Howard Roll wrote:Yeh, more than a stop. So the 50-100mm is consistently brighter? What stop was this? Do you have what would appear to be the full range of iris control on both lenses? I'd consider this difference to be larger than what would be expected from trusting manufacturer reported f numbers or the variance from differing lens control protocols. A few decimals either way sure, not this.
Long story short, something is wrong, there's no rule or principle that will compensate for this kind of shift.
At minimum I'd shoot a test at f1.8 and f16 and compare the 4 images to isolate the problem lens. If the image is not clipped or crushed there will be better data for analysis, when the picture is clipped as above it makes critical comparison challenging.
Good Luck
That was at f1.8.
The aperture is changing on both lenses as I change it on screen, but the f1.8 just doesn't seem bright enough on the 18-35mm for how that fstop should look.
I've attached images at a few different f stops and iso's for reference. The difference is most noticeable at f1.8 and least noticeable (though still there) at f16.