The Phase One XT provides 12mm of movement in any direction*, for a total range of 24mm of rise/fall and 24mm of shift left/right. This is the same range as the Canon TSE lenses, but many existing tech cameras offer a moderately or, in some cases, significantly, larger total range of movement. The Arca Swiss RM3Di, for example, offers 60mm of rise/fall range (+40 / -20) and 40mm of shift range (+/- 20mm), and the Cambo Wide RS1600 offers 40mm of rise/fall range (+/- 20mm) and 40mm of shift range (+/- 20mm).
Why was a 24 mm range of movement chosen for the XT?
The most obvious answer is that it keeps the XT small and light.
Every tech camera is a particular balance of range of movement, on one hand, and weight/size on the other. The XT is meant to be small, light, and optionally hand-holdable. Various amounts of movement were prototyped and 24mm of total rise/fall/shift range was determined to be the best balance.
So how small/light is the XT? Read our article about that here.
It’s More Than Enough for the Rule of Thirds
One of the main reasons for movement is the production of pleasing compositions without tilting the camera forward/backward (which results in converging lines), and one of the most common composition precepts is the Rule of Thirds. This is what breaks the frame into a tic-tac-toe board and suggests placing important subject matter at the intersection of those lines, keeping strong subject features in harmony with those lines. For example, in landscape photography, the horizon line is rarely dead-center in the frame, and rise/fall is used to place the horizon either one-third from the top or bottom of the frame.
For a full-frame 645 camera like the XT, the Rule of Thirds requires +/-7mm of rise. That means the +/- 12mm range provided by the XT is more than enough to apply the rule, regardless of the lens being used. In fact, at max rise, the horizon line will be one-fifth from the bottom of the frame.
It’s Enough for Panoramics
A left-right stitch of -12mm and +12mm results in 216 megapixels of raw data from a virtual sensor size of 78x40mm, just shy of a 2:1 aspect ratio. If you’re interested in producing panoramic images, this +/-12mm stitch is a pretty attractive proposition.
Of course, some photographers prefer even more extreme aspect ratios, such as the one produced by 6×17 film cameras. Cropping an XT +/-12mm stitch down to a 17:6 aspect ratio means a final resolution of around 150 megapixels. That’s not too shabby!
Many Lenses Can’t Handle More
The Rodenstock 23HR and 35HR, on paper, can’t be shifted more than 2mm. In reality, they can handle around 5mm of shift depending on the subject matter in the corners, and the pickiness of the photographer. That’s still a far cry from the 12mm shift possible with an XT.
The Rodenstock 32HR, 40HR, and 50HR hit their stated image circle at ~13mm of movement. So the 12mm provided by the XT comes close to maxing these lenses out.
The Rodenstock 70HR can handle ~18mm of movement, so 12mm doesn’t max out this lens, but it does allow most of the usable image circle.
The Canon 17TSE and Canon 24TSE are already a bit fuzzy in the corner of the frame even without movement. Remember that the IQ4 XT uses a full-frame 645 sensor, so it sees much more of the image circle, before movements, than a small-format camera. Also, the 150mp resolution demands much more of a lens, in terms of sharpness, than a small-format camera. But both of these lenses have an area of illumination (albeit slightly smeary) that extends for 2-3mm of movement if the subject matter allows it (e.g. featureless ceilings or blue cloudless sky look fine even when the lens is lightly blurring detail).
Of course, some lenses can fully use far more than 12mm of movement. The new Rodenstock 138mm offers 110mm, while the legendary Rodenstock 90 HR-SW offers a 120mm image circle that remains wicked sharp to the very edge. These lenses can make good/sharp use of ~30mm and ~33m of rise respectively. (That’s a huge amount of movement.) The 138mm allows a vertical capture with so much rise that the horizon is below the frame.
Schneider Digitar lenses often had large stated image circles (e.g. the 35XL) on paper, and could handle 13mm of movement, but in practice the quality fell apart before 10mm of movement.
The usable image circle size of the Schneider LS Blue Ring lenses (the native lenses of the Phase One XF) is still to be determined, but +/- 12mm will certainly be enough to make full use of that image circle when the LS BR adapter becomes available.
See our Image Circle Visualizer for an interactive guide to image circles. If you find this topic a bit confusing, don’t be intimidated! Our team will jump at the chance to walk you through it by phone, email, or in person at one of our upcoming events.
The XT’s range of movement maxes out, or comes close to maxing out, the image circle of most Rodenstock and Canon lenses. If you have a lens that supports huge movements, and want to use very large movements, then the XT is not the right body for that job. Thankfully, it doesn’t have to be a one-or-the-other choice. You can have both! You can STILL use your other bodies.
The Phase One XT is highly compatible with other Cambo tech cameras. The XT lenses can be mounted on any Cambo tech camera; starting mid 2020, they will be able to be powered/controlled through a cable from the IQ4. Until then you can use them in fixed-aperture mode with sensor-based shutter. Existing Cambo tech camera lenses and accessories, such as the Cambo compendium shade, can be mounted on the XT.
It’s perfectly reasonable that you might invest in a Phase One XT alongside a larger Cambo body, such as the Cambo Wide RS1250 or Cambo Wide RS1600, and choose the body for a particular shoot based upon your own preferred balance of weight/size and range of movements.
Given the extraordinary resolution, there’s argument that every XT lens should be considered a virtual zoom. Using the Rodenstock 32HR and cropping to a 40 megapixel image, you’ll have an effective 60mm lens with an additional 20mm of rise/fall/shift movement allowed.
Fix it In Post
One of the best parts of a tech camera is the number of visual problems you can solve without resorting to “fixing it in post.” Using rise/fall/shift in-camera, rather than using Keystone Correction in Capture One (or Perspective Correction in Photoshop), means less time spent in front of the computer. There is less stretching/warping of pixels, and the ability to see and set the final composition at the time of capture (as correcting in post always requires cropping). But, unless you’re a purist, this doesn’t mean you can NEVER use post processing to correct perspective. It’s employing tools that limit how often, and how much, correction is required.
With the XT, if you’re using 12mm of rise, and it’s not quite enough, you can always lean the camera back a fraction and correct the resulting parallel lines in Capture One. Say the scene requires 15mm of rise. Use 12mm of rise in-camera and make up the balance with a slight tip of the camera. Such modest use of “fix it in post” will have a fairly subtle effect on pixel quality and composition when corrected in post. In fact, with the XT, keystoning can be handled automatically, since the IQ4 embeds virtual horizon information into the raw file at the time of capture.
It’s entirely possible that once you’ve used this camera, you’ll find yourself making excuses to employ it in every plausible situation. With its versatility, physically and digitally, the XF totally changes the game.
*Technically, if you combine 12mm of rise or fall with 12mm of shift, the Pythagorean Theorem comes into play: You’ll have 13mm of total movement. That’s in contrast to a Canon TS lens with one movement, which can then be rotated, and therefore has less total movement when used at an angle.
Want to try out the XF, or have a question for our dedicated staff? Give us a call or reach out by e-mail to set up an appointment.