Introduction.This page shows a comparison between the Canon EF 28-105/3.5-4.5 USM and Canon EF 50/1.8 lenses. I was surprised by how soft the Canon 28-105 and Canon 28-135 lenses are at wide apertures, and wanted to see if a cheap (less than half the price at about $80) prime lens would deliver better results. I think it does.
Methodology. All images were taken using a Canon D60 digital camera, mounted on a tripod, using mirror lockup and self timer to eliminate any camera shake. The target was a newspaper page, taped to a wall, illuminated by overcast daylight. The chart below shows cropped portions (from the center and edges) of several test images taken with the two lenses at different apertures. The Canon 28-105 was set to 50mm (the EXIF data confirm this), although it seems to capture a slightly wider field of view than the 50mm lens. The images were captured as high quality JPEG files and have not been modified other than cropping.
Results. I encourage you to look at the images
below for yourself, but here is how I interpret these images.
Conclusions. For me, image sharpness is important. Obviously, the 50mm doesn't offer the convenience of the zoom 28-105mm lens, but when sharpness matters, the 50mm looks like the winner!