QHYCCD QHY600M-PH/SBFL+CFW3L

QHY600 Series have mutiple models which covers both photographic and scientific using. Below list different types of QHY600 PH (photographic) series:

QHY600PH : Standard version for amateur astrographers;

QHY600PH SBFL : it has shorter back focal length compared with other PH types;

QHY600PH L : a Lite, shorter and cheaper version.

Equipped with a Sony IMX455, the QHY600 is a back-illuminated Scientific CMOS Camera with extremely low dark current (0.002e/p/s@-20C) using SONY’s Exmor BSI CMOS technology. QHY600 is also a zero amplifer glow camera.

The QHY600 has only one electron of read noise at high gain and full resolution and 4FPS readout speed.  One electron of read noise means the camera can achieve a SNR>3 at only 4 to 6 photons. This is perfect performance when conditions are photon limited, i.e., short exposures, narrow band imaging, etc., making this large area sensor ideal for sky surveys, time domain astronomy, fluorescence imaging, DNA sequencing and microscopy.

2GB DDR3 image buffer

In order to provide smooth uninterrupted data transfer of the entire 60MP sensor at high speed, the QHY600 has 2GB DDR3 image buffer. The pixel count of the latest generation of CMOS sensors is very high resulting in greater memory requirements for temporary and permanent storage.  For example, the QHY600 sensor produces about 120MB of data per frame.  The data band-width is also increased from the original 16-bits to the current 32-bits.  Transferring such a large file sizes necessarily requires the camera to have sufficient memory. The QHY600 has adopted a large-capacity memory of up to 2GB.  Data throughput is doubled. This large image buffer meets the needs of high-speed image acquisition and transmission of the new generation of CMOS, making shooting of multiple frames smoother and less stuttered, further reducing the pressure on the computer CPU.

Another advantage is that when using some computers that do not have fast processors or have poor support for USB 3.0, the computer can’t transfer high-speed data well, and the data is often lost. The DDR can buffer a lot of image data and send it to the computer. Even if the USB 3.0 transmission frequently gets suspended, it will ensure that data is not lost. There are options in SharpCap to turn DDR buffering on or off. The current version of the ASCOM driver works in DDR mode.

Extended Full Well Capacity and Multiple Read Modes

With a pixel size of 3.76um, these sensors already have an impressive full well capacity of 51ke.  Nevertheless, QHYCCD has implemented a unique approach to achieve a full well capacity higher than 51ke- through innovative user controllable read mode settings.  In extended full well readout mode, the QHY600 can achieve an extremely large full-well charge value of nearly 80ke- and the QHY268C can achieve nearly 75ke-.  Greater full-well capacity provides greater dynamic range and large variations in magnitude of brightness are less likely to saturate.  The QHY600 / 268C have three readout modes with different characteristics.

Multiple Readout Modes is a new function for newer QHY Cameras.  Different readout modes have different driver timing, etc., and result in different performance. The QHY600 currently has four readout modes, and more modes will be added in the future. These readout modes are currently supported in the QHY ASCOM Camera Driver, SharpCAP software and the N.I.N.A software.

QHY600 Performance Curves in Readout Mode #0 (Photographic Mode). In this mode there is a drop in the noise between Gain 25 and Gain 26.  We recommend setting the Gain to 26 to begin.  At this setting the full well is 27ke- and readout noise is 2.7e-.  For every long exposures you can lower the gain from this point to increase the full well capacity.

QHY600 Performance Curves in Readout Mode #1 (High Gain Mode).  Please note there is a HGC/LGC switch point at gain55 to gain56. Gain0-55 uses LGC and Gain55-100 uses HGC.

QHY600 Performance Curves in Readout Mode #2 (Super Fullwell Mode).

Now QHY600 adds #3 mode Extend Fullwell 2CMSIT (yellow curve). The advantage of this mode is that it has the same full well value and system gain as the #2 mode Extend Fullwell, but the read noise is reduced by about 1.3 times.

This function needs to be used with 2020.6.26 or newer SDK. If your software cannot display this mode, please download the QHYAllInOne installation package to update the SDK in the software.

QHY600 PH

QHY600PH-SBFL

QHY600PH-L

The QHY600 can output the whole active area of the sensor, including the optically black pixels and the overscan area. The total image size including the optically black area area is 9600 x 6422 pixels. The optically black area is on the left of the image and the overscan area is on bottom of the image.

The difference of optically black area and overscan area is that the optically black area includes the dark current during a long exposure while the overscan area does not include the dark current during an exposure.

Neither the optically black area nor the overscan area respond to light, so they are regarded as the “non-effective” area of the sensor.

In the bottom of the overscan area you may find some vertical series of dots in single frame that can become vertical lines after stacking. One of the reasons for this is that the FPN calibration results represented in the overscan area can’t be found in the effective image area.

The following picture is the left bottom corner of a 300 second dark image. You can see these dots in the overscan area. The optically black level area and overscan area are usually used for precise calibration of an image and for calibration of an image without using a bias frame or dark frame, or for some scientific applications.  Because the optically black and overscan areas are not part of the effective image area, QHYCCD does not guarantee the signal quality in these areas.  If you do not use these areas, you can select the option “Ignore overscan area” in the ASCOM driver or select a ROI of effective area in SharpCAP.