It’s no secret that all lenses are a compromise from the ideal. Compromise might be weight, size, aperture, focal length, zoom range, quality, ruggedness, Image Stabilizer, close focus distance , price even but they are all still trade-offs.
If the mythical Canon TS-EF 8-1200mm f/1L 1.4x Extender Macro IS USM STM is ever to see the light of day, and be the size of a typical can of fizzy drink and weigh the same, it certainly won’t be cheap. Equip it with a 20-blade aperture assembly for super smooth bokeh at all kinds of aperture settings from the maximum of f/1 to f/90 and you just know i’m talking rubbish.
However Canon lens division, if this lens is in your sights please let me have one to test 🙂
Better pictures straight out of camera?
The comparison above shows how my EF 24mm f/1.4L USM (the older one) creates a vignette that often adds to the pictures. Indeed many people process their pictures and add a ‘creative vignette’ to pictures as a matter of standard presets. I’ve heard tales of photojournalists using older lenses for their vignetting effect, since they aren’t permitted to do such post processing effects in Photoshop.
Peripheral illumination correction – it’s like the software engineers were able to read the lens department’s secret book of “Lens Compromises” and decided to fix the certain lens characteristics using DIGIC processorsFor film cameras it was quite normal for a consumer mini-lab to not print the whole negative to ensure that prints were truly borderless. Not using a few millimetres around the edge of the negative was quite normal, camera makers knew this and in some cases made lenses that were less than perfect all the way to the edge of the frame in the drive to make ever cheaper lenses, kit lenses especially.
I once tried an old film era kit lens on an EOS-1Ds Mark III and could see visible vignetting in the viewfinder!
Digital SLR’s with their full-frame sensors use all of the image circle right to the edge, but they can process the pictures and correct the small imperfections in camera. Way back in time Canon started to implement a feature called Peripheral Illumination Correction in the camera bodies. In short this feature reversed the effect of vignetting for certain older lenses, over time the feature has added Chromatic Aberration Correction with the advent of DIGIC 5 image processors.
However with a vast array of lenses in Canon’s current and back catalogue, way over 100 lenses, there’s little chance to be able to install all the profiles of vignetting and chromatic aberration correction needed in each camera. EOS cameras have space to store up to forty lens profiles and typically come from the factory with 26 appropriate profiles loaded. The exact ones depend on the camera, EF-S lenses are only pre-loaded in APS-C sensor cameras for example. Also some of those old kit lenses are pre-loaded since they need more help than the newer lenses.
Each lens is unique
Each lens is unique, and it’s characteristics change depending on several factors including subject distance, focal length (in the case of zoom lenses) and even aperture. By linking lens and in-camera processing EOS cameras can get the best performance from even less than ideal Canon EF or EF-S lenses. It’s important that you set your camera to work with the lenses you use.
Use EOS Utility to load new lens profiles
Connect your camera to Canon’s EOS Utility Software and you can change any of the installed lens profiles, add or remove as you like. I usually go round my cameras and make sure that all the lenses I have to hand and the ones I commonly rent/loan are all installed.
Actually as new versions of EOS Utility come out then often new lenses are added to the profiles available. Certainly the new EF 24-70mm f/2.8L II USM lens wasn’t available when the EOS 7D was created, yet using EOS Utility version 2.12.0 on my Mac I can add it as a profile in the EOS 7D. For some cameras you also might need to make sure the camera is running the latest firmware, EOS Network keeps a very useful page of latest firmware versions for all EOS cameras.
JPEG images only
The in camera image enhancement only happens for JPEG images, in the case of RAW images the EOS cameras put a note in the metadata and then it’s down to the RAW converter you use. If you use Canon’s RAW converter Digital Photo Professional then it will read the values and you can reduce or increase the effect, even switch it off completely.
Recently Canon also introduced a new kind of lens improvement, Digital Lens Optimiser, this is for RAW images only and counters many more effects including diffraction loss (softening of images at small apertures). Read more about that in my earlier post Improving image quality with Digital Lens Optimiser in DPP.
Third party lenses and lens correction
Since Canon doesn’t license the EF lens mount protocol to third party lens makers, they reverse engineer it. This means that in many cases lenses from Sigma, Tamron, Tokina et al masquerade as a Canon lens – you might say they use a fake id 🙂 – and this can cause trouble.
The guys at LensRentals did
some a lot of testing earlier this year and found some interesting results. I think the different response for some lenses on different bodies is down to the default lenses configured by Canon in each camera as it leaves the factory. So if you do use a third party lens you might want to consider if the camera should process it as if it was the Canon lens or not by setting the correction on or off and/or removing the lens from the camera’s 40 stored profiles.