Panasonic FZ1000 vs GH4 with 14-140mm f/3.5-5.6 (3): image quality compared

Based on specs I deduced that FZ1000 can have slight edge over GH4 paired with 14-140 mm f/3.5-5.6 lens thanks to BSI sensor, downsampling effect and faster lens. What really matters though was of course whether the Leica glass could be comparable to Panasonic's own 14-140mm lens.

Here are charts comparing lenses' light gathering ability and achievable depth of field (equivalent of full frame aperture setting) as a function of focal length.

In light gathering ability at all focal lenghth FZ1000's lens is constantly nearly 1 stop brighter. At the same time depth of field produced by those lenses wide open is going to be also nearly identical. Mind that FZ1000 lens stops down to f/8 only.

Test procedure
Camera on tripod, IS off, 10s self-timer, base ISO (125 on FZ1000, 200 on GH4), mechanical shutter, aperture priority, the same horizontal angle of view, the same focus point (AF single, spot focus), raw image developed in LR 5.6 with default settings (all sliders at 0, sharpening 25), exported to Jpeg at 90% quality, sharpening to screen - normal, resized to 4608px on long edge (to downsample FZ1000). Crops for side-by-side comparison edited in IrfanView and saved as Jpeg at 90% (different percents than LR) quality. I have no intention nor tools to produce absolute numbers, just naked eye to subjectively judge which of a pair of images looks sharper.

First of all, due to already mentioned different aspect ratios, at given focal length 3:2 frame gives larger horizontal angle of view. In all the tests I tried to frame with the same left-to-right range and the difference of focal length is about 10% (eg 28mm (in 35mm equivalent) on GH4 required 31mm on FZ1000). That way FZ1000 also gains the most, so it is worth to bear in mind.

FZ1000 starts very wide, at 25mm, offering more than 14-140mm lens achieves. It struggles a bit at that setting, with increased chromatic aberrations and slight drop of sharpness (likely result of under-the-bonnet compensation for distortion)


Sharpness

In all side-by-side comparisons GH4 with 14-140mm is on the left, FZ1000 on the right 

Centre - far focus

Left - close focus

Right - medium focus

For wide angle I checked left hand side at about 10m distance, right hand side at about 20m and centre at about 50m (focus points marked on scene images). The reason was my typical (landscape like) use of camera. Note that FZ1000 at this setting is already at f/3, only 1/3 stop from 14-140mm initial f/3.5. At all aperture settings Leica glass is sharper, with 14-140 showing visible purple fringing wide open - exactly what affected FZ1000 at its widest. Also when comparing results at 1 stop difference, MFT combo loses.

Next test was in the middle of 14-140 range, at its (native) 50mm setting. Curiously Exif reports 92mm equivalent, but FZ1000 reporting 110mm equivalent shows to the same scene borders (I was worried unfair gain due to magnification, but later aperture vs focal length test showed GH4 reports 'bands' rather than actual values). I also set aperture accidentally at f6.3 rather than f5.6 in one case, but here differences between the lenses are even more obvious, so that did not give any advantage.

End of range of 14-140 mm lens is definitely its weakest. Here however FZ1000 at f/4 shows also big loss from its result when stopped down to f/5.6.

FZ1000 can stretch further, to 400mm equivalent focal length, but I downsampled the result and compared with crop from image taken at 300mm, and although I could see the difference, it was very tiny. So this lens also at tele end offers more on paper than there is of actual gain.

All the images are available for pixel peeping: developed from raw with default settings (WB as shot, Sherpening amount 25/ raduis 1.0) in LR5.6, exported to jpeg 90% quality, sharpened for screen standard and resized to 4608px horizontal (do downsample FZ1000 results) 

Stabilisation
I compared by shooting burst series handheld. FZ1000 seems to have produced more sharp results. I'm actually impressed that at 300mm 1/25s handheld I could pick a couple of identically sharp photos from a burst series.

Noise
I shot the same scene with FZ1000 at ISO400 and GH4 at ISO800, to test the idea that 1 stop extra of aperture can compensate (or even still keep ahead) FZ1000 shortcoming. I like FZ1000 result more, it seems of lower amplitude and proves gain from downsampling resulting in finer grain. To be honest even with both at ISO800 I could still call a draw, because increased noise amplitude of 1" sensor is partially covered by its finer structure. Note: the images were underexposed and pulled up 2 stops, so the absolute noise amount is closer to ISO1600 and ISO3200 respectively - those cameras aren't that noisy at moderate settings!

Although shot for noise, picture of FZ1000 is noticeably soft (spot focus on the vase in both cases), so I started suspect its lens may be optimised for far distance and struggle with closeups. I did a quick check in room conditions and results at wide again indicate 14-140 to be the loser, but this time it also lost at flower test. I think shiny vase is not great focusing target then...

From the left: FZ1000@ 25mm (equiv), FZ1000@ 45mm , 14-140 mm @ 280mm (E)

All crops from landscape.

Macro
FZ1000 is equipped in 'Macro AF' mode. However the way it works allows one to focus as close as 2cm from the lens front at wide angle, but with increasing focal the minimal focusing distance increases even more! That behaviour makes photographing the very close subject pretty much impossible, as there is risk of shadowing as well as scaring (live) subject away, distortion introduced by wide perspective aside. 14-140mm lens is no macro lens neither and produces the biggest magnification at its long end. Here perspective can also get distorted, on top of that lack of sharpness, small aperture and sensitivity to vibration play their roles. In such contest FZ1000 wins at its 45mm setting, where it produces the bigger magnification as frame fill factor and in absolute terms (2950 px height of the model used)

Focusing
With sunlight and in a room at daylight both cameras focused identically - instantly. Unfortunately I did not have chance to carry out any sensible test of continuous AF or tracking capabilities.
In manual focusing mode both cameras offer helpful focus peaking and image magnification, and here one of little differences show again: FZ1000 magnifies up to 6x, GH4 up to 10x.

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