Eric Pascarelli
December 7th, 2007, 10:56 PM
This is not really a big deal, but I thought I'd pass on something I noticed while doing some tests on the EX1 today.
At 81.2mm there is no measurable difference in brightness (using a grey card) between 1.9 and 2.8 on the lens.
In fact, above 25mm, at f/1.9 the brightness begins to fall off. It goes down by 1/2 stop at 32mm and one full stop at 81.2, as stated above.
Of course I'd be curious to know if everyone's camera does this or is this more pronounced on my vignette prone beauty, #122.
It's simple to do, really. Aim the camera at an evenly lit, neutral field of color (exposed so it's not clipping), turn on "Brightness Display" Start at full wide at f/1.9 and watch the number on the brightness display as you zoom in. It should start to go down at 25mm if your camera is like mine. When zoomed all the way in, at 81.2, close the stop to 2.8 and see if the brightness number changes. Mine does not.
At 81.2mm there is no measurable difference in brightness (using a grey card) between 1.9 and 2.8 on the lens.
In fact, above 25mm, at f/1.9 the brightness begins to fall off. It goes down by 1/2 stop at 32mm and one full stop at 81.2, as stated above.
Of course I'd be curious to know if everyone's camera does this or is this more pronounced on my vignette prone beauty, #122.
It's simple to do, really. Aim the camera at an evenly lit, neutral field of color (exposed so it's not clipping), turn on "Brightness Display" Start at full wide at f/1.9 and watch the number on the brightness display as you zoom in. It should start to go down at 25mm if your camera is like mine. When zoomed all the way in, at 81.2, close the stop to 2.8 and see if the brightness number changes. Mine does not.