Wide angle distortion

[Jaded62]

Hi all.

I'd like some guidance and advice please from those more experienced than me in fixing (or at least minimising) lens distortion in post processing. This is the lighthouse on Moreton Island taken from the lookout which is just a few metres away. Not that I would know but I expect that this is probably an extreme example of lens distortion cause by a wide angle lens (in this case 16mm) and the tall lighthouse being off centre in the frame.

In trying to fix this shot I realised that I was limited in what I could do with the transform tools given the limited amount of sky above the lighthouse. I have attached my transform settings FYI.

Thanks in advance.

5Ds & a EF 16-35mm @ 16mm, f11

As shot:

093A0912 Transform nil by , on Flickr

Transform applied:
093A0912 by , on Flickr

[ameerat42]

You've done most of what's required.

A note on terms (AFAI'mC):

Technically this is not a distortion but a projection, shown predominantly by really wide lenses.
The reasons are there in optics, so no use going into them here. It's predominant in such lenses
mainly because of the wide field you can still record even with tilting the lens.

To minimise it in camera, keep your subject lines parallel to the lens axes and near the central parts
of the field. Avoid subjects in compositions like this. Or, use a view camera

To fix in Photoshop, etc: more of the same as you've done I used Edit - Warp in Pshop V CS2.

Here's an illustration (taking tacit approval to edit your photo from the request in your post)...
uwa-proj.jpg

[Tannin]

A great answer from AM, particularly because it makes the crucial point that this is not lens distortion. It is not caused by the lens. It is perspective distortion, and it is caused by the laws of optics. More immediately it is caused by standing too close to the subject. The best way to deal with it is to stand further away and use a longer lens - ideally, much longer: 100mm or more provides excellent perspective if you have the room. But of course that often isn't practicable.

So what else can you do? AM covers some of the possibilities. Another one, and the one I generally favour myself where practicable, is to place the subject in the centre of the frame (change this by cropping later if desired) and use a fisheye lens. This gets the relative sizes of the subjects right - i.e., the top of the tower is not minituarised the way it is by a rectilinear lens. The result is a much more natural looking picture. (But you must compose it such that the important straight lines pass close to the centre of the lens. If you can't do that, then rectilinear ultra-wide is the only other possibillity.)

[Glenda]

Am and Tony give the best suggestions for getting it right in camera but for correcting it in PP I'd suggest using the little cross hairs on the far right to straighten rather than the vertical and horizontal sliders as you did. I've found I lose less of the surrounds doing this.

Used two to straighten
straighten.jpg

I then took it into photoshop and cropped to the left side of the small building behind the lighthouse. Use the magic wand tool to select both transparent areas, then select>modify>expand the selection by 5 pixels. I then took it into content aware fill and erased the building behind the lighthouse so it wouldn't use that area.
content aware fill.jpg

This was the result
48217719497_7811512cc6_b copy-trf.jpg

[arthurking83]

Can't offer any help re: processing, but I'll chuck in a couple of bobs worth of commentary.
Tannins reply hit the nail on the head. Perspective distortion.
It's exaggerated when using a UWA lens. You still get it with longer focal lengths too, just much reduced.
If you don't want it at all, you need a perspective control lens(or as AM replied a view camera).

Anyhow, why you got the angled light house is simply because you 'looked up' .. as in you tilted the camera/lens up towards the sky.
On an UWA this becomes almost comical, and can be used to effect if required(I've done so).
If you use a longer focal length, you still get this same effect if you also 'look up' with that lens on camera too.

So the basic tip is to (as Tannin pointed out) step back.
I'll add further to that tip by saying don't necessarily use a longer focal length, step back simply to give yourself more room(field of view) for the elements in the frame.
In this case you obviously wanted all of the light house in frame, so maybe a single step back to get more 'headroom' for the lighthouse, then because you now have more headroom on the lighthouse, you can tilt the lens down a bit more.
That step back doesn't impact the lighthouses importance in the frame, but it allows you the leeway now to tilt the camera and set up the fame so that the lighthouse is rendered vertically.
Hopefully you used a tripod .. but it seems more and more folks don't nowadays. (that's a personal choice).

Also; in taking this step back and tilting the camera down(perfectly level camera will render perfect verticals, subject to lens distortion) ... you would have also captured more of the seat and the fence post as well.

If you're more interested in the technicals of the whys and wherefores on the topic, search for the terms 'convergence' and 'divergence' in photography related websites.
Convergence is what you got, here.
Tilt up, verticals converge.
Tilt down, verticals diverge(this is mainly what I use to effect sometimes).

Note that when I use the terms tilt and horizontal, I'm referring to the forward/backward levels of the camera(ie. tilt), not the more common side to side, where the horizon may be tilted.

[Tannin]

Arthur adds a vital point when he mentions tilt/shift lenses (that's the Canonville term, it's "perspective control" in Nikonland). Dunno why I didn't think of that - especially insofar as I've owned one for years. Possibly because I seldom use it.

[Jaded62]

Thanks all for the great answers and explanations.

AM, I will try the Warp tool in PS CC.
Glenda, noted. I'll give this a go.

Perspective distortion? Yes, that is it!

I think this distortion was unavoidable in this situation which at least has taught me to use some tools in PS CC that I've seldom touched.

In taking this shot I found I couldn’t move back any further (only another 2m available to do so anyway) without bringing into shot another of the ugly sheds (LHS of where I stood) on site. This also meant framing the lighthouse in portrait with it left of centre in the frame. I wanted the path leading off into the distance to give perspective and depth to the shot and avoiding the LHS shed brought the path into shot anyway.

All told an overly complicated shot saved by the magic of PS CC.

Moreton.jpg