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Nikon D7500
Tameron 16.0-300.0 mm f/3.6-6.3Picture specs: ISO 400; 16mm; f/8.0 1/200 sec
In editing this picture, two of the first things that I noticed was that the horizon has definite lens distortion and also that the horizon is very slightly tilted.
I tilted the picture -0.35° and then used the manual lens correction – distortion tool in Lightroom 5. I set it at +18 which made the horizon almost straight. But I was noticing that now the horizon curves upward at either side of the picture.1. What is causing this?
2. Is there an easy way to fix it?Attachments:
So, for those wondering what lens distortion is… Distortion is a normal problem that comes from bending light through lenses. To get a good idea of distortion, look at some straight lines through a magnifying glass. Lens manufacturers try to compensate for this bending by using multiple lenses to cancel out the distortion, but it’s always somewhat imperfect. Barrel distortion is commonly found in wide-angle lenses and pincushion distortion is found especially in telephoto lenses.
It looks like this lens is suffering from moustache distortion, which is a combination of both, and is often found in wide zoom / all-in-one lenses like this 16-300mm. Rather than doing a manual correction you could try using Lightroom’s automatic lens correction. If they have a profile for this lens / camera combination it could do a better job than a simple manual correction.
If that fails, you could technically do two opposite manual distortion corrections with slightly different parameters, though I have never tried that, so I’m not sure it would actually work. As a last resort you could crop in quite heavily, but that is probably not what you wanted to hear.
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This is neat. I’ve never heard of moustache distortion before!
Yeah, I’d be curious what the automatic lens correction does. When I downloaded your photo, opened it in Photoshop and ran the Filter > Lens Correction tool on it, a lens profile was automatically applied and seemed to fix the problem properly (see first attachment).
When I tried to fix the distortion manually, I started having the same problem as you described (see second attachment)! So yes, fixing it manually does not seem to be the ideal way to do it.
If, for whatever reason, you do want to fix it manually, then two ideas came to mind. #1, you could clone from areas on the horizon that are straight. And #2, you could take it into Photoshop and use the Edit > Free Transform tool to make the horizon do whatever you want (see third attachment)!
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