XF 16-80mm f4 - poor definition at 16 mm across the frame

Started 3 months ago | Discussions thread
thxbb12 Senior Member • Posts: 2,031
Re: XF 16-80mm f4 - poor definition at 16 mm across the frame

Mebyon K wrote:

thxbb12 wrote:

Mebyon K wrote:

I will give the same reply as I posted in another thread. With lenses, particularly zoom lenses, there is no free lunch. A wide zoom range and high optical quality are mutually exclusive.

If high optical quality is the main criteria then the highest zoom ratio for medium focal lengths is 3:1, such as 70-200. For wide angles and long focal lengths the maximum ratio is 2:1 such as a 12-24 or 200-400. This is why Canon and Nikon do not exceed these ratios in their lenses designed and built for professional use.

I am fully aware that most camera makers exceed these ratios by using electronic correction by the camera, which brings its own problems, but when the optical performance is examined without those corrections being applied it is obvious that the optical performance is compromised in some way.

It's not always mutually exclusive, if one is ready to pay the price.

A good counter example to the zoom ratio argument is the Olympus 12-100 f4. It's 8.3x zoom, yet it's optically superb and much better than most zooms with a much lower zoom ratio.

The thing is, pretty much all lenses with high zoom ratios tend to be sold as "cheap" superzooms because manufacturers believe that most prosumers are not interested in high quality, high zoom ratio lenses.

If you read my original post again you will note that I referred to high optical quality without electronic correction of any of the important parameters. After reading your comments about the Olympus 12-100 I looked at the summary of that lens' review on the Lenstip site. In their summary they make the following statement "Our conclusion: optics specialists constructing the Olympus 12-100 mm practically gave up on distortion correction and left that task to software of a camera.

That Olympus lens clearly has terrible problems with distortion and you clearly failed to read my original post correctly. I will repeat my original assertion for you benefit.

High quality optical performance and wide zoom ranges are mutually exclusive. If they were not, then Canon, Nikon and others would have produced wide zoom range lenses with the optical quality of their high end zooms.

Their optical design teams know that the laws of physics prevent such a possibility which is why they haven't done so.

Question: how do you judge the quality of a lens?

Answer: by looking at the images it produces.

Now, whether a lens is fully optically corrected or not, the determining factor is whether it offers good IQ or not. One of the metrics is sharpness. If a lens that is not fully corrected still delivers great sharpness, why would it matter?

It's the final output that matters, not the path one took to get there.

In this context, I still believe that the Olympus 12-100 f4 is a great performer, regardless of the software processing that comes with it. And I still believes it beats any similar lens for any system, fully optically corrected or not.

Another thing: you don't know what happens in your camera before it writes the raw file of the image. In fact, some post-processing might happen to the raw data and you'll never even know it, thinking you're actually looking at the true raw data when you're not.

Again: what matters is the final output.

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