How sharp are your lenses?
Testing the sharpness of my lenses
I’m sure many people purchase their lenses on the basis of reviews/recommendations and trusting the reviews start using them straight away. Over the years we’ve done exactly that. Reviews are one thing, getting to know every inch of your lens is another. In order to be a little bit more precise about which of our lenses we use when I thought it might be useful to put some of our Nikon lenses through a sharpness test.
Having spent several hours carrying out this test, using a D7100 body mounted on a tripod, I thought I would share my results. Being a DX-format camera, of course, the focal lengths given below would need to be multiplied by 1.5 to give the effective focal length.
The lenses we tested lenses are:
AF-S Nikkor 16-85mm f3.5-5.6G
AF-S Nikkor 70-300mm f4.5-5.6G
AF-S Nikkor 50mm f1.8G Prime lens
AF-S Nikkor 18-200mm f3.5-5.6G
Below are my findings for each lens, which you can take as a quick guide, or better still spend a few hours getting to know your much-loved lenses by carrying out a similar test:
AF-S Nikkor 16-85mm f3.5-5.6
Although this has been a well used general-purpose lens, surprisingly we found it rather disappointing in comparison with some of our other lenses. Experimenting with focal lengths of 35mm, 50mm and 70mm, this lens is at its sharpest at f5.6 using the above focal lengths. The images got progressively less sharp when moving to a smaller aperture, with each of the above focal lengths.
AF-S Nikkor 70-300mm f4.5-5.6G
I just love the quality of this lens. It is a lens which I hadn’t used much until recently. Hearing so much about 70-200mm lenses being suitable for portraiture, I started using this lens for the same purpose quite recently and love the results. It provides a lovely shallow depth of field and produces very flattering portraiture. I experimented with focal lengths of 75mm, 82mm, 98mm, 102mm, 135mm, 200mm and 250mm. My experiment indicated that this lens is very sharp at 98mm, f5.6 and very slightly less sharp at f8 at the same focal length. In essence, this lens is pretty sharp using f5.6 or f8 at focal lengths of 75mm-102mm. We’re finding it a great addition to our studio lenses. However, if you need a high degree of sharpness, avoid using it at longer focal lengths and smaller apertures. At 250mm it is very unsharp.
Nikon 70-300 at 98mm focal length, f5.6
AF-S Nikkor 50mm f/1.8G Prime lens
We’ve used this lens for food and products shots including jewellery for a good while now and have been very pleased with its sharpness. Mounted on a DX body, it is equivalent to 75mm and great for portraiture. My experiment indicated that it is very sharp at f5.6 and f3.5. The sharpness progressively drops when using smaller apertures of f8, f11 and f16. On the other hand, the main disappointment came when opening up the aperture fully to f1.8 - the sharpness dropped by quite a lot. However, it started to improve when going to f2.8, f3.5 and it is at its best at f5.6.
AF-S Nikkor 18-200mm f3.5-5.6G
I’ve been using this lens for at least five years now as my general ‘do it all’ lens, particularly when out of the studio, but have been aware that it is not as sharp as our other lenses. Even though I was aware of its lack of sharpness, just for the record, I decided to carry out similar tests with this lens. I tested focal lengths of 18mm, 24mm, 34mm, 50mm, 70mm, 95mm, 105mm, 135mm and 190mm. My experiments confirmed that when it comes to sharpness this lens is definitely not a high performer! At focal length of 24mm, f8 it was at its sharpest, but not sharp enough to be used for most commercial photography purposes. However, we’re not going to dismiss this lens. It has a great range and if a high degree of sharpness is not required, for landscape, people or documentary purposes, it is very useful.