SBIG ST-7XE - Page 50

Section 4 – Camera Hardware
Page 48
In addition to the system level differences between the various cameras, Table 4.3 below
quantifies the differences between different CCDs used in the cameras:
Camera CCD Used Number of
Pixels
Pixel
Dimensions
Array
Dimension
Read
Noise
Full Well
Capacity
TC211 Tracking CCD TC-211 192 x 164 13.75 x 16 µ 2.6 x 2.6 mm
12e
-
rms 150Ke
-
TC237 Tracking CCD TC-237 657 x 495 7.4 x 7.4 µ 4.9 x 3.7 mm 12e- rms 20Ke-
ST-5C TC-255 320 x 240 10 x 10 µ 3.2 x 2.4 mm
20e
-
rms 50Ke
-
ST-237A TC-237 657 x 495 7.4 x 7.4 µ 4.9x 3.7 mm
15e
-
rms 20Ke
-
STV TC-237 320 x 200 14.8 x 14.8 µ 4.7 x 3.0 mm
17e
-
rms
20Ke-
ST-7XE KAF0401E 765 x 510 9 x 9 µ 6.9 x 4.6 mm 15e- rms
50/100Ke
-3
ST-8XE KAF1602E 1530 x 1020 9 x 9 µ 13.8 x 9.2 mm 15e- rms
50/100Ke
-4
ST-9XE KAF0261E 512 x 512 20 x 20 µ 10.2 x 10.2 mm 13e- rms 180Ke-
ST-10XE, XME KAF3200E 2184 x 1472 6.8 x 6.8 µ 14.9 x 10.0 mm 11e- rms 77Ke-
ST-1001E KAF1001E 1024 x 1024 24 x 24 µ 24.6 x 24.6 mm 16e- rms 180Ke-
ST-2000XM KAI2000M 1600 x 1200 7.4 x 7.4 µ 11.8 x 9.0 mm 15e- rms 45Ke-
Table 4.3- CCD Differences
How these various specifications affect the average user is described in the following
paragraphs:
Number of Pixels - The number of pixels in the CCD affects the resolution of the final images.
The highest resolution device is best but it does not come without cost. Larger
CCDs cost more money and drive the system costs up. They are harder to cool,
require more memory to store images, take longer to readout, etc. With typical
PC and Macintosh computer graphics resolutions, the CCDs used in the SBIG
cameras offer a good trade off between cost and resolution, matching the
computer's capabilities well.
Pixel Dimensions - The size of the individual pixels themselves really plays into the user's
selection of the system focal length. Smaller pixels and smaller CCDs require
shorter focal length telescopes to give the same field of view that larger CCDs
have with longer focal length telescopes. Smaller pixels can give images with
higher spatial resolution up to a point. When the pixel dimensions (in
arcseconds of field of view) get smaller than roughly half the seeing, decreasing
the pixel size is essentially throwing away resolution. Another aspect of small
pixels is that they have smaller full well capacities.
For your reference, if you want to determine the field of view for a pixel
or entire CCD sensor you can use the following formula:
Field of view (arcseconds) =
8.12x size (µm)
focal length (inches)
Field of view (arcseconds) =
20.6x size(um)
focal length(cm)
3
The Kodak CCDs (KAF0400 and KAF1600) are available with or without Antiblooming Protection.
Units with the Antiblooming Protection have one-half the full well capacity of the units without it.