Canon R3

[Fast Glass]

Again, all of those statements are true. The reason why I even brought this up is the exchange you had with Kari about aurora photography. Low light/nightscape images are a scenario where read noise becomes more of an issue, thus there would be a negative impact for Kari's type of photography of more megapixels. For blacks, where signal to noise ratios are low, lower megapixel cameras still show a benefit over higher MP cameras. Now part of that discussion was motion blur, but even that could be effected as if you dial in your ISO to have acceptable noise in the blacks, a higher ISO would allow for faster shutter speed and less motion blur.

To sum up, I find it misleading to state that there are not trade offs going to higher MPs.

So you are not understanding this correctly at all. There is a stop in noise because there is over double resolution, but not in the real world.

If I were to print both images at 150 DPI, and then say the 45mp image has lots more noise that would be correct. But you are looking at an image that is larger n comparison.

If we both printed them at say 20x30, then you will not notice a huge difference in noise because that is more of a function of the output size and not zooming into all the noise. The 20mp is be slightly cleaner, but nearly like it would be if you viewed them both at 100%.

This is the part where you cannot use the readout noise as a guide. It just doesn't translate here because it's only telling you the readout noise at per pixel level. Not what it would look like at the same output size.

To prove this just take a typical night time shot with lots of deep dark shadows, either print them out on a large print or downres the R5 results to R6 dimensions. You will find there would be only minimal differences in noise.

I didn't say there is no trade off's, but they are not nearly as big as you might think or what just the readout noise would suggest at a pixel level.

To clarify what I said about modern tech minimizing the differences, I'm talking about the efficiency losses associated with adding more resolution. And they have gotten pretty dang good at adding pixels and not wasting light in the process. In a perfect world, we technically could just be adding as much resolution as processing power will allow or till the pixel wells start not being efficient at gathering light. Technically it wouldn't matter at that point. And in the case of 20 vs 45, that is really minimal the efficiency losses and the bigger question is not noise. It's do I need or want the resolution or not. And cost associated with that.

It's not about how many pixels you add, it's about how many you can add without wasting light. And modern tech has done a really good job of that. Besides that, a 50mp image is equivalent to 21mp 1.6 crop camera. It is not that small in the first place, many 1.6 crop cameras exceed this by a considerable margin. So it's not like we are even pushing the limits of sensor tech at a pixel level in the first place.