Nov 292010

Just recently bought a new Nikon 50mm f/1.4 D and, since I had to agonise over whether to get the 1.8 or the 1.4 (which costs twice the price for 2/3 of a stop more) I thought I’d try to evaluate it in some objective way, and test some of my other lenses while I’m at it.

So I found and printed off a resolution test target from here and also a color test chart. I mounted these onto a piece of 6mm depron such that, with the X with a circle round it was at the center of view and focal point. So the target spans from center to corner of the frame. This allows testing all the way to the edge. This is what the whole shot looks like…

As you can see, the colour image was at the edge of the frame.

All lenses were set at 50mm apart from the 55mm prime 😛 All filters were removed. Exposure was with flashgun (on manual) to ensure reasonable consistency. I’m interested in sharpness across the frame, rather than perfect exposure here.

Other lenses tested in the series were…

  • Nikkor 35-80mm 1:4-5.6 AFD
  • AF-S Nikkor 18-55mm 1:3.5-5.6G ED
  • Micro Nikkor 55mm f/3.5 AI (manual focus)

The target was photographed from 2.55 m, which is the ideal distance for this design of target with a 50mm (read up on the target link above if you want all the geeky details – it’s a bit beyond me to be honest. I just wanted to see how good my new lens is compared to the others I have and compared to itself at different apertures). The camera was on a tripod and lenses were focussed on the circle with a cross in it. A range of apertures were used, but since the largest that they all have is f/5.6, this was used for the comparison.

So onto the results. I have cut and pasted the colour chart, the bottom left resolution chart and the central resolution chart from each lens test.

Click for full res version (2.7 meg)

Looking at the sharpness at the edge, not surprisingly the two primes, both of which are pro-spec lenses, have excellent sharpness all the way to the edge. Both the zooms (which were both “kit lenses”) are a bit soft and woolly at the edges. Obviously the 55mm lens made the picture a little bit bigger due to 5mm extra focal length – that’s why the colour section was cropped.

As for the AFD 1.4 itself, here is the comparison of various apertures…

Click for full resolution image (2.7 meg)

Looking carefully, you can see it’s a bit soft wide open, much better by f/2, but by the time you get to f/2.8 it’s great. However, its softness wide open is only “poor” compared to its own performance. If you compare it with the two zooms, it’s not that bad. Since I bought it for available (low) light portraits, I think the soft-focus feel may even be an advantage. I probably still would have preferred if it had been razor sharp wide open because you can always soften in post processing, but expecting sharpness at f/1.4 may be unrealistic. Still. job done. I think this lens is a keeper. 😀 Good job too as it’s my Christmas present from the family. :present:

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