Most cameras have a lens mounted at a fixed position exactly parallel to the film/sensor plane. There are two lens controls: focus and aperture. Focus (controlled by moving the lens toward or away from the sensor) affects how far away from the lens the plane of sharpest focus is, which is parallel to the sensor. Aperture controls how "deep" this plane of sharp focus is, as well as how bright the image will be.
View cameras - the classic "old school" camera design with a bellows - have two additional kinds of controls besides focus and aperture. They incorporate the ability to "shift" and "tilt/swing" the lens with respect to the film/sensor, in addition to the usual forward and backward focus control. This lets you control the geometry and focus of the captured image in ways not possible on "regular" cameras.
And that makes some interesting things possible. ...
First are shift controls. They're used to avoid geometric distortion caused by perspective. Most cameras look "straight ahead", such that you're photographing the middle of whatever's in front of the lens. Say you want to photograph a tall building. Normally you have to tilt the camera upward, which causes "keystoning", where the sides of the building converge toward the top. Shift controls let you keep the camera pointed straight ahead, allowing geometrically accurate photos like this:
While shift affects the shape of the image, the "tilt/swing" controls affect the focus. Tilt and swing move the lens away from being perfectly parallel to the film/sensor. This makes the plane of focus no longer be equidistant from the sensor across the frame. This can be used to either put more things into focus (e.g., a deep field of flowers), or, perhaps more interestingly, highlight very selective focus on a small region, in ways that go beyond what you can do with aperture alone.
Anyway, these controls open some interesting creative possibilities that are hard, inefficient, or simply impossible to replicate post-capture (e.g., in Photoshop). They can be tricky to master at first, but they quickly become second nature after you use them for a while.
I just checked the Lensbaby site. It appears that some of their products support a tilt function, but I didn't find any that supports a shift function for geometric accuracy. Disappointing.
@ColinOatley@wiredog Part of it is that shift requires the lens to have a larger image circle that covers more than just the frame. And most 35mm format lenses just cover the frame and little more.
@ColinOatley@wiredog So if you want to do shift (and accurate tilt/swing) and you don't want to go full view camera, you're better off with a dedicated lens. Canon and Nikon both some good ones for their 35mm cameras in various focal lengths.
Thanks. I was hoping for a lightweight and inexpensive (I know those are relative terms) tilt-shift lens for micro 4/3, and after reading the comment from @wiredog, I thought Lensbaby might be the answer. My interest in trying the shift function is not strong enough for me to buy the Canon or Nikon solutions. But maybe someday I'll rent the appropriate gear just to have the experience of using it.
@andyhilmer@ColinOatley@wiredog No, these lenses have to project a wider image circle, which is what you're moving around in when you shift. So it's like using a medium format lens on a 35mm camera.
seems like photography is similar to audio in that it's much easier to get something "clean" if you do it at capture, rather than post-processing step?
Finally, what's this Scheimpflug rule? The Scheimpflug rule (it's fun to say) gives you the relationship between the tilt/swing angle of the lens and the angle of the plane of focus. The Wikipedia page will give you a lot of equations and details, but in practice, it just involves a simple intersection of angles that's fairly easy to ballpark by eye once you understand what's going on.
So, what if you want to try this but don't want to go full large-format view camera? There are options for 35mm format (DSLR/mirrorless) cameras!
Both Canon and Nikon make a number of good lenses that support some shift and tilt/swing, in a range of focal lengths. They're expensive (and manual only), but pretty good quality.
@mattblaze Fortunately, I don't do that sort of photography, at least not now, so I'm not tempted to spend more money on camera gear… We'll, not at that kind.
@mattblaze@SteveBellovin I think you can get the same effect by using a wider lens, keeping the camera level, and the cropping the picture. Which explains why these perspective lenses are hard to build: when pushed up, the light enters at the same angle as it would on a wide angle camera. Hard to do that right without distortion.
@huitema@SteveBellovin Right. You can get the equivalent of shift by either shooting wide and cropping or by using photoshop, etc to correct. Either way costs a LOT of pixels, though.
Tilt/swing is harder to do in post. You can blur things with some work, but you can't put something shot out of focus back into focus.
@SteveBellovin@huitema You can do that, but the plane of focus will still be parallel to the sensor, at a fixed distance determined by the focus.
Say you want to photograph a deep field of flowers, and keep all of them in focus from right in front of you out to the horizon. Tilt can let you do that.
@youfoundryan@SteveBellovin@huitema Focus stacking can also achieve deep focus, but it's a little different, because it requires (obviously) multiple exposures (so moving subjects are a problem), and the resulting image has everything in focus, not just a single plane (which may or may not be what you want).
@youfoundryan@SteveBellovin@huitema Here's an image made with tilt/swing to keep a single plane in focus. You'll notice the focus is shallow, but goes back very far.
@youfoundryan@SteveBellovin@huitema Here, on the other hand, is a focus-stacked image (composite of 48 exposures). The whole thing is in focus, not just a single plane.
@mattblaze@SteveBellovin that kind of problem reminds me of high end teleconference systems, with large screens. You want to provide an image as if taken through the screen, but it is hard to put a camera there ( prisms, etc., are very unwieldy). We were trying to use several cameras, capture a 3D scene by combining the images, then project from the desired point of view. In real time.
@mattblaze colbert’s original late show opening credits featured a lot of tilt/shift video shots of NY. made the familiar city look new again, i thought. https://youtu.be/rBnsYwb0QgY
As a photographer myself (but no architectural photography, only art gallery interiors) I want to go look at some photos.
To me, with my roots as a university art major and drawing classes and vanishing points and all that I wonder what looks more "real" -- tilt-shift architectural photography or the standard lens, tapered-tall-building look
Want to go outside and look at reality to see what my eyes and my brain sees, but everything is two stories at most
@FinchHaven We're really good at correcting what we see with our eyes. Projecting onto 2D with a photograph seems to be a distortion amplifier for our brains.
Again, there's no tall buildings where I live just to think about
OTOH my art training (vanishing points) and despite working in Photoshop some (mostly Lightroom, about 95%) where I have stretched out the top of an image to reduce the taper, still has left me thinking that full-on tilt-shifting looks a little unnatural in a photograph
Probably because I know the mechanism behind producing that sort of an image
@mattblaze
It’s interesting that Cambus has a view camera product that would allow me to use a Canon or Nikon full frame lens with my Olympus micro 4/3 body. I think this combination, with it’s oversized image circle, would function as a “poor man’s” digital view camera. Is that correct? https://www.cambo.com/en/actus-series/actus-b-mini-view-camera/
@mattblaze I’ve been collecting the parts necessary to record the screen output (and maybe sensor video output) of using my actus setup to demonstrate movements
@TindrasGrove Right! It's not just helping you hold the camera steady (though that's important), it's giving you the ability to really study the frame and make deliberate adjustments to what's in it.
@mattblaze I've heard a classic example of shift making something possible is the shot that appears to be taken straight into a mirror - i.e. perpendicular to its face - but which does not show the camera/photographer.
@mattblaze the distinction between “shift” vs. “tilt/swing” is eye-opening to me, because I grew up in my old film SLR days (Minolta SRT-101!) dreaming about buying a “tilt-shift” lens, which Google confirms I am not mis-remembering. But I guess it is actually just a “shift” lens?
@misterbrandt There are some 35mm-format "perspective control" lenses that just shift, but both Canon and Nikon now make some decent lenses in various focal lengths that do both. More limited than a full view camera, but still very flexible.
@mattblaze i wish i had more useful stuff to say about it, i'm bad at art, but that 'columnar' focus effect is very cool, and i'm just amazed at how high resolution we can capture now. It's just wild to be able to keep zooming in
@mattblaze I only have a cursory background in your work but that has a surprisingly shallow depth of focus in the foreground. It does make 1 WTC stand out though.
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