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Old 04-03-2010, 02:38 PM
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Pixel size calculation

Can someone please provide me with the calculated optimum pixel size for a CCD camera imaging through a 10"SCT (fl2500mm) with an f6.3 converter?
Thanks, Allan
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Old 04-03-2010, 03:03 PM
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sheeny (Al)
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From memory the calcs are you want a star image about 4-5 pixels across so it doesn't appear too blocky or too big. At 4 arc seconds seeing, that relates to roughly 1 arc second per pixel.

2500 x 0.63 = 1500mm so 1 arc second over this distance is

1500mm x tan(1/3600) = 7.27 E-3mm so about 7Ám.

I'd suggest 4-5Ám (web cam) to 10Ám would be in the range.

Al.
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Old 04-03-2010, 03:06 PM
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Thanks Al for the calculation. Fits in with what Ive been told and at the moment the QSI583wsg is looking good for both my scopes with1x1 and/or 2x2 binning.
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Old 04-03-2010, 09:17 PM
Dennis
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Hi Allan

Here is a nomogram from Sky & Telescope circa 1997.

Cheers

Dennis
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Old 04-03-2010, 09:23 PM
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[1ponders] (Paul)
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I still use that from the first time you posted it Dennis, years ago. Its been a great help. So thanks for posting it the first time and again now.
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Old 04-03-2010, 11:08 PM
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The other option is to download CCDCalc from here for free.
http://www.newastro.com/book_new/camera_app.php
It lets you choose all the parameters and displays the field size of your scope camera combination.
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Old 05-03-2010, 09:38 AM
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Quote:
Originally Posted by Dennis View Post
Hi Allan

Here is a nomogram from Sky & Telescope circa 1997.

Cheers

Dennis
Dennis
Thanks for the nomogram and I had forgotten about CCDCalc, Terry.
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