Re: Ultra-quick evaluation of scanned photo with Mak lens

[Tom Droege <droege@wwa.com>]

Well,  I just ordered one, and with the focal reducer to 350mm f/4.  I can 
try it both ways with the Ford chip and see what it looks like.  Not a 
project I really want to do, but looks like I am it.   I can then post some
images with various lenses, and you all can have at them.

Thanks Glenn, for the offer of a loan of one, but I am pretty brutal on
things like this.  I might just start drilling holes in it to work out an
automated focus or some such thing.  So I don't like to work on other's
delicate stuff.  

This assumes that the clouds will ever go away.  I had a data run about
15 November, then the next day stars could be seen was January 1.  I
may have the new electronics built before we get clear sky again.

Note that the package is just great for this application.  It will allow
a very compact mount.  So there are a lot of advantages for my 
purpose where I want to ship units out around the world, and without
me going with.

Anyone know if there are any somewhat larger Maks around?   With 
relatively short focal lengths?   My old Orion catalog says they are hard
to make larger, and have a temperature problem.

Tom Droege

At 10:45 AM 1/8/98 -0700, you wrote:
>Tom did a quick S/N analysis center-to-edge, which looks ok to me.  However,
>a couple of points:
>  (1) The flat field that Michael used was taken through the basic
>        500mm f/5.6 lens.  If we wanted to make this lens into a
>        350mm f/4 lens, the field cruncher will make the vignetting worse.
>  (2) Since there is 0.5mag variation in actual signal center-to-edge, then
>      you must be*very* careful in how you do your flatfielding so that any
>      hint of that systematic trend is removed from the final data.
>  (3) This also means any flatfield will have ~1/2 the signal in the
edges, ok
>      as long as the sampled dynamic range is linear.
>  (4) My concern regarding scattered light remains, and will have to be
>      tested with an actual system.
>Still, unless Tom or someone else can come up with a better and/or cheaper
>solution, one of these Mak systems sounds like the best initial choice
>of aperture for the Mark IV.
>Arne
>
>
>