K3's AstroPhotography
"When I consider your heavens, the work of your fingers, the moon and the stars which You have set in place, what is Man that You are mindful of him?" -- Psalm 8:3,4

Comparison Table for SONY CCD Chips

As more types of modifications of webcams occured in the world I have decided to collect information from various SONY datasheets and place it into one place. The main goal is to compare the sensitivity of various chips and also create some comparison table with unified criteria - not all catalog measurements were done in the same conditions.
Original SONY CCD chip datasheets can be downloaded directly from SONY website.

According to SONY datasheets the sensitivity of CCD chip is defined as voltage of signal output at the center of screen when exactly defined light conditions are kept. The voltage value listed in datasheet is not directly measured value, but recalculated value from measured value for specific defined exposure time.
This sensitivity parameter tells nothing about signal to noise ratio of the output signal. Unfortunately S/N ratio of the chips is not defined in the datasheets. Also there are many other parameters which are important for overall image quality.

Before doing any conclusions from the following tables and graphs, please, read all the text carefully.
All tables and graphs are based on datasheets values with defined conditions.
The article doesn't tell, that CCD chip with the highest sensitivity value must be automatically the best choise for astro imaging.

The tables also include saturation parameter, which defines the upper limit of dynamic range.


1, Catalog parameters

The first table shows data in a form as it is provided by company datasheets:

Chip name Type Diagonal Pixel size
(H) x (V)
Effective
pixels
Minimal
sensitivity
(1
Typical
sensitivity
(1
Measurement
conditions
(2
Saturation
typ.
Used in webcams or cameras
ICX098AK Color 4.5mm
(Type 1/4)
5.6m x 5.6m 659x494 350 mV 440 mV 706cd/m2, F5.6 500 mV Philips:
Vesta 675, Vesta Pro (PCVC680K)
ICX098BQ Color 4.5mm
(Type 1/4)
5.6m x 5.6m 659x494 460 mV 580 mV 706cd/m2, F5.6 500 mV  
ICX098AL B/W 4.5mm
(Type 1/4)
5.6m x 5.6m 659x494 440 mV 550 mV 706cd/m2, F8 500 mV  
ICX098BL B/W 4.5mm
(Type 1/4)
5.6m x 5.6m 659x494 560 mV 700 mV 706cd/m2, F8 500 mV  
ICX424AQ Color 6mm
(Type 1/3)
7.4m x 7.4m 659x494 600 mV 750 mV 706cd/m2, F5.6 500 mV SC3 modified cameras,
look at Steve Chambers website
ICX424AL B/W 6mm
(Type 1/3)
7.4m x 7.4m 659x494 700 mV 880 mV 706cd/m2, F8 500 mV SC3 modified cameras,
look at Steve Chambers website
ICX414AQ Color 8mm
(Type 1/2)
9.9m x 9.9m 659x494 670 mV 840 mV 706cd/m2, F5.6 500 mV  
ICX414AL B/W 8mm
(Type 1/2)
9.9m x 9.9m 659x494 700 mV 880 mV 706cd/m2, F8 500 mV  
ICX254AL B/W 6mm
(Type 1/3)
9.6m x 7.5m 510x492 1300 mV (3 1600 mV (3 706cd/m2, F8 1000 mV SAC8
(based on JG modifiication)
ICX255AL B/W 6mm
(Type 1/3)
9.8m x 6.3m 500x582 1300 mV (3 1600 mV (3 706cd/m2, F8 1000 mV 1004X JG modified cameras,
look at Jon Grove website
ICX409AL B/W 6mm
(Type 1/3)
6.5m x 6.25m 752x582 680 mV (3 850 mV (3 706cd/m2, F8 1000 mV Astromeccanica KC381

(1 Sensitivity measurement
The sensitivity of color CCD chips is measured for G (green) signal

(2 Measurement conditions
Use a pattern box (luminance 706cd/m2, color temperature of 3200K halogen source) as a subject. (Pattern for evaluation is not applicable.) Use a testing standard lens with CM500S (t = 1.0mm) as an IR cut filter and image at F5.6 or F8. The luminous intensity to the sensor receiving surface at this point is defined as the standard sensitivity testing luminous intensity.
The value of signal is recalculated to nominal 1/30s exposure (i.e. if exposure during measurement was 1/100s, then the voltage value is multiplied by 100 and then divided by 30).

(3 Sensitivity measurement
The value of signal is recalculated to nominal 1/50s exposure (i.e. if exposure during measurement was 1/100s, then the voltage value is multiplied by 100 and then divided by 50).

As we can see, the chips were measured in the same light conditions, but color chips were measured with larger relative aperture (F5.6).



2, Parameters recalculated for the same objective lens (F8)

The next table shows the same data recalculated to the same measurement conditions - all with F8:

Chip name Type Diagonal Pixel size
(H) x (V)
Effective
pixels
Minimal
sensitivity
(1
Typical
sensitivity
(1
Measurement
conditions
(2
Saturation
typ.
Used in webcams
ICX098AK Color 4.5mm
(Type 1/4)
5.6m x 5.6m 659x494 171.5 mV 215.6 mV 706cd/m2, F8 500 mV Philips:
Vesta 675, Vesta Pro (PCVC680K)
ICX098BQ Color 4.5mm
(Type 1/4)
5.6m x 5.6m 659x494 225.4 mV 284.2 mV 706cd/m2, F8 500 mV  
ICX098AL B/W 4.5mm
(Type 1/4)
5.6m x 5.6m 659x494 440 mV 550 mV 706cd/m2, F8 500 mV  
ICX098BL B/W 4.5mm
(Type 1/4)
5.6m x 5.6m 659x494 560 mV 700 mV 706cd/m2, F8 500 mV  
ICX424AQ Color 6mm
(Type 1/3)
7.4m x 7.4m 659x494 294 mV 367.5 mV 706cd/m2, F8 500 mV SC3 modified cameras,
look at Steve Chambers website
ICX424AL B/W 6mm
(Type 1/3)
7.4m x 7.4m 659x494 700 mV 880 mV 706cd/m2, F8 500 mV SC3 modified cameras,
look at Steve Chambers website
ICX414AQ Color 8mm
(Type 1/2)
9.9m x 9.9m 659x494 328.3 mV 411.6 mV 706cd/m2, F8 500 mV  
ICX414AL B/W 8mm
(Type 1/2)
9.9m x 9.9m 659x494 700 mV 880 mV 706cd/m2, F8 500 mV  
ICX254AL B/W 6mm
(Type 1/3)
9.6m x 7.5m 510x492 2167 mV 2667 mV 706cd/m2, F8 1000 mV SAC8
(based on JG modifiication)
ICX255AL B/W 6mm
(Type 1/3)
9.8m x 6.3m 500x582 2167 mV 2667 mV 706cd/m2, F8 1000 mV 1004X JG modified cameras,
look at Jon Grove website
ICX409AL B/W 6mm
(Type 1/3)
6.5m x 6.25m 752x582 1133 mV 1417 mV 706cd/m2, F8 1000 mV Astromeccanica KC381

Note - sensitivity of ICX254AL, ICX255AL and ICX409AL chips was recalculated to 1/30s exposure.

Now we can see noticable higher sensitivity of B/W CCD chips.



3, Parameters recalculated to the same object pixel size

As ICX424 chips have larger pixel size, for the same object size (in pixels) higher focal length must be used. For the same scope (objective lens/primary mirror) it means, that bightness of object will be descreased (by the other words - the F ratio will be changed).

The next table compares sensitivities for the same object size:

Chip name Type Diagonal Pixel size
(H) x (V)
Effective
pixels
Minimal
sensitivity
(1
Typical
sensitivity
(1
Measurement
conditions
(2
Saturation
typ.
Used in webcams
ICX098AK Color 4.5mm
(Type 1/4)
5.6m x 5.6m 659x494 171.5 mV 215.6 mV 706cd/m2, F8 500 mV Philips:
Vesta 675, Vesta Pro (PCVC680K)
ICX098BQ Color 4.5mm
(Type 1/4)
5.6m x 5.6m 659x494 225.4 mV 284.2 mV 706cd/m2, F8 500 mV  
ICX098AL B/W 4.5mm
(Type 1/4)
5.6m x 5.6m 659x494 440 mV 550 mV 706cd/m2, F8 500 mV  
ICX098BL B/W 4.5mm
(Type 1/4)
5.6m x 5.6m 659x494 560 mV 700 mV 706cd/m2, F8 500 mV  
ICX424AQ Color 6mm
(Type 1/3)
7.4m x 7.4m 659x494 168.4 mV 210.5 mV 706cd/m2, F10.6 500 mV SC3 modified cameras,
look at Steve Chambers website
ICX424AL B/W 6mm
(Type 1/3)
7.4m x 7.4m 659x494 400.9 mV 504 mV 706cd/m2, F10.6 500 mV SC3 modified cameras,
look at Steve Chambers website
ICX414AQ Color 8mm
(Type 1/2)
9.9m x 9.9m 659x494 105 mV 131.7 mV 706cd/m2, F14.1 500 mV  
ICX414AL B/W 8mm
(Type 1/2)
9.9m x 9.9m 659x494 224 mV 281.6 mV 706cd/m2, F14.1 500 mV  
ICX254AL B/W 6mm
(Type 1/3)
9.6m x 7.5m 510x492 737 mV (4 907 mV (4 706cd/m2, F8 1000 mV SAC8
(based on JG modifiication)
ICX255AL B/W 6mm
(Type 1/3)
9.8m x 6.3m 500x582 707 mV (4 871 mV (4 706cd/m2, F14 1000 mV 1004X JG modified cameras,
look at Jon Grove website
ICX409AL B/W 6mm
(Type 1/3)
6.5m x 6.25m 752x582 841 mV (4 1052 mV (4 706cd/m2, F9.3 1000 mV Astromeccanica KC381

(4 Sensitivity recalculation
Because of not square pixels, the sensitivity value was recalculated for getting the same pixel resolution in horizontal direction and even higher vertical resolution as it would be in case of
5.6m x 5.6m chip.

The following graph shows the chip sensitivities from the above table (the higher values are better):

As we can see, the most sensitive chip for the same object pixel size is ICX255AL chip used in surveillance cameras. In webcam category the most sensitive is ICX098BL.



4, Comparison table for exposure times needed for the same object brightness and pixel size

The following table compares exposure times of the chips for achieving the same object size and brightness.
As a base for comparison was selected ICX098AK chip and exposure time 100s.
The values are calculated according to typical sensitivity values (linear CCD characteristic is assumed).

Chip name Type Exposure
time

The shorter times are better
ICX098AK Color 100 s
ICX098BQ Color 76 s
ICX098AL B/W 39 s
ICX098BL B/W 31 s
ICX424AQ Color 102 s
ICX424AL B/W 43 s
ICX255AL B/W 24.5 s
ICX409AL B/W 20.5s



4, Conclusion

The aim of the comparisons was to compare various chips for achieving the same image size and brightness.
Although ICX424 chips offer higher sensitivity catalog values than ICX098 line, for the same object size the longer exposures are required.
The most sensitive is ICX409AL chip. The only pitty is, that Astromeccanica's KC381 camera is not able to do long exposures (it's planetary camera).

However the image quality is affected not only by sensitivity, but also by signal to noise ratio, dark current and dark shading. The backgrounds from the newer SONY CCDs are very uniform, making small signals easier to pick out.

Back to Astro Photography page


Computer generated images, real images, drawings and texts are property of the author and may not be reproduced or used without permission of author.


Home

Last Update: 14.09.2005