Re: [ATM] 32" Focal ratio
>
>
>>Hi Scott,
>>
>>Basically a fast F ratio will reduce the exposure time, as well as the >>tube length and weight.
>>I suggest you use parabolic mirror + wynne corrector. commercial coma >>corrector are not designed specially for your system and the performance >>may not as good as you can.
>>
>>Below is a 20% obstruction telescope that perform diffract limit image in >>whole 24.6x24.6mm area. You can put secondary right behind lens 2 so that >>camera or eye pieces can be easily connected after lens 3.
>>
>>If you do not need to connect eye pieces, please let me know and I will >>modify the design to get less obstruction.
>>
>>Best Regards,
>>Ukyo Chen
>>
>>F/5 32" wynne corrector
>>SRF RADIUS THICKNESS APERTURE RADIUS GLASS SPE NOTE
>>OBJ 0.0 1.0e+20 4.3633508207e+17 AIR
>>
>>AST -7135.270890953675 V -3000.0 407.0 AS REFL_HATCH *
>>
>> 2 -160.6112693212592 V -15.0 77.8465641180188 S BK7 C
>> 3 -282.4400424991707 V -40.0 74.2797145556817 S AIR
>>
>> 4 -427.5044558225438 V -10.0 65.2910476243541 S BK7 C
>> 5 -144.0836019042825 V -500.0 63.2897662600067 S AIR
>>
>> 6 -226.6123202207288 V -10.0 25.2464843501938 S BK7 C
>> 7 -655.2293854027363 S -57.6514303221301 S 24.3649768490518 S AIR
>>
>> 8 0.0 0.0 17.7588378402554 S AIR
>>
>>
>>
>>>From: Polaraligned <polaraligned@optonline.net>
>>>To: aplanatic@aol.com, atm@atmlist.net
>>>Subject: Re: [ATM] 32" Focal ratio
>>>Date: Mon, 01 Aug 2005 20:17:56 -0400
>>>
>>>>Hi Scott,
>>>>
>>>>What is the largest camera you will be using with the scope? Are you >>>>figuring the mirror or is someone else? Will you be buying (or making) >>>>a focal reducer? How picky are you about the images at the edge of the >>>>field? Do you plan on doing mosaics?
>>>>
>>>
>>>
>>>Probably a KAF 1001 with a 24.6 x 24.6 mm size. 24 um pixels. It's
>>>pixel size is a good match for the long focal legnth without binning.
>>>Plan on having someone else make mirror.... Buying a coma corrector....
>>>Well, of course I would like the best possible images to the edge of >>>field,
>>>and I can't rule out mosaics. Am I asking too much? How will this scope
>>>compare to an RC? Oh, and the original question: Is a longer f ratio >>>going
>>>to help me achieve better images, even with a corrector?
>>>
>>>Opinions appreciated,
>>>
>>>Scott
>>>
>>>
>>>_______________________________________________
>>>ATM mailing list http://www.atmlist.net/
>>
>>
>
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