Panasonic developing two full-frame mirrorless cameras with Leica L-mount

I'm big into Lumix m4/3 and will be strongly considering this as I've had some beautiful shots out of my GF2 and more recently GX1, though that's probably a lot to do with the decent primes I use (20mm and 25mm). I doubt I'll be able to afford the rumoured £2k price tag at the outset but hopefully a year or two down the line. Also hoping there might be some cheap primes offered as there are for other systems - I read somewhere that (for some reason that escapes me now) m4/3 primes require more expensive glass, and my other half was able to get a decent Canon prime for less than half what I paid for my 20mm pancake.

Don't overestimate the value of full frame. Unless you're trying to get a shallower depth of field than you can achieve with your MFT lenses, a full frame camera doesn't offer much inherent advantage.

For example, the Panasonic 42.5mm f/1.7 lens is visually equivalent to a hypothetical 85mm f/3.4 lens on a full frame (35mm) sensor. When I say equivalent, I mean these combinations would have the same practical field of view, the same depth of field, and—this is the part which trips people up—the same overall quantity of photons falling on the sensor area.

Historically, larger sensors have been more efficient at converting said photons into data, but the difference has narrowed greatly to the point where it doesn't matter so much, particularly at the relatively modest resolution of 4K video (approximately 8.3—8.9 megapixels) where the limits of lens diffraction don't tend to come into play.

Of course on full frame systems you can easily find inexpensive 85mm f/1.8 and very high quality f/1.4 lenses. But if you don't use the extra depth of field and you shoot FF at f/3.4 or greater, there was no fundamental benefit. (Of course you should never discount the glass advantage, as the mid-range FF glass tends to be optically superior to high-end MFT glass... but does that benefit apply to a new lens mount? Will these cameras do a good job focusing EF and/or F mount glass?)

Hoping this technology will eventually make its way to a prosumer mini camera like the lx10. I’ve been waiting for 4k60 with some form of built-in stabilization. Sorta wish GoPro would make something along this front given their investment in custom ASICS for hypersmooth - dream of something like a hero 7 with a bigger sensor size to deal with low light.

If you're currently running a GH4, you should be more excited about the GH5S. It's not cheap but this future Pana FF is probably going to be more expensive again.

You get a camera that does everything your GH4 does, but a lot better. The only thing it misses out on compared to the GH5 is sensor stabilisation, which your GH4 doesn't have anyway.

You get the full benefit of all your existing glass. In fact you get more benefit because the effective crop factor of the GH4 in 4K is 2.3, whereas on the GH5S with the multi-aspect sensor it's between 1.8 and 2. It's a bigger sensor both physically and logically.

Whereas a full frame Pana means an expensive body and a new glass collection, with barely any advantage over a GH4/GH5/GH5S with a speed booster.

I bought one (the Sony A73). For me, low-light performance was the big draw vs sticking with a cheaper crop sensor. I'm just a hobbyist photographer, but I kept getting disappointed by things like an indoor family gathering where if I didn't want to use a flash, I had to bump the ISO up to super-grainy and drop the shutter speed lower than what my kid can keep still for.

With the A73 and a nice prime lens, I can go all the way to ISO 6400 with perfectly acceptable noise levels, and thanks to the great dynamic range, bring the shadows up further at my computer. It allows me to capture certain scenes that would be hard to get a "keeper" from at all on a crop.

For well-lit outdoor photography, including sports & wildlife, I agree that the gains over a high-end APS-C are marginal. Even for portraits, the bokeh on a full-frame is going to be better, but it'd probably be fair to call it marginally better.

Full frame is a pretty standard term for 35mm. There is medium format, full frame, crop sensor, micro four thirds, and compact sensors (in decreasing sensor size). You can certainly take great photos with any sensor size. I've enjoyed my m43 setup. The main benefit is you can get a shallower depth of field with a larger sensor. And I suppose for a given resolution a larger sensor will have bigger photoreceptors, which will tend to be less noisy and better in low light.

I'm in the market for m43 and have been reading into some of this. One of the things I get told is that full frame produces 'better looking' images due to differences in focal length. Things like certain bokeh effects that aps-c/m43 cannot achieve, even with wider apertures and zoom lenses.

Also the sensor resolution trick only works on stationary subjects, so probably a no-go for sports photographers.

But I'd love to hear otherwise, as m43 seems a lot more appealing to me, considering cost, weight and size.

It's the size of the pixel that matters, rather than the size of the sensor. Sensors with fewer pixels will perform better than the same sized sensors with more pixels simply because they each have a larger surface area and can capture more light.