Stumbling upon a recent article ‘Finding the Sweet Spot’ by Ontario-based photographer, Steve Richardson, reminded me of questions posed by friends on particular lens sharpness of various makes. Generally, a standard answer would be-the relative optimum sharpness of a lens would be f/7 to f/8 to f/9 or the maximum aperture of the lens and decrease aperture by 2-stops. With the Canon 24-70 f2.8L a bias answer would be that it’s sharp throughout.

Of course, sharpness depends greatly on brand and sheer luck. A dependable brand (Canon, Nikon, Olympus Zuiko, Zeiss, etc.) will produce lenses with about an 85% success rate without obvious flaws. Until it gets dropped and the focus mechanism will need repair.

With third party brands (Sigma, Tamron, Tokina, etc.) sheer luck plays a huge role in getting a sharp lens. As too many factors come into play and most notably, third party lenses are reverse engineered from actual samples of lenses from the  big two-Canon and Nikon. Resulting in a bigger chance a buy will result in a faulty lens. From a personal stand point, the Sigma 50mm f/1.4 and 10-20 f4-5.6 are excellent and cheaper third party options to their more expensive counterparts but still not impervious to flaws.

Pro quality lenses are also prone to it’s fair share of faults. Take the Canon 85mm f/1.2L II(US$1,800)-it’s not necessarily sharper than the Canon 85mm f/1.8(US$400) but the L version has weather sealing and produces a much more beautiful bokeh(background/foreground blur) than the non L f/1.8. Do these factors substantiate a purchase for a greatly more expensive lens? To each their own.

After thorough research and lens purchase the best thing to do to ensure a good copy is to test it’s sharpness. Here is a very simple and effective way of doing it. Just follow the simple instructions on Steve Richardson’s post over at Photogrpahy Bay.


Shot details: Canon 50D+EF 85mm f/1.8 USM, AV Mode(Aperture priority), f/2.0, ISO 100, AWB, Flash Off, Adobe RGB, Center-weighted average. RAW converted in DPP and post processed in Photoshop. The photo was cropped to approximately 2/3 of the original 15 mp and zoomed in (right) to check clarity of detail.

In ‘Finding the Sweet Spot’,  the Canon 50mm f/1.8 II was used for testing. Photographer Steve Richardson’s copy of this lens had a maximum sharpness  at  f/8. Does this mean the nifty-fifty should be used at all times at f/8? Determining  lens sharpness should not deter you from capturing good photographs at any aperture. It is just a guide for knowing the exact opening for maximum sharpness when the need arises. All lenses should be used to it’s full potential by testing different apertures and shutter speeds on various subjects and compositions.

This author has used the nifty-fifty from it’s maximum opening of  f/1.8 to minimum opening of f/22 and gotten excellent results time and time again. Not every photo is equal but you will get a good one most of the time. Finding the sweet spot on the cheapest and lightest lens in Canon’s line up only makes the nifty-fifty much more fun to shoot with.