I was not feeling good to go out for shooting so thoughts let not waste time and do some experiments at home hands-on rather than trying to convince people by breaking the keyboard.
I have told endlessly at on various photography forum that focal length of any lens is a number and it has NOTHING TO DO with the sensor size or thing call "Equivalent" focal length. NO, IT'S NOT EXISTS. 50mm is a 50mm across all format of sensors. I did a little experiment at home and I used 2 lenses on Full Frame Nikon D850.
A- Nikon 35mm f/1.8G DX (Crop Sensor Lens at the left-hand side)
To some people, it will be a shocker to see that Left-hand side DX lens almost not produced any sort of Vignette at all on the full frame body. There is very very small sort of vignette which was expected because of the small circle of projection by the DX lens on the FX body but the magnification of the 35mm DX lens at the left-hand side is the same just like a Full Frame 35mm f/2D. This proves nothing but a simple fact that there is such thing call lens equivalency. A 35mm focal length is a 35mm focal length across both formats. I said multiple times in past at various photography forums that LENS HAS NO IDEA WHAT SENSOR BENEATH IT. THEY PASS THE SAME AMOUNT OF LIGHT TO THE SENSOR REGARDLESS.
And there is ONE MORE THING .....
Check the second image screenshot down that I took at 100% view and look very very closely. Why the right-hand side image looks more 3D in compared to the left-hand one? I guess we already discussed a lot lately about the 3D characteristic of some old lenses which not many people know about it .... And here is the proof of it. Many old manual focus lenses produced 3D projection images on 2D plane sensor with rich color, sharpness and high contrast. I took the image where ISO, Aperture & S.S. was the same including the distance of the camera from the subject including did NO POST EDITING AT ALL and YET Right-hand image is more saturated, more contrasty and it is literally JUMPING out from the screen, unlike the left-hand side. Click on the image and look closely.
Next experiment will be done about the performance of the APS-C vs Full Frame with hands-on evidence showing that now it doens't matter what format of DSLR you have, they all are performing the same. The performance gap of the APS-C vs Full Frame is almost gone now. Wait for the next blog guys.