Canon Macro Lens EF 180mm 1:3.5 L USM
|Aperture Range [f]||3.5 to 32||Closest Focus||0.48m / 1.6 ft.|
|Dimensions||187mm x 82mm / 7.3 in. x 3.2 in.||Magnification Ratio||1.0x / 1:1|
|Weight||1.09kg / 2.4 lb||Filter Size||72mm|
Analysis of this lens resolution chart revealed that it is the sharpest at f/8, athough at the adjacent apertures is nearly the same. The image quality on a camera's chip depends on the distance from the center, as shown below, with the average resolution in hundreds of line widths per picture height (LW/PH) given below each chart.
The sharpness is relatively uniform throughout the entire frame, and reaches the theoretical maximum (resolution of "37" is the max. theoretical number in this test) at f/5.6 through f/11. It is exceptionally sharp. Contrast in the center is slightly lower at wide apertures, but at f/3.5 only.
Vignetting is very low. Chromatic aberration is negligible. The size of the circles remain constant trhoughout the frame. The circles have also perfect proportion (no ellipses). The lens has virtually no distortions.
Test macro at magnificaction 1:1. A house fly wing has been placed between two microscopic slides and sealed tightly to flatten it as much as possible. A source of light (flood matte bulb) was placed behind the slide. Two photos on manual focusing (at ISO 50) were made at each f-stop, with mirror locked up, one that placed the wing in the center of the frame and another on the side, approximately 15 mm from the center, as shown below.
Actual magnification ratio:
1.017 : 1
23.62 x 35.40 mm
1 pixel = 6.31 micrometer
The 200x200 pixels cropped images are shown below.
The best sharpness was achieved between f/4 and f/8. On the sides a light chromatic aberration is visible. I would not recommend making photos at above f/11 due to the loss of sharpness.
This is a high quality lens, better than the 100mm macro lens. Most useful for macro applications, with a 1:1 magnification ratio you don't need to be so close to an object to capture it. Because of the extreme working range, 48 cm to infinity, the autofocus seems to be too slow.
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