I am unclear about what the effect is of different size sensors and am hoping someone can explain it to me. I own two cameras - Sony a7r2 with which I use Sony G and G master lenses and the Sony Rx10 miv which has a fixed 24-600 Zeiss lens. The A7r2 has a ff sensor and produces a file size of 42mb in ff mode and a 20mb file in APS-C mode. The rx10 has a one-inch sensor and produces a 20mb file. So, comparing the a7r2 in APS-C mode to the RX10 what difference would the sensor make? I don’t see a difference, but I haven’t tried printing any of the images in huge sizes

I am unclear about what the effect is of different size sensors and am hoping someone can explain it to me. I own two cameras - Sony a7r2 with which I use Sony G and G master lenses and the Sony Rx10 miv which has a fixed 24-600 Zeiss lens. The A7r2 has a ff sensor and produces a file size of 42mb in ff mode and a 20mb file in APS-C mode. The rx10 has a one-inch sensor and produces a 20mb file. So, comparing the a7r2 in APS-C mode to the RX10 what difference would the sensor make? I don’t see a difference, but I haven’t tried printing any of the images in huge sizes

I hope that I am not adding to the confusion, but the physical dimensions of the sensor are a strong influence on image quality but not determinative.

The pixel density (pixels per square mm) or, more importantly, its reciprocal (pixel size in microns) is determinative within the constraints of the manufacturer's technology. The optimal pixel size with current technology is still roughly between 4 and 6 microns. Since almost all the sensors are using the same light-sensitive chemistry, there is no giant difference that would change this simple truth.

The A7R2 has a pixel size of 4.5 microns. The RX10 m3 or m4 has a pixel size of 2.4 microns. Since they are both Sony's new or newest sensor technology, the A7R2 has considerably better dynamic range and image quality overall. Dynamic range is largely a function of pixel size (more size=more range) but the explanation is TMI for this response.

The second feature, (again, influenced by but not strictly controlled by physical dimensions) is pixels horizontal and vertical which does determine the total mega pixels. The A7R2 and A7R3 have 7952 x 5304 pixels. The RX10 m3 or m4 have 5472 x 3648. You didn't mention the crop frame a6xxx series, but they are in between on both pixel size and dimensions at 6000 x 4000.

Ignoring sharpness, if you have more pixels then you can make a bigger print at the same DPI (dots per inch) which for prints up to perhaps 11x14 or even 16x20 would usually be 300 DPI but that is not a hard/fast rule. So if all else were equal, the A7R2 could make a bigger print and in most cases, lens dependent, a somewhat better one.

Example: 7952/300 = 26.5 inches. 5472/300= 18.2 inches. The way I'm equating pixels in the image file to dots per inch in the print has its critics but I think it is a practical, simple way to look at it. The use of 300 DPI is very flexible, of course. In fact, although you will usually not see commercial printers use a higher number, some will use a lower number and without it being noticed. BUT if you make a smaller print than those sizes they are down-sampling which simply means combining pixels via some program's logic. That can mean that if you make a 4x6 print or a 5x7 print, just for example, you have even less difference between the cameras' final product. Something similar happens when you look at them on a 1920x1200 screen; the picture is compressed to fit.

There are other Sony full frame camera with larger pixels and thus fewer megapixels which are thought of as better for low light. Bigger pixels are better for low light.

This is not a slam on the RX10m3 or m4. I had the m3 and now have the m4. They are excellent cameras and the RX10 is my go-to camera more often than the a6500. I have used the A7R2 and some of my highest quality pictures came from it. But I found it too heavy, etc.

The poster who pointed out that the RX10m3 or m4 is actually a 220 mm maximum length lens is correct but it has the same angle of view as an A7R2 with a 600 mm lens.

Now, one more thing. The A7R2 can allow more and better cropping and that can be an important aspect of wildlife and other kinds of photography when your lens just wasn't long enough.

BTW - I did not include file size in this because it is not directly in control of any of this and especially with JPG (vs raw) it's much less important.

BTW#2: I can't see any value at all to using APS-C mode on the A7R2; you'd just be throwing away pixels.

I am unclear about what the effect is of different size sensors and am hoping someone can explain it to me. I own two cameras - Sony a7r2 with which I use Sony G and G master lenses and the Sony Rx10 miv which has a fixed 24-600 Zeiss lens. The A7r2 has a ff sensor and produces a file size of 42mb in ff mode and a 20mb file in APS-C mode. The rx10 has a one-inch sensor and produces a 20mb file. So, comparing the a7r2 in APS-C mode to the RX10 what difference would the sensor make? I don’t see a difference, but I haven’t tried printing any of the images in huge sizes