18-135 Focus issues.

[rob s]

Hi everyone.  I'm an experienced Canon photographer who has become somewhat disillusioned with their products.  A couple of different friends and acquaintances have talked me into looking at Fuji products and I've recently bought an X-E2 with the kit lens and also a new 18-135.  I started with the camera and kit lens and was impressed enough to buy the 18-135.  This is my preferred walk-around focal range and I have the Canon STM version which I use on my 7D.  That is a cheaper and more poorly constructed lens but one which is adequately sharp although it does suffer from nasty CA in certain backlit conditions.

 

To my surprise I can't get a sharp image of light aircraft overhead or the moon with my brand new Fujinon XF.  Focus for both subjects is set on auto for fairly obvious reasons and the lens appears to focus but the images simply aren't sharp.  Palm trees a 100 yds away however, are tack sharp in similar circumstances.  Adequate shutter speeds in all cases.

 

I noticed a picture in the current Astro thread which showed excellent sharpness with this lens.  Do I have a bad lens or ..........?

 

[Nero]

I never really had focus issues with my copy (an original pre-order copy which I have since sold), but I did have some very poor contrast issues with anything in the distance. It seemed to be very poor in dealing with having a lot of air between you and a subject, even if it wasn't a visibly hazy day. Whether I focused in the foreground with a very small aperture or used a focal point in the distance, it didn't matter. Even with an anti-haze filter it didn't really help much.

 

I could pull some of the sharpness back into the image to acceptable levels with clarity, sharpening, and dehaze when I was processing the RAW file, but it was just too much work for the sake of a little bit of versatility in focal lengths unless I applied the settings to the whole image, which made the non-hazy parts look over-processed. Now I tend to use a prime on one body and the 55-200mm on a second. 

 

A lot of people love the 18-135mm and there's nothing wrong with that, but it doesn't fit me and I was very disappointed with the quality control on my early copy. From what I have read, it has improved over time, but my experience with it was disappointing overall.

[rob s]

Further info.

 

I have a useful group of palm trees in a neighboring yard which I use a test subject.  Yesterday a small plane flew across some distance behind the palms.  Everything was in focus.  So it seems the issue may be the camera's inability to focus on small distant objects.

 

Any thoughts anyone?

[dfaye]

An interesting discussion. As a general comment, I've noticed that the camera's AF (XT2/XPro2, and my previous XT1/Pro1) is easily fooled into "thinking" it has achieved the correct focus when actually it hasn't. The AF works best if the focus point is on something that presents clear contrast or an obvious line/edge (sometimes easier said than done). Otherwise, I find the AF can be a bit approximate, and I need to do some manual tweaking.

 

In the case of small, distant objects I find that atmospheric effects such as heat haze or pollution can impede the AF. I don't think these problems are specific to the 18-135, but it may well be that the 18-135 is more easily "fooled" than some others. For example, my 56 f1.2 will spend a while hunting for focus in challenging conditions (and may or may not get it right first time), whereas my 18-135 will quickly snap into focus - but not always the right focus. I've learned to love the manual override! 

 

Again, as a very general comment, I find the newer f2 range of lenses (90, 50, 35, 23) are pretty good for focusing speed and accuracy. If I'm photographing my hairy dogs (low contrast, no sharp edges) I stand a better AF chance with one of these!

[rob s]

Thanks for the input.

Rob