----- Original Message -----
Sent: Saturday, November 17, 2001 12:54 AM
Subject: [M]: Choosing the right ccd camera for an LX200 10" f/10


> I've been looking for several months now for an entry level ccd
camera.
> I'm probably more confused than ever. My skies are not great. I can
see
> the Milky Way from zenith to about 60 degrees on a moonless night. I
suspect
> many of you could obtain great images with most of the equipment out
there;
> but ease of use, no permanent pier and good software are important to
me.
> The Starlight Xpress MX5C and MX516 caught my attention because of the
> possible use of Star2000 and eliminating the need for a separate guiding
> system. I understand the resolution suffers due to the guiding function
> uses half the ccd. I will be using an LX200 10" F/10 and have a 6.3 FR.
> Other issues seem to be focusing and download times. Meade's
advertising
> talks about auto focusing. Does it work? I have the 1206 electric
focuser.
> What other software will I need to buy to compliment a system? Also,
what
> about focusing for planets. What I've read talks about focusing on a
nearby
> star. How could that work given the extreme differences in distance
between
> the planet and any star?
Lots of questions!...
'Resolution' doesn't as such suffer from the guiding system on the MX
cameras. Though you image from half the CCD at a time, _provided_ the
scope is guiding accurately, and tracking well (it has to remain stable in
the 'unguided' interval), you get the full CCD resolution. Otherwise the
famous 'Venetian blind effect' rears it's head. However you lose half the
_sensitivity_ that the camera has available when operating unguided. You
also add more thermal noise to the image, making dark frames vital (they
allready are...).
You lose 'real' resolution on the colour cameras, because of the need to
use four cells to get the colour data.
Auto focussing does work (look at something like 'FocusAide'), but will
not work with the Meade focusser. You need a 'repeatable' focusser, that
can goto an exact position. Either the 'RoboFocus' system, or one of the
Crayford focussers with DRO.
Both planets and stars are focussed at 'infinity'. The point at which the
focus becomes indistinguishable, depends on the focal length of the system
concerned, but with a camera lens at 50mm focal length, is only about
30feet. With normal telescopes, it is about three to five miles, with
anything beyond this point, having effectively the same 'focus'.
As a 'comment', Meade don't really make CCD cameras. They are marketting a
rather 'old' design from another company. Look at the SBig products or the
Starlight products for 'better' systems.
The USB interface option on the Starlight cameras, radically reduces the
download times for the smaller cameras, and makes cableing simpler.
Obviously for large/upmarket cameras, there are other solutions like SCSI,
but cost then becomes prohibitive...

Best Wishes

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