Re: It's The Optics Stupid!

[Tom Droege <tdroege2@earthlink.net>]

Uhhh!  One thing I forgot to mention.  The focus for the I lens is now 
sharper.  Still not quite as good as the V lens but closer than before.  So 
it looks like the lens may be the culprit.

Every so often in science, one is lucky.  In this case, the lens most in 
need of a stop is the one which produces the brighter images and thus can 
stand the stop.  Let's here it for good old luck.

Tom Droege

At 05:57 PM 10/20/02 -0400, you wrote:

>   Tom -- you can check this idea in the following way: examine
>old and new (pre- and post-mask) images in I-band.  Pick two or three
>stars in the center of the frame and in each of the 4 corners.
>Measure the size and shape of the PSF of those stars -- you can fit
>gaussians to the profiles, or, heck, just move your cursor around and
>count pixels.  If you see that the PSF is more uniform across the
>frame in the new (post-mask) images (and I'll bet it is), then I'd
>guess a large portion of the blame can be laid at the feet of
>the PSF ... and, hence, of the lenses.