Tuesday, February 28, 2012

Lens test: M.Zuiko 14-42mm II vs. Zuiko 14-54mm

The purpose of this test was to see how the M.Zuiko 14-42mm II kit lens compares to the Zuiko 14-54mm (the original version and not the II version) at the 42mm focal length. Why 42mm? Because I’ve had the impression that 14-42mm II isn’t quite as sharp at 42mm as it is at shorter focal lengths, and I wanted to test that theory.

I did this test by using a tripod, and shooting a Microsoft Word document displayed on my computer screen. The 14-42mm II lens was mounted on the Olympus E-PM1 and the 14-54mm was mounted on the Olympus E-620. Unfortunately, I don’t have the adapter to use the 14-54mm lens on the E-PM1. However, both cameras use the same (or very similar) 12MP sensors, so the results should be comparable. Unfortunately, the E-620 doesn’t display the focal length that the lens is zoomed to on the LCD screen, so I had to guess based on the markings on the lens, and as you can see I overshot by 1mm.

You are looking at 100% crops from the center of the images. The top row shows the unsharpened images from Adobe Camera Raw, and the bottom row has the Photoshop Smart Sharpen filter applied (71%, 0.3px, Remove: Lens Blur, More Accurate checked).

I think the results show that there’s a noticeable improvement stopping down the 14-42mm II lens from f/5.6 to f/8.0. I didn’t show the intermediary f-stops, but trust me that you have to stop down to f/8.0 for maximum sharpness in the center (at least on my copy of the lens). However, the 14-54mm lens is noticeable sharper and it’s only stopped down to f/6.3.

I think I was correct in my impression that the 14-42mm II lens isn’t as sharp when fully zoomed in to 42mm. But I want to remind my readers that this is the lens’ worst focal length. I think this lens is only barely less sharp than the highly regarded 25mm f/1.4 and has the same sharpness as the 14mm f/2.5, although in both cases this zoom lens needs to be stopped down more to equal the same sharpness as the prime lenses. It’s disappointing that this lens drops off a little in quality at 42mm, but I still love this lens for being so small and light yet covering a such a useful range of focal lengths.

My take is that you probably won’t notice the lack of sharpness if you are making 8 x 10” prints, and you won’t notice it in the 800 pixel wide photos I post on my blog, but if your goal is to print really large, or if you want to do a lot of cropping, then you will get some benefit from using the 14-54mm if you intend to shoot at the longer focal lengths. Perhaps the benefit of the 14-54mm will be even more apparent on the newer 16 MP cameras.

On my future testing to do list:

1. Figure out exactly at what focal length the 14-42mm II falls off in quality. At slrgear.com, the test shows that this lens, when stopped down is very sharp at 35mm and only falls off at 42mm.

2. Take some real-world photo with both lenses in order to get a better real-world comparison, rather than a comparison based on taking pictures of my computer monitor.

But I also think that it took a lot of time to do this test, so I can’t guarantee that I will ever get around to this follow-up testing.

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