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

Sittatunga wrote:

User1303423862 wrote:

Sittatunga wrote:

User1303423862 wrote:

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

A bigger aperture with a constant focal length and subject distance reduces the depth of field. This blurs the background more and increases the subject differentiation, which is what mraifman wants.

The basic geometry doesn't alter no matter how or how much you crop, whether by using a smaller sensor than the lens will cover or by cropping in post processing. Teleconverters and focal reducers confuse the issue by changing the crop and changing both focal length and aperture, but these changes cancel each other out for what we were originally discussing unless their size is a significant proportion of the subject distance. The format size a lens was designed for has absolutely no effect on depth of field for a constant sensor size.

You're right and I was wrong. Mea culpa.

That's OK. Easily done in the heat of the moment and the circle of confusion around this subject is huge. I meant to say that teleconverters and focal reducers change the f/number, not the aperture - the physical size of the aperture isn't changed by them at all.

This was an interesting exchange. Thank you both for your thoughts on this. I realized that my initial question wasn't entirely clear on this front. My general preference (like many) is maximum reach and greatest subject differentiation when often shooting in low light for wildlife. The latter two preferences point to faster glass and so I've purchased the 300mm f/2.8 mk ii and enjoy using it in these conditions. It is just about the largest lens I can handhold as well, which i value. The downside, though, is 300mm is rarely enough reach for wildlife. So I am using the 1.4x TC mk iii on it most of the time and occasionally using the 2x mk iii TC but I find the 2x to be soft wide open. So the R7 + 300mm f/2.8 combo seems appealing to me because (unless i'm mistaken) it maintains the lovely depth of field of the 300mm f/2.8 while cropping to create a field of view of more reach. That 300mm f/2.8 becomes an effective 480 f/2.8. Now the R7 is lower resolution than the R5, so some of that gain is lost, but there is a noticable extended reach with the R7 in the comparison shots I've seen. The 300mm f/2.8 is very sharp and probably works well on the R7 despite the crop. I would expect to use the 1.4x TC mk iii occasionally on the R7 + 300mm f/2.8 combo to extend reach towards 700mm equiv.