A Better Mousetrap? A Review of the LensAlign MkII

LensAlign MkII
The LensAlign MkII from Michael Tapes Design


As long as cameras have featured autofocus, photographers have complained about its shortcomings: sometimes autofocus (AF) is dead-on, sometimes it focuses ahead of the intended target, and sometimes it focuses behind it.  These flaws have been described as front-focus and back-focus, respectively.  The reason for the fault in AF is found in the manufacturing process: a camera body’s AF is calibrated to a “standard” lens.  However, the lenses that are produced on the assembly line are made within tolerances for deviation.  With their higher resolution, DSLR’s have revealed that the tolerances in manufacturing clearly are not as strict as demanding photographers would like.

A few years ago, Michael Tapes of the eponymous Michael Tapes Design was working to create a device that photographers could use to accurately determine if and what type of focusing problems they had with their equipment.  Tapes’ vision was that photographers would have proof to show the manufacturer that what they were seeing in their images was not, in fact, user error but the result of equipment.  Coincidentally, just as the LensAlign Pro was coming to market, camera manufacturers provided a means to correct front-focus or rear-focus problems in-camera with Autofocus Micro-Adjustments (referred to as AFMA in this review), often buried deep in the user menu.  Canon was the first to announce such a feature in its 1D Mark III body, and Nikon quickly followed suit.  Note that Nikon refers to this feature as “AF Tune.”

In the fall of 2010, while reviewing a LensAlign Pro on loan from Michael Tapes Design, it was hinted that a new product was coming that would replace the less expensive but discontinued LensAlign Lite.  The new unit would offer the same rear-sighting ability as the larger LensAlign Pro, it would ship flat, and it would be more cost effective for the company to produce.  In total, these would make it, at least on paper, a win for customers and for the producer.  And it would bear a “Mark II” designation that seems quite popular among many manufacturers at the moment.

The LensAlign MkII functions much like its larger stablemate, the LensAlign Pro, so you may wish to refer to my review of the LensAlign Pro (Part One and Part Two) before continuing.  Also, if you own a LensAlign MkII, you should consult the LensAlign resources page for documentation and the ever-useful distance tool.

First a prototype and then a final production version of the LensAlign MkII was provided to me by Michael Tapes Design to prepare this review.


What you see is what you get: seven pieces come together to form the new LensAlign MkII
What you see is what you get: seven pieces come together to form the new LensAlign MkII

The LensAlign MkII is essentially a scaled down LensAlign Pro that weighs in at a mere three ounces.  In comparison, the LensAlign Pro is almost four times heavier at 11 ounces.  One of the most exciting elements of the design of the MkII is that it shares the rear-sighting system of the LensAlign Pro.

While offering the same accuracy as the Pro model, the MkII’s construction is radically different: the pieces are cut on a precision die and are assembled by the end user.  The MkII ships (and can be stored) flat in seven pieces: a sturdy base made of extruded PVC with an aluminum bottom plate and quarter-inch tripod socket, a front and back plate with sights for both standard and macro lenses, and three parts that fit on the side to keep the front and back parallel all come to support the most important part of the unit: the ruler.

The components are made of thin polystyrene but they have a lot of “flex” to them; at first I feared if I didn’t put them together correctly they would crack, but they go together quite smoothly.  And because the pieces can bend there’s little risk of their breaking during assembly–in fact, the ruler is designed to “bow” into place.  I have taken apart and put together both the prototype and the production version multiple times without any problems.

Click through the photos below to see how the LensAlign MkII fits together:

Note that this sequence was made while I was using the prototype of the LensAlign MkII. The final production version is assembled in the same fashion.

The Ruler

Calibrating a macro lens on the LensAlign MkII
Calibrating a Canon 100mm f/2.8 macro lens on the LensAlign MkII: the focus is on the “macro” target (closest to the ruler). Note that distortion can fool the eye into thinking that the lens is not centered on the target.

Since all of the other pieces come together to support the ruler, I would be remiss not to discuss it.  The ruler on the MkII is an inch longer than the Pro’s, as well as half an inch wider, and double-sided with  two different patterns.  The first side has white numbers within black shapes, and the opposite side has black numbers within white shapes.  My preference is for the white-within-black pattern, but users should try both to see which seems to be easiest for them to “read.”  However, unlike the Pro, the ruler on the MkII is fixed at a 20-degree angle (Position Three on the Pro).

Initially I thought this might present more of a problem than it really does in practice.  With the LensAlign Pro I will use the 20 degree position the most, but will occasionally switch to the 12.5 degree-angle when it seems too much of the ruler is in focus as the harsher angle limits can make the boundaries of the DOF “pop” a bit more.  With the MkII the left-most row of numbers can sometimes be obscured by part of the front standard–this happens when calibrating wide angle lenses and macro lenses where the distance from sensor plane to LensAlign is two feet or less.  However, the extra width of the MkII’s ruler means that there are more patterns to compare on opposite sides of the 0 Mark, so the difficulty in evaluating the smallest column of numbers is mitigated by comparing the two patterns immediately to the right, as in the photo above.

In Use

The LensAlign MkII has both a quarter-inch thread as well as four feet on the bottom for tabletop use.  While it would be possible to use the MkII on a table, mounting it on a tripod offers far greater flexibility for making the face of the unit square to the camera.  As discussed in the first part of my review of the LensAlign Pro, both the camera and tripod need to be positioned at a distance equal to 25 times the focal length of the lens (for instance, a 100mm lens should be calibrated from 2500mm away, or 8.2 feet).  The camera and target are in alignment when the central AF sensor is aimed at the central view port on the LensAlign, with the bulls-eye perfectly centered within.  For more details on the process of squaring the target to the camera, Tapes’ recent article about “Using True Parallel Alignment (sighting system) best practices” is a quick but good read.

For my testing of both the prototype and production MkII I attached Arca-Swiss style quick-release plates to make mounting on the tripod an easy affair.  Another advantage of using an Arca-Swiss style quick release is that the LensAlign MkII or your camera body can slide from left-to-right within the channel of the quick-release clamp.  This can make fine-tuning the position of the red AF target within the bulls-eye a snap and help avoid re-positioning a tripod when a minor adjustment is all that is necessary!

As I discussed in my review of the LensAlign Pro, there are three different ways of evaluating the autofocus performance and subsequent micro-adjustments:

  • reviewing the images on the camera’s rear screen
  • taking the flash card inside and reviewing the images on a computer monitor
  • shooting tethered so that the images appear instantly on a computer.

I’ve found that shooting tethered is the most effective way of working with the LensAlign MkII, but it certainly has its share of disadvantages, among them glare off of the laptop screen when working outside and power and USB cables to avoid tripping over.  Simply reviewing the images on the back of the camera may be one of the “fastest” means of calibrating the focus, and it seems to work well most of the time.  However, there are times when two or three micro-adjustment settings all look “pretty good” on the rear screen.  In a situation like that,  importing the JPEG’s (no need to shoot RAW) into Photoshop to use the emboss filter can help to determine which is the best setting.

Using the Emboss Filter
Using the Emboss Filter: set the angle to 135 degrees and the height to three to make the depth of field “pop” on the LensAlign ruler

At the moment I cannot find a way to identify AFMA settings in a photograph’s metadata (evidently Canon DPP software can provide this information on Canon cameras).  It is important to be mindful that the MkII does not have an “enumerator” like the Pro (there’s no built-in visual reference for which AFMA was used or how far apart the camera and LensAlign were in a given image), but a sticky note is an easy stop-gap!

My Method

Tethered capture in Adobe Lightroom
Tethered capture in Adobe Lightroom

I prefer to work indoors, with the camera tethered to my computer when I’m calibrating lenses no longer in focal length than my 70-200mm zoom.  I keep Adobe Lightroom open in tethered capture mode and review the JPEGs at 100% on my 24 inch monitor.  A standard 16 foot tape measure will suffice for placing the camera and target at appropriate distances whenever working inside.  If there’s diffuse light coming in through the window, I’ll use that.  However, while I must be tripod-mounted to use the LensAlign, I prefer not to use slow shutter speeds.

LensAlign with off-camera flash
Calibrating with the LensAlign MkII indoors with a wirelessly-triggered off-camera flash to illuminate the ruler.

So, if my shutter speed dips below 1/100 second using available light I will set up an external flash and bounce it off of the (white) ceiling in my office.  Note that the flash is there to help evaluate the ruler, not the front standard, so bouncing off the ceiling is ideal as it will evenly illuminate its surface .  Just be sure not to overexpose the ruler!

While I set up a flash wirelessly using an ST-E2 transmitter and a single Canon speedlite mounted on a light stand (unless I’m calibrating the 7D, in which case I will use its built-in wireless flash control), mounting a strobe in the camera hot shoe and bouncing it off the ceiling will work.

When calibrating the AF with a lens longer than 200mm I wait for good weather and set up outdoors, grabbing a 50 foot reel tape measure on my way out the door.  I have tried to work tethered with a laptop outdoors, but I’ve found the glare off my laptop screen to be unacceptable.  Your mileage may vary as not all screens are the same!  I typically try to work off of the camera’s rear screen, but sometimes I have to make a series of images (with sequential changes in AFMA) and take the flash card inside to scrutinize the images on my computer.

I recommend recording individual cameras and lenses and the best AFMA for each combination in a spreadsheet.  Include the date that you perform the adjustment!  As I discussed in the second part of my LensAlign Pro review, it would behoove users to calibrate their lenses before any major shoot, and then again a month later, and once again three months to the day of the original calibration.  This is because the best AFMA for a given camera and lens may change with time–although the change need not be universal.  This February both my 5D Mk. II and 1D Mk. III required a change in AFMA with my 70-200mm lens–I calibrated it with a LensAlign MkII prototype over Christmas–but the setting I had found for my 7D last fall with the LensAlign Pro remained “good.”

Compared to Lens Align Pro

LensAlign MkII and LensAlign Pro
LensAlign MkII and LensAlign Pro side-by-side

While it doesn’t exactly replace the LensAlign Pro, the LensAlign MkII offers the same ability to test and adjust the autofocus performance of DSLR’s as its bigger brother, for for $100 less.  Of course there are differences between the two models, but how significant they are is ultimately up to the end user, but even their designer has a preference.

While speaking to me about the design of the new LensAlign, Tapes said: “Personally, I use the MkII: it’s smaller, lighter, easier.”  Retail price aside, the fundamental differences between the MkII and the Pro lie in their construction, the ruler angles, the enumerator, and the Long Ruler Kits.


The LensAlign MkII is made of thin, lightweight, and flexible polystyrene; the components are designed to be locked together and taken apart by the end user.  The MkII is more portable than the LensAlign Pro, which is made of beefier extruded PVC, assembled at the factory and then laser-tested for accuracy before shipping.  (It should never be taken apart since it may no longer be accurate after being reassembled.)  To travel with the MkII, simply put its pieces in a rigid envelope and drop it in the bottom of a suitcase with folded pants or other clothes.  I simply cannot recommend air travel with the LensAlign Pro.

Rulers & Angles:

The improved, wider ruler pattern makes up for the fixed 20 degree angle on the MkII.  On the LensAlign Pro I only use the 20 degree and 12.5 degree positions any ways.  Additionally, the MkII’s ruler has a matte surface whereas the Pro’s ruler is highly reflective, making the MkII easier to work with in sunny situations.


This might be the only thing absent on the MkII that makes me nostalgic for its predecessor.  The enumerator on the LensAlign Pro can be very helpful when comparing changes to the AFMA on a computer.  However, a pad of sticky notes and a pen will do the same thing, if nowhere near as elegantly.

Long Ruler Kits

An optional accessory, the Long Ruler Kit on the LensAlign Pro creates a four-foot ruler.  Because the material is nowhere near as rigid, the MkII’s Long Ruler Kit will feature only a two-foot ruler.  The idea behind the Long Ruler Kit is that a photographer may set up the target at a greater distance than the recommended 25 times the focal length of the lens.  Tapes explains that this can be beneficial for photographers with super-telephoto lenses who often photograph their subjects from great distances and therefore would prefer to calibrate from healthy distances.  Not having used one of these kits I cannot speak to their functionality, but I will say that so far I have not felt the need for one in calibrating lenses up to 1000mm in effective focal length (500mm with a 2x TC).  If the idea of a four-foot ruler appeals, there is only one choice.


In my review of the LensAlign Pro I wrote that “The good news is that even if LensAlign is the only practical tool available, it’s a good one.”  This holds true for the LensAlign MkII: no other company makes a tool that offers the accuracy of the LensAlign family of products.  DataColor didn’t try very hard when they came up with the Spyder Lens Cal, and no one else has stepped up to the plate.  The LensAlign Pro is a great tool, but an expensive one both for the consumer and the manufacturer.  The LensAlign MkII is every bit as accurate and more gentle on consumers’ wallets.  Yet, I know there are those who are going to ask whether the product is “worth” the $80 expense.

I think the LensAlign MkII a no-brainer as it helps a bag full of expensive lenses produce the absolute sharpest images they possibly can.  Personally, I never knew that the 16mm end of my 16-35mm zoom could resolve the level of detail that it does now that I’ve used a LensAlign; it’s like having an entirely different–and better–lens.

In a world full of hundreds of accessories that are priced in the range of $50-$100, the LensAlign MkII might just be the best value on the shelf.  Highly Recommended!

Back-focused? Front-focused? A Solution: A Review of the LensAlign Pro in Two Parts

Part Two:

LensAlign Pro ruler
LensAlign Pro ruler

This is a continuation of my two-part review of the LensAlign Pro.  You may wish to refer to part one before continuing!

Final Preparation for Testing

So you’re set: you’ve calculated the distance you need, set up your camera on a tripod (and possibly placed LensAlign on another tripod or a sturdy table), and you’ve confirmed LensAlign is square to the camera/lens in Live View or by zooming into a review image. What now? Close the Sight Gate so that your camera cannot focus on the rear standard of the LensAlign.  Set the ruler to the third position (20 degrees) for initial testing.  Ensure that you are set to you lens’ largest aperture; if you’re calibrating a 50mm f/1.4 lens, you need to be shooting at f/1.4.  Expose properly for your lighting situation–you do not want overexpose the ruler!

A Brief Note on Technique

Even though you’ll be working on a tripod at reasonably fast shutter speeds, I find it can help to set the camera in mirror lock-up with a two-second countdown timer when working with 70-200mm lenses and smaller. For larger lenses with tripod collars I switch out the ball head for a gimbal-style head and employ the long-lens techniques I’ve learned from Arthur Morris: I lock down the lens with my arm hooked around the head and down onto the lens while applying pressure to the top of the camera with my forehead as I look through the viewfinder.

To make the test image you will manually rack the focus so it’s blurred, and then have the camera autofocus on the center of the target: you want the camera to have to “work” to get the image in focus. Make an image and review it.

For now, I’m going to assume you are using a prime lens.  Check the LensAlign Distance Tool for a calculation of how much DOF should extend in front and back of the focus target (0 mark on the ruler).  For this example I will assume the calculation is close to 50-50.  The first thing you need to determine when looking at the review image is where the DOF begins and ends, bearing in mind that you want the DOF to split evenly on the top and bottom halves of the ruler.

When you’re reading the ruler, look for noticeable crispness in the numbers, starting with the large ones.  Is the “8” sharp on both the top and bottom?  How about the “6” or the “4?”  Sometimes, the larger numbers are a bit confusing, but as your eye scans the ruler, look at the columns of smaller numbers and ask yourself what is the last number you can read clearly on the top of the ruler, and then look and compare that to the corresponding number on the bottom of the ruler.

If you think the numbers on the ruler are hard to read, or that it is difficult to tell where the boundaries of the DOF lie, try adjusting the ruler angle.  Rarely do I use the first (45 degrees) or second (30 degrees) position, but I frequently will make the angle harsher and go to the fourth position (12.5 degrees) to camera.  Especially for longer lenses, a shallower angle really helps to clearly spot the boundaries of the DOF.  Note that for those who want a longer ruler to judge autofocus on long lenses from greater distances than the proscribed eight feet per 100mm of focal length, the LensAlign Long Ruler Kit gives the Pro a larger focus target and a four-foot long ruler.

If the DOF is pushed to the top half of the ruler, your camera is back-focusing, and you will need to use a negative AFMA correction to “pull” the DOF back down the ruler.  If the DOF has mostly sunk to the bottom half of the ruler, your camera is front-focusing, and you will need to use a positive AFMA correction to “push” the DOF up the ruler.  If the DOF falls perfectly on both sides of the “0” mark of the ruler, then congratulations, you’re done with this lens, and can move on to the next!

Correcting Front or Back-Focus

Begin with a simple adjustment: one increment in the direction needed to correct the focus.  After setting the AFMA in the camera menu, turn the focus ring by hand so that the camera will have to re-acquire focus, and make a new test frame. (If you wish, you may alter the enumerator so that the AFMA is recorded in the frame.)  In my experience every lens/camera is different, and responds differently to AFMA corrections.  Sometimes, a +1 adjustment appears to have no effect in pushing the DOF up the ruler to correct front-focus, and it may take more drastic increments (+5, +10) to get into the ballpark.  Other times, the change is dramatic and +1 or +2 moves the DOF significantly.  Start small, and work your way up (or down) the AFMA scale until you find the right setting for your lens.

The following video is an example of one lens/camera combination where changes in AFMA were very, very slight, and it wasn’t until -18 that I found a good balance of the DOF on both sides of the ruler.  Here you will see it step-by-step, but in practice, I first attempted -1, then -2, and -5.  When no change was apparent, I jumped to -10, and then to -15.  From there I went step-by-step until hitting -18, the “sweet spot.”

LensAlign Pro Demonstration from David Kennedy on Vimeo.

At 0 AFMA, the back-focus is quite significant, so you will only gradually see the numbers on the bottom half of the ruler come into focus in balance with the focus on the top half of the ruler (achieved at -18 AFMA).

What about zoom lenses?

Put simply, calibrating zoom lenses is a balancing act.  Most cameras provide only one AFMA per lens (Olympus seems to be the exception to the rule), but zoom lenses comprise a great number of focal lengths!  Test the focus performance of the lens at some of its designated focal lengths marked on the barrel; on a 16-35mm lens, you might test at 16mm, 24mm, and 35mm.  Unfortunately, the AFMA that is ideal for one “end” of the zoom range might not be as good for the other.  In such circumstances, you will have to make a choice of which one is more important to you for that lens.

For instance, I have both a 16-35mm lens and a 24-70mm lens, and there is obvious overlap between the two.  When calibrating my 16-35mm, I found that the ideal AFMA for the 16mm setting resulted in severe front-focusing at 35mm.  However, my 24-70mm lens works quite well throughout its zoom range, so I decided to keep the setting on my 16-35mm to make the widest end perform the best, knowing that if I want to zoom in longer than 24mm I will change lenses.

Using the Emboss Filter

Photoshop Emboss Filter Dialog
Photoshop Emboss Filter Dialog Box: Angle 135 Degrees, Height 3, Amount 100%

Whether reviewing the images on the back of the camera or on a computer, there are times when it is less obvious which AFMA correction offers the very best balance of DOF on both sides of the ruler.  When trying to choose between two or three AFMA settings, try loading the photos into Adobe Photoshop and applying the emboss filter with an angle of 135 degrees, a height of 3, at an amount of 100%.  The “relief” image you will create can help identify the exact edges of the DOF.

Lens Align Ruler
Lens Align Ruler: Hover over the image image to see it with the emboss filter applied. Note that the back-focus issues are more visible in the embossed version. Compare the large 8’s and the medium-sized 12’s to see how the “top” numbers are sharper than those on the bottom half of the ruler.

How long does calibration last?

For a while I believed that AFMA is something you could “set and forget.”  There are exceptions to this, of course: every time you send in a camera or lens to the manufacturer for service you should put it back on the test bench with the LensAlign. Do not be fooled if the AFMA changes are still in the camera you just had returned from the factory: test and verify for yourself that they still work well.  This happened to me in the fall of 2010 when I sent in my Canon 5D Mk. II for a “clean and check” and it was noted that autofocus had been re-calibrated at the factory.  The body came back wiped but with AFMA changes still registered, but they were no longer ideal adjustments: I had to calibrate my lenses all over again.

There are times when the ideal AFMA setting may shift for a host of reasons that are beyond a user’s control.  It would seem to me that testing AF performance on a quarterly basis is an easy rule of thumb that most users can follow, but for professionals a more proactive approach might be needed.

In talking to Michael Tapes, he offered the following advice: calibrate using LensAlign before any big shoot (travel, a high-paying portrait shoot, etc.) and then again a month later.  Wait two months from that day and confirm if the AFMA is still working for your camera/lens combination.


The LensAlign family is products is, for the moment, the only game in town for accurate autofocus micro-adjustment calibration.  None of the major camera manufacturers have a consumer product to use with their micro-adjustment-capable cameras, and it wouldn’t appear that any of them intend to fill the void that they created when they released a feature with no corresponding tool.  Yes, Datacolor is attempting to compete with the Spyder Lens Cal, but their product has no means of squaring the target to the camera, making it pretty much useless.  It simply doesn’t provide the accuracy or repeatability that you find in Michael Tapes’ LensAlign.

The good news is that even if LensAlign is the only practical tool available, it’s a good one.  The LensAlign Pro is a very sturdy and capable product: squaring it to the camera is fast, the ruler can be locked into several different angles so you can adjust the experience to your preference, and the handy enumerator makes visual “note taking” of distances and AFMA settings a snap.  At $180 the LensAlign Pro is not an inexpensive product, but  this is not another injection-molded plastic wonder: each one is assembled by hand individually in the United States and then laser-tested for accuracy.

The disadvantage of the LensAlign Pro is that its sturdiness and size means that it doesn’t travel well: it’s a unit that stays home or can be packed in a car, but air travel is almost entirely out of the question.

Michael Tapes clearly recognized that retail price was an issue for some people, and the size of the LensAlign Pro meant that shipping internationally was a problem for the company, so he created a new stablemate, the LensAlign MKII.  The new product sells for $80 and offers much of the same functionality as the LensAlign Pro in addition to packing flat both for shipping and travel.  A review of the MKII will be posted here before the end of the month, but in short new product is essentially a scaled-down, less expensive LensAlign Pro.  There are some advantages to the bigger brother, however, and as Michael Tapes explained over the phone people will buy the LensAlign Pro if: “They want the enumerator, they want the ruler angles, or they want the 4-foot ruler.”

The bottom line is that if you are serious about getting the sharpest images from your micro-adjustment capable camera, you cannot go wrong with the LensAlign Pro.  Highly recommended!

Another option for focus calibration: LensAlign MkII

LensAlign MkII rendering
LensAlign MkII rendering courtesy RawWorkflow/Michael Tapes

Michael Tapes, the entrepreneur who invented the “LensAlign Focus Calibration System” e-mailed me a few weeks back and said that he had a new product coming, but by reading the information I was under a NDA.  However, many of the details of the LensAlign MkII, which replaces the LensAlign Lite (I reviewed the LensAlign Pro earlier this fall), are available on Michael’s blog.  I just received a prototype yesterday, and will be writing a review of the new product and comparing it to its “bigger brother.”  Final production versions will retail for $79.95 and will ship in the United States for $6 as it comes flat/disassembled to fit inside of a Priority Mail envelope.  This conceivably means that it can be taken apart easily for travel, something the LensAlign Pro simply cannot do.

Stay tuned for more!

Back-focused? Front-focused? A Solution: A Review of the LensAlign Pro in Two Parts

Part One: Overview and Setup

LensAlign Pro ruler
LensAlign ruler revealing a good balance of depth of field on either side of the “0” mark | Canon 5D Mark II and 100mm f/2.8 macro lens

LensAlign Pro

LensAlign Pro
LensAlign Pro

Earlier this month, Michael Tapes, president of RawWorkflow, e-mailed me because he saw my mention of  Datacolor’s product, aimed to complete with his LensAlign, the Spyder LensCal. He also referenced my account of working briefly with one of his company’s LensAlign Pro units this summer.  Michael then offered  to have a review copy of the LensAlign Pro sent to me for a closer look at this useful, if somewhat expensive, tool for properly calibrating the autofocus performance of a camera and lens.

While many manufacturers, including Canon, Nikon, Sony, and Olympus, now provide a means for end-users to calibrate the autofocus performance their prosumer and professional cameras via “autofocus microadjustment” (AFMA), none of them offered a tool for making these changes in a meaningful way.

LensAlign, then, is a platform for measuring the focus accuracy of a camera/lens combination.  One takes this information and then, if necessary, change the AFMA to shift the depth-of-field (DOF) so that it straddles the “0” mark on the LensAlign ruler.  I will explain the overall functionality (although I do not intend to re-create the wheel–the LensAlign manual is on the company’s resources page) and consider why one would purchase such a product.

Debunking the 1:2 Depth of Field Myth

One of my initial concerns about this process is that I’ve heard for years–from anecdotes in photography books to some of my professors in graduate school–that depth of field is split in a 1:2 ratio around the point of focus.  That is, 1/3 of the DOF resides in front of where one focuses and the remaining 2/3’s lies behind it.  But LensAlign is designed to make the DOF 1:1 in front and back of the focus mark, which seemed to go against the grain.  Someone has to be wrong!

In researching this, I found a page of “Common photography myths,” and sure enough, number 14 was that DOF was 1/3 in front and 2/3 in back.  Essentially, DOF is mostly 1:1 front to back. However, as magnification is decreased (distance from subject becomes greater, i.e. farther back in the frame), DOF slowly grows to become closer to the 1:2 ratio of lore.  Then, as one focuses more towards infinity, the ratio becomes 1:∞, and hyperfocal distance is achieved.

The DOF ratio is not always 1:1, hence my saying “mostly.”  For example, with wide-angle lenses, particularly at close distances, the split becomes 40% in front and 60% behind the focus mark.  If you want to know more about how depth of field is calculated, you can find the formula here, and a list of known values for the circle of confusion of several camera models can be found here.

All this aside, I suppose if  one desires a 1:2 ratio for depth of field, one can use LensAlign to shift it to one’s liking, but it is a choice to alter the way that things are designed to work for one’s creative needs, it is not “the way it should be.”

Inside the Box & Initial Setup

Upon opening up the white clam-shell box, one finds the main unit, and a postcard detailing how to set up the following components:  its metal ruler, the “sight gate,” a magnetic on an adhesive strip for the “sight gate,” and four small, cylindrical magnets for use with the LensAlign’s “enumerator.”

The body of the LensAlign Pro is made of four pieces of extruded sheets of PVC that have been cut with a router.  Two vertical pieces are parallel to one another–the front containing a the focusing target that also holds the “0” mark of the LensAlign ruler.  The rear vertical piece contains the bulls-eyes for making the unit square to the camera position.  A third piece is perpendicular to the other two, and keeps them straight.  All three are screwed into a square of PVC with a 1/4″ tripod thread in the center.  To keep the two focusing pieces parallel to one another, and to prevent them from bending in transit, a length of poster tube is packed between them for shipment.  Keep this piece in the event you ever want to travel with LensAlign Pro!

The ruler is a 9.5″ strip of metal, and it is how one gauges the focus calibration of their camera/lens.  Every other part of LensAlign is designed to work to support this ruler.  So, while in the initial setup the user concentrates on everything except the ruler, during the actual measurement stage, the ruler will be all that matters.

The sight gate is a plastic card that will slide up and down to open and close the bulls-eye’s in the front of the LensAlign.  However, to make it slide, one has to adhere a magnetic strip on the back of it (it’s a little odd that the user has to do this, and I assume it has something to do with labor costs to produce LensAlign, but it is a trivial matter to do it one’s self).

Once set up, the main unit could be used on a tabletop, but a 1/4 inch thread allows it to be mounted onto a tripod.  One could mount the unit onto a light stand, but for reasons explained later, it is better to have the unit on a tripod head that allows movements, such as a ball head.

The enumerator and the ruler

The ruler has various positions that it can be set to (and held in place by magnets). They range from virtually parallel to the imaging plane to almost perpendicular.  However, the LensAlign documentation recommends beginning with the ruler at the third position, and my experience seems to confirm that this is usually a good starting point.

That said, I tend to use the “flatter” ruler positions, 4 and 5, just as frequently as I do position 3.  The greater the distance between the camera and the LensAlign, the flatter the ruler should be, as it makes it easier to distinguish the boundaries of the DOF.

LensAlign Enumerator
LensAlign Enumerator: Fresh from the factory (left), set up with a neutral AF adjustment at a distance of 5 feet from target (middle), and set with a negative 3 AF adjustment at a distance of 25 feet from target (right)

The enumerator is not essential for the operation of the LensAlign, but it is a handy feature if one makes a series of images at different AFMA’s and reviews them later on a computer screen, as it provides a visual record of the AFMA setting.

Working with Test Photos

That is to say that there are at least three ways to work with the test photos of the LensAlign: review them immediately on the rear LCD screen and tweak the AFMA on the spot, shoot tethered to a computer and review the pictures in the field with the camera, or make the initial (neutral AFMA) test picture and review it in-camera, and then make a series of incremental AFMA changes and download all of the images to a computer for review.

The advantage of the first option is that it might be a little faster, but the latter two choices tend to be more accurate as they involve larger computer monitors for viewing the test pictures.  Hence, if one chooses to review the images on the computer, the enumerator provides an easy reference for the settings used.

Personally, I have tried all three options, and find that they all have their time and place.  I don’t have a setup like Joe McNally, but if I did I would shoot tethered for everything.  (To make his setup, one needs a tripod, a Manfrotto dual-head “bar” to mount on top of it, a laptop table to mount on one side of the bar, and a tripod head of some kind for the other.)  Since I don’t have those parts, I chose to tether only when I was indoors.  Outdoors, I find that I can roughly eyeball whether I’m front or back-focused on the rear LCD of the camera.  Once I believe that I have found the proper AFMA for the lens I’m using, I’ll bring it inside and check it on my computer monitor.

A Word About Placement

Aligning the LensAlign
Orienting the LensAlign towards the camera and lens. Note that I have taken the unnecessary, but helpful step of placing a bubble level on the LensAlign platform.

Before one can make a test image to determine any front or back-focus, one must first place the camera and LensAlign on separate platforms, space them, and make them square to one another.

It really helps to have the LensAlign either indoors with indirect lighting, but I suppose if you’re feeling motivated, you could set up flashes to illuminate it.  When using it outdoors, be sure to place the unit in shade, or use it on an overcast day.  The ruler is extremely reflective, and direct sunlight turns it into a blinding mirror.  You want the light falling on the ruler to be even for easy-reading!

The online distance tool helps to determine how far apart the camera should be from the LensAlign, as well as how “deep” the DOF should be with a given focal length and sensor size.  This distance can also be calculated manually by multiplying the focal length by 25.  So, for a 400mm lens, one would need to be 10,000mm from the target, or 32.8 feet.  TIP: A 50-foot reel measuring tape will be very helpful for this step if you own telephoto lenses!

I have also tried calibrating lenses at their minimum focusing distance (MFD) instead of the recommended distance.  In a way, it’s easier because one just moves back as far as one needs in order to get LensAlign in focus.  Additionally, the target will be larger in the frame the closer one is to it, making the markings on the ruler easier to read.  In fact, in my first draft of this review, I suggested that MFD might be all you need.  But then I was proven wrong!

My advice for telephoto lenses 400mm and longer would be to first make an adjustment for the MFD, and then back up to the suggested distance to confirm the adjustment.  I recently calibrated a 500mm f/4L with my 1D Mark III and discovered that the adjustment made to counteract back-focus at MFD was too extreme, and actually caused front-focus when set at 41 feet from the target.

Aligning LensAlign

Making the lens and target square
Making the lens and target may involve tilting the camera downwards or upwards at the target, depending on height differences. In any event, it is not necesary to make them level to the world, but to make the two devices square to each other.

The first step you should take is use your tripod head (you have to be tripod-mounted) to position the camera at the LensAlign.  Aim the center focusing point (the most accurate of the focusing points, irrespective of camera brand or model) at the center bulls-eye of LensAlign.  Then, run behind the LensAlign, and looking through the “peep hole” through the center bulls-eye, lock it in position so that you are looking through the center of the lens.  Often, you can see light coming in through the viewfinder of the camera through the middle of the lens, which can help to make it just right.Return to the camera, and switch on Live View (or take a picture and review it on the LCD) and zoom in to see if the center bulls-eye is truly centered in its viewing port.

LensAlign's bulls-eyes
LensAlign’s bulls-eyes – note the (close to) bilateral symmetry. At shorter focal lengths, not every bulls-eye will be centered, and the target of greatest importance is always the bulls-eye in the center

An aside:To my knowledge, every camera that has the ability to make AFMA changes also has live view.  However, the LensAlign is helpful even with cameras that do not have this feature, as it can confirm whether or not there is a focus problem with a given lens.  If there is a problem, the user can take the data and decide whether the front or back-focus exhibited warrants sending the camera and lens to the manufacturer to be professionally calibrated.

While the LensAlign manual does explain how to make the unit square to a camera, I have found that it helps to pay attention to more than the center bulls-eye, but to consider all of them.  Especially at shorter distances and wider focal lengths, the other four bulls-eyes will not be centered in their viewing ports, but making sure that they are symmetrical on opposite sides of the center bulls-eye ensures that the plane of the LensAlign is parallel to the camera’s sensor plane.

Corrections and A note about Keeping Things Level

In the original version of this review, incorrectly stated that the body of the LensAlign is made from black masonite.  While it has that apperance, it is actually made from PVC.

Additionally, in the original posting I emphasized that keeping both the camera and LensAlign level, by means of a hot shoe bubble level or otherwise, would be a good idea.

After speaking to Michael Tapes directly, I stand by thinking that it’s helpful to keep things level, but agree that it is not essential for the operation of LensAlign. Hence, I have removed it from the section about aligning the focus target to the camera lens.  In fact, he told me that the absence of a level “wasn’t a casual omission.”  He believes that adding a level the product would make it appear to the user that being level was part of making the camera and focus target square, when it is not, in fact, a necessary step.

A level camera and a level focusing target will not change the DOF–it’s a constant.  Camera lenses do not draw rectangular images, but circular ones, so how the camera is rotated on the lens doesn’t change the DOF.  However, I find that leveling both helps in reviewing the images from LensAlign, because my beleaguered brain doesn’t like to look at picture of a ruler that is skewed at a 5° angle.

Tilted LensAlign
The LensAlign functions the same whether level or not, but you may find you prefer to read a straightened ruler as opposed to a tilting one!

For me, I find the lack of a level to be my lone frustration with the product.  I say this because it is downright annoying to constantly walk back and forth between the camera and the LensAlign while trying to remember to take the level with me each time.  When I walked 41 feet out to the 500mm lens that I was trying to make square to the focus target, and realized that the level was still sitting on the back of the LensAlign, I really started grousing!

But to reiterate: it is not necessary to do this extra step of leveling the two devices, I just prefer to work this way, and I think many photographers who will take the time to change the AFMA in their cameras will feel the same as I do that looking at a level measurement tool is easier than looking at one that is tilted, even if the data is the same.

Read part two of the review now!

Datacolor announces product similar to LensAlign

Datacolor SpyderLensCal
Datacolor SpyderLensCal - image from datacolor.com

Have I seen this before?

Yesterday, Datacolor announced a new addition to its “Spyder” line of calibration tools: the Spyder LensCal.  In many ways, it’s a spitting image of the LensAlign Pro I briefly reviewed here earlier this summer, and significantly less expensive at a suggested price of $59.00 (the LensAlign Pro sells for $180, while lensAlign Lite goes for $80).

While the design of the two systems is uncannily similar–an autofocus target with a ruler to the right–there is a significant difference between them: I see no way to confirm that the camera and the focus target are perfectly square to one another with the SpyderLensCal.  This is a significant advantage for the LensAlign, and in fact begs the question of just how accurate the Datacolor product could be if it is not feasible to make the target and camera square.  If they are skewed, so too will the out-of-focus areas, and the reliability of the product comes into question.

Furthermore, the SpyderLensCal offers no advice about the distance that should separate the camera from the target (only that it be “a fixed distance”), nor do they offer any clues about how much depth of field should be expected to be in front or fall behind the “0” point of the ruler.  (While the depth of field for many lenses is pretty much 49% in front of where you focus, and 51% behind it, with extremely wide focal lengths, such as 16mm, the depth-of-field shifts to become 40% in front and 60% behind the point of focus.)  I can already envision many of Datacolor’s customers having to rely upon LensAlign’s Web site for their online “Distance Tool.”

Of course, it will be interesting to see how these models really stack up once they can be compared side-by-side.  The SpyderLensCal will begin shipping in about three weeks, during Photokina.

Horicon after LensAlign and Focus Tweaks

Black Tern in flight
Black Tern in flight alongside Hwy. 49, Horicon National Wildlife Refuge, Mayville, Wis. | Canon 7D and 400mm f/4 DO IS lens | Exposed 1/1600 sec. @ f/4, ISO 400 (neutral EV)

A Brief History of “Back-focus”

Last weekend I was at Horicon National Wildlife Refuge and experienced some focus problems with my Canon 7D heretofore non-existent, or so I thought.  Upon reviewing photographs from the 7D from the past several months, I noticed that none of them were actually as sharp as they could have been.  I attributed the softness to the lack of acutance in the files, and while I continue to believe that is an inherent property of cramming 18 megapixels into an APS-C format sensor, there was a real problem in play.

I didn’t want to believe that it could be a question of the camera “back-focusing” (or front-focusing) because I’ve grown to distrust people’s claims that their camera, and not their own inabilities, are to blame for their out-of-focus photographs.  I don’t remember these claims from the film days.  Perhaps I was just oblivious to the complaints, but I tend to believe that the instant feedback of the digital camera is partly to blame for the knee-jerk reaction that anything wrong with the pictures must be camera, not operator, error.

I will not mince words: ever since the Canon 10D and the Nikon D70, there’s been a lot of bitching and moaning in online forums about back-focused images, and I did not believe them.  At all.  Until now.

Now, I will argue that there is definitely operator error to blame in most many cases of complaints about back-focusing.  Last weekend I was convinced that I must have chosen the wrong focus point or didn’t have the AF locked by holding in the rear button–some prefer AF to only be activated by using the back button, I prefer AF to only be turned off if I hold in the back–and allowed AI Servo (Continuous AF for Nikonians) to screw up the focus.  To confirm my assumption, the next day I took test photographs in the garden around my parents house in Racine, Wis. and was shocked to discover that none of them were sharp.  Sure, the wind was to blame in a couple cases, but even when conditions were perfectly still the results were poor, so I rented a LensAlign from Lensrentals.com to investigate whether front or back-focus was to blame.

And what did I find after I unpacked and set up the LensAlign?  The 7D and the 5D Mark II both back-focused with the 400mm DO IS lens.  Well, there goes the neighborhood.  And a lot of preconceived ideas, with it.

Post continues after the jump! Continue reading “Horicon after LensAlign and Focus Tweaks”