Support@Seestar This is a common error in understanding the role of sub-exposure time vs total stacked time when stacking multiple frames.
For a single exposure which will not be stacked with additional exposures, a longer exposure absolutely increases SNR compared to a shorter exposure.
However, when stacking images, either live or in post processing, using longer exposures for the sub-frames does not necessarily improve SNR compared to stacking shorter exposure frames so long as the total stacked time is the same. For instance, stacking 60 x 10sec exposures for a total of 600sec will result in the same SNR as stacking 20 x 30sec exposures with the same total of 600sec in the final image so long as the read noise is the minor source of noise in the images. And with today's extremely low read noise cameras such as the one inside the Seestar this is likely the case, especially if the gain is set low. Light pollution shot noise is likely the dominant source of noise for many, if not most users, this is the case. Dark current shot noise will likely be the dominant source of noise for anyone working at a dark site, not read noise since the Seestar uses an uncooled sensor.
When doing post processing of the collected images longer exposures does have the decided advantage of having fewer frames to run through the post processing software which can greatly speed up the processing time.
