Sell the R5 and get an R7 and R? Crazy?

User1303423862 wrote:

Sittatunga wrote:

mraifman wrote:

... For my bird photography, I find myself always using crop mode on the R5 and also wishing for more subject differentiation and nicer blurred backgrounds.

If you're always cropping your shots a lot, subject differentiation and nice blurred backgrounds are a function of the size of your lens aperture, not the size of the sensor. If the distances are the same and the focal length and aperture are constant, the geometry doesn't change, so the subject differentiation and background blur won't change, whatever the crop. You need a bigger aperture (in mm, not f/ number) to improve those things.

A bigger aperture only makes a difference if the sensor fully uses the projected image circle.

The size of the aperture has nothing to do with the projected image circle.  Nothing.

The size of the image circle is called the coverage.  That depends on the lens, but the coverage is the size regardless of the lens aperture.

Putting FF glass with a big aperture in front of a crop sensor won't help, unless you put a focal length reducer between the lens and the camera.

Yes it will.  It collects more light, i.e., more photons from the bird.  And this is independent of the sensor size.

But then you lose a lot of the extra reach the crop sensor provides, as well as some light in the optical path due to the extra glass.

If the OP wants blurrier backgrounds behind the birds, he needs a hide and some camo clothing, not an R7.

The only thing that will do that is a larger aperture diameter.  And he has that with his EF 300/2.8.