I decided to stage my own lens test of my new/refurbished Canon 100mm f2.8 Macro lens to make sure it was focusing as it should and to rule out user error (my inability to focus accurately and the stability of the camera and object) although the latter is what I have considered the most likely factor in focus or image sharpness problems.

The subject for these photos is a foot long triangular shaped drafting type ruler that I used in some of my early stock photos (which rarely sell, for good reason). It was setup so that “0″ point on the ruler was at the lens’ minimum focusing distance with the rest of the ruler angled away from the camera. The idea was that if the camera/lens wasn’t focusing where I intended it to focus, I could find out where it was focusing or if it was ever in sharp focus at all. In these photos the focus on the lens was adjusted (very, very slightly) so that the 1/2″ mark was a perfect in focus as I could get it. I used a Canon 40D in aperture priority metering mode with the ISO set a 800 so that the longer exposures at smaller apertures wouldn’t become too much of a factor in evaluation sharpness. Without changing focus I took 8 photos at f32, 1/13 sec; f22, 1/20 sec; f16, 1/50 sec; f11, 1/100 sec; f8, 1/200 sec; f5.6, 1/400 sec; f4, 1/800 sec; and f2.8, 1/1600 sec. On the 40D the focus was adjusted manually by using the live view mode set at 10X magnification for as much precision as possible. On a side note, I’ve found that using the live view at 10X also helps you to make sure there is absolutely no movement of the camera equipment and/or subject. The images were taken in RAW format, then converted to PSD in Lightroom 3. I didn’t perform any changes or add noise reduction in Lightroom with my default sharpening set at amount: 25, radius: 1.0, detail: 25, and masking: 0. (On another side note, if you have any good suggestions about a better starting place for a “generic” sharpening amount in Lightroom, please let me know.)

In Photoshop I stacked all the images together into layers in one image so that I could do one crop at 100% magnification and they would all be cropped the same (just figured out how to do this myself today). Then I copied each layer into a new image file and saved it as a separate image.

My observations (besides noticiing the incredible amount of dust and goop that’s obviously on my sensor at f16 and smaller) are that the lens seems to be doing its job very well and that even the slightest movement of the focusing ring can change the focus by 1/16th inch at these close focusing distances.

If you have this lens or any other macro and, like me, you’ve been wondering if the lens is as sharp as you’ve heard it was or thought there might be something wrong with it or suspected that your macro technique isn’t as  precise as it should be, you might want to duplicate these tests yourself with your equipment. One other note concerning macro technique: I started out in my “studio” area using a very flimsy music stand as a support for ruler. I usually like this stand because it will raise stuff up high enough that I don’t have to torture my back with low camera placement. That combined with living in a pier and beam (or actually just beam – but that’s another story) house that easily transmits vibrations throughout caused me to rethink that approach and settle on the kitchen counter which is a lot more stable. If you haven’t tried viewing with live view magnified to 10X you probably have no idea how much vibration there is even with a pretty good tripod and tripod head.

One other thing I learned is that if I going to shoot a lot of really close 1:1 macro images I’m going to need to get a good macro focusing rack. There’s always something.

So, check out these test photos! Click on an image to see the 100% crop of the original  photo.

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