Photography, Reviews

Check and correct Auto-Focus errors with LensAlign and FocusTune 4

LensAlign and FocusTune 4

Are you one hundred percent sure the Auto-Focus of your expensive lens/body is accurate? No improvement possible? I was surprised to find the opposite. Heck, I was surprised to see my expensive Zeiss Variogon 24-70 deviate from 100% sharpness even when I’m manually focussing. I wouldn’t have known without the tools I’m reviewing today: LensAlign and FocusTune 4 from Michael Tapes Design. The combination of these tools allows you to check and correct for all types of focus errors. To benefit from it, you’ll need a camera that at the very least has a lens you can focus. This includes dSLRs, system cameras, and video cameras capable of still images even.

LensAlign MkII is the physical target you will use to calibrate the Auto Focus Adjustment (AFA) feature of your camera. Using the AFA to correct the autofocus system is LensAlign’s primary purpose. The method is simple: you take a series of B&W shots in AF mode, setting the AFA to a different value with each four to five shots (you take that many to smoothen out any anomalies in-between shots). You could evaluate each shot visually, but that wouldn’t be accurate. That’s where FocusTune enters the equation. This software analyses the shots based on EXIF metadata and the visual measurements of the LensAlign target itself.

LensAlign and FocusTune 4

You can also use LensAlign with FocusTune to evaluate the accuracy of your camera’s manual focus system, as well as focus consistency using different aperture openings, or shot-by-shot.

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LensAlign MkII

The latest version of the LensAlign target comes in a flat packaging. It’s disassembled upon arrival. Assembling the LensAlign isn’t difficult. It requires about ten minutes to do it right. The target is made up of a focus ruler, a target for setting up your camera correctly and the target you’ll use to analyse the images. The target can be mounted on a tripod or placed on a flat surface.

Once it’s been assembled, it is best to leave it that way. This avoids you introducing inaccuracies as a result of accidentally bending the panels. Each panel of the LensAlign structure contains printed instructions on the unused side. The parts that you won’t use for lens analysis have instructions for assembly, those that you do use contain instructions for use — very well thought out, very efficient.

LensAlign and FocusTune 4

Even without the software, LensAlign is a solid investment, because it tells you more than just the focus quality of your lens. For example, you can visually — not measured — assess its resolution and its volume deformation quality.

The LensAlign target has a patented system for aligning your camera with the target. It’s called True Parallel Alignment (TPA) and it’s amazingly easy to use. The goal is to position your lens in parallel with the test target’s surface — the only piece that you are supposed to mount and remove regularly.

To do so, you first place your camera in front of the target approximately where you think it lines up with the bull’s eyes of the positioning panel. You then look through the holes in the back of the target and when the lens is more or less centred in the viewing circle, you can start fine tuning. The rest of the aligning phase is spent shooting the line-up target and checking whether you can see right through the holes — with no red from the back bull’s eye visible.

This sounds very complicated, but in practice it’s quite simple to do. It took me a quarter of an hour the first time, then only some six to ten minutes on subsequent tests. The hardest part is to move your camera (or the target itself) in small enough increments not to overshoot your target. When the holes are clear in your test image, it means the lens plane is parallel to the target’s plane and centred as well.

At that point you must be intelligent enough to fix everything in place. If you’re ignorant as I was the first time, you’ll not fix the position of the target — I placed it on a table without making sure it couldn’t move — and when you’ll be mounting the lens test target, the whole thing will slide out of position and the room will fill with all kinds of biblical terms that aren’t meant to be published.

FocusTune v4

FocusTune is what makes LensAlign really effective. The software has a very simple interface with a few buttons, two image panels and a data table. The LensAlign test target is to be shot using finest JPEG in B&W mode at lowest possible f-stop, with no stabilisation or other enhancements turned on and preferably at an optimised distance you can calculate online, on the LensAlign site. You take about five shots per AFA setting and then move on to the next level of adjustment. When you’ve shot all AFA levels your camera allows for, you’re ready to offload the images into FocusTune.

LensAlign and FocusTune 4

If you haven’t got an AFA camera, you can still evaluate your manual focus accuracy, or even your AF accuracy, but without the software being capable to determine the “zero” point for your AF system.

FocusTune supports several analysis modes, including one to measure the focus consistency at different apertures. Operating the software requires little or no knowledge beyond understanding what “Sharpest” means, how to press a button and how to read a report. The button “Process files” reacts to the mode you select from the one dropdown menu available. The result inevitably is a PDF file with analysis data and graphs showing you the performance of your lens.

My own testing experiences

I wanted to test LensAlign and FocusTune using a Sony SLT 99 and an Alpha 700, both with Sony’s Zeiss lenses. Unfortunately, right after my first tests with the 99, the camera had to be sent back to the store who loaned me the unit. The AFA results for this camera and lens combination were quite accurate, but I was a bit surprised to find the lens wasn’t perfect. I’m probably very naive, but I thought a Zeiss lens that is more expensive than the camera body shouldn’t have a deviation at all.

You can whine over these results as I’m doing now, but with LensAlign/FocusTune you can compensate for them as well. Even in manual focus mode you can compensate because the report will clearly show you the direction of the adjustment you need to make. If you can’t compensate, the test results will at least allow you to choose a higher f-stop so you get a larger depth-of-field.

LensAlign MkII and FocusTune v4 are money well spent. Expect to pay approx. €113.55 for the combo.