A friend gave me a lens. It's the Nikon 20mm I mentioned yesterday. After a long day of accounting and chasing down vendors so I could pay them in a timely manner --- I decided to put the lens on an adapter I have and to walk around the downtown area taking random photographs. I came back with nothing spectacular or even very good. But I did come back with some thoughts about the lens and maybe an appreciation of how far lens design has come since the 1990s. At least where wide angle lenses are concerned.
I used the lens, with adapter, on a Leica SL. It's a camera famous for the thin glass stack on the imaging sensor which is supposed to give better edge performance with Leica's huge selection of legacy lenses that were designed to work best on the more forgiving medium of film. Seems light rays hitting film emulsions tangentially aren't degraded in the same way they are when interfacing with the pixel wells in digital cameras. The thin stack wasn't enough though to bring this lens into the excellent or stellar category.
Like most lenses of just about any in the modern, multi-coated era of lens design the 20mm has a sharp central area and only really falls apart near the corners. At f2.8 the performance overall is mediocre to just good. At f5.6 and f8.0 it sharpens up, increases its contrast and looks decent. On all the images I took there was vignetting in the corners. In the very far corners the vignetting was massive and dense. Sure, you could crop but why not just start with a fully corrected 24mm lens in the first place?
One thing the lens has in quantity is distortion. And the distortion is not the easy to correct barrel distortion but the more pernicious mustache distortion. With a lot of patience and some talent in post production one could go a long way toward correcting it but..... again....there are better options at hand.
At f8.0 the lens is capable of high sharpness in most quadrants of a frame and the trick is to use a camera with a good manual focus magnification feature. If you punch in as far as you can you can make images come alive with detail. But careful focusing is critical even when considering the vast depth of field the lens and aperture provide.
The pros of the lens are: that it can be found for not much money. Samples are rampant at around $200. The lens is very light and very small compared to more modern (and more corrected) lenses. The focusing ring on my samples was smooth and had a short focus throw which is really neither a plus or a minus.
The negatives include that the focusing ring is hardly damped at all and feels different than most manual focusing and AF lenses with nice focusing rings which provide some tactile feedback. MF was definitely an afterthought on these lenses. But the flip side is that a short focus through and a very light MF construction probably increases the autofocusing speed a lot. The "cons' also include the fixed vignetting and the geometric distortion. Which largely disqualifies this lens as a choice for serious architectural photography.
In a side-by-side, quick test I have to say that the Panasonic 20-60mm kit lens is better when used with any L mount camera because both vignetting and distortion are corrected in camera, via software. If I needed good technical performance at 20mm I'd grab the zoom first. But really, if you hang out at 20mm a lot then something like the Sigma 20mm f2.0 Contemporary might be the best choice for overall optical performance in the system. I owned the 20mm Art f1.4 Art lens from Sigma for a while and at most of the wider apertures the vignetting is bad enough to show through even with in-camera corrections. I'd rather have a better corrected lens with a more modest aperture. I could never really divine the value of the f1.4 aperture on a such a wide lens...
On the other hand this lens does have a lot of character. If you have an editorial use for the lens it could be fun. I'm withholding final judgement on this lens until I have the opportunity to shoot it on a sunny day and until I have more experience with it on the various L mount cameras.
some might suggest that the lens adapter may be responsible for the vignetting but it's not a hard, mechanical edge as a physical blocking would cause and there is photographic detail if you take the time to correct for the vignetting in post.
It was a fun distraction from an otherwise busy and fussy day.
f5.6 at ISO 12500.
ISO 12500.
I am looking forward to using this lens in good light.
I think the color rendering can be quite nice. Some of that is
down to the camera....
