>>4218061A sensor needs to be about twice as large to offer a slightly discernable benefit, and four times as large to offer an immediately noticeable benefit. This rule also applies to megapixel counts. Assuming both cameras are using the same CFA/AA filter arrangement you need to double the megapixels to get a slight improvement and quadruple them to go "wow, ok, it matters".
APS-C is twice as large as micro four thirds, for instance. Full frame is four times as large. Micro four thirds is twice as large as 1", and APS-C is four times that size.
Already, you know FF can be a chore to use and punishing to buy and really get the most out of. $1000-1500 for a camera with at least 36mp, lenses averaging $500, zooms double if they're not trash, GOOD zooms quadruple. The camera weighs 1.5-2lbs, the lenses weigh 0.5-2lbs. Put a sony lens collection next to one for a fuji and you'll see. That's a lot of glass. The best FF bodies are $4k new and the older slightly shittier ones are slowly drifting below $2k used. Yikes, huh? You can buy a canon 90d for nearly $500 if you snipe auctions.
You could say that FF was a mistake and APS-H was good enough.
Now as you pass FF, which the industry has heavily invested in, and which is already expensive as shit, you run into technological and financial challenges due to the state of semiconductor technology and the optics industry. Just make the sensor a little large, stop halfway short of making it twice as big for the more noticeable difference:
Video shits itself (it was already shit on FF past 45mp). AF is suddenly uber shit. Framerates drop back to DSLR levels. If you thought FF lenses were huge and expensive, primes are now on average twice as large and four times more expensive. Zooms have truncated ranges. The camera body is 2lbs+, and $6000+.
Make the sensor ALMOST twice as big. Now behold:
Cameras are pushing into five figures
So are lenses
What AF? What burst rate?
10lb camera+prime lens.
Yikes.
