Final Test of the ASI2600

M63 - Comparison ASI2600 vs. ASI1600

As a final test of the ASI2600 I decided to compare the results I obtained imaging M63, the Sunflower galaxy using the ASI2600 with the same object using the ASI1600.  Both images had pretty much the same number of subs, all taken with 60sec exposures. Each was calibrated and processed using the same workflow. 

First, a comparison of the field of view (FOV) of each camera. Note that both images were cropped a bit during postprocessing as needed to account for slight shifting of the masters among the multiple filters and to eliminate vignetting at the corners. As reported in my previous post, I was pleased that the vignetting due to the use of 31mm filters was minimal. The ASI2600 has a wider FOV, mainly in the long axis. The images below are not exactly to scale; the ASI1600 had more cropping than the ASI2600, so the change in FOV is a little bit exaggerated. The actual sensor sizes are:

ASI1600:  4656x3520
ASI2600:  6248x4176

Next, with some cropping of the ASI2600 image to bring the scale of each closer to 1:1 we can examine each for actual image details. Please note that the sky conditions were not completely identical in each session and so there may be some differences due to quality of subs, not the actual difference in the sensors.

However, some of the 'promised' improvements in the ASI2600 over the ASI1600 can be seen. First, the artifacts due to the microlens light scattering in the ASI1600 are completely gone in the ASI2600 (see bright star just to the right and above the galaxy). Second, the overall brightness of the galaxy is greater in the ASI2600, likely due to the greater quantum efficiency of the 2600 over the 1600 (91% vs. 60%).

In addition, but not obvious in these quick comparisons, is the much lower noise in the ASI2600. Dark frames were consistently measured as 500ADU, across all typical durations (30sec - 1200sec)! And, the total absence of any amp glow makes post-processing even easier.

One thing that is noticeable in the 2600 image is the size of the stars - they are bigger than the ones in the 1600 image. This might be due to slightly different post-processing. Another contributing factor may be the lower full well capacity of the ASI2600 at gain of 100.

Overall, I am very pleased with the performance of this new camera.