I think these comparisons like that are done by people with way too much money and time on their hands. The lenses are soooo different. If you have only one DSLR body, you either have the 12-60 on for general use or have switched to the 7-14 to get the 7-11 that the 12-60 does not have. If you have the 7-14 mounted and you hit a case when you need to shoot at 13mm, well I would just shoot instead of pausing to flip the bag open, open the camera throat to dust and moisture, juggle two expensive lenses in my hand whilst the rest of the gang around me go dum te dum.....
I Know that.
The distortion of ZD 12-60 at 12mm(more) and 14mm(less) against ZD 7-14 at the same focal length is a fact and also obvious in my test (the first thing cross my mind is the geometrical correction of 7-14) but I think not justify the wider area covers my 12-60 at 12mm and 14mm against 7-14 at the same focal length.
I suspect that even the slightest movement of the camera at this focal length is going to give you differing results.
What focus distance was involved?
The test was perform at infinity focus without tripod , daylight at Majorca on my vacations, the target was the forest from the balcony terrace (300m away), exif checked for same focal length (12mm & 14mm), aperture priority,
Is a profound statement!
Back to your "test" photos. When you compared them, you say the 12-60 was covering more horizontal.
Pretty much so, yes. Firstly, you should use the same focus distance when comparing the lenses since focus distance can affect the focal length on a zoom lens. Secondly, the lens groups move in a complex set of relationships when the lens is zoomed. While the focal lengths marked on the zoom ring of the lens are approximately linear since we humans like to visualize things that way, the actual focal lengths achieved by a linear movement of the zoom ring are not linear. The result is that the focal lengths marked on the zoom ring of the lens are totally accurate only at the shortest and longest positions and are only approximations at the intermediate positions.
The lenses are what they are. Each is its own creation and whether 12mm on one lens is identical to 12mm on the other is largely irrelevant.
The test was made for different reasons as already said , and because the 7-14 lens is the ultimate wide lens of 4/3 (it costs also 1.8X the 12-60) if the test result was reverse, nothing odd happened because we all know that 12-60 is geometrically worst at 12mm and 14mm from 7-14, but when I saw the strange result my mind goes immediatelly to defective 7-14 lens (it's on quarantee yet) , also I can't compare it further with something wider (focal lengths 7mm to 11mm).
