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Subject: [M]: Re: 416 XT question
From: Blair MacDonald
Reply To: mapug@shore.net
Date: Mon Apr 03 03:09:36 2000
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Ed:
Try changing the screen stretch after taking the image and leave =
autofocus off. I had some problems with the display in focus mode and =
just use the normal mode and draw a subframe around the star I want to =
focus on.
Blair
----- Original Message -----=20
From: amnet_ed=20
Sent: Monday, April 03, 2000 2:25 AM
Subject: [M]: 416 XT question
Hi everyone....
I have written about this problem before and never got an answer on =
what is going on. Can someone give me some help.
Tonight I took some images of NGC2244.=20
=20
The star group looks ok but.... the brightest star in the field has a =
black dot in the center. The star looks like a de-focused image that =
you want when you are going to colminate. However the camera is in focus =
and all the other stars are perfect.
Here are the steps I took to prepare for the image:
1. focused on nearest star near NGC2244 with difraction focus method. =
This came out perfect. Star was 100 % in focus.
2. moved to NGC2244 and removed strips from scope which I used for =
difraction focus.
3. selected autofocus mode, analog bin on, auto dark frame, prescale =
image on.
4. the camera took about four images. The final one was for about 13 =
seconds. This one was good but the brightest star in NGC2244 had a =
black dot in the center of the star. the DN setting showed 0,21333.
5. next I set the antibloom to 6. The camera beeps, the black box =
camera takes the image, I wait for the image to come on the screen and =
when it does the entire screen is white. No stars, no nothing.. the DN =
is 0.
Can anyone help with this problem? Why does the brightest star have a =
black dot (torn center)? If the star is overexposed wouldn't the pixel =
be pure white not pure black? If I cut back my time to 5 seconds the =
black dot goes away but so do all the minor stars in the cluster. That =
is why I think the black dot has something to do with overexposure.
ED REGISTRATO
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<BODY bgColor=3D#ffffff>
<DIV><FONT size=3D2>Ed:</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=3D2>Try changing the screen stretch after taking the =
image and=20
leave autofocus off. I had some problems with the display in focus mode =
and just=20
use the normal mode and draw a subframe around the star I want to focus=20
on.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=3D2>Blair</FONT></DIV>
<BLOCKQUOTE=20
style=3D"BORDER-LEFT: #000000 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: =
0px; PADDING-LEFT: 5px; PADDING-RIGHT: 0px">
<DIV style=3D"FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV=20
style=3D"BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: =
black"><B>From:</B>=20
<DIV style=3D"FONT: 10pt arial"><B>To:</B> <A =
<DIV style=3D"FONT: 10pt arial"><B>Sent:</B> Monday, April 03, 2000 =
2:25=20
AM</DIV>
<DIV style=3D"FONT: 10pt arial"><B>Subject:</B> [M]: 416 XT =
question</DIV>
<DIV><BR></DIV>
<DIV><FONT face=3DArial size=3D2>Hi everyone....</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial size=3D2>I have written about this problem =
before and=20
never got an answer on what is going on. Can someone give me =
some=20
help.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial size=3D2>Tonight I took some images of =
NGC2244.=20
</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>The star group looks ok but.... the =
brightest=20
star in the field has a black dot in the center. The star =
looks=20
like a de-focused image that you want when you are going to colminate. =
However=20
the camera is in focus and all the other stars are =
perfect.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial size=3D2>Here are the steps I took to =
prepare for the=20
image:</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial size=3D2>1. focused on nearest star near =
NGC2244 with=20
difraction focus method. This came out perfect. Star was 100 % =
in=20
focus.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>2. moved to NGC2244 and removed =
strips from=20
scope which I used for difraction focus.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>3. selected autofocus mode, analog =
bin on, auto=20
dark frame, prescale image on.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>4. the camera took about four images. =
The final=20
one was for about 13 seconds. This one was good but the =
brightest star=20
in NGC2244 had a black dot in the center of the star. the DN =
setting=20
showed 0,21333.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2>5. next I set the antibloom to =
6. The=20
camera beeps, the black box changes its readout. I next take the =
same=20
image to=20
come on the screen and when it does the entire screen is white. =
No=20
stars, no nothing.. the DN is 0.</FONT></DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial size=3D2>Can anyone help with this=20
problem? Why does the brightest star have a black dot (torn=20
center)? If the star is overexposed wouldn't the pixel be pure =
white not=20
pure black? If I cut back my time to 5 seconds the black dot =
goes away=20
but so do all the minor stars in the cluster. That is why I think the =
black=20
dot has something to do with overexposure.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=3DArial size=3D2>ED REGISTRATO</FONT></DIV>
<DIV><FONT face=3DArial size=3D2><A=20
<DIV> </DIV></BLOCKQUOTE></BODY></HTML>
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