Nostalgia & History > Keystoning

Keystoning occurs when you tilt a camera and shoot scenes with vertical and horizontal elements.  The elements in the resulting photograph are not parallel and perpendicular to each other.  Here is a photograph Roger Puta took with his camera tilted upward.  The centenary towers to the left and the vertical elements of the barn to the right lean inward.  The face of the EL EMU is also slightly keystoned.

Photo 1 is the scan.  My VueScan software has already worked on correcting the fading, removing noise, and sharpening the image. For Photo 2 I worked a little more on these but, as you can see,  removed the keystoning.  This resulted in a little cropping.

I feel fixing the keystoning in Roger's photo was the proper thing to do.  What do you think?

Your eyes also do keystoning but you are usually not aware of it.  But looking at a static photo keystoning jumps out at you.

Oh, a keystone is the top stone in a stone arch.  Stone railroad bridges with stone arches have keystones.

If you take a wedgie of a train you get a form of keystoning.  The front of the train is much taller that the rear in the photo.

Marty Bernard

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Oh yes.  Any ideas on location.

Marty

With 3 wired tracks and a separate bridge on a curve, I'm going to surmise that it's the curve over I-280 between Highland Ave and Orange, NJ, here: https://www.google.com/maps/place/City+of+Orange,+NJ/@40.7715297,-74.2376221,20z/data=!3m1!1e3!4m2!3m1!1s0x89c3ab40923dfc83:0x4cff358afe3ae7e5



Edited 1 time(s). Last edit at 10/06/15 22:43 by knotch8.

I run into this problem a lot.  I tend to shoot mostly wide angle, and can't seem to find the horizon to save my life!   Digital editing (I use Lightroom) has repaired quite a few of my shots.  Generally I correct the verticals in the center and let the outside edges fend for themselves.  In less extreme images I can tilt the whole thing and line up all the verticals, but sometimes that seems to take the drama out of it and leaves it kind of flat.  (Is that a pun?)
As to "fixing" another's photos?  I'm not sure..  I suppose intent comes into play and would be the deciding factor.  I guess is some situations the subject of the photo is all that matters and pushes aside the historic value of representing the artist's work- but it could be a tricky call.
SR

Gosh guys, I'm not concerned much with keystoning. If it happens it just adds a bit of "artsiness" to the photo. I'm mnore concerned about making sure the image is straight, that is, the horizon line is parallel to the everything else. With digital I usually end oup having to straighten images in Photoshop. The photos presented here look just fine to me.

Of course, photography is an interpretive art so we all have different criteria when shooting. Yes?

I think in my case the answer is the good old "it depends". As Crudpunko mentioned, keystoning is natural, and in general I just compensate for it menially. Unless it is extreme, it is acceptable. And if it is extreme, the photog should have seen it in the viewfinder -- was extreme keystoning part of the artistic intent? Are you undoing something that shouldn't be undone?

In the case at hand, the original image doesn't bother me at all. I think that is because it is obviously a low shot, so keystoning would be natural. If anything, there is something I can't quite place about your adjustment that bothers me more than the original; I'm not sure what. Maybe the lack of distance from the subject. Just for discussion I've attached a quick hack I made after experimenting with the original for a while. I like it more than your modification, perhaps because it keeps the back-off distance from the lead car. Do I like it more than the original? I'd be inclined to say they were two completely different images and so not directly comparable. I like them about equally.
 

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As I shoot mostly indoor events these days, keystoning becomes apparent every time two parallel lines are diverging or converging.  Corners of walls and door frames are the most obvious non-parallel problems I find.  As in the the first of Marty's photos, the angular catenary supports and even the front of the MU car are noticeably keystoned. 

As Marty noted, our eyes see the keystone effect in a photograph, but our brain 'fixes it' so we don't really see the problem, unless we are actually looking for it.  And, of course, the wider-angle the lens, the more keystoning will be apparent, especially when the subjects are within 100 feet or so.  As anyone with a wide angle lens knows, taking a portrait of somebody with a lens wider than 35mm or so will seemingly enlarge their nose.  That's effectively keystoning as their ears are now slanted outward and upward from their normal appearance.

I don't remember if it which of the newer versions of Lightroom added the keystoning correction capability, but I use it a lot!  Fortunately, it also has predefined internal definitions for 3 of my 4 lenses, so I throw in lens correction as well (which corrects various lens issues such as barrel distortion, etc)  Most often, I find it 'squeezing' the top of the image together creating a trapezoid effect of the picture.  I then have to crop the picture to get it back to rectangular for saving/printing/projection.  That opens up the can of worms regarding cropping as far as what can I cut out and what MUST stay in the image.  Cutting someone's head vertically (in the image) is not an option!  Similarly, cutting off part of a locomotive, or important building, etc, has to be considered when cropping after the image has been 'straightened'.  Sometimes, I've had to undo the keystoning correction in Lightroom because critical portions would be cut off when cropping.  So be it.  Whether auto corrected or not, I often have to 'split the difference' in trying to get the picture to 'look right'.  Sometimes, making it absolutely horizontal throws other elements 'out of whack' or makes them look 'weird' after keystone correction and/or horizontal correction (usually done manually).  As I result, sometimes it takes a couple of tries to 'get it right' on my screen.

Unlike the film days of take the picture, send or take in the roll and get your slides back, nowadays, computer post-processing takes far more time than developing and mounting a roll of film in a darkroom.  Ain't technology great? 

BRAtkinson Wrote:
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> Unlike the film days of take the picture, send or
> take in the roll and get your slides back,
> nowadays, computer post-processing takes far more
> time than developing and mounting a roll of film
> in a darkroom.  Ain't technology great? 

More time but a hell-of-a lot more fun!

Marty

I dunno, I find digital (Lightroom) processing much faster overall than the olden days in the darkroom. My darkroom sessions were usually measured in hours and I was tied to a site. With Lightroom: any time, any where, one hour or six- VERY efficient! I love it!
SR