Nikkor 50mm f/1.8G Nikon
The 50mm f/1.8G tests great on the FX D700 camera, but how does it do on a crop sensor body?
The Nikon 50mm f/1.8G lens is Nikon’s new inexpensive standard lens. The build quality is good given the cost of the lens, and it feels about the same as the new Nikon 35mm f/1.8G for DX. It has a metal mount with plastic outer barrel. The included hood is nice and deep to prevent stray light from hitting the lens and it offers a lot of protection.
The focus ring is twitchy for manual focus, making it very difficult to focus bracket, and manual focus is the only way to use this lens on the NEX. Small tweaks cause no change in focus then a sudden jump. It has a clear plastic cover over the distance scale like the more expensive Nikkors, and it has about 2:1 gear reduction so 1/2 turn of the focus ring would turn the focus mechanism 1/4 turn, but the issue is the focus throw is very short. Even with the reduction a 90 degree turn of the ring will go from end to end.
The aperture has 7 curved blades, so even stopped down out of focus specular highlights appear as near circles. Being a G lens it lacks an aperture ring.
The lens is unique for a standard lens with 1 aspheric in a 7 element, 6 group design. This should give similar correction as the 50mm f/1.4G, which has 1 additional element. With a minimum focus distance of 0.45m (1.5 ft) the magnifications is a so-so 0.15x. The filter threads are 58mm and the lens is fairly light at 185g (6.6 oz).
Optical Characteristics as Tested on the D700
MTF 50 (Sharpness)
Examining the data closely it looks like the aperture might be off a bit (there is no ring and I have to use a flakey adapter). I think what is marked as f/8 might be closer to f/11 as that would put it close to the diffraction limit on other lenses. It doesn’t really change a lot with this particular lens since performance at f/1.8 is already very good, but it would probably mean what is shown as f/2.8 in the graph above is probably closer to f/4 and performance at actual f/2.8 would probably still be fairly close, somewhere between the f/1.8 and f/2.8 (as marked in graph) performance, which is still very good to excellent. On my newer tests I eliminate this by setting cameras exposure using a lens with known aperture set at f/5.6, then set the same exposure on the Nikon lens with no aperture ring. This will get the f/stop within 1/3 stop, which is as close as I can do. My experience is that f/5.6 is very consistent exposure between lenses.
MTF 20 (Resolution)
Lateral Chromatic Aberration
The lens measures a noticeable 0.58% barrel distortion (numeric average between all apertures), following shows the coefficients and a sample test chart.
All data gathered using Imatest.
The performance of the lens is excellent. It has very good to excellent central performance throughout the range, and corners that are good resolution from wide open, and very good to excellent by f/2.8. It is definitely one of the better 50mm f/1.8 lenses I have tested.
Lateral CA is noticeable, but not major.
– Optical Performance
– 7 Bladed Diaphragm with curved blades
– Manual Focus Feel on the NEX
– Large for 50mm f/1.8 lens
This lens is an excellent buy for the image quality, but on the NEX 7 it must be used with manual focus, and manual focus feel for this lens isn’t good. Also, with no aperture ring you can only adjust the aperture if your adapter allows it. For these reasons I would much rather shoot with an older manual focus prime with smaller size, better manual focus feel, and only slightly worse optically.