Power Converters

· 26.December.2017

Having access to a lens with a long focal length is really important for sport and wildlife photographers and Fujifilm make two of the best long zooms on the market, the Fujinon XF50-140mm f2.8R OIS WR and the XF100-400mm f4.5/5.6R OIS WR. The longest focal length gives an equivalent of 600mm in full frame terms and for most subjects that is usually more than enough.  However if you want a bit more pulling power then Fujifilm have a 1.4x and a 2x tele converter that can increase the focal length even further.

The FIA World Endurance Championship – XF100-400mm f4.5/5.6 + 1.4x converter


First of all the Fujinon tele converters are only compatible with three of the current Fujinon lens, the 50-140mm and 100-400mm zooms and the new 80mm f2.8 macro.  Because of the design where part of the converter slots into the back of the lens, the converters wont fit to any other Fujinon lens. Personally I wish they were compatible with the superb 90mm f2 prime, but they aren’t so let’s move on.

Focal Length

With the 1.4x fitted to the 50-140mm f2.8, the focal length becomes 70-196mm (105-300mm equivalent) and with the 2x fitted it becomes 100-280mm (150-420mm).

The increase of focal length is even better on the 100-400mm, with the 1.4x giving you a focal length of 140-560mm (210-840mm equivalent) and the 2x pushing the boundaries with 200-800mm (300-1200mm).

This sounds great but there is an old saying that you don’t get something for nothing and there are some trade offs for this increase in focal length.

Let me explain further.

Melrose Rugby Sevens Tournament – XF50-140mm f2.8 + 1.4x converter

Image Quality and Lens Performance

The two Fujinon teleconverters are superb bits of engineering and the image quality lose is minimal.  I have found that I can fit the 1.4x to either of the Fujinon zooms and the loss in quality and performance is insignificant with the AF locking and follow focusing the subject as if the converter wasn’t fitted.

The 2x is a different matter.  On the 50-140mm the loss in quality and performance is minimal and I have no hesitation fitting the 2x to this lens. The 2x on the 100-400mm is a different matter, there is a visible drop in image quality and AF performance.

Aperture and Light

The first downside is the loss of light when you fit a teleconverter.  For the 1.4x you lose one stop and for the 2x you lose two.  The Fujifilm X Series indicates this by changing the aperture value in camera.

For example if you shoot with the 50-140mm f2.8 with the 1.4x fitted, the widest aperture changes to f4, and with the 2x fitted it goes to f5.6.  Now this is OK as long as you are shooting in bright or slightly overcast conditions, but if you want a subject freezing shutter speed and the light isn’t that good, then the ISO will have to be pushed up to compensate, with the resulting loss in image quality the higher up the ISO scale you go.

With the converters fitted to the 100-400mm, the aperture also changes.  For the 1.4x the widest aperture changes to f6.4-f8 and with the 2x it becomes f9-f11, which can cause you some issues even in the brightest conditions.

FIA World Endurance Championship – Audi R18 – XF100-400mm f4.5/5.6 + 1.4x converter

When to use a converter

I only fit a converter when I absolutely need the extra focal length to capture an image.  I know some photographers who leave a 1.4x converter on their lens permanently and that’s fine if that’s what works for them.  However I only use the converters when I need to use the maximum focal length of the lens to capture an image.

If I fit the 1.4x converter to the 50-140mm, it is only useful in the range 141mm to 196mm because if I shoot at 140mm or less with the converter fitted I am losing one stop of light and a slight drop in image quality for no gain in focal length over the lens without the converter.

This point is really important for the 100-400mm, where the drop off in image quality is more marked when shooting with the converters.  With the 1.4x fitted the useable range is 401mm to 560mm and the 2x is 561mm to 800mm, the difference between the lens fitted with the 1.4x and the 2x converters.

I will only use the 2x converter on the 50-140mm if I don’t have the 100-400mm with me.  The focal length on the 50-140mm changes to 100-280mm with an aperture of 5.6.  The short end of the 100-400mm covers this focal length with no converter fitted and the widest aperture is f4.5. So it is better to use the longer zoom over the shorter lens with a 2x converter.

Le Mans Classic – XF50-140mm f2.8 + 2x converter

Out in the Real World

I have been using the two converters for a while now and as an X Photographer I was part of the test team for both the 1.4x and 2x converters.  I have found these converters to be excellent and I use them with the limitations I have highlighted earlier firmly in mind when I fit them.

I have no hesitation in fitting the 1.4x teleconverter to either of my Fujinon zooms if the need arises.

For motor sport when shooting at some of the big international race circuits I find myself behind a large gravel trap and too far away from the track for a frame filling shot of the action, so will fit the 1.4x converter to the 100-400mm zoom.

I rarely fit the 2x to the 100-400mm because of the loss in image quality due to several factors.

The maximum aperture is f11, so not really useful in a fast moving environment such as a race circuit.  The autofocus performance is affected by the small maximum aperture, which is really noticeable when tracking a fast moving object.  Finally when shooting over distances the subject can look distorted due to atmospheric condition magnified by the long focal length.  This looks like heat haze in final image.

Instead of using the 2x on the 100-400mm, I usually fit the 1.4x and the crop the final image in post production if necessary.

The 2x on the 50-140mm produces some great images, with the quality of the final image and camera performance at an acceptable level.  I use it when I don’t want to take the 100-400mm with me as well when shooting in the pitlane or at the podium ceremony.

Sir Jackie Stewart – XF50-140mm f2.8 + 2x converter


The 1.4x and 2x Fujinon teleconverters are excellent and, when used with thought, will produce a great image.

I love the 1.4x converter and will always have it in my camera bag.

The 2x is more of a considered purchase.  This is by far the best 2x converter I have ever owned but, as with all 2x converters, there is the drop in image quality and camera performance to take in to consideration.  But as demonstrated by the sample images, it can also produce some great results.

At the end of the day I would much prefer to use the lens without a converter wherever possible to maximise the image quality but I know the Fujinon converters will give me extra pulling power if needed with few compromises.

Melrose Rugby Sevens Tournament – XF100-400mm f4.5/5.6 + 1.4x converter

6 Hours of Mexico – XF100-400mm f4.5/5.6 + 1.4x converter

6 Hours of Mexico – XF100-400mm  f4.5/5.6 + 2x converter

24 Hours of Le Mans – XF50-140mm f2.8 + 1.4x converter

Three time World Touring Car Champion Andy Priaulx – XF50-140mm f2.8 + 2x converter

Michelin Le Mans Cup – XF50-140mm f2.8 + 1.4x converter

RBS Six Nations – Scotland v Wales – XF50-140mm f2.8 + 1.4x converter