Which m4/3 lens to use for photos of slides
I have an Olympus E-PL1 camera and want to digitize some 35mm slides. The kit zoom lens does not focus close enough to fill the frame. I am wondering which lens would serve a dual purpose as a fast prime as well as being able to capture these slides. btw: the slides were taken with very high quality gear and are in excellent condition.
A macro lens would be your best bet. They usually provide up to 1:1 magnification so you'd be able to easily fill the frame with a 35mm slide since the m4/3 sensor is smaller than the slide. To fill the frame (approximately, since the slide has a 3:2 aspect ratio, not 4:3) your lens would need a maximum magnification of about 0.5x. The 14-42mm kit lens has a maximum magnification of only 0.19x at 42mm.
Additionally, macro lenses are designed to eliminate field curvature, making them the lenses to use for photographing flat objects like stamps, slides, etc.
A far more elegant solution to overcome field curvature is found in the use of a dedicated macro lens. Such lenses are aberration-corrected for use at close range, including astigmatism, field curvature and distortion, to enable copying work.
Macro lenses are usually moderately fast, often f/2.8. Fast primes probably won't provide the magnification needed to take high quality images of the slides, so you have a choice to make. Get a macro lens, get a fast prime, or get both. To make sure that the image quality isn't degraded by diffraction blurring you should probably avoid using small apertures like f/11.