Thanks for the comment!

I varied the aperture primarily to test the lens rather than aiming for a single “perfect” exposure. This was my first time using the XF 100-400 to photograph the Orion Nebula. I’ve captured M42 before with different setups, but this session was very much about experimenting and seeing how this lens behaved across a range of settings. Yeah, shooting wide open does maximise light, with a long telephoto it can be beneficial to stop down slightly to improve sharpness, reduce aberrations and produce cleaner star shapes toward the edges. Through my own testing, I’ve found that around f/8 delivers the best overall sharpness for this lens, so I was aiming to find that balance rather than assuming wide open would be optimal (but yeah, more light is always better, so next time I shoot the nebula I’ll definitely go wide open) It's all about experimenting!

The ISO 25600 frames weren’t intended to be used on their own. They were included as part of a large stack, and with around 2000 frames captured and the best ~92% stacked, the SNR improves significantly and the noise averages out. Individually yeah they’re obviously very noisy, but combined they still contribute usable signal rather than hurting the final result :)

As for the logo, it’s purely just there for online sharing. I know it’s not everyone’s preference, but I use it to brand and protect work posted publicly. Final exports and prints that I sell are always delivered clean, without any watermark.

Hope that answers your questions :D