Different versions of XF 18-55? need some advice...

elzardelanada wrote:

Hi Bill,

thanks for your reply.

Bill Ferris wrote:

Hi - The test chart image made with the lens manufactured in Philippines does not appear to be in focus. Either focus was missed, the exposure captures some degree of motion or the lens is just plain soft.

The center of the whole image seems to be absolutely ok to me. It's just the corners that are soft, and I believe it is the lens. I will make some more shots and see if maybe AF had a hickup.

Were the comparison photos made with the camera on a tripod or were they handheld? Manual focus or autofocus? If autofocus, AF-S or AF-C? Did you use the central AF point and focus on the crosshair or a different method to achieve focus?

The camera was sitting on a static tripod and before every shot i refocused twice with autofocus AF-S, and on the center AF point, to then release the shutter with a 10sec timer. The lens OIS was off. I actually felt very confident about the comparability of my method. (coming to think of it, I should have taken two or three shots at each setting...)

I'm a big believer in setting up and conducting such tests to give the lens every chance to shine. That way, any aberrations or weaknesses in performance can be more accurately attributed to the lens, itself, as opposed to the operator or test conditions.

I will offer an anecdotal observation that my 18-55 OIS (purchased with X-T20 / Philippines) is quite sharp at the center but soft in the corners. Considering it's a "kit" lens priced at $300 when sold with the X-T20, I find it to be a solid performer, an excellent value and really appreciate the f/2.8-4 maximum aperture throughout the zoom range.

I'm a big fan of this lens as well, it's only the existence of different built lenses, and the reports of better and worse lenses, that makes me wonder.

Best regards!

When doing a test, it would be better to manually focus the lens using focus peaking. At least that way, you will know where you focused on. It's a good idea to square you tripod rig and camera by using a bubble level inserted into the hot shoe. My favorite target is a plain brick wall. You can magnify the grout and see how sharp those little grains are. Go to LensTip.com and look at the resolution chart for the 18-55. Careful examination of the chart shows that the center (44lp/mm @ f/2.8/18mm) vs the edge (35lp/mm @ f/2.8/18mm) is not so bad. What this means is that images taken at 18mm will be fairly close in resolution from center to edge. Considering the 18-55 is a kit lens, that's pretty good.

I checked my 18-55 and it looks like the on the right.