Let’s start by saying that digital cameras can use native lenses and foreign ones. Native lenses are those made specially for the camera or its family and while the lenses may need some assistance from the software this is usually done automatically especially for geometric distortions and colour aberrations. Foreign lenses are those that need an adapter to be used with the camera and these adapters can be simple tubes to produce the correct flange back distance in order for the lens to focus properly to infinity or can be adapters with lenses and/or electronics to provide aperture and other control where there is no mechanical option for this.
There are four aberrations or effects that may require compensation. Geometric ones that create barrel or pincushion distortions; colour fringing ones that produce false colours (red or blue but usually a mixture of the two) adjacent to picture elements in highly contrasty scenes; vignetting ones that darken the corners and edges of a frame usually associated with very wide angle lenses; and colour shading ones that occur as a result of the rear lens element being very close to the sensor. Any lens can suffer from the first three of these. Geometric ones usually occur at the extremes of zoom ranges and can easily be fixed in editing software and the same goes for colour fringing ones and vignetting is lessened by choosing a narrow aperture. Colour shading is usually confined to wide angle lenses made for the Leica rangefinder cameras with a focal length of less than 35 mm where the lens is designed to be symmetrical rather than retrofocus. Principally these were and are designed by Zeiss or Cosina though there are “pancake” lenses designed by Leitz that also suffer from the effect. There is no easy way to remove colour shading in editing software other than by making an image that shows only the false colour and vignetting and using specialised software to effect a subtractive process.
Fujifilm, for its cameras that use the X-Trans sensor, sells an adapter to mount Leica M lenses on the cameras that has a button which enters a routine whereby the user may set the amount of vignetting that should be removed and use a slider to set the level at which the colour shading is likely to disappear. These sliders are in the range cyan to magenta and blue to yellow and only one may be used. If you have cyan shading then you move the slider towards the magenta, take a picture, inspect the result, go back and make alteration if necessary and finally save the settings Each corner may have a different shading setting if required. It’s not difficult to set up. Four pre-allocated slots are for 21, 24, 28 and 35 mm lenses and there are two more where you can set the focal length yourself that I use for my 12 and 15 mm lenses.
Sony has the same basic system but it is driven by an application from the “Play Memories” series that costs US$ 10. Plug your A7(r) into your computer via USB, use your browser to go to https://www.playmemoriescameraapps.com/portal/ , join the Sony Entertainment Network if you have to, pay for the Lens Compensation app and have it downloaded to your camera. You will use this app not only to create a profile for your lens but to take the shot when using the lens.
When you profile your lens you need to give it a name you will recognise it by, fill in the focal length and also the aperture that you will be using. I usually start at an aperture two stops down from wide open. You can create a profile for as many apertures for a lens as you need or like but the compensation doesn’t seem to be over sensitive to aperture and one stop either way seems OK. Make sure you have Live View Display in the main menu set to Setting Effect ON because then all the settings give visual feedback on the LCD so it is easy to make a profile. It is possible to give settings for both cyan-magenta and blue-yellow but if you do you will confuse the app and yourself.
You will probably find your first attempts at a profile make the corners brighter than they should be. I think it’s good to leave a little vignetting but eliminate all the colour shading. Note here that the Sony app does not provide the option for separate settings for each corner.
Before you shoot using a profile, check the settings as the app will have saved the previous ones but do realise that this is very useful as it provides a way of having custom settings on a per-lens basis. You are only limited by camera memory, of which there is plenty, in the amount of profiles you can store and profiles are dynamic insofar as you can edit them or delete any. Because it is an application Sony can introduce new features much more quickly than if it had to form part of a firmware update. It’s a smart way to extend functionality and it works very well.