I Bought Another Copy Of The Fujifilm 100-400mm f/4.5-5.6 Lens; Why?

First test images with the new lens.  Rose; 100% crop from JPEG file (click to enlarge)
Fujifilm X-T3, 100-400mm f/4.5-5.6 lens @ 400mm; 1/ 750th sec. @ f/5.6; ISO 320;
in other words, the lens was wide open and this was shot hand held.

The subjects I normally photograph are nature, landscapes, old infrastructure, urban-scapes, travel, family events, etc.  Also, I enjoy photographing wildlife when the opportunity presents itself.  For that reason, when the Fujifilm 100-400mm f/4.5-5.6 lens was introduced, I purchased one.  The lens has a full frame field of view (FOV) of 150-600mm.  Add the superb Fujifilm 1.4x tele-converter (which I already owned) and that takes you out to an 840mm FOV, for a continuous full frame FOV from 150-840mm.  From what I had read, seen and heard, the lens focused quite rapidly and could produce sharp images.  Additionally, it was deemed to be hand holdable with its excellent image stabilization.  Finally, its cost is reasonable when compared to similar lenses from other manufacturers.  With those attributes, I felt it would serve my purpose well for the occasional wildlife photography I practiced.  But I soon discovered a problem.

Full size of the cropped  image at the top of this post

My elation in buying this well regarded tool soon turned to angst.  I found about a quarter of my images were not sharply focused.  No matter what I tried, from changing camera settings to only using the lens on a large, sturdy tripod with IS turned off (or on), or using only shutter speeds above 1/2000th of a second, it didn't seem to matter.  About a quarter of my images were soft.  I tried every conceivable  combination of settings with my X-T2 as well.  For whatever reason, I just couldn't get the "hit rate" of sharp images that I saw others, including my friends, getting with this same combination.  Was it the lens?  Was it the camera?  Was it me?  I was unable to nail it down.  

The lens focused properly 3/4 of the time so I was pretty convinced the lens was okay.  The camera focused accurately 100% of the time with all of my other Fujifilm lenses.  I didn't think it was the camera.  What's left?  It must be me.  I tried a variety of techniques, being extremely diligent in how I used the lens, including buying a new, large gimbal head and only using the lens on my largest tripod with fast shutter speeds.  Still, the results were about the same.  Stationary subjects or moving subjects, it didn't matter. Finally, frustrated, I came to the conclusion that this lens and I just didn't get along.  So, several months ago, I sold it.  It was in pristine condition—used very little for obvious reasons.  I thought if there was anything wrong with it, I would hear from the buyer (I was prepared to fully refund the money including shipping if there was something wrong with the lens), but again, I was convinced there was nothing wrong with the lens.  The new owner seemed to be happy with it as I have not heard from him.

Top of oak tree about 75 feet (23 m) away (click to enlarge)
100% crop; 100-400mm f/4.5-5.6 lens + 1.4x tele-converter @ 400mm; 1/640th sec. @ f/8; ISO 200
This is the full frame equivalent field of view of 840mm shot with the lens/converter combination wide open.

After selling the 100-400, I purchased the Olympus 300mm f/4 PRO lens to use in its place.  That lens has a full frame FOV of 600mm.  Add the superb Olympus 1.4x tele-converter and you get the same full frame FOV of 840mm as with the Fujifilm lens.  With that lens, attached to my Olympus E-M1 Mark II, I had superb results.  Focus was fast, locked on quickly, tracked very well and was accurate almost 100% of the time.  I was easily able to determine what "I" did wrong when I missed focus.  It was either my technique or I had the camera set wrong.  My experience with the Olympus gear had me reassessing as to whether or not the problems I had with the Fujifilm gear was my technique or with the gear combination.  The only problem with the Olympus setup was that versatility was reduced due to the 300mm lens not being having zoom capabilities.  Also owning the stellar Olympus 40-150mm f/2.8, I could get out to 300mm equivalent FOV with that lens.  Then adding the same 1.4x tele-converter could take me out to 420mm FOV.  But—everything between 420mm and 600mm could only be attained by cropping a 420mm FOV image.  Potentially inconvenient at times, but I was and continue to be extremely happy with that combination.  Stellar, in fact.

When the X-T3 was introduced, I decided that I needed a backup Fujifilm camera and decided to go with the new X-T3 rather than lesser or older technology of an X-T20 or X-T100.  Since Fujifilm was also having a quite generous sale on almost all of their lenses, I decided to take another swipe at the 100-400mm lens.  If I had the same issue with the X-T3 and this new lens, I then would know it was me.  If it was the lens or camera, I could send the lens back within 30 days.

Full size of the cropped image above.

I took delivery of the lens and started testing it with both cameras.  The lens nailed all of my test images with perfect focus and sharpness when using my new X-T3, both hand held and on a tripod.  A smile came to my face.  However, when I used the same lens under the same conditions with my X-T2, again, about 1/4 of the images were not in sharp focus.  Revelation!  It seems to have turned out to be the camera, not the other lens nor my technique that was the issue.

I have no idea as to why the camera doesn't focus these particular focal lengths well.  After the first of the year, I plan on sending my X-T2 to Fujifilm USA for a thorough checkup (I now have over 20,000 exposures on it) and I will clearly define the issue I had and see if they can figure it out.  My camera can't be the only one with this issue.  I'm hoping they have heard of this before and have determined a fix.  My hopes aren't high, however, as my experience with factory repair centers is that they give a piece of gear a cursory look and ascertain if it meets factory specs and send it back.

In the mean time, I'm planning a "shootout" between these two systems this upcoming weekend on my annual wildlife photography outing with my buddies.  I'll write more about this in my next post.
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Thanks for looking. Enjoy! 

Dennis A. Mook 

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