That a can of worms. I have photographed for over 50 years and none of my lenses have ever been fine tuned. I own a Nikon 300 2.8 and the 200-500 5.6 and I have shot them on five different Nikon digital DSLR's platforms, both lens are sharp as a tack with no adjustments EVER needed. With today's focusing systems and post production processing sharpening it comes down to the individual. And folks who are able to fine turn sometimes are never quite pleased with the results. These are the same people who get the BAD COPY of a lens and return it. Like I said, maybe I am just lucky that ALL of my auto focus lenses focus great or maybe I don't get out a microscope and look for flaws in my images. Most of my show work is printed to 20X30 and they look sharp to me and to the folks who buy them. But hey, who am I, just a guy who loves photography.

That a can of worms. I have photographed for over 50 years and none of my lenses have ever been fine tuned. I own a Nikon 300 2.8 and the 200-500 5.6 and I have shot them on five different Nikon digital DSLR's platforms, both lens are sharp as a tack with no adjustments EVER needed. With today's focusing systems and post production processing sharpening it comes down to the individual. And folks who are able to fine turn sometimes are never quite pleased with the results. These are the same people who get the BAD COPY of a lens and return it. Like I said, maybe I am just lucky that ALL of my auto focus lenses focus great or maybe I don't get out a microscope and look for flaws in my images. Most of my show work is printed to 20X30 and they look sharp to me and to the folks who buy them. But hey, who am I, just a guy who loves photography.

A couple years ago, when I bought my 6D, I noticed some of my Canon "L" lenses were not quite as crisp as I felt they should be. I also noticed my focus point was a little off. So, I pulled the main offenders, and took some careful shots for testing purposing. I did some really close pixel peeping and found these lenses were either front or back focusing slightly. I tried several suggested was to adjust the problem out of the lenses, but sometimes the situation got even worse. It was suggested to try FoCal, from Reiken Techology, in Great Britain. I bought a copy of the program, read the manual, and set-up and tested my lenses, even the zooms. Problem solved. FoCal has recently come out with a real upgrade, and it really takes out front/back focus but really puts out a full set of graphs on how your lens is performing on your camera. The system is rather easy to set-up, but you need a sturdy tripod, and area large enough to put up a target, and adjust the distance from the target to the camera. Lighting is important too. I use a 100 watt bulb in a clamp on fixture, clamped to a chair back. The program will also tell you if the lighting is proper. Just set-up your camera to the program specs, and allow it to run. The program will take several shots of the target, and give a print out, if desired of the calibration, color rendering, and more. If you select full auto, it will make the adjustment in your camera for you. The system so easy to set-up, and execute that I use it almost every time I have a paid shoot for all the lenses I plan to use. FoCal can also tell you if something has happened to your lens over time. Like a wide swing in adjustment from one time to another, indicates something has happened within the lens. I feel that any photographer, who is seeking that tack sharp image, must make exact micro-adjustment to their lenses to body. It really makes a difference in the final output of your product.

B

I used a similar method for years and I thought I was getting good results. Last year, I received Lens Align and Focus tune software as a gift. I couldn't believe how variable the results were when plotted out with the Focus Tune software. Sometimes as much as 15 on the camera micro adjustment (Nikon D7100). The Focus tune software throws out those outlying points and plots a curve which shows which camera micro adjustment setting is correct MOST OFTEN for your camera and lens combo. I ended up changing all of my lenses between 4 to 7 micro-adjustment values on the camera and I did see a noticeable difference in the sharpness of the lenses when I used them wide open (with the focus tune settings vs the ruler:target method).

I would have never bought the software nor the alignment tool since I thought I was getting good results with the target and ruler method. I am a firm believer in the software now. You could do the same thing with the ruler and target method by shooting multiple points at each micro-adjustment camera level and then hand plotting them, the software just makes it faster and easier. You probably discuss this variability issue in your course but I thought it important to mention since most of the YOUTUBE's on micro-adjustment auto focus don't mention it.