photoblogography - Just some stuff about photography

ZD Lens Magnification

in Olympus E-System , Tuesday, February 08, 2005

For a long time before I bought the Zuiko ED 50mm macro lens, I (and others, I think) was intrigued by the apparent fact that the 14-54mm zoom actually focusses closer than the 50mm. How could this be ? There was plenty of comment on forums such as DPReview about the magnification factors of the lenses. This didn't make much sense to me, as surely a 50mm is a 50mm, no ? Well no, not exactly, as the closest focussing distance of a zoom lens is not necessarily constant at all zoom settings (focal lengths). To illustrate this, and to see how various Zuiko Digital lens combinations shape up, I've conducted an informal comparative test of the 50mm, the 14-54mm and the 50-200mm to see which can give the best magnification. I'm not really into heavy testing, so it was a bit rough and ready. The subject is a Swiss 2 Franc coin, which is about 26mm across: I set the lens at closest focussing distance and moved the tripod until the edge of the coin was in focus. All shots are at f/8. The lighting and aspect differs as I had to move the tripod to different positions for each lens. All files were rapidly processed in Capture One immediately to sRGB JPEG, with nominal sharpening. Here are the test shots: 50mmExt_001.jpg
ED 50mm Macro, with EX-25 Extension Tube 50mm_001.jpg
ED 50mm Macro 14-54TCat54_001.jpg
ED 14-54mm Zoom, with EC-14 1.4x Teleconverter, at 54mm 50-200TCat283mm_001.jpg
ED 50-200mm Zoom with EC-14 1.4x Teleconverter, at 283mm 14-54at50mm_001.jpg
ED 14-54mm Zoom, at 54mm 50-200at283mm_001.jpg
ED 50-200mm Zoom, at 200mm 14-54at37mm_001.jpg
ED 14-54mm Zoom, at 37mm Obviously the 50mm with extension tube gives the highest magnification. The 14-54mm does focus closer than the 50mm, but it does this focusses closest at around 37mm. At 50mm it is someway off. Of the three, the 50-200 is perhaps the most flexible. Although it isn't compatible with the EX-25 [CORRECTION - it has been pointed out to me that this is a mistake - it is in fact compatible] , it can be used to get some quite effect close-ups. There are some combinations I didn't try, such as the 14-54mm with the EX-25 (I ran out of time), but it wouldn't change the result. ps - this entry, and quite a few recent ones, was posted with the brilliant Mars Edit from Ranchero Software. Whilst writing this, for the first time ever it crashed on me, just as I opened iTunes - maybe it found David Sylvian's "Blemish" a little too avant garde for its tastes ? :-) Anyway, I soon stopped cursing - Mars Edit also has an autorecovery feature which rescued everything I wrote, unprompted and immediately. Now that's what I call software.

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