M4/3 System - Lens Evaluation

Panasonic 100-400 lens testing.  Report by Adrian Harris 18july2016 - Updated 20november2019.
  • PL100-400 & Panasonic GX8 Dual IS = Strange Results.
  • PL100-400 & Olympus Em1-Mk2 = Stunning Results.

UPDATE: At the end of this article there are now 2 UPDATES that also need to be read, as in my opinion they go a long way to prove what a tremendous lens the PL100-400 really is and also explains why I was originally getting frequent poor results.
    UPDATE 1 - 5 February 2017: Panasonic and Dual-IS
    UPDATE 2 - 20 November 2019: Olympus Em1-Mk2 Camera & PL100-400.

NOTE: The tests below were not to show how great the Panasonic 100-400 lens is (but it is a stunning lens), these were performed only to try and discover the cause of the poor photographs I was getting when the lens was fitted to a GX8 with it's first generation Dual IS stabilisation....

I will say straight off that the lens under test is capable of producing some fantastic results and it has allowed me to achieve some spectacular images that I could not have got otherwise. However the tests below were undertaken to try and understand what was causing such a large number of unexplainably poor images from many photo-shoots, notably when using my trusty Panasonic GX8 with this new Panasonic PL100-400 lens.

I noted the poor images were nearly always when using the lens at or near its maximum 400mm zoom, at long range and with the OIS Dual stabilisation switched on. My photography is normally always handheld and the blurred images I was capturing always looked rock solid in the EVF viewfinder before I pressed the button. And as I have never had issues like this before even when shooting with much longer lenses, I needed to investigate further…

Test Setup:
Panasonic 100-400 lens + GX8 with firmware 2.1.
As a reference check for fault diagnosis elimination purposes, the 100-400 lens was also tested on a Panasonic GX7 camera, and another lens - the Olympus 75-300 - was also used on the GX8.

No 'flat on the wall' lens charts here, only real life scenes shot using both tripod and handheld, and tested at the maximum 400mm focal length, using the Electronic Shutter only.

I use the Electronic Shutter for 98% of my photography, so all tests were performed using electronic shutter, which has the added benefit of excluding any possibility of shutter shock arising to affect results.

1) OIS switched on (Dual IS) produces soft images.

Although when tripod mounted, both OIS ‘on’ and ‘off’ produced similarly and consistently sharp images. When handheld (even when braced) with OIS ‘on’ the images were nearly always soft. However when the OIS was switched ‘off’, although as to be expected many images were soft or blurred due to my movement, about 1 in 3 was very sharp, generally exceeding the sharpness of any that had been taken using the Dual IS - OIS switched on !

This test was tried at various high shutter speeds with little difference being made to the images which tended to remain soft when the Dual IS was switched on. Obviously as to be expected, at very high shutter speeds the hit rate of sharp non OIS images improved !

A Note Regarding Stabilisation: With the GX8 stabilisation ON, uses the new Dual stabilisation mode - lens OIS and camera IS together, - stabilisation OFF uses neither, there is no option to choose IS or OIS separately. I believe that the GX7 does not have the Dual IS feature, so I must assume that since this is a stabilised lens, that the GX7 must use only the lenses stabilisation?

The images in the sequences below were not 'cherry picked', the system used was first 3 shots taken with stabilisation ON and the next 3 shots with stabilisation OFF, crops from ALL shots shown...

Click image to view full size test Click image to view full size test Click image to view full size test

(T1) GX8 + 100-400 Tripod Mounted.
Dual IS v no IS comparison

(Haytor-3) GX8 + 100-400 lens Handheld.
Dual IS v no IS comparison

(T5) GX8 + 100-400 lens Handheld.
Dual IS v no IS comparison
Click image to view full size test Click image to view full size test Click image to view full size test

(T7) GX8 + Olympus 75-300 on Tripod.
In camera IS v no IS comparison

(T3) GX7 + 100-400 lens Handheld
IS v no IS comparison
2) Duplicated images in Bokeh.

A series of photos were taken of a bird on a dead tree in a lake about 100metres from the photographer. Observe duplication in the reeds, which were positioned about 30 metres or so behind the focal point (bird and dead tree), every reed seems to have an echoed image. Unfortunately this was not a one off situation as similar locations have shown that this ‘effect’ is easily repeatable. I have only ever seen this duplication effect before, when using a very cheap ‘add-on’ converter lens. Could the background images being ‘duplicated’ possibly suggest a non operative internal element in this particular lens copy or an uncoated lens surface causing internal reflections ?  

(Note: The lack of sharpness of the foreground tree in these images - where the camera was focussed - was probably due to the above suspected Dual IS problem causing image softness. Similar images taken using the Olympus 75-300 do not show this background Bokeh ‘duplication’).

Update: I have since learned that this Bokeh duplication effect is common on expensive long lenses. For further 'deep' reading on lens Bokeh, this links to a very informative Bokeh Article written by Jakub Travnik.

Bokeh Test Examples
Click to view full size

3) Image Blooming.

I keep seeing what appears to be a ‘glow’ around white or bright objects on darker backgrounds. At first I thought this was lens ‘blooming’, however after some testing I now think this could possibly be due to partial image blur being induced by the OIS as discussed above, especially as sharper non-stabilised images do not tend appear to do this. Although further tests regarding this are still in progress, optically I feel confident that this is a very competent lens when used correctly.


Lens Blooming test check example
4) Exceedingly stiff zooming operation?

The zoom action of the Panasonic 100-400 lens is quite stiff, which can at times be both a blessing and a curse. But many decisions needed to be taken by the Panasonic engineers when creating this incredible lens which covers the unheard of Full Frame equivalent of 200-800mm. A lot of elements need moving a long way to cover this sort of zoom range and if the lens didn't have a telescopic style expanding action, then it would have had to permanently extended, which would have made it far to large to be practical in the otherwise very portable M43 line-up.  Also in wanting to make it an all weather lens tight sealing was needed between the moving parts, which of course then causes a lot of friction. This could have been overcome by a low geared zoom-ring action, but that would require having to twist your wrist far to much to be practical. And finally no one likes a lens barrel accidentally extending itself when walking along. So in my mind the engineers came up with a good compromise. And one side benefit of the high geared zoom action is that I can extend the zoom very quickly just by pulling it out (which may or may not be recommended!!!).

For the first few weeks I thought some of these issues may have been down to me having to ‘learn’ how to use the lens. However after much testing, and as I am getting such great success with all the other long lens setups that I am using (up to1000mm), I am now confident to report that the above mentioned issues with the Panasonic 100-400 lens when fitted to the GX8 are not down to 'user error' and many I suspect seem to be attributable to the new Dual IS system.

What is so strange, is that through the electronic viewfinder the handheld Dual Stabilised image at full zoom looks rock solid steady and is very impressive indeed, however the resulting photographic image taken doesn’t reflect this. Furthermore – and although I can not confirm this without further testing – I think I recall that at full zoom with the Dual IS on, the image taken when shooting handheld was not centred in exactly the same position as the EVF image. Which if true, suggests some movement - other that what is being displayed - is actually being captured (further testing needed to confirm).


My tests have proven to me that (at least with my copy) the Panasonic 100-400 lens has superb optics capable of producing very sharp images at all focal lengths. But there appears to be some detrimental interaction regarding the Dual Image Stabilisation when this lens is fitted to my Panasonic GX8 camera, which is causing a very large proportion of handheld photos to be blurred when OIS is switched on. However testing has shown that when this Panasonic 100-400 lens is fitted to my GX7 the difference between handheld photos with the IS 'on' or 'off' appears minimal , the GX7 + 100-400 lens combination works very well and the results are generally very sharp. Furthermore, when my GX8 is fitted with the non stabilised Olympus 75-300 lens, the image sharpness using only the GX8 in-camera stabilisation is also very good.

As far as I can see others have not yet as of July 2016 reported concerns like this on the forums, so from the results above I was assuming that I possibly had a faulty lens! (continue reading below to see two updated comments on this article).

Note: For the nay-sayers I have to report that this lens has many excellent qualities that make me want to keep it. Terrific contrast, detail and sharpness at all focal lengths (when working correctly), fast focus, superb for macro work, birding, surfing, aircraft, motor sport, and many other things beside, plus it has good balance which is very important for a long days shooting.

For those that think f6.3 isn't fast enough at 400mm full zoom I have got news for you... at a full frame equivalent of 800mm (which is what this lens is) your depth of focus is so small at f6.3 that in real world shooting situations I most often have to stop down to f7.1 or f8 to get the whole subject in focus. Those that bought this lens will have no doubt already discovered this. Panasonic made a very wise choice sticking to f6.3. It has kept the lens at a sensible price and size, and also light enough to be practical and useable. Now all I need to do is to get this Dual IS system functioning as it is meant to be!!!

This report will be updated after I have contacted further tests, also I would be very interested to hear from other 'power' users who may well have conducted other tests. Photographing test targets is one thing, but real world shooting is what photography is all about and it is here that performance matters. Some scenes just cannot be replicated, in real life we very rarely have another opportunity or a second chance to get it right. When competent photographers can not guarantee whether they will get a shot or not, I feel action needs to be taken by the manufacturers.

A failure scenario for professionals is not acceptable. If the conclusion is that the Panasonic M4/3 system does indeed have some major failings in respect of these two items, which are after all sold as professional tools at premium rates, then I feel it would be my duty to contact Panasonic with my findings. Of course whether they will take any notice or not is another matter !

Adrian Harris 18july2016  

UPDATE 1 - 5 February 2017: New Dual-IS, & Sensor Box alignment...

Well quite a lot has happened since I first wrote this test report, including Panasonic introducing new cameras with an 'updated Dual IS system', which does I admit make me wonder!

However after I contacted Panasonic it would appear that although my GX8 has worked fabulously in most situations, a few alarm bells started to ring after testing a few wide angle Pro lenses. I sent the test results to Panasonic and after examination they have confirmed that the sensor mount box needed re-aligning and that this could have been causing some of the problems I have been having. However having only received it back today and the weather is currently awful, so have not yet had chance to test it!
.... so as they say 'Watch this space!'.

UPDATE 2 - 20 November 2019:  Olympus Camera & PL100-400

For the last 2 years I have been using the Panasonic PL 100-400 lens fitted to an Olympus EM1-Mk2 micro 4/3 camera and what a different beast it is now. Unlike the Panasonic GX8 which forces you to use either Dual or No stabilisation, the Olympus EM1-Mk2 lets you choose Camera + Lens Stabilisation, or just one or the other.  At first I preferred just in camera stabilisation and the sharpness improvement - especially at long focal lengths - was stunning.  More recently for the PL100-400 I have been using only the lens stabilisation and the results are equally as good. For some reason the PL100-400 does exhibit some strange behaviour when the Dual IS option is engaged with Panasonic's own GX8 camera (But is fine on the earlier GX7 with single IS stabilisation!). When using the GX8 and PL100-400 combination the stabilisation when both are on is absolutely fantastic, but for some reason when shooting distant subjects at maximum zoom the image softens a lot when the GX8's Dual IS is activated. Whether Panasonic have finally sorted this dual stabilisation issue out with their more recently released G9 camera I do not know, but let's hope so because the PL100-400 is a stunning and very versatile lens and worthy of the highest praise.

It is worth mentioning that in over 5 years of use, the PL100-400 has certainly become my most treasured lens.

Panasonic 100-400 lens testing.


  Article Adrian Harris