In-camera lens compensation

High resolution sensor are really demanding

when it comes to the resolution of the lens as

well as to shading, chromatic aberration and

distortion which are more important on

DSLMs like the Sony A7 and the Sony

A6000 due to the shorter flange (distance

between sensor and lens mount). Most of

these optical errors can already be corrected

in the construction of the lens for a higher

price (see Zeiss Otus). In-camera lens

compensation is one mean to reduce the costs of lens construction. This article shows the

effects of the three different correction parameters of the in-camera lens compensation on

JPG and RAW based on pictures taken with the combinations of Sony Vario-Tessar® T* FE

16-35mm F4 ZA OSS on the Sony A7 and Sony E 10 – 18mm F4 OSS on the A6000.

Trade-Off

Many DSLR (Digital Single-Lens Reflex) and DSLM (Digital Single-Lens Mirrorless) user

want more and more megapixel; be it the professional photographer who wants the best

possible quality for large prints or be it the ambitious hobby photographer who simply wants

the best gear for his hobby or the beginner who thinks that more resolution is equal to better

pictures.

The trade-off between lens price and quality called „in-camera lens correction“ is fed by the

ambitions of the manufacturer who wants to build the best product possible and the

photographer who wants to use the best possible lens for the lowest price. The most

uncomprising lenses currently available which deliver outstanding image quality on mainly

all available sensors are surely the Otus lenses build by Zeiss. Image quality, which one can

expect at a price level far above the level of $ 3.000. This lens are surely made for the

enthusiasts which have the money and the willingness to pay the price and less interesting for

the professionals that think in economic dimensions or the hobbyist with smaller budget. The

later are rather interested in those lenses found at mid-range price levels which deliver the

best performance in combination with the internal lens corrections – as far as available in the

camera firmware.

A note to the image material

Cameras and lenses

Using a full-frame lens on a camera with APS-C sensor would not really show the real

amount of distortion and shading because the APS-C sensor is only using the good center part

of the full-frame lens. The following drawing shows the relationship of image circle and

sensor size of full-frame and APC-C sensors:

The in-camera lens correction is best shown when using wide-angle focal length and surely in

the outer image areas and corners of the picture. The following combinations of camera and

lens have been used to create as much lens errors as possible:

Sony A7 with Sony Vario-Tessar® T* FE 16-35 mm F4 ZA OSS Sony A6000 with Sony E 10 – 18 mm F4 OSS

RAW and JPG

There is an ongoing discussion whether the in-camera lens correction is applied to RAW

images. All pictures have been made in RAW and JPG each with activated and deactivated

lens correction to find out whether lens correction is applied to RAWs.

All comparable pictures have been taken with the same event of simultaneous shutter release

in Sony A7 and Sony A6000 to create the highest rate of comparability and to avoid

difference in images caused by e.g. cloud moving into sunlight. The cameras have been

mounted as shown in below picture and the shutter was released by a radio trigger.

Analysis of images

Shortly after Sony started selling the lens I wrote a first Hands-on about the Sony Vario-

Tessar® T* FE 16-35mm F4 ZA OSS. In one of the comments of the German version of the

hands-on I was asked about my opinion on the in-camera lens correction – here it is.

Frame 1 – Chromatic aberration

JPG 10-18 Obj.korrektur Aus / lens corr. off PG 10-18 Obj.korrektur Auto / lens corr. auto

RAW 10-18 Obj.korrektur Aus / lens corr. off RAW 10-18 Obj.korrektur Auto / lens corr. auto

SEL 10-18mm F4 OSS, JPG and RAW, mit und ohne Korrektur / with and without correction

The red marked area is used for comparison of JPGs and RAWs:

left: lens correction off | right: lens correction auto

Looking at the crops the JPGs shot with deactivated lens corrections there are green and

purple lines next to the tree branches – as expected. Surprisingly, these chromatic aberrations

are not visible in the RAWs even with deactivated lens correction. Hardly believable, but I

checked all RAWs one by one and this looks like the proof that the correction of CAs can’t

be disabled for RAWs. As a comparison below the the crops from the images shot with the

FE 16-35 mm F4 ZA OSS at 16 mm and at F5.6, because I made a focussing mistake taking

the pictures at F4 which I realised to late, but this does not influence the assessment of

chromatic aberrations.

left: lens correction off | right: lens correction auto

Obviously the FE 16-35mm F4 ZA OSS mounted on alpha 7 shows the same results like the

SEL 10-18mm F4 OSS mounted on alpha 6000 regarding the correction of chromatic

aberrations on RAWs.

Frame 2 and 3 – Shading and distortion

JPG 10-18 Obj.korrektur Aus / lens corr. off JPG 10-18 Obj.korrektur Auto / lens corr. auto

RAW 10-18 Obj.korrektur Aus / lens corr. off RAW 10-18 Obj.korrektur Auto / lens corr. auto

The following pictures show the effect of in-camera lens correction regarding corner shading

and distortion.

SEL 10-18mm F4 OSS @ F4 – JPG:

SEL 10-18mm F4 OSS @ F4 – RAW:

It is easily visible that the correction of shading is applied to the RAWs as well, whereas the

activation or deactivation of the correction of distortion has no effect on the RAWs. The

following comparison between JPG and RAW with deactivated correction of distortion

shows, that JPG and RAW are the same. The small differences in shading are caused by the

selected creative style „Neutral“ and are not related to any lens correction.

Let’s have a look on the same images shot with FE 16-35mm F4 ZA OSS mounted on the

alpha 7.

FE 16-35mm F4 ZA OSS @ F4 – JPG:

FE 16-35mm F4 ZA OSS @ F4 – RAW:

FE 16-35mm F4 ZA OSS @ F4 – JPG+RAW deactivated correction:

There is a lot more image material taken from other subjects and with different apertures and

focal lengths and lens correction activated or deactivated which I did not include in this

article but which I provide as zip-files for download at the end of this post and which can be

used for your own analysis. If you use this material for your own publications I only require

being listed as reference with a link to this post.

Verdict

Pictures are worth more than a thousand words and following this motto the diagramm below

provides an overview on which correction parameter is applied to JPG and RAW when the

lens correction is activated or deactivated (black means that this particular corrections shows

in the pictures).

Two results are quiet suprising: First is that the correction of chromatic aberrations can be

deactivated for RAWs when there is a lens corrections profile for the used lens contained in

the installed firmware and second, that that there is no correction of distortion in RAWs, no

matter whether this parameter is activated. Lens-correction profiles can only be added to the

camera with a new firmware.

The alternative is to use the Sony PlayMemories Camera App „Lens Compensation“ to create

your own profile for lenses not yet supported or that will never be supported (legacy lenses)

by the firmware and automatically apply the lens correction – but this is a different and very

interesting subject.