Professionals live or die by the high standards of their work, so if you’ve spent thousands on top quality glass and results are soft then you need to calibrate. Richard Bradbury explains. WORDS RICHARD BRADBURY
SO, YOU’VE TAKEN a killer closeup portrait, caught in that special moment of love, laughter and joy that your client will remember forever. You focus on the eyes at f/1.4 for that beautiful bokeh effect, softening the skin texture and pulling the viewer’s attention into the soul of your subject. Shooting with your trusted 85mm prime at 1/200sec guarantees no camera shake and ISO 100 will give a clean, noise free, super sharp capture: what could go wrong?
Loading up your session to your desktop you wait with anticipation only to find that the subject’s eyelashes are sharp but the eye is definitely a little soft. You swear blind that you focused on the eye so why has the point of focus jumped forward?
These are the tell-tale signs of lensto-camera misalignment. Front or back focusing traits are incredibly frustrating but, sadly, remarkably, fairly common, and they can ruin your images and cost you sales.
It can happen to any DSLR with any lens and any camera body, so don’t despair. The good news is that it can be resolved by mastering the dark art of lens calibration.
There are a few reasons why misalignment can happen. It can be something that has simply developed over time, especially if your system is well used. As a professional, your kit does take a beating, so it’s hardly a surprise that the delicate components can be jolted and moved by tiny amounts over time.
It’s also perfectly possible that a brandnew camera and lens from a respected brand can be misaligned straight out of the box. Manufacturers like Canon and Nikon are used to building high precision equipment, but they all have allowable tolerances. If those tolerances have an accuracy rating of, let’s say, +3 to –3 (I’m making that figure up by the way) then it’s perfectly possible that a lens can be –3
and a camera body can be +3. This, in turn, equates to an unacceptable level of misalignment, which becomes visible when shooting in extreme circumstances, especially if the lens is also set to its widest aperture. You probably won’t notice this if you’re shooting landscapes or wide-angle scenes at weddings set to f/11 or more but, for anything shot at f/2.8 or wider, the chances are that you’re going to see the difference.
Sharpness in your final image is arguably the most important technical factor of all. The wonders of post-production software can adjust exposure, colour balance, contrast and composition but even the most skilful Photoshop technician can’t make a soft image sharp. So how does a DSLR attain sharp focus and how can we ensure that all our lens and camera combinations give us those pin sharp results time after time, even in the most critical of conditions? All will be explained!
CHOOSE YOUR OPTION
There are essentially three options for calibration, with each one you choose being more accurate than the next.
IN SIMPLE TERMS you can carry out calibration yourself. Set your camera to factory basic settings in manual metering mode and make sure you turn off any setting that will aid or enhance the focusing, such as image stabilisation.
Then you need to lay out a piece of white card on the floor and position your camera on a tripod at around 45-degrees from the centre of the card. Draw a thin black line horizontal to the camera in the
LEFT TOP: This image was focused on the eye but close inspection shows that the focus point is actually on the eyebrows. This is an example of the camera ‘Front Focusing’.
LEFT BELOW: You can see now that the eye is perfectly sharp. It’s subtle but very important if you want to blow up the final print.
centre of the card and, using a suitable bright light source, adjust your setting for the finest ISO (50-100 ISO) and set the lens to its widest aperture. Looking through the viewfinder, set the focus mode to Centre Focusing and autofocus to AF-S (single focus not continuous). Then you need to auto and focus the lens on the line, and it is best to do this
with a remote shutter release, so as not to affect the critical camera set up with minute camera movements. Now lay a ruler crossing the line vertically, just off centre, away from the camera with the 10cm mark aligned with the line. Finally you need to shoot an image.
Zooming in on the image within the viewing screen you should see the 10cm mark pin sharp. If 11 or 9 is sharper than 10, then you have a back or front focus problem. Now go to your camera menu and look up the Autofocus AF settings. Every camera is different but most highend professional models will have an AF fine adjustment setting.
ABOVE, LEFT TO RIGHT: Here I made a Micro Adjustment of minus 10. Throw the camera out of focus then auto focus again on 10. The resulting image should be perfectly sharp on number 10. The camera will then remember the adjustment you’ve made for that lens.
Nikon – AF Fine Tune
Canon – AF Microadjustment
Sony – AF Micro Adjustment
Pentax – AF Adjustment
Olympus – AF Focus Adjust
They normally show a graph line with +20 to -20 allowances. If you are front focusing you need to set plus settings,
You can also buy specific focus targets designed solely for the purpose of calibration, such as the Datacolor SpyderLenscal. It’s durable, has a screw thread mount to fix on a studio stand and can be folded away to store. It includes a built-in bubble spirit level to enable you to accurately set up on the same plane as your camera shooting horizontally at eye level. Cost is around £60, very reasonable when it can be used time and again for accurate manual calibration of lenses.
■ Datacolor SpyderLensCal:
YOU CAN NOW purchase software that will essentially do everything that the manual calibration does, only better. The market leader in the home calibration game is Reikan FoCal. FoCal has been around for a few years now and it’s constantly being updated. It can be downloaded for Mac or PC and it will come in various different guises, from Basic all the way through to Pro.
To operate the software you’ll need to download and print out their bespoke target or you can purchase a pack of pre-printed targets that come in various sizes. You need to set up the camera and target in a well-lit environment with your camera in Aperture priority (AV). The distance from camera to target is specified for each different lens and you will then need to connect the camera to your computer via the usual tethering cable.
Once connected you’ll be guided through the process with varying degrees of automation, depending on the camera you’re using. At the highest level the software will take over the camera operation entirely, shooting and adjusting as it goes, but most models require you to make adjustments manually at the request of FoCal’s funny computerised voice.
You usually have to undertake several settings and re-settings as it tests to find the perfect sweet spot. Finally, you can see the target before and after to be sure you are now shooting sharp. The basic software currently retails at £39.95, with the Pro version at £69.95. Pro gives a few extra options, such as multi point focus, dust analysis and stabiliser testing. It also allows historic test analysis, which can be very useful over time.
Other software options include Michael Tapes Design – Focus Tune. This requires you to shoot a very large number of comparable images, around 45 each time, at ever more finite stages. I’m sure the results are good but it looks like a lot of work.
MOST OF US SPEND large amounts of money on our cameras and lenses and it’s ridiculous to think that these expensive pieces of kit with thousands of delicate working parts do not deserve to be regularly serviced.
Should you do it yourself? To my mind you’re best off spending your time taking photographs, not fixing your misaligned kit. Don’t get me wrong: the manual and software options already explained are perfectly adequate for most situations, but how long do you really want to spend adjusting your kit and, more importantly, do you really think you know more about it than a trained technician might do?
There are many reasons why your equipment may not be performing as it should, and no amount of calibration is ever going to be able to fix a badly bashed lens element that has gone and moved inside the barrel.
Just over a year ago I had a zoom lens that just kept on misfocusing. I tried everything but eventually handed it to Fixation in London (they also have a base in Manchester). They took the lens in and quickly assessed the problem as a dislodged element, and it was returned like new just days later. Fixation is very well respected as a repair shop and an equipment dealer, both new and second hand. Many camera manufacturers use Fixation for their own overflow work and I can vouch for the fact that they really know their stuff. You can also get your kit cleaned and serviced at the same time.
Based in the town of West Chiltington in West Sussex, Cameracal is a good example of a business set up for the sole purpose of camera-to-lens calibration. Cameracal offer various full-service options or you can choose to simply calibrate one camera and lens. They have a comprehensive website explaining the principles as well as the importance of the calibration process and I’ve found that they have a refreshingly open book attitude to what they do.
Joe Orlando from Cameracal is keen to stress the key importance of good servicing. “Most of our regular clients calibrate their equipment every 12-24 months,” he told me. “It depends on the usage and, of course, how critical fine focusing is to the photographer. Many professionals will buy second-hand lenses to complement their existing kit, but for some of the sports and nature guys that still means an outlay of eight to ten thousand pounds for a lens. If that lens has travelled around with its previous owner then it’s going to need calibrating, and that’s money well spent.”
Cameracal also offers a diagnostic service as well as professional sensor cleaning and fixed price annual service packages, and it’s excellent support.
CAMERA FOCUS SUPPORT SERVICES
Moving west to Cardiff you will find Camera Focus Support Services. In many photographic circles and societies, the name Jon Mullins is synonymous with technical excellence. He launched CFSS just over five years ago, and CFSS were the first to offer a Peli transport case as part of their fully insured courier service
They now offer a guaranteed three-day turnaround on all booked sessions and can offer the professional an even faster turnaround service on request.
Jon specialises in mainly Canon and Nikon equipment, but is also happy to calibrate independent lenses from the likes of Sigma, Tamron, Tokina and Samyang. “It’s true that people can do their own calibration,” he told me, “but there’s no replacement for experience. We can calibrate top end zooms at both extremes and even identify the sharpest sweet spot aperture of an individual lens. There’s a lot more to it than just plugging it in and pressing a button.”
In the end it’s usually true to say that you get what you pay for. If you’re the DIY type then go for it! But if, like me, you like riding your bike more than you like pumping up the tyres then I recommend you leave it to the experts.
If you’ve never calibrated your lenses and camera bodies then it would certainly pay you to give this critical subject some attention. You might just be a little surprised at what you find.
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