Part of Nikon’s resurgence during the past year was the announcement in January ’08 of three new Perspective Control lenses, a 24mm f/3.5, 45mm and 85mm. The 24mm was the first of the three to ship, (and arguable the most useful for the landscape photographer), and is the subject of this report. I write “report” because this isn’t in any way a formal lens test. Rather, it is a look at what a tilt / shift lens is and does, and what it can do for photographers using today’s DSLRs.
Firstly, I should make the point that this lens is primarily usable with full frame (FX) and film cameras. Nikon’s suggestion is that they are not suitable for use with DX format cameras. I tried it on a D300 and some of the control knobs will hit the projecting built-in flash housing. Not an insurmountable problem, but not ideal. Also, the lens is now a 36mm, not a 24mm. I have not tried it on other reduced frame Nikon cameras, but beware of any that have protruding prism housings.
For someone that has never shot with a large format technical camera a lens like the 24mm PC-E will be both enticing and intimidating.What the hell does it do, and how on earth do I use it? That then is the purpose of this article. To help you with answers to both questions.
I’ve been using view cameras for decades. I used to be the Canadian product manager for Sinar view cameras and used to teach view camera technique at the community college level. Nevertheless I understand how intimidating a lens like this can be at first so don’t let it intimidate you. Though sometimes confusing it’s a lot of fun to use, and a lens like this can be highly productive for certain types of photography.
While some perspective control can be done digitally in Photoshop and similar programs, often with decent results, in the end if you can do them with a rising front on a tilt / shift lens the results will be superior. And, as for simulating the effect of swings and tilts digitally, as will be seen that simply isn’t possible.
A lens like theNikon 24 PC-Edoes two fundamental things that no other type of lens can do.
– it allows you to change the plane of focus, from near to far to any other axis. (Hang in there, this will be clear soon)
– it provides a very large image circle, much larger than the image area needs, and then allows you to move the image area anywhere within that circle. (Seems easier to understand, but still a bit opaque, I know. Patience Grasshopper. All will be revealed).
In a technical view camera the board and standard onto which the lens is attached is free to move up, down, left and right. It also can tilt forward and back, and swing sideways. The tilt and swingmovements(as they’re called) take advantage of an optical principal called theScheimpflugPrinciple. This late 19th century scientist and photographer discovered and codified the principal that …
When the extended lines from the lens plane,
the object plane and the film plane intersect at the same point,
the entire subject plane is in focus“.
In a lens such as the ones usually found on a DSLR the film plane (sensor plane) lens plane and subject plane are all rigidly fixed. But in a technical or view camera the lens plane can be tilted. This ability means that if the lens is tilted just the right amount the apparent depth of field of the lens, which normally would extend forward and backward from the camera to infinity, instead become a tilting plane extending from an imaginary point in space (actually usually at ones feet) to infinity.
And, just to make things clearer (or more confusing) if this movement of the lens plane takes place sideways it’s called a swing, rather than a tilt, and allows depth of field to extend from ones side to infinity rather than ones feet to infinity. This is shown in the example immediately below.
Nikon D3 with 24mm PC-E lens @ f/16 & ISO 400
This rock face is just inches from my left shoulder, yet apparent depth of field stretches all the way to the most distant trees. Note that I stopped the lens down to f/16, not to gain depth of field from near to far, but rather to ensure that depth of field was sufficient from left to right, becausethathad now become the new subject plane.
Nikon D3 with 24mm PC-E lens @ f/16 & ISO 200
Here is a similar story, this time with the plane of focus extending from the foot of my tripod to the distant tree line. Again f/16 was used to ensure that there was sufficient depth of field from the ground upwards, which is now the way in which it extends.
On some technical view cameras back standard movements are also possible, which adds increased flexability. These are beyong the scope of this article.
Note to Nit Pickers:
In writing an article such as this it is appropriate and sometimes necessary to describe the Scheimpflug effect as changing the depth of field. Of course I know that what it’s doing is in fact changing the plane of focus. But for the beginner it is easier to visualize using terms that are more familiar. Mea Culpa for my occasional lack of technical rigour in favour of clarity of explanation.
Below is a real-world challenge which a perspective control lens such as the Nikon 24 PC-E can address, and which no other lens can unless one is using a technical view camera.
The foreground bridge girder is just inches from the lens, and the city skyline a mile or more away is effectively at infinity. Without using an ultra-wide angle lens, thus distorting perspective and reducing the distant skyline to minuteness, no amount of stopping down can render the girder and the skyline both in focus simultaneously.
But, by swinging the lens so that the lens plane intersects an imaginary line drawn from about my left shoulder all the way to the distant tower, everything can be kept in focus. The rest of the enlarged image segments tell the tale. Note though that depth of field now extends from left to right, rather than front to back, and therefore stopping down is still necessary to provide left to right depth of field.
The Rising and Falling Front
The other major capability that a lens like this offers is the ability to photograph subjects like buildings and trees without converging verticals. In other words, so that they don’t look as if they are toppling over.
This is a typical shot showing the front of a house, which because I wanted to include a bit of sky required that I tilt the camera upward. As a consequence the house is starting to look as if it was falling backwards because of the converging verticals.
But, if I level the camera so that the house’s verticals are straight, I see too much of the stone path and none of the roof line. What to do?
One solution would be to keep the camera level and to back up into the middle of the road. This would maintain proper perspective but it would also make the size of the house quite a bit smaller, and would therefore reduce quality in my final print. It also could mean that I get hit by a car. (And, of course, sometimes backing up simply isn’t possible).
The solution to the problem (you knew this was coming) is to use the rising front capability of the 24 PC-E. The perspective is correct, there isn’t too much foreground, and the roof line is visible.
So what is arising front, and how does it do its magic? The answer is quite simple.
A lens like the 24 PC-E actually projects a much larger image circle that is needed to cover the sensor or film.
The above illustration shows how this works. The gray circle is the image projected by an ordinary lens, and the red rectangle within it shows the standard image area recorded by the sensor or film. The image circle is usually only slightly larger than the image area on its longest dimension.
But a lens like the Nikon 24 PC-E projects a much bigger image circle than an ordinary lens, one able to include the entire image area shown. (I have not drawn the lens’ full image circle, to keep the illustration simple, but it would fall within the area that’s in yellow).
So, now you can see that by shifting the lens up or down, left or right, we are able to let the sensor or film recording area “see” a wider area, equivalent to stepping back into the street.
This is why photographers using large format cameras, when they buy a lens are as concerned about the size of the lens’ image circle as they are about its focal length. The wider the circle, the more latitude is available for shifts, rises, and falls.
Incidentally, having a large image circle is not a particular requirement for using the Scheimpflug effect. They are quite independent of each other.
Shifting for Mirrors and Panoramics
When a PC lens is shifted vertically it’s called a rise (or fall) and is mainly used to prevent converging verticals. But they can be used on the horizontal axis as well. One use for this capability to to be able to shoot straight into a mirror, or mirrored surface such as a glass wall, without seeing the camera’s reflection. This is often very useful in architectural photography.
More common among landscape photographers is to shoot two frames, one with the lens shifted left, and one with the lens shifted right, and then to stitch them together to create a very high resolution wide-aspect-ratio image. There may be some visible vignetting if an extreme shift is used, but this is easy to correct with the new post-cropping vignette tool in Lightroom 2.
Note to Nit Pickers:
It is theoretically preferable to stitch images shot this way when the back is moved, rather than the lens. The reason for this is so as not to shift the lens’ nodal point. But, shifting the lens creates very high quality results – ones that are much preferable to those produced by actually rotating the lens when shooting panoramics.
Using Live View with a T/S Lens
AsLive Viewstarted to become common within the past couple of years I didn’t object to it, but simply didn’t see much advantage for the type of work that I do. This has changed in recent months, particularly as I became familiar with the Live View implementation on the Nikon D3 and D300.
Firstly, there’s the very high resolution screen along with high magnification modes. This can make judging sharpness quite easy in all except the most direct daylight.
The above frame taken in my office was the very first done with this lens on the day I brought it home. I was having difficulty judging the focus on the far left and wondered how well I could judge it in Live View. To say I was pleased with how it worked is a huge understatement. This is what I had enjoyed when working with a view camera; the ability to accurately judge points of focus and depth of field. Highly recommended, even if it means bringing a dark cloth along when working outdoors, just as in the days of the view camera.
A lens like this at first appears complex to use, and even if you visit a store that has one in stock it’s unlikely that the clerk will know how to demo it properly. I’ve therefore produced a brief video which shows the lens in use and its major controls.
Please note that this video clip wasnotshot and edited by our professional producer / director Chris Sanderson, but is simply a quicky which I did myself to show the lens’ controls as a compliment to this article’s illustrations.
Adjusting the Adjustments
If you’ve ever used a view camera you know that there is no restriction on combining swings and tilts and shifts. Indeed with some subjects and shooting situations it is often necessary to combine them. This can be done as well with a lens like the Nikon 24mm PC-E, but there are limitations.
The lens comes from the factory with the tilt / shift and the rise / fall movements on opposite axis. If you want to have them on the same axis, so you can use a rising front and Scheimpflug at the same time, for example, then you need to bring the lens to a Nikon service center for adjustment.
This is the same requirement that owners of Canon Tilt / Shift lenses have. It’s a shame that Nikon did not find a way to make this user configurable.
I have always had my Canon 24 T/S set so that the axis are lined up, and I intend in having the Nikon 24mm PC-E set the same way.
I have not had the 24mm PC-E long enough to do any formal testing or comparisons. But have shot some hundreds of frames on location and made exhibition size and quality prints from it, and I can say that this lens does not disappoint in any way. Resolution is first class, as is mechanical construction.
As to how it compares to the Canon 24 TS/E lens which I’ve been using for some years, I simply can’t say with any certainty. But anecdotally I can confirm that they appear equal in quality, and so depending on which camera platform you own, you now have an appropriate choice.
Should You Buy One?
The Nikon 24mm PC-E costs close to $2,000. This is a serious commitment to a lens which does not have every-day applications for most photographers. But, if you do a lot of landscape or architectural work it’s hard to imagine any single lens purchase that will generate greater dividends.
The Nikon 24 PC-E lens is very exciting for Nikon owners, especially those with full frame DSLRs or film cameras. For the first time in some ten years Nikon owners have a lens which rivals and in fact may exceed the capabilities and optical performance of the Canon 24 T/S. Indeed almost everything in this article is relevant to the Canon lens as well as the other perspective control lenses in both the Nikon and Canon line-ups.
Focusing The Tilt / Shift Lens
This article provides a very limited introduction to the theory and practice of using a tilt / shift lens. For those that would like to learn more, particularly about how to focus a T/S lens when tilts and swings are used, I am publishing a tutorial by David Summerhayes titledFocusing the Tilt-Shift lens.