昨晚拍的M42猎户座大星云，上面是自动增益，下面的手动调至最高，曝光从左至右依次是1、3、5、10、20、30分钟。

凭使用两个月下来的经验，在普通天空下拍比较明亮目标，三五分钟曝光已能把大部份细节拍下，十分钟以上仍有好处，二三十分镜以上增益轻微。

摄于星河科研社新界西基地，Seestar S50加外置Antlia QUAD band滤镜，但不是必须，https://eshop.astro.hk/hk/catalogs/products/9084575a-a826-41d9-a8f3-0f04ef5fd2f3 

Last night, I captured images of the M42 Orion Nebula. At the top, automatic gain is used, and at the bottom, I manually adjusted to the highest setting. The exposure times, from left to right, are 1, 3, 5, 10, 20, and 30 minutes respectively.

Based on my experience from using this setup for 2 months, under ordinary skies and when photographing relatively bright targets, an exposure of three to five minutes already captures most details. Exposures beyond ten minutes still have benefits, but the gain beyond twenty to thirty minutes is minimal.

Taken at Galaxy Scientific Group New Territories West base, by Seestar S50 with an external Antlia QUAD band filter, but the filter is not essential, https://eshop.astro.hk/en/catalogs/products/9084575a-a826-41d9-a8f3-0f04ef5fd2f3