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Dont'
be afraid of CCD's
CCD's
performances (III)
This
next table display data of several among the most used CCD cameras. The
Binning mode selected is 2x2 and has a direct effect on the effective pixel size
which is doubled in this case. The scope f/ ratio determining the effective focal
of the telescope it has also a direct influence on the pixel and chip coverage.
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To
help you understanding these laws, here
are two useful formulae :
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Basic
Formulae |
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Sky
coverage by the CCD in arc-minutes :
3438
x CCD size (mm) / focal length (mm)
Resolution
in arc sec/pixel :
206
x pixel size (microns) / focal length (mm) |
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In
summary the smallest is the pixel size and largest is the chip size, the highest
is the potential resolution and the sky coverage (smaller pixel coverage but
larger chip coverage).
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CCD camera |
AP-6 |
AP-7 |
AP-8 |
AP-9 |
HiSis-22 |
Lynxx2000 |
Pictor416 |
Pictor1616 |
MX516c |
MX916 |
ST-4 |
ST-7 |
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Chip
|
KAF-1000 |
SIA502AB |
SIA502AB |
KAF-6300 |
KAF-0400 |
TC-255 |
KAF-0400 |
KAF-1600 |
ICX055CK |
ICX083AL |
TC-211 |
KAF-0400 |
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Chip
size (mm)
|
24.6x24.6 |
12.3x12.3 |
24.6x24.6 |
27.6x18.4 |
6.9x4.6 |
3.2x2.4 |
6.9x4.6 |
13.8x9.2 |
4.9x3.6 |
8.7x6.7 |
2.6x2.6 |
6.9x4.6 |
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Pixels
(Lxl)
|
1024x1024 |
512x512 |
1024x1024 |
3072x2048 |
768x512 |
320x240 |
768x512 |
1536x1024 |
500x290 |
752x582 |
192x165 |
768x512 |
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Pixel
size (m)
|
24x24 |
24x24 |
24x24 |
9x9 |
9x9 |
10x10 |
9x9 |
9x9 |
9.8x12.6 |
11.6x11.6 |
13.75x16 |
9x9 |
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Effective
pixel size (m)
|
48x48 |
48x48 |
48x48 |
18x18 |
18x18 |
20x20 |
18x18 |
18x18 |
19.6x25.2 |
23.2x22.4 |
27.5x32 |
18x18 |
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Pixel
coverage (arc-sec)
|
7.7x7.7 |
7.7x7.7 |
7.7x7.7 |
2.9x2.9 |
2.9x2.9 |
3.2x3.2 |
2.9x2.9 |
2.9x2.9 |
3.2x4.1 |
3.7x3.6 |
4.4x5.2 |
2.9x2.9 |
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Chip
coverage (arc-min)
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61x61 |
33x33 |
61x61 |
74.1x49.4 |
18.5x12.4 |
8.6x6.4 |
18.5x12.4 |
37.1x24.7 |
13.2x9.7 |
23.4x18 |
7x7 |
18.5x12.4 |
Here
are some examples of simulated coverage. At left, the size of Jupiter (0.8 mm) as recorded using a 8" f/10
scope with a 2x Barlow compared to a 35 mm film (grayed background). The small box
represents the resulting
image on a KAF-0400 chip, the larger one on a KAF-6300 chip.
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Jupiter |
Messier
51 |
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At
right the size of M51 galaxy (5.1 mm) as recorded using a 8" f/10 scope with
a 0.63x focal reducer compared to a 35 mm film. Similar comparison.
Of
course each of us would like to use the largest chips equipped with the
smallest pixels. But the price of such devices will rapidely calm your
appetite; such high-end CCD's reach the price level of a large SCT or a
quality aprochromatic refractor, and you haven't your computer yet...
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