Originally posted by hilbert5 Are we all sure that a slider at +4 in Lightroom actually is +4 stops? Has Adobe this ever published? Are we even sure the sliders are actually following the same scaling (namely that plus every stop means doubling the amount of light)? Maybe I'm missing something.
No, that's just a common assumption worth a validation. Go for it!
Best would be to compare with pushing the exposure in Photoshop.
One should switch PS into 32 Bit mode (which applies a color model w/o gamma correction -- sRGB values are NOT linear!!).
The exposure slider in PS goes up to +20EV and avoids the LR layer trick which isn't verified to work either...
One may control the PS slider that it does indeed double the rgb values in 32 Bit mode (it does so!) for a +1EV push.
Reverting back to 8 or 16 bit changes rgb back to sRGB (values change) but the image stays the same. Then it can be read into LR and compared side by side.