In summary
Autofocusing is one of the most important features of modern cameras but there can be times when the camera’s system doesn’t quite hit the target and images end up being slightly soft.
Datacolor’s SpyderLensCal enables photographers to check whether their lenses are focusing precisely without having to send the camera and lens in for service.
This tool is particularly useful when your camera is able to store AF correction data for several lenses because it enables you to store corrections in your camera’s custom settings.
Full review
Autofocusing is one of the most important features of modern cameras but there can be times when the camera’s system doesn’t quite hit the target and images end up being slightly soft.
Datacolor’s SpyderLensCal enables photographers to check whether their lenses are focusing precisely without having to send the camera and lens in for service.
This tool is particularly useful when your camera is able to store AF correction data for several lenses because it enables you to store corrections in your camera’s custom settings.
The SpyderLensCal set up for use. (Source: Datacolor.)
The SpyderLensCal device is made from lightweight plastic and includes a focus target and a calibration scale that is set up at a 45-degree angle on a base. The base has a standard metal-lined tripod socket and an integrated bubble level.
The flat target has a sharp, high contrast, black and white design, while the calibration scale is marked off in black horizontal lines. The numbered lines (six on each side of the zero position) are separated by intervals of roughly 15 mm, which equates to 10 mm when seen from the camera’s perspective. Intermediate lines are printed at five mm and one mm intervals (again from the camera’s perspective).
The SpyderLensCal comes in a flat package that also contains a multi-lingual ‘Quick Start Guide’ and promotional ‘Thank you’ card. (Source: Datacolor.)
A printed, multi-lingual ‘Quick Start Guide’ is included, providing a brief summary of the steps involved in setting up the target, evaluating the results and making adjustments. It also outlines warranty registration and product support.
There are additional resources on the Datacolor web site, and you will also need to know how to set individual AF adjustments on your own camera. Nothing else is required, except for some way to align the camera to the target and keep both steady while test shots are taken and assessments made.
Who’s it for?
The SpyderLensCal is best used with cameras that support AF micro-adjustment, a function that is provided in most of the latest professional and enthusiast models ““ both DSLR and CSC.
Datacolor provides a list of cameras in the information supplied on its website. The list includes DSLR cameras from Canon, Nikon, Olympus, Pentax and Sony, although at the time of review it hasn’t been updated since July 2012 and it doesn’t include any mirrorless CSCs, which means users of more recent cameras will need to check their own gear.
The SpyderLensCal can also be used for checking interchangeable-lens camera without AF micro-adjustment. If you find lenses that consistently mis-focus on different camera bodies, it indicates a problem with the lens. Similarly, if your camera mis-focuses by a similar amount with every lens you test, it’s a good sign that it might need servicing.
Setting Up
Choose a location with appropriate lighting. It doesn’t matter whether you are indoors or out as long as most of the light comes from in front of the target. Avoid backlit situations, wherever possible. A studio setup can make testing easy, although it’s not essential since ambient lighting can be used very successfully.
Setting up the SpyderLensCal is simple; the target hinges up and is locked in place by the ruler to be perpendicular to the base, as shown in the illustration below. A moulded ridge on the underside of the ruler sits behind the extension on the side of the target (which cradles the ruler when the target is packed flat) to line up the zero position on the ruler with the centre line of the target.
A typical indoor set-up for testing camera/lens combinations with the SpyderLensCal.
The SpyderLensCal and your camera must be set up in parallel positions, at the same height, with the front of the lens parallel to the face of the target. You may need a spirit level to achieve this, although many cameras come with level indicators that can be displayed on the monitor screen.
The camera should be mounted on a tripod but the target can be attached to a tripod or simply stood on a flat and level surface. Use the bubble level on the base of the target to ensure it is totally flat. Make sure the centre of the camera’s monitor screen is in line with the central line on the target and you can see the full width of the ruler in the frame.
DataColor recommends you set up your testing with the distance between the camera and the target is the same as the distance you would normally use for shooting images with the lens you’re testing. However, we found it easiest to set up the camera so the target covers between half and one quarter of the viewfinder/monitor screen. This allows you to test several focal length settings on a zoom lens without having to move the camera.
The zero mark on the ruler should be aligned with the main horizontal lines across the centre of the target.
Set your camera to the aperture priority or manual shooting mode and the lowest ISO setting the camera supports. Maximize the camera’s contrast and sharpness settings to make the readings of the SpyderLensCal easy to see. Switch off any stabilisation systems in either the camera or the lens and use mirror lock-up if it’s available. Set the aperture of the lens you are testing to its widest value and use the self-timer to trigger the exposure to minimise the effects of any possible vibrations.
The red box emulates the AF sensor position for focusing on the target.
Select the single-point AF mode and focus the lens on the small bulls-eye on the target, just to the left of the ruler’s edge. If you can see a red dot or box in the centre square of the target in the viewfinder, the camera’s AF system has locked onto it.
Take a shot and review it on the camera’s monitor screen. Zoom in as tightly as you can on the section of the ruler next to the target, examining the lines and numbers to determine which one is sharpest. This mark represents the centre of focus as determined by your camera and lens AF systems. If the monitor image isn’t large enough to let you see differences in sharpness between adjacent lines, transfer the image file to your computer and view it on a larger screen.
If your camera and lens are correctly calibrated, the line at the zero position (0) should be in sharp focus. If one of the lines behind the zero mark is sharper, the lens is back-focusing; if a line in front of the zero mark is sharper, the lens is front-focusing.
The illustration above shows a camera/lens combination that is correctly calibrated.
Open the AF calibration page in your camera’s menu and select the ‘Adjust by lens’ function. The lines on the SpyderLensCal ruler indicate precisely how many millimeters the camera is front or back focusing. This lets you correct the focus millimeter by millimeter, moving forward for front-focusing or back for back-focusing adjustments. Note that the numbers on the ruler do not correlate to the numbers in the adjustment menu on the camera.
The screen grabs above have been taken from the Canon EOS 5D Mark II’s menu system and are indicative of what to look for in cameras that support AF micro-adjustment. The bottom screen shows a two-step adjustment to correct back-focusing.
Check your adjustments by re-testing the lens, making sure you de-focus the lens and allow the camera to re-focus before taking the test shot. (Sometimes, if the lens is almost focused, it will not autofocus again.) Canon recommends taking three shots for each setting when checking AF micro-adjustment. It also adds the following advice:
- For best results, manually set the focus on the lens to infinity for every exposure before allowing the camera to autofocus the reference target.
- Expect some minor variations in focusing accuracy within each set of three test images, even though they were all taken at the same micro-adjustment setting. This is completely normal, and is due to the tolerances of the camera’s AF system.
- Expect smaller micro-adjustment settings to have a greater effect with telephoto lenses, and vice versa for wide-angle lenses.
- If you are attempting to set micro-adjustments for a zoom lens, it is important to realize that the camera’s setting may only be accurate for the focal length setting you test.
Results
We used the SpyderLensCal to test the performance of two lenses (the EF 24-105mm f/4L IS USM and the EF 70-300mm f/4.5-5.6 DO IS USM) on our Canon EOS 5D Mark II body. We also tested several of our Olympus lenses, including the M.Zuiko Digital 12-40mm f/2.8 PRO,M.Zuiko Digital 14-42mm f/3.5-5.6 III EZ,M.Zuiko Digital 40-150mm f4.0-5.6 R and M.Zuiko Digital 60mm f2.8 Macro Lens on the OM-D E-M1 and E-M5 camera bodies.
It’s easier to see discrepancies in focus when you use a camera with a larger sensor in combination with a fast lens because the depth of field from such combinations is shallower than you obtain with a smaller sensor. Longer lenses are also easier to test for the same reason.
None of our tests revealed any lens with noticeable front- or back-focusing. This was very re-assuring but it left us without any examples to show. If you account for setting up and alignment times and the times needed to change lenses, it took approximately 15 minutes to test a camera and lens combination from scratch.
Conclusion
Lenses vary and camera bodies vary and most photographers could benefit from being able to measure the autofocus accuracy of their equipment. Photographers with expensive gear who are picky about autofocusing should find a SpyderLensCal a worthwhile investment. Even if it shows your equipment has been correctly calibrated, it is reassuring to know that any focusing errors you see in your shots are not the fault of the equipment. (This can also save you time by reducing the number of factors you must check.)
If you’re not all that worried by slight deviations in AF precision, the SpyderLensCal probably isn’t for you. Nor would it justify its investment cost to photographers with a single camera body and one or two kit lenses. However, it could be a worthwhile investment for anyone who conducts photography classes and also for camera clubs.
Rating
RRP: AU$95; US$64
- Build quality: 8.5
- Ease of use: 8.5