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Wednesday
Apr272011

SpyderLensCal: Camera Focusing Target

Digital cameras are technological marvels.  Manufacturers are continually updating their products with new features.  In the last few years, one of the features added to many digital SLR cameras is autofocus (AF) micro-adjustment.  AF micro-adjustment allows the camera owner to make small—but noticeable—changes to the depth of field (also referred to as the depth of focus) for a given camera/lens combo.  As tight as manufacturing tolerances may be, experienced photographers know that autofocus precision can vary from lens to lens, even within a given lens model.  Manufacturers provide a service allowing camera owners to send in a lens for professional calibration, usually for a fee.  Unfortunately, manufacturers sometimes ask that the photographer send in his camera along with the lens so the two can be calibrated as a pair.  In rare cases, that is what is ultimately necessary.  But thanks to the AF micro-adjustment feature, photographers can frequently make the necessary adjustments on their own.

A Suitable Target

To use the AF micro-adjustment feature you need an appropriate target.  This could be just about anything but, ideally, you want to use a target that has high contrast so the camera's autofocus lock will be reliable and repeatable.  In addition, you want a target that allows you to measure the depth of focus in the image.  The Datacolor SpyderLensCal is one such target.

Datacolor SpyderLensCal Retail Package 

Datacolor SpyderLensCal (click image to expand)

The SpyderLensCal features a proper contrasting target, an angled rule (to measure the depth of focus), a bullseye bubble level, and a standard 1/4-20 tripod socket.  It is constructed of rigid and reasonably strong plastic.  The focus target and the marked rule are quality paper stickers attached directly to the plastic.  Using the SpyderLensCal is easy but you need to follow a few basic steps to ensure good results.

On The Level

Throughout the autofocus testing, you want to be sure that both the SpyderLensCal and your camera are level.  Thanks to the bullseye bubble level on the SpyderLensCal, this is an easy process.  I used a light stand with an adjustable swivel to support the SpyderLensCal, but you can also use a tripod with a ball head or just use a level tabletop.

Datacolor SpyderLensCal Bubble Level (click image to expand)

For ease of positioning and stability, it's best to mount the camera to a tripod with a ball head.  To level the camera, I recommend using a two-axis hot shoe bubble level.

Two-axis Hot Shoe Bubble Level (click image to expand)Lining Things Up

Once both the SpyderLensCal and the camera are perfectly level, you need to adjust the distance between the lens and the SpyderLensCal.  Datacolor recommends a distance of 5 to 10 times the focal length of the lens.  If it is a zoom lens, Datacolor recommends you use the longest zoom position.  Using a 24-105mm lens as an example, you would set the lens to 105mm and calculate the distance. 105mm x 5 = 525mm, or about 20.7 inches.  So, you would position the lens between 20.7 to 41.4 inches from the SpyderLensCal.  Also, it's a good idea to position the target in a spot with good lighting.  I chose a spot next to a window.

Datacolor SpyderLensCal Setup (click image to expand)

The next step is to raise or lower either the tripod or light stand so the center focus point in the camera's viewfinder falls on the smaller contrasting squares on the SpyderLensCal (next to the zero line on the rule).  You also want to be sure that the back of the SpyderLensCal and the plane of the camera's image sensor are parallel.  However, since the appropriate focus point is right next to the rule and the lens is relatively close to the target, this is not as critical as it would be with a larger target at a greater distance.

Camera Settings

Note: The settings menu structure varies from camera to camera.  Please refer to your camera's user manual.  The example screens shown here are for a Canon 5D Mark II.

To ensure the sharpest images, I recommend turning on the camera's mirror lockup feature.

Set Mirror Lockup (Canon 5D Mark II)

Next, check the AF micro-adjustment setting to be sure it is enabled and set to "Adjust by lens".  Start with the adjustment set to zero (0).

AF Micro-adjustment Menu (Canon 5D Mark II) 

AF Micro-adjustment Scale (Canon 5D Mark II)

Ready To Shoot

Now it's time to take the first test photo.  To help eliminate vibration, I recommend using a cable release or the camera's self-timer.

First Test Shot w/AF micro-adustment at 0 (click image to expand)

You can attempt to review the image on the camera's rear LCD screen, but I recommend viewing the image on your computer.  Look at the rule to check where focus begins and ends.  As examples, here are two image crops demonstrating the AF micro-adjustment range from -20 (front focus) to +20 (back focus).

Front Focus Example -20 (click image to expand)Back Focus Example +20 (click image to expand)

Ideally, you want the center of the rule (0) to be in the center of the depth of focus.  Here's a crop of the first test image, shot with the 24-105mm lens and AF micro-adjustment set to zero (0).

Crop of First Test Shot Showing Slight Front Focus (click image to expand)

My 24-105mm wasn't off by much, but it was front-focusing slightly.  Click the image for a better look.  The forward .5 mark was in better focus than the rear .5 mark.  The AF micro-adjustment setting needed to be moved in the backwards direction.  After some experimentation with different settings, I decided an AF micro-adjustment of +2 was about right.

AF Micro-adjustment Scale (Canon 5D Mark II)Crop with +2 AF Micro-adustment (click image to expand)

Use Photoshop's Emboss Filter

Tip: You can use the emboss filter in Photoshop to improve the visualization of the in-focus and out-of-focus areas of your test shots.  Here are those two 24-105mm lens crops again with the emboss filter applied.

Emboss Filter Applied w/AF Micro-adjustment at Zero (click image to expand)

Emboss Filter Applied w/AF Micro-adjustment at +2 (click image to expand)Check Each Lens

After you've repeated the process for each lens using the appropriate distances (also being certain that you keep the SpyderLensCal and camera level and square), you're all done.  The camera will remember the AF micro-adjustment setting for each lens and set it automatically when you attach the lens.

Mine All Needed Some Adjustment

I have four lenses.  Each of them needed a slightly different amount AF micro-adjustment.  My 17-40mm lens was back-focusing slightly and needed a setting of -2.  My 100-400mm lens needed the least amount of AF micro-adjustment, which is not surprising because I sent the 100-400mm to Canon for professional calibration about two years ago.  The setting for the 100-400 ended up at -1.  Lastly, my 100mm macro lens needed the most AF micro-adjustment.  I've been suspicious that it was front-focusing, which was occasionally noticeable when I used it for portrait photography.   Sometimes I'd have a nose in focus with an eye that was slightly out of focus, yet, I was aiming at the eye.  Sure enough, the testing proved the 100mm macro lens was front-focusing and needed an AF micro-adjustment of +5.

Poor Documentation

Datacolor provides a really sparse set of instructions with the SpyderLensCal.  It was next to worthless.  Fortunately, I found much more thorough documentation on Datacolor's European site in the form of a PDF file: SpyderLensCal User's Guide

Summary

I'm happy with the results I obtained by using the SpyderLensCal focus target.  I've fiddled with homemade focus targets in the past with mixed results.  My results with the SpyderLensCal were consistent and easily repeatable.  The SpyderLensCal costs more than a homemade target, but as digital camera accessories go, it's not exactly expensive.  The included tripod socket and bullseye bubble level make for a nice package.

The Datacolor SpyderLensCal earns my recommendation for those wishing to take advantage of the AF micro-adjustment feature available on their digital SLR.  If you found this review useful and are interested in purchasing the SpyderLensCal, please consider supporting Mark's Hangout by using the Amazon link below.  Thank you.

Friday
Apr222011

EZ66 Guide For Travelers

Discovering Route 66

In May of 2007, Cathy and I were driving home in our Miata following a road trip to the midwest to visit family.  One of our overnight stops was a hotel in the little town of Grants, New Mexico.  That evening, tired of fast food on the road, we decided to look for a nice restaurant.   We headed away from the interstate and into the heart of Grants.  That put us on Santa Fe Avenue, which parallels I-40.  As we drove along, we noticed business after business that was either closed or looking like they were barely in business.  That's when we noticed our first Route 66 sign.  Having seen the movie Cars the year before, we suddenly realized we were driving through the center of the real-world equivalent of Radiator Springs.

Route 66 in Grants, NM (click image to expand)

At the west end of town, we found a Mexican restaurant (one of the few non-fast food businesses open) and sat down to eat.  But our minds weren't on the food.  All we talked about was that we were sitting in a business that had probably been dozens of different businesses over the years, and that it was located on Route 66.

Bitten by the Route 66 Bug

Back at the hotel, I used my trusty MacBook to search the web for more information about Route 66 in and around the area of Grants.  I found several Route 66 sites that featured turn-by-turn directions and explained how to drive as much of the original Route 66 as possible.  I looked at dozens of photos and read numerous stories about getting your kicks on Route 66.  I was at it for hours.  By the time I turned the MacBook off to get some sleep, I was hooked!  For the remainder of our drive back to Southern California, Cathy and I explored as much of the original Mother Road as we could, given our time constraints and lack of proper printed directions (if only the Apple iPhone had been released a couple of months earlier).  By the time we got home, we knew we'd be visiting Route 66 again, and soon.

EZ66 Guide For Travelers

Since May 2007, we've driven hundreds of miles of Route 66 between Oklahoma and California.  In a few weeks, we'll be joining with friends to drive every paved mile of Route 66 from Chicago to Los Angeles.  Navigating our way along those many miles of original Mother Road will be relatively easy, thanks to Jerry McClanahan's EZ66 Guide For Travelers.

EZ66 Guide For Travelers, 2nd Edition

McClanahan's book is considered the "bible" for Route 66 travel and exploration.  He really put a lot of thought into the design of this guide.  His love for The Mother Road is evident on every page.

EZ66 Guide For Travelers is spiral bound for easy reference while on the road.  Obviously, it's best to have a navigator to read the directions as you drive along.  But even a solo driver could manage to follow the route with some careful stopping to refer to the route directions as needed (though, things could get tricky in some cities where one turn quickly follows another).

Logical Layout

The first part of EZ66 Guide For Travelers features an introduction from McClanahan.  He then goes on to explain how to use the book, including explanations of the various terms and abbreviations used in the guide.  Finally we get to the meat of the book, the actual route directions, which are broken down into chapters by state, starting with Illinois.  (Route 66 passes through eight states in all, including the full widths of Illinois, Missouri, Oklahoma, New Mexico, Arizona, California, plus the Texas panhandle and just 13 miles through the southeast corner of Kansas.)  Each state chapter is numbered independently in the book.  IL. page-10, MO. page-25, and so on.  Within each state chapter, there are numbered Section Maps that precede that section's driving directions and give you an overview of how you'll get from one city to the next.

EZ66 Guide For Travelers, Section Map (click image to expand)

On the maps, the boldest line represents the Official Tour Route.  This Official Tour Route is by no means the only route possible.  Route 66 had dozens of different alignments over the years.  McClanahan is simply recommending this Official Tour Route as the basic foundation on how to best drive The Mother Road from Chicago to L.A. (or vice versa).  In fact, McClanahan includes numerous optional routes throughout the book.  These optional routes are also marked on the maps with a slightly thinner line.  Each Section Map also includes a box showing city names relevant to that map, and the mileages between some of the cities.

Clever Formatting

McClanahan used clever formatting on the actual driving directions pages.  At the top of each directions page there is a box containing the westbound (WB) directions covered by that particular page.  The directions are easy to understand and follow.  Reading them in your easy chair at home may feel somewhat confusing, but once you actually start driving the route, or following along using a Google map of the area in question, the directions become abundantly clear.

EZ66 Guide For Travelers, Driving Directions (click image to expand)

At the bottom of each directions page there is a box containing the eastbound (EB) directions covered by that particular page.  This clever design allows the EZ66 Guide For Travelers to be used regardless of which direction you are traveling on Route 66.  The book is arranged from front to back starting with Chicago.  After all, as the song goes, "From Chicago to L.A."  If you're traveling eastbound, you simply start at the back of the book and follow the EB directions as you flip pages forward.

More Detail in the Middle

Between the westbound and eastbound direction on each page, McClanahan provides frequent Detail Maps that show a closer view of the appropriate route through cities.  Also included in this middle area of each directions page are details about points of interest, optional routes (different alignments), side trips, and other useful information.

EZ66 Guide For Travelers, Detail Map (click image to expand)

Website Updates

To his credit, McClanahan provides regular updates on his website, McJerry66.com.  This is an important plus for users of EZ66 Guide For Travelers because things like longterm road construction and bridge closures occur along the route.  McClanahan's thoughtful updates really help to ensure a smooth and enjoyable Route 66 adventure.

Map Series

I should also mention the Here it is! - Route 66 Map Series from Ghost Town Press.  Jerry McClanahan was co-author of the map set along with Jim Ross.  The Route 66 Map Series is an eight map set (one per state) and also includes turn-by-turn directions.  Each map folds out to approximately 22" x 17" in traditional map fashion.  They can be used alone to navigate The Mother Road (we've done it), but I feel the map set best serves as a companion to EZ66 Guide For Travelers.  If I were only buying one, I'd go with the book first, but it's not a bad idea to have both.

Where to Buy

Whether you've been thinking about exploring small sections of Route 66, or jumping head-first into driving the entire route, I highly recommend EZ66 Guide For Travelers.  It truly is the "bible" for Route 66 aficionados and, in my opinion, pretty much a must-have for the best Route 66 driving experience.  The book is available at your favorite bookstore, or at numerous online retailers such as Amazon.com.  If you found this review helpful, please consider showing your support for Mark's Hangout by clicking the link below to purchase the guide through Amazon.com.  Thank you!