Sony RX100 M4: Lens

Lens Characteristics in Short | A Few Technical Data | Some Quotations from Lens Reviews | References

On this page, I would like to discuss one the specific characteristics that lead us to buy the Sony RX100 M4, namely the lens. I investigate what the available test results and the reviewers say, and I also offer links to camera reviews.

Lens Characteristics in Short

The Sony RX100 M4 features a fixed Carl Zeiss® Vario-Sonnar T* 8.8-25.7mm (24-70 mm equiv.) f/1.8- f/2.8 lens with a zoom range of 2.9 x (10 elements in 9 groups, including AA lens). Thus, it offers the equivalence of five "classic" prime lenses: 24 mm, 28 mm, 35 mm, 50 mm, and 70 mm. Zoom is set using the zoom lever or using the control ring around the lens (this is configurable). Manual distance is set using the control ring. There are no marks on the lens, and the camera regrettably lacks distance and depth of field indicators on the LCD screen (only a coarse distance scale is shown when focusing manually).

Figures: The lens in "off" state from the front (left) and in the "on" state from above (right)

The lens does not have a filter thread for attaching filters or close-up lenses. Sony offers an adapter that you can glue to the lens (VFA-49R1 49-mm filter adapter), but does not recommend it for the newer models (only for the models 1 and 2). Lensmate offer a similar adapter, and I ordered one from the U.S. It is said to be on its way (and also has to go through the customs)...

Find more technical information about the lens below.

In-Camera Correction of Lens Deficits

All lens designs are a compromise between different requirements and therefore have certain deficits - the Sony RX100 M4's lens is no exception to this rule. Therefore, the lens's deficits are corrected in software for JPG images, but not for RAW images (ARW format).

A Few Technical Data

Data	Sony RX100 M4	Comment
Lens	Carl Zeiss® Vario-Sonnar T* 8.8-25.7 mm (24-70 mm equiv.) f/1.8-f/2.8 10 elements in 9 groups ( including AA lens)	The number of elements was taken from Ken Rockwell's site; I am not sure as to whether this data is valid.
Zoom	Optical Zoom: 2.9 x Clear (Image) Zoom: 20 MP approx. 5.8 x / 10 MP approx. 8.2 x / 5 MP approx. 11 x / VGA approx. 44 x Digital Zoom: up to 11 x	There are two types of digital zoom: Clear (Image) Zoom (higher quality, lower range), and Digital Zoom (lower quality, wider range)
Filter diameter	None	Use the Lensmate filter adapter to attach filters and close-up lenses (the Sony filter adapter VFA-49R1 does not seem to be compatible)
Aperture range	From f/1.8 to f/11 (at 24 mm) / f/2.8 to f/11 (at 70 mm) in 1/3 EV increments
Distance setting range	iAuto: AF (W: Approx. 5cm (0.17 ft.) to Infinity, T: Approx. 30cm (0.99 ft.) to Infinity) Program Auto: AF (W: Approx. 5cm (0.17 ft.) to Infinity, T: Approx. 30cm (0.99 ft.) to Infinity)	Macro is only practically usable at the wide end.
Smallest object field	W: Approx. 99 x 66 mm (according to own tests - do not take this too seriously)	Magnification: 0.132 (without close-up lens)

Maximum Aperture Versus Focal Length

This is what I found out:

Focal Length (mm)
Equivalent	24	28	35	50	70
Actual	8.8	10.3	12.8	18.3	25.7
Maximum f-stop	1.8	2.5	2.8	2.8	2.8

Minimum Object Width and Zoom

I also tested the minimum distance and thus, the minimum object width, for some "standard" focal lengths (equivalent). Without showing the respective photos here, I list the minimum object widths for these focal lengths:

24 mm: approx. 100 mm (at 5 cm object distance according to camera, not measured)
28 mm: approx. 140 mm (at 9 cm object distance according to camera, not measured)
35 mm: approx. 190 mm (at 20 cm object distance according to camera, not measured)
50 mm: approx. 210 mm (at 30 cm object distance according to camera, not measured)
70 mm: approx. 162 mm (at 30 cm object distance according to camera, not measured)

These are just coarse numbers, because I did not do "controlled" tests (these tests were done with autofocus).

Sharpness Data

See the Lens Reviews below.

Some Quotations from Lens Reviews

In the following, I cite a few sections about the lens of the Sony RX100 M4 from reviews that I found on the Internet. This selection is, of course arbitrary, but may help readers gain a certain "feeling" for the lens.

dpreview.com

On the "Lens Performance" page (page 13) of its review of the Sony RX100 M4, dpreview.com uses the images taken with the RX100 M3 because the lenses are identical. I also cannot find any resolution data in this test; the same applies to the test of the RX100 M3.

Here are two quotations from the camera review:

Sony has chosen to make a trade-off between brightness and zoom range, offering a much more consistently bright lens than its predecessors, but losing some reach to avoid the camera becoming too big. (page 13)
... This makes it much more comparable with the Panasonic LX100, which is also pretty impressive, wide-open, at both the wide-angle and telephoto extremes of its zoom range. The difference, of course, is that the Sony brings significantly greater resolution to the table, which you can still see even when the images are compared at a common output size. (page 13)
The RX100 IV offers some of the best image quality you can get from a camera this size. We were hoping for low-light improvements from potentially larger active pixel area due to the stacked sensor, but image quality is not noticeably improved compared to the Mark III. That's sort of a compliment though, given the class-defining image quality of the sensor in the RX100 III in combination with the bright 24-70mm equivalent lens, which we found to be sharp even wide open over a large portion of its focal length range. (page 16)

dpreview Studio Shot Comparison Tool - New Version

More detailed test results, but not really any words on the lens, can be found on the "Studio Comparison" page (page 14) of the Sony RX100 M4 review. This camera was tested with the new studio shot comparison tool, which no longer includes a "resolution" test (which is probably the reason for the missing resolution data mentioned above). The new test tool allows even a comparison with the RX100 M1, although there is no direct access to the test shots for this camera:

Sony RX100 M4 review ("Studio Comparison" page): www.dpreview.com/reviews/sony-cybershot-dsc-rx100-iv/14
General access to the new studio image/shot comparison tool: www.dpreview.com/reviews/image-comparison (select the Sony RX100 M4 as primary camera, e.g. the Sony RX100 M1 as secondary camera; all RX100 models are available in this tool)

Again, the results are meant that you make up your own opinion on the lens...

digitalkamera.de (Free and Pay Content)

The German photography Website digitalkamera.de published a test of the Sony RX100 M4 (in German, performed with DxOMark software). Here is an excerpt of the result for the lens (too long for translation...):

Dass das F1,8-2,8 lichtstarke 24-70mm-Objektiv (alle Brennweitenangaben entsprechend Kleinbild) bei allen Blenden und Brennweiten am 20-Megapixel-Sensor ausreichend scharfe Bilder von der Bildmitte bis zum Bildrand für 20 mal 30 Zentimeter große Ausdrucke bietet, verwundert nicht. Dabei bleibt die Randabdunklung mit maximal 36 Prozent (0,6 Blendenstufen) stets gering, auch die Verzeichnung spielt keine Rolle. Selbst Farbsäume finden auf einem nur sehr geringen Level statt, so dass von einer digitalen Korrektur optischer Fehler ausgegangen werden muss, die hervorragende Arbeit leistet. Bei der Messung der tatsächlichen Auflösung bei 50 Prozent Kontrast (MTF50) zeigen sich schon eher die Stärken und Schwächen des Objektivs. Bis zu 60 Linienpaare pro Millimeter (lp/mm, Kleinbild-Äquivalent) löst es auf, was für einen physikalisch 20 Megapixel auflösenden Sensor sehr gut ist. Dieses Maximum wird im Weitwinkel bei F4 erreicht. Bei Offenblende löst das Objektiv im Weitwinkel etwas geringer, aber mit deutlich über 50 lp/mm ebenfalls sehr gut auf. Ab F5,6 setzt bereits Beugung ein, die vor allem bei der kleinsten Blende F11 deutlich zuschlägt und die Auflösung auf 47 lp/mm drückt. Am Bildrand löst das Objektiv im Weitwinkel zwar stets über 30, aber nie über 40 lp/mm auf und zeigt damit bei größeren Ausdrucken einen sichtbaren Randabfall.
Beim Zoomen steigt zwar die Randauflösung, dafür fällt aber auch die Auflösung im Bildzentrum. Je mehr man zoomt, desto gleichmäßiger wird die Auflösung also. Bei mittlerer Brennweite braucht es schon die Beugung, um die Auflösung bei Blenden kleiner F8 auf unter 50 lp/mm zu drücken. Das Maximum von 54 lp/mm liegt bei F4 an. Die Randauflösung liegt, mit Ausnahme von F11, stets über 40 lp/mm bei einem Maximum von 43 lp/mm bei F5,6. In Telestellung muss das Objektiv auf F5,6 abgeblendet werden, um die bei 45 lp/mm startende Auflösungskurve über die Marke von 50 lp/mm zu heben. Bei F5,6 wird mit 52 lp/mm das Maximum erreicht, beim weiteren Abblenden setzt die Beugung ein. Am Bildrand werden in Telestellung sowohl bei F2,8 als auch bei F5,6 jeweils 46 lp/mm erreicht, was für das gesamte Objektiv die maximale Randauflösung darstellt.
Das Objektiv kann sich also durchaus sehen lassen. Die Auflösung liegt sogar leicht über der von der RX100 III, wobei die IV jedoch auch etwas stärkere Schärfeartefakte zeigt. Damit liefert das Objektiv für ein Kompaktkamerazoom teilweise sehr gute Werte ab.

The lp/mm values have been scaled to 35 mm values, but I do not quite understand what this means.

They also published a thorough technical lab test of the Sony RX100 M4 (in German), which can be downloaded for a fee from this page. Since this is pay content, I cannot report on this test here.

Sony RX100 IV Review on Imaging Resource

The following citations were taken from the Sony RX100 Review on Imaging Resource (page Optics):

Zoom: A shorter than average zoom, with above average performance.
Details: Far-field performance in general is quite good at f/5.6 as shown above, with very good sharpness and contrast across most of the frame, low chromatic aberration (the RX100 IV suppresses it) and only minor softening and coma distortion in the corners at full wide angle. Performance at full telephoto is also quite good with good sharpness and contrast across almost the entire frame, though some vignetting can be see in the extreme corners.
Macro: A larger than average sized minimum coverage area, with very good detail. Flash throttled down well, but the lens casts a large shadow at minimum distance.
Details: The Sony RX100 IV captured a larger than average sized minimum area measuring 3.83 x 2.55 inches (97 x 65 millimeters) at maximum wide angle. Sharpness over much of the frame is very good, but corners show quite a bit of softness even at f/8 (most lenses show some softening in the corners at macro distances). The flash did a good job throttling down, but the lens casts a large shadow in the bottom half of the frame. You'll likely want to use external lighting for the closest RX100 IV macro shots.
Geometric Distortion: Very low distortion in camera JPEGs, but very high in uncorrected RAW files at wide angle.
Chromatic Aberration and Corner Sharpness: Very low to moderately low chromatic aberration in JPEGs. The lens produces some soft corners wide-open, though corner sharpness improves stopped-down.

Sony RX100 IV Review (Amy Davies, TechRadar)

Resolution:

The resolution chart shows values from about 28 (line widths per picture height x100) for JPEG and RAW files between ISO 100 and 400 to about 23 at ISO 6400 and 16 at ISO 12800.
>> That is, 2800 lines/picture height, and so on.

Sony RX100 IV Review (Nasim Mansurov, Photography Life)

Starting from the RX100 III, Sony decided to change the lens out for a 24-70mm equivalent lens with an aperture range of f/1.8 to f/2.8. This was surely a welcome move for several reasons. First, those 4mm of wider coverage make a huge difference when one needs to fit more of the scene into the frame. Second, the reduced focal length range allowed Sony to design the lens with better overall performance, giving more even sharpness across the frame from 24mm all the way to 70mm. And lastly, the larger maximum aperture of f/2.8 at 70mm is not as limiting as f/4.9 anymore, which when coupled with the excellent image stabilization and Auto ISO capabilities allows the camera to be used hand-held in low-light environments, without blurring images due to camera shake. For me personally, shooting with a 24-70mm equivalent lens really hit home, because that’s the zoom range I use the most when shooting landscapes with my full-frame cameras.
Optically, the lens is very good. The extreme corners are a bit soft, especially at the long end, but it is not too bad. The camera does a great job at correcting distortion exhibited by the lens, so if you shoot JPEG, you will not see any signs of it. If you shoot RAW and use software like Lightroom, optical corrections will be automatically applied to all images, so you won’t have to worry about issues like distortion and chromatic aberration. However, if you use other RAW processing software, you might be surprised to see pretty hideous amounts of barrel distortion at 24mm and a bit of pincushion distortion towards the telephoto range. The same goes for chromatic aberration – it is very noticeable in uncorrected RAW files.
When it comes to ghosting and flare, the lens does a pretty decent job at handling very bright objects in the frame such as the sun. However, if the light source is very bright, you might see discolorations and other artifacts in images.

References

The following online reviews of the Sony RX100 M4 typically include a review of the lens:

Review of Sony RX100 M4 on dpreview.com: www.dpreview.com/reviews/sony-cybershot-dsc-rx100-iv
Review of Sony RX100 M5 on dpreview.com: www.dpreview.com/reviews/sony-cybershot-dsc-rx100-v-review
Sony RX100 Mk IV (Ken Rockwell): www.kenrockwell.com/sony/rx100-mk-iv.htm
Sony RX100 IV Review (Imaging Resource): www.imaging-resource.com/PRODS/sony-rx100-iv/sony-rx100-ivA.HTM
Sony Cyber-shot DSC-RX100 IV: Tests and Reviews (DxOMark): www.dxomark.com/Cameras/Sony/Cyber-shot-DSC-RX100-IV
Sony Cyber-shot DSC-RX100 V: Tests and Reviews (DxOMark): www.dxomark.com/Cameras/Sony/Cyber-shot-DSC-RX100-V
Testbericht Sony DSC-RX100 IV (digitalkamera.de): www.digitalkamera.de/Testbericht/Sony_Cyber-shot_DSC-RX100_IV/9920.aspx (in German)
Labortest-Protokoll Version 6.1 - Sony DSC-RX100 IV (digitalkamera.de; pay content): www.digitalkamera.de/Labortest/Test.aspx?ContentId=10559 (page for paying and downloading the test; in German)
Sony RX100 IV Review (Amy Davies, TechRadar): www.techradar.com/reviews/cameras-and-camcorders/cameras/compact-cameras/sony-rx100-iv-1302751/review
Sony RX100 IV Review (Nasim Mansurov, Photography Life): photographylife.com/reviews/sony-rx100-iv