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Subject: RE: [M]: Anti-Blooming setting
From: Michael Hart
Reply To: mapug@shore.net
Date: Wed May 28 00:13:05 1997

On Tuesday, May 27, 1997 11:26 AM, Yuval Ben-Haim
[SMTP:yuvalb@shani.net] wrote:

> Hi all,
>
> Thanks for your responses. My problem here is that when
> I am taking an image with an over-exposure setting, I get a wedge shaped
>
> "trail" of the star (say Mars) that, I assumed, caused by blooming.
> When I tried a large setting of the anti-blooming (255), it did not
> prevent this, and I was imaging Mars with a 50 mSec setting. Is the
> Camera taking 255
> 200 microsecond exposures and downloading them to the PC, or adding
> them,
> in analog or digital method inside the camera ?
> If so, it seems (to my *very* limited knowledge) like the ultimate
> solution.
> Is it really done that way ?

First, your camera has a practical exposure limitation of the dual shutters.
Meade rates the Pictor 416XT at 10ms (arguably one of the fastest mechanical
CCD shutters). I recall exposures as low as 8 ms. For Mars, since it's
resolvable, I would use a double barlow setup or eyepiece projection to
enlarge the image. The resulting high focal ratio will increase the exposure
considerably. The anti-blooming setting for your system at 50 ms would
be 5, possibly 6. A higher number might actually worsen the blooming
problem unless the software is aware of the practical limitations.


>
> Thanks !
> Yuval.
>
> --
> +--------------------------------------------------------------+
> | Yuval Ben-Haim |
> | 61 Haerez st. |
> | Or-Yehuda 67396 |
> | ISRAEL |
> | |
> | Tel. +972-3-5334257 |
> | FAX +972-3-9266411 |
> | E-mail(home): yuvalb@shani.net |
> | E-mail(work): yuval@ecitele.com |
> +--------------------------------------------------------------+
>
>

There are experienced CCD owners on MAPUG that can offer good tips
specific to imaging Mars with double barlows or eyepiece projection.



--
Michael Hart
Husen Observatory
mhart@netexpress.net