Distortion questions

Myrddhn wrote:

Larry Rexley wrote:

Myrddhn wrote:

Hi,

I am very new to the Canon M50 and advanced photography, and may ask dumb questions, but I'm a bit disappointed by some of the pictures I've taken with the Canon.

I have all the options for Lens Aberration Correction applied, but am now wondering if applying them may not even be the cause of the problem.

Any comments and suggestions would be appreciated!

This Image was taken two weeks ago:

What irritates me is that the two buildings on the sides seem to be leaning in on each other. Other images I've taken don't show this effect as profoundly.

The questions I have around this:

1) Does aperture have anything to do with aberration? (this is the dumb question)

2) This was shot with the general purpose standard lens that came with the M50, i.e. no wide angle and no telephoto. Is this a perhaps a wide angle artifact because of the all-purpose nature of the lens?

3) It seems like the in camera settings for aberration correction had no effect, or would it have been worse without them enabled?

4) I haven't tried any software, not even the Canon Utilities. Would they be able to correct this, since the effect goes quite far into the center of the picture?

Anyway, it's not the worst shot I've taken, so I'm not having sleepless nights over it, but I would like to understand the lens artifacts a bit better.

Thank you!
Andi

Welcome to the Canon M forum!

Keep in mind that 'distortion correction' term used in photography and 'perspective correction' are not the same thing.

When a camera corrects distortion, it tries to make straight lines in the image as straight as possible. Pincushion or barrel lens distorion would make straight lines near the edges of the frame slightly curved, and lens distortion correction should correct this.

The buildings lean towards the center because the camera is pointing slightly upwards. The camera was not level. This appearance is normal and natural, your eyes see it too but we don't really notice that because of the way our mind processes images. Sometimes photographers want to make the 'angled' lines vertical again --- this is referred to as perspective correction. General purpose image editing software often does not contain tools to do perspective correction, but it can be done in more advanced programs or in separate programs such as DxO Viewpoint.

It does look like distortion correction was applied to your image, as the lines are relatively straight. Perspective correction would not be applied by the camera to make the building walls vertical and parallel --- this would have to be done in special software. However, correcting perspective can be tricky and can only go so far... small amounts of correction can be done without reducing the image quality, but the more correction needed (as much as or more than your image needs) becomes tricky because parts of the image need to be stretched out, and there may not be enough resolution detail, so those parts start to look muddy and blurry.

To avoid the need for perspective correction, try to shoot with the camera 'level' - not pointing upwards, which usually requires a pretty wide angle lens if you're close to the buildings (or subject), or stepping back if possible (often this is not possible to get the shot and angle you want). Use the rear screen or viewfinder image while shooting to try to line up the sides of the buildings with the side of the frame as perfectly as possible.

The Canon EF-M 11-22mm f4-5.6 lens is a great, sharp ultrawide angle lens which is quite a bit wider than the kit EF-M 15-45mm kit lens that M cameras often come with. Lots of folks here use the 11-22, it's one of the best and most useful lenses on the mount. Shooting with that lens would give a better ability to get straight, vertical buildings. After shooting, you can then crop the image to get the composition you want (because shooting with the camera level often gives you too much in the bottom of the frame, and you want to cut it off).

There are some even more extreme, more expensive wide angle lenses such as the extremely wide Laowa 9mm f2.8 manual-focus lens which are about as wide-angle as you can get, keeping lines parallel, without distortion, and without the need for perspective correction if you hold the camera level.

Hi Larry,

Thank you for the comprehensive answer! It's now clear that the issue is related to perspective and not distortion, no blame on the the camera or the lens.

You're welcome. Here's a post I wrote in the DxO thread on using DxO Viewpoint to do both vertical and horizontal perspective correction. Other software can also do perspective correction, but how it's done probably varies.

https://www.dpreview.com/forums/post/66132882

With wide angle lenses, sometimes it's helpful to stretch the image horizontally as well to make it look more natural or improve the overall composition.