We currently have three different types of Canon lenses:
- EF 50mm (3) -- standard telephoto lens -- prone to focus blur around the edges of a capture, especially the bottom edge
- EF 100mm (1) -- macro lens -- deals with light pollution very well but captures limited material sizes
- EF 14mm (2) -- ultra wide angle lens -- susceptible to light pollution but can capture very large material sizes
Each lens works differently and produces an image with different characteristics. See Cameras for notes on compatibility.
Each lens has settings that will produce optimal quality images. The image below is a screenshot from EOS Utility, showing where the shutter speed and aperture display. Right-clicking on either button will allow you to change the value for that setting.
- 50mm: for maximum sharpness f/5.6, for most even focus across image f/9.0
- 100mm Macro: f/8.0
- 14mm Wide-angle: f/8.0
There is no one optimal setting. Visualize exposure in EOS Utility to determine the correct setting during each capture session, which will be influenced by F-stop setting, lighting, and whether you're using glass.
Setting shutter speed:
- In EOS Utility, click on Depth-of-Field Preview, then place the color card on the table and look at the histogram in the Live View window. The last peak on the histogram (reflecting the white square of the color card) should be in the middle of the last section of the histogram.
- Each section of the histogram is a range of 50 points. If you shoot for the middle of the last section(200-250), you'll be somewhere around 225. Anything from 220-235 is on target for white.
- If your white is out of range, right click on the shutter speed and adjust it until the histogram reflects that the white is in range.
100mm Image Stabilization double exposure problem
The image below shows the tell tale double exposure caused by the IS feature on the 100mm lens. This feature is meant for free hand shooting and can cause a problem when the camera is mounted to a stand.
The double image is caused by the IS feature moving one of the lens elements while the image is being exposed. eliminate this problem by simply switching the image stabilizer switch to the off position when it is mounted on a tripod or stand.
F-stop focus blur
The images below show the chromatic aberration effects of low aperture number f-stop settings on the quality of image focus.