Reversed 50mm - a dedicated Macro lens

Few aspiring macro photographers realise that they probably have lying about in the back of some cupboard a highly sophisticated, highly corrected macro lens just waiting to be used. What I'm talking about is the standard 50mm lens from a (now obsolete?) 35 mm SLR film camera. These lenses are also readily available from 2^nd hand dealers or swop shops at next to nothing. I recently purchased two at under R50 each. The standard 50 mm lens has been designed for long lens to subject distances (infinity) and a short lens to film distance (focal length). This principal is illustrated in the sketch below.

In macro photography, however, these conditions are reversed and the lens to subject distance needs to be less than the lens to film distance in order to attain the desired degree of magnification of the subject. It only makes good sense therefore to reverse the lens to achieve this.

The shorter the focal length of the lens the greater is the magnification that can be achieved. A 28 mm lens for instance will allow you to get considerably closer than a 50mm. The shorter focal length lenses, however, do present other problems such as vignetting (darkening of the edges of the image) so we'll stick with the 50 mm lens for the moment.

A reversed lens can be fitted directly onto the front of virtually any fixed or zoom lens, this is known as stacking or when a SLR camera with a removable lens is being used the reversed lens can also be used with a bellows unit or extension tubes only.

When stacking all the functions of your fixed lens such as exposure control and auto focus can still be fully utilised, these functions will of course fall away when the lens is used with extension tubes only. Even if you are using dedicated extension tubes they won't be operative on the reversed lens.

In order to fit the reversed lens to your existing lens (or extension tube / bellows unit) you are going to need a reversal ring. You can try your local camera dealer, although be warned, they are difficult to obtain. An alternative is to combine two filter rings which should be glued together in such a way that that they fit both the camera lens and the supplementary lens.

A 50 mm lens fitted to a Canon Powershot G3 which has a fixed (non-interchangeable) zoom lens.

Reversed lens fitted to a DSLR via extension tubes. When extension tubes are used exposure is controlled by the aperture on the reversed lens. The usual exposure compensation applies.

The author using a stacked 100 mm macro and a reversed 50 mm in the field.

For further details and full instructions on how to make your own reverse rings and fit and use reversed lenses on your camera see my book Remarkable Insects of South Africa - A Photographic Safari.

Text and photographs copyright Lambert Smith.

© COPYRIGHT Lambert Smith, 2009