Tilt-Shift theory

Scatterbrained wrote in post #17942751
True, but if you want or need tilt shift capabilities for macro shooting then a LF camera can be ideal. A 105mm or 210mm lens on a LF camera with a DSLR (or in my case now a mirrorless body) can give you excellent control, but it does take a bit of time to set up. Still beats focus stacking for me though.
IMAGE LINK: https://flic.kr/p/nonK​nq Diesel: Square Chronograph by tltichy, on Flickr

IMAGE LINK: http://s103.photobucke​t.com …0816_zpsd64f4cf​2.jpg.html

Of course this is a very specialized usage.

Alveric wrote in post #17942757
Do you get the same FOV on the DSLR's sensor as you'd get on a 4x5? (I'm guessing no, but I'm a total ignoramus in this area).

I was eyeing this solution: https://www.cambo.com …/ultima-35-camera-system/ . Apparently you can use LF lenses with it, but they also don't say how to trigger the rig.

I was thinking that the lenses could be used both with that Ultima 35 system and a Cambo SC 4x5 and film.

farmer1957 wrote in post #17962947
I don't understand why the word theory was thrown in ?
But I own a TS-E 17mm and the TS-E 24mm mk I.

Something you guys might want to keep in mind is the TC 1.4 extender will fit on the TSE 17 mm lens

A TC 1.4 will not fit on the TSE 24mm MK I

I don't know if a TC 1.4 extender will fit on a TS-E 24mm MK II ? but I think it would be good knowledge to know before you buy.

Personally I think the easiest way to focus the TSE17mm or 24mm is to be tethered.

I am extremely happy with the lenses.........
But there is some what a learning curve to them ....but once you start using the lenses focusing doesn't have to be a issue.

I like my TSE lenses.
Good luck .

Benitoite wrote in post #17392480
Ive read the pamphlet from canon about the TS lens, and understand it can help with shots that have an angular perspective. From reading the forum for a bit, I understand it's popular for shots of houses...
How do you know a shot would benefit from a TS lens? How do you know how much to tilt? When do you use the shift? What do the tilt and shift do optically that I can't do in post?
Thanks for any help you can give.

TCampbell wrote:
What you can't do in post without a tilt-shift lens: You can use a keystone adjustment in post processing to do pretty much the same thing you can do with the "shift" axis on a tilt-shift lens. You'll probably burn yourself once or twice and realize that if you plan to keystone your image to a building that's leaning then you have to shoot wider (sometimes surprisingly wider) or you end up cutting off part of a subject that you didn't want to cut. When a building appears to "lean back" the keystone adjustment will let us pinch the bottom of the image inward to match the top so now the building doesn't appear to "lean" anymore. But you end up with a trapezoid shape image instead of a rectangle. So now you have to crop the image back to a rectangle and when you do that, anything in the left or right corners near the top is going to be lost. You can effectively perform a "shift" adjustment using a normal lens and software (there are actually a few ways to do this in Photoshop... one is to use the "lens distortion" corrections... the other is to use the Photoshop "transform" tools.

TCampbell wrote in post #18055966
I realize you posted this back in January... but I can give you a couple of examples. I have the Canon TS-E 24mm f/3.5L II.

SHIFT

The first image is taken with no correction (it's used just like an ordinary lens). The next image uses correction via the "shift" adjustment (no tilt) and a bit about that later.


In the first image, the camera's lens axis is pointing upward toward the center of this building and remember this is a 24mm lens so that building is actually closer than it looks. When the image sensor on your camera is "parallel" to your subject (in other words if the camera were perfectly level to the ground - nose to tail) then the building would not lean backward ... but then we'd end up cutting off the top of the building because it is both tall and close.

The "shift" axis on the lens allows the lens to slide upward or downward on the camera body (or left / right depending on how you orient the lens because the lens barrel does have a rotating axis to allow you to change the both the tilt and shift axis... the "II" version of the lens actually has two rotations so you can independently adjust the direction of shift vs. the direction of tilt if using both adjustments at the same time).

To use the "shift" you "level" the camera (so the sensor plane is parallel to the building -- and in fact the top of the building would be cut off) but then we "shift" the lens up to center the building in the frame. Now we have a building that doesn't lean.

One tip I came across... the human brain actually *does* expect things to seem smaller as they get farther away and the top of the building is no exception. The building should get just a tiny bit slimmer. If it gets a LOT slimmer it looks bad (this is the point of the shift feature) but if you use gridlines to make sure the building remains "perfect" (no slimming at all) then this will mess with the brain of the viewer. It creates an illusion that the building must be getting wider at the top.

So the tip is to correct the building... and then just back it off a hair (so technically if you put a grid over the image you'd notice it does pinch in by a tiny fraction to keep the brain happy with the perspective.) You may come across images where it seems like the building is getting wider as it goes up -- and if you put a grid over the image you may notice that the image is actually perfect -- that's your brain being unhappy that it knows the top of the building is farther than the bottom and yet the size of the top didn't get any smaller at all which must mean the top of the building is really wider than it's base (all of which is wrong, but that's how the brain works.)

TILT

The "tilt" axis is a little more complicated but there's a math formula. You probably won't use the math formula, but I'll share it anyway.

When I received my TS lens, I immediately noticed the index marks on the shift and tilt axes and thought there should be some formula to know if your adjustment is correct... and you can find anything on the Internet (sort of). I was surprised at how hard it was to find any straight-forward articles that described the "math" (you can find articles on the Scheimpflug principal but that's perhaps a bit too much math.)

Suppose you wanted to take an image of a Persian rug or an Oriental rug - lots of intricate detail in the rug - but you want tack-sharp focus from front to back.

You'd set up a tripod at one end of the rug, point the camera at the rug to frame it (with no tilt or shift adjustments) and frame the rug just like it's a normal lens.

Now you can take some measurements.

First... you'll notice the camera is tilting down toward the rug... we'd like to know that angle (we're talking about the angle of the camera body itself... ignore any tilt on the lens for the time being.)

Second... the rug itself is laying on the floor -- that's our plane of focus. We want to adjust the angle of the camera's plane of focus so that it matches the plane of the floor. This way anything resting on the floor would be in tack-sharp focus (literally it can be ANYWHERE on the floor... distance to the camera isn't important because of the way a tilt-shift lens works.

The idea is that the "plane of the camera's image sensor" and the "plane of the floor" have a common intersection.

What we really want to do is measure the distance from the center of the camera's sensor plane... to that intersection point. And this is where the angle of the camera comes in. While you could use a tape measure to measure the distance from camera straight down to the floor... that measurement wouldn't quite be accurate because it fails to compensate for the camera's angle. The intersection of the sensor plane & the floor is not actually directly BELOW the camera... it's slightly BEHIND the camera because the camera is angled downward.

To calculate the precise tilt angle you need to dial in, you need to know TWO numbers.

1) You need to know the focal length of your lens (in millimeters, of course). That's easy. If you have a 24mm tilt-shift lens then the answer is "24" (it's not a trick question).

2) You need to know the distance from the center of your focal plane to that "intersection" point (where the sensor plane intersects with the plane of the floor (or the plane of any subject.)

Suppose I measure the distance from the camera sensor to the intersection point and it's 305mm (which means my camera is "about a foot" above the floor).

The tilt-angle is equal to the arcsine of the focal-length of the lens divided by the distance from the sensor to the intersection point.

In my example I used a 24mm lens and measured that distance to be 305mm.

So it's 24 ÷ 305 = .0786885...

But that's not the number I want. I want to know the arcsine of that number. So using a scientific calculator, I punch the arcsine button ("2nd" function + "sin") gets you the inverse-sine or arcsine and the answer is: 4.513... (and that's measured in degrees assuming my calculator was in "degrees" mode (and that's the mode we want to use).

This means... if you use that scale on the tilt-axis of your tilt-shift lens and adjust the tilt angle DOWN 4.5º... you've just swung the focus plane down to the correct angle to match the floor. Now just focus the lens and shoot. You'll have a tack-sharp image from front to back. You will have nailed that shot.

So that's the math. You need that dimension (camera sensor to intersection point) and the focal length of the lens... then just plug it in.

PRACTICAL USE

But in truth you're unlikely to run around with a metric measuring tape and a scientific calculator as you shoot. So most people use a couple iterations of trial and error and adjust the lens in to the correct plane. If I focus the lens to the near part of the rug, then tilt down the lens tilt-axis to bring the back of the rug into focus, then re-focus, and re-tilt, after about two iterations you'll probably find a fairly good focus across the plane.

What you can't do in post without a tilt-shift lens:

You can use a keystone adjustment in post processing to do pretty much the same thing you can do with the "shift" axis on a tilt-shift lens. You'll probably burn yourself once or twice and realize that if you plan to keystone your image to a building that's leaning then you have to shoot wider (sometimes surprisingly wider) or you end up cutting off part of a subject that you didn't want to cut. When a building appears to "lean back" the keystone adjustment will let us pinch the bottom of the image inward to match the top so now the building doesn't appear to "lean" anymore. But you end up with a trapezoid shape image instead of a rectangle. So now you have to crop the image back to a rectangle and when you do that, anything in the left or right corners near the top is going to be lost.

You can effectively perform a "shift" adjustment using a normal lens and software (there are actually a few ways to do this in Photoshop... one is to use the "lens distortion" corrections... the other is to use the Photoshop "transform" tools.

As for the "tilt" function... you can't do that in software. If you need to change the plane of focus then nothing can do this quite like a tilt-shift lens. However if you wanted tack-sharp focus from front to back of a long subject (something you might do with the "tilt" adjustment on a tilt-shift lens) then you could just shoot lots of images, each focused to a different distance, and then use focus-stacking to merge the results. It would not look the same as an image shot with a tilt-shift lens but at least you'd get a sharp subject from front to back.

Wilt wrote in post #18056034

I used these two illustrations in another thread

The first shot is as taken in the camera and imported into Lightroom.

Then I used Paintshop Pro and its Perspective Correction feature to straighten the converging verticals.


Note that the paper in the photo now looks like its inherent square shape
But note that the photo is no longer 1.5:1 in aspect ratio. It only frames a 11:9.5 area, although the square item in the photo looks correct!
Using Paint Shop Pro, the correction function automatically eliminate the trapezoidal image outside shape, but the aspect ratio of the resultant shot is not the original dSLR aspect ratio,

Also note that the corrected photo illustrates the need for careful selection of lens to avoid the noticeable pincushion distortion that wide angle designs can display.

TCampbell wrote in post #18055966
You can effectively perform a "shift" adjustment using a normal lens and software (there are actually a few ways to do this in Photoshop... one is to use the "lens distortion" corrections... the other is to use the Photoshop "transform" tools.

PhotosGuy wrote in post #18056140
3rd way: Not perfect, but instead of pointing the camera up at a building, an alternative is to keep the back of the camera "level" (vertical), & use a wider angle lens than you would normally use to include the building. Then you can crop off the excess image.