Q: Hey my friend I am trying to figure out if it´s worth the extra money to get the 127 or if I´m fine with the 102 version. It´s hard for me to imagine the difference in image quality.
A: I would say the difference in image for planets and the moon will be quite small. The 127 should (on a stable night) take more magnification than the 102, but the 102 is lighter and will cool down faster. So I would ask if you prioritise the need to occasionally go to v high powers vs portability and speed of getting out under the stars. As you may know I’ve long extolled the virtues of the C90. The 127 is better but not that obviously so. The smaller Mak does 90+% of what the 127 can, but it can just about sit on a photo tripod. The 127 definitely won’t .
Update: Since my first post on this topic I’ve bought a 102 Mak in the form of a Skywatcher StarQuest 102MC. There are a couple of videos on this scope on my Youtube channel. This is a lightweight OTA, and one built to a tight budget, which doesn’t include any facility to collimate, unlike the C90 and 127. Having spent longer with my 127 now I can see it gets clearly better results that the 90mm scope on a night with the all important clear seeing, no doubt. There are some results here. My previous advise re portability and mounts remains the same.