Keystone correction & when to use it?

gilbouk

gilbouk

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Gil
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I'm struggling to understand when to use vertical keystone correction. For example when taking photos of a building for example, I've found that converging lines become more apparent with the use of wider lens - so much so, that trying to use keystone correction can result with edges of the building getting too close or going off the frame

Also I sometimes find that photos look better without vertical keystone correction.

Also dependant on the vertical angle of the camera to the subject, would it be correct to say that keystone correction in some instances can result in contorted image? For example if there is a slight angle of elevation from the camera to the building. Here is an example

Without Vertical Keystone Adjustment
JSC_4653 1 by Gilbo B, on Flickr

With Vertical Keystone Adjustment
JSC_4653 2 by Gilbo B, on Flickr

When it comes to photos indoors using a wider lenses, is it a good idea to use Keystone Correction on extremes of an image - using vertical wall structures as reference points? I've used this method to level images, and when keystone adjustment is not possible (throws the subject off the frame) I have used the closest vertical structure (normally behind the subject) as reference when levelling a photo.
 
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I'm afraid that you have to play it by ear, as with many other aspects of photography - there's no one-size-fits-all guide.

If you think you might have to correct, try to leave a bit of room in your framing.

Aren't the two images above identical?
 
droj said:
I'm afraid that you have to play it by ear......

Aren't the two images above identical?
Click to expand...

Well they do appear to be the same file number!
 
Apologies folk - corrected now - two different images now
 
Take care how you line up the shot (angle/height) and/or get a 'corrected' lens (I use an Irix 15mm f2.5 MF). :)
 
I think that in this case, since it's a straightforward depiction of a building rather than some kind of 'mood' interpretation, it's going to be best corrected, and more corrected than you've shown. The tower in particular grabs the eye as being out of kilter.
 
Essentially the choice is whether to excite the eye (which can be disruptive!) or allow it repose.
 
Many things can be useful -
1. drone
2. telescopic camera pole
3. hydraulic platform
4. very long stilts ...
;-)
 
I've just remembered what is in a way a parallel (sorry!) circumstance, that occurs if you're putting up a shelf or a cupboard in an irregular old house.

You might reach for the spirit level, but find that if you obey it, the result doesn't look right, because the room, the context, influences your perception of the shelf.

So you do it by eye. You improvise.
 
droj said:
I've just remembered what is in a way a parallel (sorry!) circumstance, that occurs if you're putting up a shelf or a cupboard in an irregular old house.

You might reach for the spirit level, but find that if you obey it, the result doesn't look right, because the room, the context, influences your perception of the shelf.

So you do it by eye. You improvise.
Click to expand...

fallingbook.jpg


:ROFLMAO:
 
I often use a keystone (type) correction, and then back it off a bit, On its own it can often look unrealistic, whereas when we look with our eyes there is often a natural perspective, its trying to get that natural perspective, which is something IMO between what the camera sees (especially with a WA lens) and the keystone version.
 
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Back in the day when we used large format cameras with movements for virtually all archetectural photography. Verticals were correct as a matter of course. No one ever though it "odd". The same is true when you use tilt shift lenses.
The difference is not in what, how much, or how you are doing it. It is to do with the recent use of lenses that include extreme angles of view.
This was not an option In the past, as lenses much wider than an equivalent of FF 24mm. Were vanishingly rare. A Tilt shift lens has to have an image circle far larger tha an normal equivalent focal length. which limits them to about a nominal 24mm. And for large format there were not many lenses wider than 90mm on 5x4 that allowed much movement at all. And virtually no vertical shift, which is needed to prevent keystoning.

Images taken with standard or long focus lenses, with corrected verticals, rarely if ever causes visual problems in the way they appear, however it is achieved.
 
Back in the day when we used large format cameras with movements for virtually all archetectural photography. Verticals were correct as a matter of course. No one ever though it "odd". The same is true when you use tilt shift lenses.
The difference is not in what, how much, or how you are doing it. It is to do with the recent use of lenses that include extreme angles of view.
This was not an option In the past, as lenses much wider than an equivalent of FF 24mm. Were vanishingly rare. A Tilt shift lens has to have an image circle far larger tha an normal equivalent focal length.î which limits them to about a nominal 24mm. And for large format there were not many lenses wider than 90mm on 5x4 that allowed much movement at all. And virtually no vertical shift, which is needed to prevent keystoning.

Images taken with standard or long focus lenses, with corrected verticals, rarely if ever causes visual problems in the way they appear, however this is achieved.
 
I apply keystone correction almost as a matter of course. It’s become an integral part of my personal style, what contributes to making a picture mine.

I trained as an architect and I like my verticals very much vertical unless the shot was deliberately composed otherwise; my eye is sensitive to as little as a tenth of a degree out of true. What may get lost at the edges is something I factor in while arranging the frame.

My Sony A7II has a 2-axis level display in the viewfinder, which helps enormously get things right in camera (along with an old Olympus OM shift lens when I take that out).

In PP there is usually something in the scene to help establish a plumb line, even if some buildings themselves are a little wonky at the edges.
 
gilbouk said:
I'm struggling to understand when to use vertical keystone correction. For example when taking photos of a building for example, I've found that converging lines become more apparent with the use of wider lens - so much so, that trying to use keystone correction can result with edges of the building getting too close or going off the frame

Also I sometimes find that photos look better without vertical keystone correction.
Click to expand...
I think the reason you find converging lines more apparent with a wider lens is because with a wider lens there is a tendency to stand even closer to the subject, which makes the convergence more apparent.
When I shoot with a wider lens, I try (not always succesfully!) to stand back a bit and keep the camera more level in order to make the convergence less, even though this can result in a larger area of unwanted foreground. Having some additional space in the lower corners is also useful to avoid "blank triangles" at the corners, when applying software perspective correction.

Terrywoodenpic said:
Back in the day when we used large format cameras with movements for virtually all archetectural photography. Verticals were correct as a matter of course. No one ever though it "odd". The same is true when you use tilt shift lenses.
The difference is not in what, how much, or how you are doing it. It is to do with the recent use of lenses that include extreme angles of view.
This was not an option In the past, as lenses much wider than an equivalent of FF 24mm. Were vanishingly rare. A Tilt shift lens has to have an image circle far larger tha an normal equivalent focal length. which limits them to about a nominal 24mm. And for large format there were not many lenses wider than 90mm on 5x4 that allowed much movement at all. And virtually no vertical shift, which is needed to prevent keystoning.
Click to expand...
You may have had the luxury of a "rise and fall" camera front, but us mere mortals with regular 35mm cameras had to do the best we could.
If you were shooting B&W and home printing, there was some chance of applying correction if the enlarger allowed it, but those of us shooting colour slides were pretty well stuck with what we'd taken.
One of the great advantages of shooting with digital cameras is the possibility of applying these sort of corrections in PP.
 
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