Yesterday I showed a few screen shots of pixel peeping the 23mm f/1.4 against the 18-55 little guy zoom. I also shared a few thoughts that boiled down to the higher-priced primes are really in a different class when it comes to pixel peeping whereas the newly coined "Fuji-crons" really are not. I wanted to follow that up with a bit of reality as well as a couple esoteric "better" is all in the eye of the beholder.
Not Safe For Work
The non-clinical testing I've shown shot with far more controlled circumstances than most real-world work is a torture test of sorts. All the threads on the synthetic morass of fine-detal are micro-fiber-esque. They are incredibly hard to resolve. I also have all of the lenses at very close to their minimum focus distances (which Fuji allows to be extremely close for most lenses, except the 56mm f/1.2 which you'll see what a huge difference that makes backing off just a foot).
The picture at the very top was shot with the 18-55mm @ 35mm zoom f/4 1/125s ISO 800. The "noise" is some fake LR grain. Actually the banner picture if you are on a laptop/desktop is a small horizontal slice of a vertical composition below.
Almost wide open, within like 1/3 stop. I'm moving, Alicia is moving, shutter speed kinda slow, etc. All of those trump minor differences in lens performance in most cases. Corners? Who cares, generally the performance at even the extreme vertical edge is more than good enough. If I pixel peep the eye lashes are crazy sharp, so is the fine detail of anything that actually lands in the very shallow f/4 plane of focus shooting this close. I tend to use wide-ish apertures anyway to reduce unwanted skin detail.
For the most part the 18-55mm is damn good and I have no issues using it close to or even at wide-open. Personally I feel it renders well even in the OOF areas (all relative) and is really not any sort of IQ constraint for most subjects and most circumstances. The one characteristic it has that I would say on the whole is worse than the primes, in many cases far worse, is that it flares more easily. Not only does it flare more easily but at certain oblique angles of light sources striking the front element it is almost useless. What's more is the hood is not super effective as it has to allow for the 18mm end.
How 'Bout Those Flaws?
I've shown before a while back how the 18-55mm reacts terribly to certain angles of light hitting the front element. You can provoke bad behavior in terms of ugly flare out of most lenses if you try hard enough. Some lenses far harder to make them behave badly than others. The 18-55mm is on the easy end of the ugly flare spectrum relatively speaking. It also reacts a bit differently than the primes I have if you include a light source in the frame.
I used the word "ugly" on purpose meaning not attractive and generally unacceptable no matter which way you slice it rather than some way of saying all flare or lowered contrast is unacceptable. Knowing it's behavior you might even be able to use that characteristic aesthetically.
Let's take a look at a short sequence of pictures as a random example.
Above pretty much no flare to speak of. If I would have shot this side by side against the 35mm f/2 I could probably see a minor difference in overall contrast if I looked really hard. Next up lets take a look at a wider view and include a little bit of the light source in the frame.
No giant difference in contrast for sure but a few of you might notice the halation kind of effect in and around the light source itself. Generally most of the Fuji X lenses exhibit this "look" when light sources are included in the frame to one degree or another. I kind of like it most of the time. Is it due to the design? The coating? Who knows. I can generally say most Nikon lenses render light sources in the frame differently, maybe more clinically, maybe "better". Then again the 50mm 1.4G looks awful wide open in most backlit situations. Truly bad.
Next up, let's include even more of the light source and also change the angle getting a bit more towards that soft spot where the 18-55mm just falls apart contrast wise.
Without a lot of close inspection you can probably see an overall softening and even more halation effect. In this case I kind of like it. Especially when the lighting conditions are crazy contrasty with shadows going to black. The next one goes right to the edge of where the 18-55mm goes nuts.
If you couldn't see what I was talking about before I think this should do it. Now that halation effect is clearly visible to all but the blind as well as an overall softening of contrast everywhere in the image. I like the effect here even better. You can look at this as a fault, somehow making it a worse choice than other lenses that do less of this or even none but I would submit to you that's not what photography is about.
A Leica Aside
Does Leica even make a lens that's not perfect any more? I don't know but I can say there are many Leica lenses where when more photographers were using them that everyone was not super-stoked about "better-ness". Sure some people were but a good example are the 35mm Summicron lenses. There was a sharp divide between the pre-ASPH and post ASPH 35mm photographers in terms of which one they liked better. Interestingly enough it was about a rendering issue very similar to what I've just walked thru along with a few other things that were farther down the list like OOF rendering and focus transition, etc.
Different tools, different job. Not all flaws from a laboratory perspective are some measurement that indicates what you might want and like from a visual point of view. The 18-55mm is a great tool, so are the primes but I have no hesitation using the 18-55 even when I excite some of it's inadequacies as shown. I regularly recommend the XT-10 (or 20) with the 18-55mm as a do-almost-everything kit to people that just can't swing a few thousand bucks. I use my XT-1 and 18-55mm as a beater now and also when I'm shooting with strobes for product-shot photography etc. Why not
All images made with the Fuji XT-1 and 18-55mm XF with some random preset of mine jammed on with some fake grain in Lightroom CC.