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part 2: comparison of popular astropho image sensors, CMOS

excerpt from excellent blog of Piotr Malinski , planetary cameras and equipment for 2016

and censys3d white paper in longer version

CMOS sensors have advanced tremendously recently, and its quantum efficiency and readout noise is as good as, or even surpass,  CCD sensors.


CMOS is more affordable.

Various manufacturers, especially Sony, has  been launching a vast list of CMOS sensors for low light condition. Their applications in digital cameras, surveillance, and some good for astrophotography too.

They have STARVIS and PREGIUS trademark

  • Starvis is a BSI pixel design optimized for surveillance cameras with improved sensitivity and noise reduction, typical sensitivity of more than 2000mV per 1 μ㎡ (color, F5.6, 1s accumulated conversion), and improved light utilization by including the NIR range.
Pregius is global shutter pixel technology for APS CMOS image sensors that use a low-noise CCD structure, and realizes high picture quality. Good for hi speed photography.

IMX174 is of 1st gen Pregius.

Detailed comparison of ASI120MM (using Aptina MT9M034 sensor) vs ASI174MM (using IMX174 sensor) here

In general, several additional criteria must be considered.

pixel size: 3.45 um or larger preferred. 2.4 um minimum

Amp glow to be well controlled ( unlike CCD, cooling helps) cooling in CMOS does not seem to improve the situation. So normally exposure is kept for a few seconds max, taken several shots with stacking.

early 2015 sensors
entry level CMOS:   3.75 um onsemi MT9M034 sensor(mono) , 3.75um AR0130 (color). However, they may suffer fixed pattern noise ( FPN ) in long exposures, eg in methane band or UV imaging.

high level CMOS: IMX174

late 2015 sensors
entry level: IMX178(color), IMX290(mono)

high end CMOS: IMX224(color), IMX265, IMX250, IMX252

2016 best camera :
entry level CMOS: ASI120, QHY5L-II , Point Grey Blackfly
high end CMOS color: based on IMX224, and maybe IMX290
high end CMOS mono: based on
IMX178, 2.4 um 6.41 MP Starvis

from Qiu HongYun(QHY):

I must say the IMX178 sensor has much lower amp glow than IMX174 and 224. Even without the amp-glow control. I will continuous to find some new way to see if I can remove it .



IMX250  3.45um 5 MP 2nd gen Pregius and IMX252 ( 3.5 MP version )
cost down version : IMX264, 3.45um 5MP 55 fps 2nd gen Pregius   and IMX265 ( 3.2 MP version 35 fps)

From cloudynights forum, Qiu HongYun (QHY) said controversially
 In fact I have compare all these four types. It really hardly to say which is absolutely good not bad. Both of these sensor has its advantage and disadvantages.

          If just compare the mag. I can say in IMX290 I can see mag 9.  The 224 I can almost see mag.9 . And 174(mono) I see mag 9 and 178 I can not see it.

IMX224 press release from Sony



Though diehard astronomers don't care about mV sensitivity, and they only ask read noise, QE and Full well capacity ; )

Pavel Pech's "All you need to know about CCD Cameras, from a practical point of view". Must read

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