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Old 17-11-2013, 09:17 PM
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Shiraz (Ray)
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icx694 some measured performance info

Hi

Just completed measuring some aspects of the performance of the icx694. The following should be treated with some caution, since the measurement techniques were not ultra-precise - however, the results are generally consistent with other other published data and quite good enough to be used for designing future systems based on this and related cameras.

1. binning: 2x2 binning provides 4x the signal and only a 20% increase over the 1x1 read noise. Thus, the camera very nearly provides the full theoretical advantage to be gained from hardware binning.

2. linearity. in both 1x1 and 2x2 bin modes, the linear range (within measurement accuracy) extends to beyond 55000 ADU. ie, almost the whole signal range is linear, which was a surprise considering that this is an ABG chip. The measurements were taken with an incandescent lamp source, which could have varied in output, but the results were consistent when repeated. This chip could probably be considered for serious photometry.

3. read noise is about 5.4 electrons RMS at 1x1 and 6.45 electrons at 2x2.

4. if my determination of internal gain is somewhere near the mark, the well depth is 19200 electrons at saturation and 16800 at the top of the linear range, so the linear dynamic range is a very useful 70dB.

5. overload. the anti-blooming gates (ABG) appear to work effectively in both binning modes. There is no sign of either vertical or horizontal blooming until the ABG circuits overload - this happens only in extreme over-exposures on very bright stars and produces the standard vertical line beloved of NABG owners. The maker claims an 800x margin before the overload mechanism is swamped and this appears to be reasonable - didn't measure it though. As a practical observation, I have not seen blooming in any light images taken since I got the camera, although it can show up when imaging mount-alignment stars.

6. dark current was roughly measured at ~0.003 electrons/pixel/sec at -15C

7. Residual Bulk Image (RBI) - none observed under any testing

8. fixed pattern noise factor (due to variability in pixel response) was measured roughly to be about 0.004 - ie it is inconsequential for imaging.

thanks for reading - hope it was of some use. regards ray

Last edited by Shiraz; 18-11-2013 at 09:49 PM.
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Old 18-11-2013, 01:24 PM
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Interesting results, Ray. Have you thought about doing a full PTC for the camera?
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Old 18-11-2013, 01:52 PM
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Shiraz (Ray)
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Hi Rick. I though about a PTC, but decided that it wouldn't really tell me anything new, so I don't plan on doing one for now - maybe next time I get clouded out for 6 weeks.
The testing was very interesting and I came away with great respect for the design team. Looks like they pushed every aspect of the design to the limits to get the last ounces of performance and ended up with a really remarkable chip in every respect. Even just looking at it is interesting - no shiny interference pattern - this thing is a flat dull grey/green colour as it sucks in almost every photon that falls on it. Regards Ray

Last edited by Shiraz; 19-11-2013 at 06:50 AM.
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Old 18-11-2013, 03:56 PM
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There won't be any RBI as its an interline sensor. Full frame (Kodak KAF sensors) have RBI in varying degrees.

Greg.
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