INTRODUCTION:

Having a regular Olympus based magazine to produce focusses the mind and between the magazine Quest, The Olympus Circle and this web site my time is pretty well occupied. However, I subcribe to many of the Internet forums based around Olympus digital cameras to try and keep abreast of the current issues. Here I notice many posts asking about the performance of 4/3rds lenses, especially whether there is a lot of difference between the medium tele zooms currently available. Being a telephoto fan myself I first tried the ZD 40-150 and was suitably impressed. My write up about this lens is here. Next I tried the Sigma 55-200 DC - mainly because of its extremely reasonable price - and again was very pleased. The ZD 50-200 remained a pipe dream until quite recently when I had the opportunity to purchase a new one for a reasonable amount.

This appears to be a rather illogical way to buy lenses I agree, but available cash and opportunity always plague my purchasing policy! Now owning all three lenses it occurred to me I should undertake some comparative testing before I part with any of them. So that's what I've done. Building on my own standardised approach to lens testing I devised for testing the ZD 14-54 see here, against OM Zuiko's I've adopted the same technique.

ABOVE: My standard 'test' target.

This is my standard target image. It is 10" x 7.5" (4:3) printed on A4 and laminated. It is mounted on a south facing wall and a 4:3 area marked around it with 4 white tipped screws that enables consistent cropping in later post processing.

As I'm endeavouring to compare similar focal lengths but across three different zoom lenses I've decided to set the tripod mounted E-1 at 42.5 feet away from the target. (This is based on the ZD 50-200 minimum focal length of 50 x 85% = 42.5, and can be applied to any lens thus giving the viewer a consistent representation of the lens' performance.)

Images are taken in A mode with aperture set to lens maximum throughout the zooming range, ISO 100, SHQ. E-1 settings are Sharpness -1, Contrast CS1, Saturation 0. Post processing is kept to a minimum and is restricted to cropping and auto balance only. In addition I set the E-1 mirror lock-up to 3 seconds to provide a shake free exposure. No sharpening is applied.

I try to pick a bright but overcast day to avoid direct glare from the sun. Whilst this is the intention occassionally I have to test in conditions not perfect. As with all 'amateur' lens testing the results only represent findings on one day in one set of circumstances and should only be taken as indicative, not definitive. Having said that the lack of formal lens test results on the Internet leave the researcher (you) with little choice.

I start with the Zuiko Digital 50-200. Images are taken at 50, 70, 100, 150 and 200mm with the aperture kept at the lens' maximum. Why? Well Olympus constantly remind us that the ZD lens design and construction enables us to use max aperture with no image degradation. My own observations indicate, in line with most commentators and optical wisdom, that whilst ZD's do perform well wide open they perform best at around mid aperture range but this will be subject of another testing session. This test is primarily designed to see how these lenses perform wide open.

Next and without moving the tripod I mount the Sigma DC 55-200 and repeat the process.

Finally I mount the ZD 40-150 and repeat the process up to its max focal length of 150mm.

I've put the results for each lens on separate pages.

For the ZD 50-200 press here.

For the Sigma 55-200 press here

For the ZD 40-150 press here

COMPARISON & OPINION PAGES

Here you can compare results from the three test lenses at similar focal lengths. Due to different barrel sizes and lengths and differing nodal points comparable images are not exact in their dimensions. However, it does serve to illustrate reach, native sharpness, edge definition, contrast capability and colour rendering.

ADDITIONAL IMAGES FOR REVIEW - PAGE ONE

Press here for some additional comparative shots of another standard target I use. These results may be more revealing.

ADDITIONAL IMAGES FOR REVIEW - PAGE TWO

Press here for a wider range of examples following a request from Andrzej Wrotniak, who found the 2D chart shots a little unenlightening (fair comment). So I've included these. They might persuade you the expensive ZD 50-200 is worth its salt. There's no doubt about it, the background rendering with this lens is delightful; far superior to the other two lenses tested. Take a long look before you decide.