tuthdoc wrote:
Planning to begin buying into one of the systems soon. Your thoughts are welcome! I do all kinds of photography however my first love is landscape photography. I have developed neck and back problems so a lighter system is a must for me.
Size matters! For landscape photography, the larger the sensor, the better. The most serious digital landscape shooters use "medium format". However, even the lightest of the bunch, the sole mirrorless medium format model, the Fuji GFX is probably ruled out by size and weight (2 lb/920 grams with the removable electronic viewfinder, 1.6 lb./740 grams without it), it's $6500 price tag, and it's rather limited lens selection (so far). The GFX is 50+MP GFX with a 43.8 x 32.9mm sensor, 1441 sq mm. (Some other medium format digital vary slightly in sensor size and range up to 80MP resolution.)
Second choice would be "full frame" mirrorless.... which only Sony and Leica currently offer, with sensors measuring 24x36mm (864 sq mm) and with as much as 42MP resolution in some models such as Sony's A7R III. (Note: both also offer APS-C models.) Of course, these can be expected to be larger than the smaller sensor models... but you might want to look and compare closely both with what you have now and with the smaller sensor formats. (For example, a full frame Sony a7R III weighs in at 1.445 lb/657 grams, while an APS-C Fujifilm X-T2 weighs 1.15 lb/507 grams.)
Third choice would be "APS-C" mirrorless.... those measure 23.6 x 15.6mm (368 sq mm) and have 24MP resolution in the most recent models: X-T2, etc. ... Fujifilm has the top APS-C system IMO, while Sony's is probably second. But there are also Leica (quite expensive, both camera and lenses) and Canon (limited lens selection so far, though there are some interesting third party lenses being made for them, as well as a lot of adapters for vintage, manual focus rangefinder lenses).
All Olympus use a slightly smaller "micro Four/Thirds" (also "m4/3") format sensor... those measure 17.3 x 13mm (225 sq mm) and have 20MP in most recent models such as their OM-D E-M1 Mark II. Panasonic uses similar and makes cameras and lenses that can be used interchangeably with Oly. Specifically for landscape photography, I'd have to rank the micro 4/3 sensor Oly and Panasonic in fourth place.
Nikon's mirrorless system are about the smallest of all ILC mirrorless, but will likely be discontinued (actually might already be...) and eventually replaced with a larger sensor model (they say maybe full frame... but who knows!). Nikon 1 models use a so-called 1" sensor, that measures 13.8 x 8.8mm (116 sq mm).... the latest models with 21MP resolution. For lanscape photography, I'd have to rank the sensor cameras (and limited lens selection) last place among interchangeable lens mirrorless cameras.
Finally, look into each system's lens selection carefully. Something that's not often talked about with mirrorless is their very short register (also called flange focal distance... i.e the distance between the flange of the lens mount and the sensor plane where the image/film plane needs to be precisely focused), which is a big part of what allows them be smaller and lighter. Today's APS-C and full frame mirrorless digital often use a register between 17mm and 20mm approx. Even the medium format GFX is only about 27mm. Compare that with DSLRs and film SLRs that commonly use between 40mm and 47mm. Medium format film cameras often had roughly 65mm to more than 100mm register. Even the "mirrorless" of yesteryear... rangefinder cameras, were usually around 28 or 29mm.
Very short lens register makes for some wide angle lens design challenges. And since "landscape photography" often equates with "wide angle", it's something to think about and investigate. Good, thorough reviews of specific lenses should tell you more. Pay special attention to distortion (barrel/pincushion), chromatic aberrations, vignetting and resolution fall off toward the edges and corners of images.
BTW... I used to have back, neck and shoulder problems. I switched to backpacks instead of shoulder bags and upgraded to better quality camera straps such as OpTech... and have a lot less problem. Yeah, I'm still pretty sore and popping some ibuprofen at the end of a 12 hour session... but it's a lot better than it used to be! Plus, as much as I love "big glass", I'm seriously considering replacing 24-70/2.8 with a 24-70/4 and 16-35/2.8 with a 16-35/4! The "slower" lenses are not only smaller and lighter, they're also image stabilized (in the system I use, the f/2.8 lenses aren't) AND less expensive AND sometimes even have better sharpness from corner to corner AND are closer focusing! Higher usable ISO cameras are also making "slower" lenses more viable.