Testing: Longitudinal Chromatic Aberration and focus shift
Lenses with focal ratios of f2.8 or larger are often prone to longitudinal color aberrations (loCA, a.k.a. “axial color” or “bokeh CA”). These normally show up as magenta coloration in the foreground and greenish hues in the background and are not easily corrected in post-processing. The Sony has very little loCA.
There’s also no focus shift to speak of. For comparison see the Tamron 70-180mm f2.8 Di III here.
The following real life shot shows that the Sony FE 70-200mm f2.8 GM OSS produces a bit of purple fringing around high-contrast edges in the focal plane:
The Tamron 70-180mm f2.8 Di III in comparison is practically free of coloration around dark edges but produces a lot of glare which reduces contrast around bright light-sources considerably. Both shots were exposed identically.
Sharpness and contrast
Let’s have a look at the theoretical performance of the new Sony FE 70-200mm f2.8 GM OSS first and compare it to the performance of the Tamron 70-180mm f2.8 Di III:
These MTF charts show the computed lens-performance of lenses wide open without influence of diffraction. Higher values are better (more contrast) and the closer the line-pairs are together the less astigmatism (= resolution depends on the orientation of the test-pattern) the lens has. The x-axis displays the distance from the optical axis (=center of the sensor) in mm. I’ll show you the real-life performance at 4 mm (center), 13 mm (APS-C-corner), and 20 mm (FF-corner) on a 42MP Sony A7R II camera.
From the charts the Sony 70-200mm f2.8 GM looks weaker than the Tamron III at the short end. At the long end both lenses should produce very good resolution with the Tamron showing a significant gap between sagittal and meridional contrast.
Let’s see how this theoretical performance translates into real life results in the sharpness test based on Siemens-stars. Processing was done in Lightroom 9.2/CRAW 12.2 from RAW to Adobe Color profile with the built-in lens profile for shading and CA compensation applied. Noise-reduction is set to 0, sharpening to 50/0.5/36/10, with no extra tone, color, or saturation adjustment. White-balance was adjusted to a neutral white and I did some exposure compensation to make the brightness of all crops match. So you will not see light fall-off in the corners.
The following are all 100% crops!
First up is an overview of the wide-open performance at different focal lengths. You can jump to the detailed results at different apertures and comparisons with the competition by clicking on the crops of the respective focal length.
Sony’s telephoto zoom lens is very sharp across the full-frame sensor throughout the zoom-range except for the FF-corner at 70mm focal length. The lens also exhibits very little field curvature at all focal lengths.
If you want to see all the details, read on. Or you can fast-forward to the performance at long distances.
The following 100% crops for each focal length show the Sony FE 70-200mm f2.8 GM OSS from f2.8 down to f11 compared to the Tamron 70-180mm f2.8 Di III at f2.8.
Performance at 70mm:
At 70mm focal length the Sony is very sharp in the center but falls back behind the Tamron III outside the center ending with a pretty mushy FF-corner. The Sony shows also a bit of magenta coloration from loCA up until f5.6 which the Tamron III totally lacks.
Performance at 105mm:
At 105mm focal length the Sony has now caught up with the Tamron III which has still a slight edge in the FF-corner but is just a bit less sharp in the center. Traces of loCA are mostly gone from the Sony at f4.0.
Performance at 150mm:
At 150mm focal length the Sony is now slightly sharper across the full-frame sensor at f2.8 than the Tamron III. The coloration in the crops is now purely from color moire, not loCA.
Performance at 200mm:
At 200mm focal length the Sony again is just a little bit sharper than the Tamron III (at 180mm).
Overall the Sony FE 70-200mm f2.8 GM OSS zoom lens produces very sharp images – except for the FF-corner at 70mm. But the Tamron 70-180mm f2.8 Di III is pretty close – even surpassing the Sony at 70mm focal length.
Performance at long distances
The Siemens-star test-targets are shot at a distance of 45x focal length (i.e. at around 3m for 70mm focal length). But performance of lenses also depends on the shooting distance. Therefore I present another series of test-shots of a city around 1 km away. Processing was done in Lightroom 9.2/CRAW 12.2 from RAW to Adobe Color profile with the built-in lens profile compensating CA and vignetting. Noise-reduction is set to 0, sharpening to 50/0.5/36/10, with no extra tone, color, or saturation adjustment. I used manual focus at the largest aperture and did not change focus for other apertures. All shots were made at ISO 100 and image stabilization switched off.
Following is an overview of the wide-open performance at different focal lengths. You can jump to the detailed results at different apertures and comparisons with the Tamron 70-180mm f2.8 Di III by clicking on the crops of the respective focal length. As usual I have selected the diagonal that provided the better corner results as almost any lens is a bit decentered.
In this long-distance test the Sony looks (again) very good. But the drop-off in FF-corner resolution at 70mm focal length remains.
If you want to see all the details and comparisons with the Tamron 70-180mm f2.8 Di III, read on. Or fast-forward to the next chapter on vignetting and distortions.
The main image shows the complete scene wide open to give you an impression of the angle of view and to judge vignetting. Following the main image are 100% crops from the center, APS-C-corner, and FF-corner for each focal length from the Sony FE 70-200mm f2.8 GM OSS down to f11. For comparison I use the Tamron 70-180mm f2.8 Di III shot only minutes apart.
You can access the large originals but please respect our copyright and only use those images for personal use.
Results at 70mm:
In comparison to the Tamron III the Sony FE 70-200mm f2.8 GM OSS looks a bit sharper in the center and the FF-corner but a tad softer in the APS-C-corner.
Results at 105mm:
At 105mm focal length the Sony again has a slight lead in the center but the Tamron III matches it in the corners.
Results at 150mm:
Again the Sony FE 70-200mm f2.8 GM OSS has a slight lead over the new Tamron 70-180mm f2.8 Di III in the center but otherwise both lenses look almost indistinguishable.
Results at 200mm:
At 200mm focal length the Sony FE 70-200mm f2.8 GM OSS has a clear lead in the center at f2.8 and also looks sharper than the Tamron III (at 180mm) in the corners.
In this long-distance test the Sony FE 70-200mm f2.8 GM OSS again performed very well – with the Tamron 70-180mm f2.8 Di III close at its heels. The weakness of the Sony in the FF-corner at 70mm is still there but it actually now looks a little bit sharper than the Tamron .
Vignetting and distortions
To make it easier to see light fall-off in the corners of a full-frame sensor I’ve arranged a series of three shots each at f2.8, f4.0, and f5.6 at 70mm and 200mm focal length. All images were developed to the same brightness in the center (matching the brightness of the surrounding frame) and with the built-in lens profile compensating CA and vignetting:
The sample images above show that even with the lens profile applied vignetting is not completely eliminated. But on the wide end it’s very mild from f4.0 onwards. A strange thing that I didn’t encounter for the first time is that vignetting is slightly stronger at f5.6 than at f4.0 on the long end. This also shows up in JPGs straight out of camera. But I wouldn’t worry too much as the effect is relatively mild. With automatic shading compensation the extreme corners are lifted about 1 EV at 200mm f2.8. Adobe’s RAW converter automatically applies shading compensation as it was set in camera. For comparison see the Tamron 70-180mm f2.8 Di III here which looks very similar.
Distortions are of the barrel type at 70mm focal length and turn to pin-cushion at 200mm (see below). The setting for distortion compensation in camera is currently ignored by Adobe’s RAW converter and treated as OFF. So you have to manually activate Adobe’s lens profile. Just make sure to reduce its vignetting compensation as this is added on top of the already applied shading compensation and leads to artificially bright corners. This is all pretty confusing and I can only hope that one day Adobe and the lens/camera makers can agree upon which part of the lens profile is automatically applied in RAW development and which part has to be activated manually in post-processing. But Adobe’s lens profile at least does a pretty good job to correct for distortions – as does the distortion compensation in camera when you shoot JPGs:
Rendering of point-light sources at night-shots
Night-shots pose a different challenge for lenses as the contrast is even higher than under bright sun and point-light sources can reveal some weaknesses such as coma, haloing and colour-aberrations that do not show up as prominently in other test-shots. The 100% crops below the main image show the effect of coma in the FF-corner of the Sony FE 70-200mm f2.8 GM OSS and the Tamron 70-180mm f2.8 Di III at various apertures:
Both zoom lenses show very little coma at 70mm.
Rendering of out-of-focus point-light sources
This test is for the rendering of point-light sources in an out-of-focus background. The circle of confusion that is produced by this test is pretty indicative of Bokeh performance (in the background) and light fall-off. Ideally the out-of-focus image of the point-light is evenly lit and perfectly circular, with no “onion-rings”, and without coloration. Large aperture lenses normally produce an effect known as “cat’s eye” the further away from the optical axis the point-light is projected. This is due to optical vignetting in the lens barrel when light enters the lens from an angle.
All images were shot at the longest focal length and largest aperture. The new Tamron is first followed by the Tamron 70-180mm f2.8 Di III. Crops are from the center, APS-C-corner, and FF-corner resized to make them comparable across all my reviews.
The biggest visible difference between the lenses above is the larger size of the Bokeh balls from the Sony at 200mm focal length. But that was to be expected due to the 10% smaller entrance pupil of the Tamron III from its shorter focal length of 180mm. The effect is a bit overstated here as I could not exactly match magnification on both lenses for my test. Both lenses show mild onion rings with some additional grainy texture in the Bokeh balls of the Tamron III. Outlining is negligible on both lenses as is coloration. Looking towards the corners both lenses develop a very similar degree of cat’s eye effect – which is quite visible already at the APS-C-corner.
Now let’s see how this analysis of out-of-focus point-light sources translates into Bokeh-performance shooting a book-shelf. Crops are from the foreground, middle-ground, and background resized to make them comparable across all my reviews. I used the longest focal length that I could to produce a comparable shot to my other reviews which was in the case of the Sony 173mm while the Tamron III had to be zoomed in to 165mm to achieve the same magnification from the same distance:
As was to be expected from the night shots both lenses have a very similar background Bokeh. Although to be fair the Sony could produce a better blur when used at 200mm focal length. In the foreground the Sony is slightly more nervous than the Tamron III. The Tamron III also renders the transition zone (middle-ground) with a bit softer edges while the Sony FE 70-200mm f2.8 GM OSS seems to produce a bit stronger but harsher blur. The Sony also shows some greenish coloration from loCA in the middle-ground.
The Sony goes down to 1:3.6 magnification at 200mm which is just a little better than the Tamron III at 180mm. The following images were shot at 1:3.8 magnification where the area of sharp focus is just 137 x 91mm. The crops shown below are from 3mm, 12mm, and 18mm off the center of the sensor respectively:
The Sony FE 70-200mm f2.8 GM OSS produces very usable results when stopped down to f5.6 or f8.0. But the Tamron 70-180mm f2.8 Di III is quite a bit sharper when used at 180mm.
Flare, ghosting, and sun-stars
Catching a strong light-source shining directly into the lens is always a risky business: it could produce strange colorful ghost-images or reduce contrast considerably through flare and glare. The appearance of flare and ghosting depends on factors like the aperture and the angle of the light hitting the lens. So to judge the proclivity of the Sony FE 70-200mm f2.8 GM OSS for these artifacts I went through a series of well calculated shots against a strong light source to provoke glare and ghosting.
The Sony FE 70-200mm f2.8 GM OSS produces some ghosting artifacts at the short end but overall contrast outside these artifacts is not reduced too much through veiling glare. See comparison with the Tamron 70-180mm f2.8 Di III below which shows a much higher level of veiling glare when the light source is within the APS-C image-circle:
The little bright square inset in the upper left of both images shows the respective area with an exposure compensation of +3 EV to make it easier to see which levels of black the lens renders at that point. What you can also see in the images above: Both lenses do not produce well-defined sunstars at f11.
When the light-source is just outside the corner there is an obvious streak/flare at 70mm focal length. Fortunately this only happens in a very small area around the corners:
Next check out my sample images!Check prices on the Sony FE 70-200mm f2.8 at Amazon, B&H, Adorama, or Wex. Alternatively get yourself a copy of my In Camera book or treat me to a coffee! Thanks!