Calibrating a CMOS - ZWO 1600mm with Pixinslight

I've been using my ASI1600MM for last month or so, along with the PixInsight BatchPreProcessing script.

I've read multiple posts to try to understand what should be the proper settings, and at this stage my conclusions are:


1- All exposures should be longer than 0.2 seconds, as the sensor is not consistent under that.
2- Take light frames as usual, at lowest temperature reasonable (-15C for me these days), with proper gain and offset (gain 200 and offset 50 for me, as I do narrowband), and for me exposures are determined using help from the tables in this post.
3- Take matching dark frames: same length, same gain, same offset, same everything as the lights.
4- Take flat frames: adjust gain as needed so that exposures of over 0.2s are achieved, giving a SGP ADU readout of around 12,000-16,000
5- Take dark flat frames: same gain and offset as the flat frames, and same length. For me, this means one set of dark flats per filter.
6- No bias frames
7- In BPP, put Dark Frames in Darks, Dark Flat frames in Darks, nothing in Bias, Lights in Lights, Flats in Flats. Dark Optimization set to OFF. What I understand this does is:
    a. Create a master dark of same length as light frames
    b. Create a master dark flat of same length as flat frames, for each filter
    c. Flat frames for each filter are calibrated with the master dark flat that corresponds to the length of each filters' flat exposure
    d. Flat frames for each filter are calibrated into a master Flat
    e. Light frames are calibrated with Master Dark (from step a.) and Master Flat (for each filter)
    f.  Light frames are star aligned/registered
    g. Light frames are integrated into a Master Light
8- If needed, manually perform a drizzle or Local Normalization integration


For flats I am using a technique using the daylight instead of a light panel, tests have proven that the quality is much better then a light panel, and its easy to do.

Cover the telescope, Filter Wheel and camera to avoid light penetration to the sensor.

You need tin  paper, tee-shirt and an elastic band

In SGP I set the ADU level to 25000 with 1000 tolerance.

First CMOS Camera

Modern CMOS Sensors Are Often Superior to CCD Sensors

CMOS sensors have undergone significant upgrades in recent years, in many cases surpassing CCD sensors. Their high speeds (frame rate) and resolution (number of pixels), their low power consumption and, most recently, their improved noise characteristics, quantum efficiency, and color concepts have opened them up to applications previously reserved for CCD sensors.

The improvements to CMOS technology and the strong price/performance ratio in these sensors make CMOS sensors increasingly attractive for industrial machine vision. In particular, the very high frame rates that can be achieved, almost without any compromise in image quality, are one of the primary hallmarks of the current generation of CMOS.

CMOS development over taking CCD

  1. High speeds (frame rates)
  2. High resolution (number of pixels)
  3. Strong dynamic performance
  4. Low power consumption
  5. Improved noise performance
  6. Improved quantum efficiency
  7. Improved color concepts
  8. Good price/performance ratio
What is a CMOS sensor?

There are two types of image sensors for industrial cameras on the market: CCD and CMOS sensor. The right sensor for any given job is a case-by-case question. At the same time, the trend seems to be toward CMOS sensor technology as the wave of the future. This should come as no surprise, as CMOS sensors have made major strides in recent years in two important parameters for area and line scan cameras, namely image rate and noise level. Since the beginning of 2015, it has become official that CMOS technology will be the future technology.

My New CMOS Camera


One beautiful thing about the 1600MM pro is it's huge size chip. The MN34230 CMOS sensor comes with a resolution of 4565*3520 and has a 3.8um pixel size, which makes it a great camera for imaging widefield objects with my 105MM refractor. Another important reason for me to buy this camera is that it also contains DDR3 256MB memory, which should help to improve data transfer reliability and minimize amp glow caused by a slow transfer speed when using a USB 2.0 port on your laptop or computer to connect the camera. Moreover, the camera has a low read noise of 1.2e.

Testing noise and ampglow levels

You can guess that the first thing i did was taking some dark frames and checking the amount of noise and amp glow at various shuttertimes, while cooling the camera at -25 degrees celcius (77 degrees fahrenheit) at unity gain (139) setting. I went as far as 5 minute (300s) frames.