I'm very happy to be corrected and i'm not getting into the photon argument but here's my starting point.
Rant On.....
F Number is a function of the lens not the sensor size and is a pure ratio.
F Stop and ISO will give Shutter speed completely independent of Sensor size.
The DOF does change based on sensor size for the same Aperture value.
Using 2x crop factor in further sentences....
The offence I take all the time is the simplistic view that so called specialist and the amateur armchair forum users keep peddling is that a 40-150 F2.8 = 80-300 F5.6,
The reality is it equals 80-300 F2.8 with respect to shutter speed and only when considering the actual DOF does it equate to the dof achieved at 5.6 on a FF body.
The reality for a FF user is that to get the same FOV/AOV and the same shutter speed as the 40-150 they need to use a 80-300 F2.8. I've always thought that to take a correctly exposed photo needed to trinity of Shutter Speed - Aperture - ISO, none of which are affected by sensor size.
Please let's not get into the number of photons and square millimetres of sensor as this seems to be nothing more than an effort to justify the whole equivalence merry-go-round whilst ignoring the basic exposure triangle.
The DPR Opinion piece perpetuated this even more and contradicted their own article on Equivalence. People have complained in depth about the expense/size/weight of the new 40-150 F2.8 but have completely failed to actually compare and price a 80-300 F2.8 for FF if they decided they wanted needed a FF camera.
And lets get real, most FF users get told to stop down to F4 immediately negating one stop of the dof advantage
and most shooters at long end really want more dof not less anyway
Rant off...
To me the only equivalence that really matters is the Angle of View and anyone that actually needs the narrow DOF will already own a FF or will have worked out how to deal with it in whatever crop factor they are using....
Cheers
Phil
Rant On.....
F Number is a function of the lens not the sensor size and is a pure ratio.
F Stop and ISO will give Shutter speed completely independent of Sensor size.
The DOF does change based on sensor size for the same Aperture value.
Using 2x crop factor in further sentences....
The offence I take all the time is the simplistic view that so called specialist and the amateur armchair forum users keep peddling is that a 40-150 F2.8 = 80-300 F5.6,
The reality is it equals 80-300 F2.8 with respect to shutter speed and only when considering the actual DOF does it equate to the dof achieved at 5.6 on a FF body.
The reality for a FF user is that to get the same FOV/AOV and the same shutter speed as the 40-150 they need to use a 80-300 F2.8. I've always thought that to take a correctly exposed photo needed to trinity of Shutter Speed - Aperture - ISO, none of which are affected by sensor size.
Please let's not get into the number of photons and square millimetres of sensor as this seems to be nothing more than an effort to justify the whole equivalence merry-go-round whilst ignoring the basic exposure triangle.
The DPR Opinion piece perpetuated this even more and contradicted their own article on Equivalence. People have complained in depth about the expense/size/weight of the new 40-150 F2.8 but have completely failed to actually compare and price a 80-300 F2.8 for FF if they decided they wanted needed a FF camera.
And lets get real, most FF users get told to stop down to F4 immediately negating one stop of the dof advantage
Rant off...
To me the only equivalence that really matters is the Angle of View and anyone that actually needs the narrow DOF will already own a FF or will have worked out how to deal with it in whatever crop factor they are using....
Cheers
Phil