Last week Sony released their latest full frame mirrorless camera, the a7 Mk iii, not to be confused with the a7r Mk iii. That little "r" after the "7" makes a big difference.
The a7 iii is a 24MP full frame camera, whereas the a7r iii is 42MP. The price difference between the two is also big. For the body only, the a7 iii is likely to be very close to $3,000 when it becomes available in Australia, while the a7r iii is a shade under $5,000. Basically you are paying $2,000 for those extra 18MP on the sensor.
While there is no way I could justify the $5,000 for the full frame a7r iii body, at around $3,000 I might be able to talk myself into the a7 iii.
If I finally, after all these years, went full frame then the total cost is going to be in the order of $5,000 because after the $3,000 for the a7 iii I would then need to buy a full frame lens. The Sony lenses I currently have are half frame lenses. While you can use a half frame lens on a full frame camera, you obviously don't get to use the full size of the sensor when taking pictures. Depending on the particular lens you only get about 60 percent sensor coverage, which would relate to about 14MP on a 24MP full frame sensor.
The question becomes, is 24MP enough?
There are presumed upsides to the lower MP rating of the sensor. In theory, it should be better in low light, thereby exhibiting less digital noise. Also, in theory, the dynamic range should be better on the lower MP camera. Finally, due to the larger sensor sites, the colour and vibrance should be better—although modern post-processing tools make this a non-issue.
However, the view is that the higher resolution a7r iii is better for landscape pictures, which is a lot of what I do. 42MP would obviously also be better for making large prints. But then, I rarely do large prints and these days tools like ON1—which I have—can do amazing enlargements with relatively low loss of quality. Finally, having 42MP to play with, you have a lot of latitude for cropping down. But being an ex-film photographer, most of my pictures are well framed and typically only nominal amounts of cropping is ever done in post processing.
The a7 iii should become available in Australian stores in early April. So I have some time to cogitate about it.