Comparing sharpness of 16-80 to other lenses

Started 9 months ago | Discussions thread
Alexis-C New Member • Posts: 2
Re: Questions

"Interesting would be to have Alexis' analysis of the 16-80 versus the 55-200 for the overlapping range."

Unfortunately, the gist of my post is that unless you're comparing things that are comparable (i.e. two graphs taken at equal f/ratio and focal length) and unless you have enough data points, it's really hard to make an analysis that tells you which lens is supposed to be "better" when trying to shoot the same picture.

Here we're overlaying MTF graphs that are usually only at the extremes (which differ in focal length) and at different f/ratio, which makes it hazardous to make iron-cast judgments based on just the MTF graphs.

OTOH, I think if the bulk of the 16-80 doesn't scare you, I do think it's a very interesting kit lens alternative to the 18-55, since within the range of the latter lens it's usually better most of the time (except perhaps in corner performance at the extremes of the range), and the price difference is moderate. But that only holds if the extended range is useful for you, of course.

Yes, the extended range isn't quite as good if you look at corner performance, but no one forces you to use it, and if you have the 18-55 instead you don't have the choice at all.

The only thing that the 18-55mm really does better within its range is open below f/4, which the 18-60 does not, though it comes at the cost of a tad of what I'd call image resolution (which may or may not be a problem -- it's still no slouch).

Plus the image stabilisation really is better on the newer lens.

All that being said, just to discuss the 55-200's MTF graph: it is a bit better than the 16-80s.

The centre MTF is a tad less than perfect when open at the widest, but that's perfectly normal -- given the already fairly high base f/ratio at the different focal lengths Fuji would have been foolish to make the lens slower just to make everything "perfect". If that bothers you, then don't use it wide open.

At the wide end the 55-200 also has quite some astigmatism, as much as the 16-80 at 80mm, so it's a fair bet (but still only a guesstimate) that the 16-80 is better at 55mm-80mm than the 55-200, but that corners aren't perfect in either closer to 80mm (where the 16-80 is at the extreme of its range but the 55-200mm probably not yet in the most comfortable part of its focal length range).

At the tele end of the 55-200's range, though, the astigmatism is there but a lot less so, and stopping down just a couple of stops should get rid of almost all of it, looking at the less complex form in the MTF graph.

Again, just as with comparisons between the 18-55 and 16-80 vs. the 16-55 f/2.8, the MTF graphs of the 50-140 f/2.8 are much better: not a shred of astigmatism, almost no residual aberrations in the image centre even when wide open, and very moderate field curvature. But you pay that in price, bulk and heft.

I guess if there is one lesson in all of this, it's that there are no miracles. If you want a perfect lens, it's going to end up bigger, heavier, more expensive, have a more limited range, or a combination thereof. Pick your poison.

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