That (Sony 135mm f\1.8 lens) is a nice lens but, as you note, the range is sort of a “tweener”. But with that IQ, you can always stand a crop.
Like you, I’m still sitting on a collection of A mounts but will probably die with them leaving my heirs to wonder what the devil they’re gonna do with these.
My most expensive lens is an E mount, 24-70, f2.8, GM. I forgot the cost but it was in the low 2,000’s. I rarely use it because it is big and heavy. It is capable of stellar results but almost all the really good results were with my now gone A7R2 body with the 46 mp sensor. My current A7IV, almost always wears a Sony G series, 24-105, f4.0. It has a more usable range, I rarely need f 2.8, weighs half, costs half, and if there’s a difference in IQ (image quality), I’ve yet to discern it.
The main reason f2.8 (or lower) was needed was to gather more light or to increase bokah. These new cameras are astonishing in their low light performance. I limit my ISO to 12,800 but constantly come up with images at that ISO that need no “noise” reduction and are usable as shot. My old A850 (like yours) was getting to be unusable at an ISO of 1600.
Anything around 2400 and forget it. That’s why I am perfectly fine with f4.
Below is a photo that I think I recently posted here, it was shot at 12,800 and has had no noise reduction. It is perfectly clear but if you look at the blurred background, you can barely make out the beginnings of noise. I don’t need 2.8, this camera will almost shoot in the dark. This lens is the 24-104; read the reviews, it’s an incredible lens.
