Date: Thu, 25 Aug 2016 08:47:10 -0400 (EDT)
From: jegunn
Subject: Re: [sloan-25mlog 3061] Re: 2.5m obslog 20160823 (SJD 57624)
Yes, the R and B conversion SHOULD be almost the same.
--jim
On Wed, 24 Aug 2016, Daniel Oravetz wrote:
> While we were manually focusing R2 and B2 tonight, we determined that a +1
> deg adjustment on the R2 focus ring corresponds to -316 collimator steps,
> which is the same conversion as b2.
>
> E.g., the output from 'hartmann collimate noCorrect' (frames 225735 &
> 225736) indicated r2PistonMove=-6627 steps. The R2 focus ring was adjusted
> +10 deg and the subsequent hartmann output (frames 225737 & 225738)
> indicated r2PistonMove=-3471 steps. I.e., +10 deg on the ring ==> -3156
> steps. We used this conversion to successfully complete the focusing of R2
> using the focus ring and the hartmann output.
>
> Dan & Karen
>
>
>>>> We planned to take focus sweep data for R2, but could not focus R2. We
>>>> sent
>>>> several hours in taking arc exposures at every 300 degrees or so from
>>>> an
>>>> thread
>>>> end of R2 focus ring to the other end. We didn't see changes in arc
>>>> images.
>>>> Compared with out-focus images on r1, we believe that R2 is out of
>>>> focus
>>>> by more
>>>> than 300 degrees. Looks like that, for some reason, moving R2 focus
>>>> ring
>>>> doesn't
>>>> move R2 camera itself; or the real R2 focus is more than 500 degree
>>>> away
>>>> from
>>>> the movable range of its focus ring. See log for more details. Please
>>>> check.
>>>
>>> From the Hartmanns taken on Cart 4 earlier last night, i can see the
>>> centers of the
>>> Hartmann half-circles moved by about 12 pixels in the Y-direction
>>> between
>>> left and
>>> right hartmanns. IF the coefficients of the red focus ring is identical
>>> to
>>> the blue focus ring,
>>> then this translates to about 250 deg of focus ring rotation, or 54.7
>>> microns in the CCD
>>> position, roughly (assuming each 360 deg turn is 1/32 inch).
>>
>> Hi Renbin,
>> this is not directly connected to your question, but
>> just in a case, the rotation-to-focus length translation
>> for the red ring is different. When I moved it, the red r2
>> move translated as +10 degrees = +1000 piston steps
>> (compared to +10 deg = -3170 steps for the blue.)
>>
>> Cheers,
>> Dmitry
>>
>>
>>> best,
>>> -renbin
>>>
>>> --
>>>
>>> Renbin Yan
>>>
>>> Assistant Professor
>>> Department of Physics and Astronomy
>>> 177 Chemistry-Physics Building
>>> University of Kentucky
>>> Lexington, KY, 40506-0055
>>> (1) 859-257-0795
>>>
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>>
>>
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>
>
>
>
>
>
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