300mm to 600mm fov in lightroom

[pope]

In Lightroom,
If you have a image taken with a 300mm lens, and you want to find out what the field of view would have been with a 600mm,
is it simply in lightroom, cropping the original /zoom by 1:2
or some thing more complicated.

Thanks in advance.

 

[overbez]

Good question.

I been wondering about this too. From my POV as to how my superzoom bridge (10MP) at 720mm equiv would compare to a DSLR (16-18MP) at 450mm equiv.

On the Nikon lens comparison tool, I took the results at 150mm and 300mm (300mm was longest lens on there) and overlayed the results.

The 300mm was resized to 50% in each side (so 25% area) and fitts perfectly in the middle of the 150mm version.

Logic would state that 300 to 600 would be the same.

So a 10MP image at 300mm would equal a 2.5MP image at 600mm equivalent.

Not saying I'm right and there may be a more technically reasoned argument.... but hopefully will get the ball rolling.

------ edit -------

and having just done some maths to answer my question, 720mm , 10MP is (theoretically / mathematically) equivalent to 565mm, 16MP. (In terms of pixels in the equivalent FOV).

1/((720/565)^2)=61.5% area

10/0.615 = 16MP