[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]
Re: [APML] A Fresh Lens Recommendation Thread
That aparratus looks like it would do the job. I've already got a 3/8"
thick plate used for guiding two OTAs. Now, all I need is $8K in loose
change to get the rest. To bad there's not a group of enterprising
people living in a short radius that could toss something together for a
test....
-s
Mike Cook, AF9Y wrote:
>You might be interested in this approach if you haven't already seen it:
>
>http://www.galaxyimages.com/focus.html
>
>Of course with a CCD, only the center FOV of the lens would be used so
>the performance would be even more impressive.
>
>
>Mike
>
>
>
>
>>From: stephen pitt <lthuedk@pe.net>
>>
>>
>>
>>>This might be an ideal lens for use with an ABG CCD like the ST-2000. I wonder
>>>if RoboFocus could be adapted to drive it.
>>>
>>>
>>I don't know. The focus ring is ~2.5" in dia, located in the center of
>>the lens, which is 9.5" long. I too would like very much to attach a
>>CCD camera to this optic. You probably noticed slightly elongated stars
>>at the top of the corner shots, but the degree is rediculously small.
>>
>>While no correction in a camera lens can be perfect, this SD has very
>>low chromatic aberration-about what one would expect in a very good ED.
>>
>>I shoot at Joshua Tree, where the skies are fairly dark. As I said
>>elsewhere, the lens will vignette with other films of less contrast and
>>broader value range, especially when clarity is down. But its never
>>objectionably bad. On a bad night, I'm sure there would be some
>>vignetting with the EII at f2.8. Unfortunately, I made no notation to
>>that effect on the sample night. Clearly, it was a good night.
>>
>>Stephen
>>
>>
>>
>>
>>>Mike Cook
>>>AF9Y
>>>
>>>Date sent: Tue, 17 Dec 2002 14:42:17 -0800
>>>From: stephen pitt <lthuedk@pe.net>
>>>To: astro-photo@seds.org
>>>Subject: Re: [APML] A Fresh Lens Recommendation Thread
>>>Send reply to: astro-photo@seds.org
>>>
>>>
>>>
>>>>Hi Mike, sure:
>>>>
>>>>http://www.light-to-dark.com/corners
>>>>
>>>>>From the 2700 dpi image. Stephen
>>>>
>>>>"Mike Cook, AF9Y" wrote:
>>>>
>>>>
>>>>>Stephen,
>>>>>
>>>>> That looks quite impressive, especially if it was taken at F/2.8.
>>>>>Could you show a 1:1 crop of the corners to give us an idea of
>>>>>how good it really is?
>>>>>
>>>>>Mike Cook
>>>>>AF9Y
>>>>>
>>>>>Date sent: Tue, 17 Dec 2002 10:26:13 -0800
>>>>>From: Stephen Pitt <lthuedk@pe.net>
>>>>>To: apml <astro-photo@seds.org>
>>>>>Subject: [APML] A Fresh Lens Recommendation Thread
>>>>>Send reply to: astro-photo@seds.org
>>>>>
>>>>>
>>>>>
>>>>>>In my previous post, I recommended the Tokina 2.8 SD. Here is a
>>>>>>positive taken with it:
>>>>>>
>>>>>>http://www.light-to-dark.com/EII
>>>>>>
>>>>>>When viewed over a lightbox, the stars are perfectly pin pointed.
>>>>>>
>>>>>>Stephen
>>>>>>
>>>>>>
>>>>>>-- APML Archives at <http://astro.umsystem.edu/apml/> ---
>>>>>> Unsubscribe at <majordomo@seds.org>
>>>>>>
>>>>>>
>>>>>>
>>>>>Mike Cook, AF9Y
>>>>>http://www.af9y.com
>>>>>mwcook@cris.com
>>>>>
>>>>>-- APML Archives at <http://astro.umsystem.edu/apml/> ---
>>>>> Unsubscribe at <majordomo@seds.org>
>>>>>
>>>>>
>>>>-- APML Archives at <http://astro.umsystem.edu/apml/> ---
>>>> Unsubscribe at <majordomo@seds.org>
>>>>
>>>>
>>>>
>>>Mike Cook, AF9Y
>>>http://www.af9y.com
>>>mwcook@cris.com
>>>
>>>-- APML Archives at <http://astro.umsystem.edu/apml/> ---
>>> Unsubscribe at <majordomo@seds.org>
>>>
>>>
>>-- APML Archives at <http://astro.umsystem.edu/apml/> ---
>> Unsubscribe at <majordomo@seds.org>
>>
>>
>>
>
>
>Mike Cook, AF9Y
>http://www.af9y.com
>mwcook@cris.com
>
>
>
>
>
>-- APML Archives at <http://astro.umsystem.edu/apml/> ---
> Unsubscribe at <majordomo@seds.org>
>
>
>
>
-- APML Archives at <http://astro.umsystem.edu/apml/> ---
Unsubscribe at <majordomo@seds.org>