The 24 PC-E is not for the faint hearted. As I remarked in an earlier post, if you're trying to get the 'full monty' Medium Format technical camera look, don't handhold it. Ironically, with my Phase backs on a Cambo Wide camera and Schneider 35XL lens, I could get perfectly good results with full rise, handheld, at 1/60th or even lower - but that was with practice and experience, a leaf shutter, and one of the world's best lenses.

The problem with the PC-E is its inexplicable field of focus. After Lord knows how many experiments I have realised that despite diffraction, the best results are at F11 because the field of focus is not just curved, it's downright twisted. Even with no movements it is a bitch, a real, true, what have I done to deserve this bitch, to focus and get anything vaguely like sharp across the frame. Using tilts and swings is another matter and I'll post about that another time but it can be great fun handheld.

So here's a photo from today and after it, I'll go into what the building is and how I shot it.

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This is the Paimio Sanatorium by Alvar Aalto, in South West Finland. Built to treat tuberculosis patients, it is one of the most famous Modernist buildings in the world, nominated to become a UNESCO World Heritage Site. Set in a silent pine forest, it is incredibly beautiful and peaceful. It's also a royal PITA to photograph because it has limited clear space around it and it's quite tall. Which means either vertiginous converging verticals, or a camera with movements.

Bear with me here: I know a lot of Medium Format photographers who have been quietly selling their gear and buying D800s. The DR is arguably slightly better, the noise characteristics at anything over ISO 100 are far superior, and the ergonomics and flexibility are a joy by comparison to shooting MF digital backs attached to studio (i.e. generally monster SLR type) bodies. The rub, however (and this is what stopped a lot of people from switching when the Leica S2 came out - I know this only too well, I had one) is that these photographers often have a technical camera too, onto which the back can also fit, in order to allow tilts, swings, rises and falls in all any any permutations. And a number of these potential switchers have held back until it is clearer whether the Nikon (or limited range of alternatives) PC-E lenses can 'cut the mustard'. The 24mm PC-E is critical here because Canon make a great 17mm AND 24mm and because these MF guys (again, I am one of them) really really badly want a wide perspective control lens. Frankly for many, it's a deal breaker. I'll come back to this.

So, about the shot. Tripod. Preferably not the Giottos Traveller I had with me: I wished I'd had the Gitzo 3 series Carbon Fibre and I badly wanted the Arca Cube I use with it - the best tripod head that (a lot of) money can buy, because it allows perfect, tiny movements in every plane and is rock solid.

Anyhoo... frame the subject in Live View and level the camera as exactly as you humanly can but with the top of the building cut off. Now apply rise (here about 7 millimetres) until the top of the building is visible and leaves whatever amount of sky you want. Now point the camera up a touch and re-frame. This is vital: perfect verticals look weird, so you need to have a slight upward viewpoint in order to allow a light tapering of the building but nowhere near as much as if you weren't using shift.

So far so generic. Now it gets specific to this lens on this camera.

Take some test shots to get exposure right. If you're fussy (I am ) use a Colour Checker Passport to take reference shots for colour and WB. Get the exposure so that it just shows a tiny bit of blinkie in the sky. Ignore specular highlights if there are any: they are built to sparkle!

Set the camera to use a three second delay, or use a remote release: at F11 and trying to keep ISO low, you'll need stability.

Now, and this is the vital bit, in Live View 100% Zoom view, take a series of focus bracketed shots (even though you're at F11) starting with focus on the furthest part of the building away from you and then moving along its length towards you with more shots. Why? Because only God understands where this lens focusses and this is the only way to be reasonably sure of getting the shot. Even so, it's not guaranteed because the field effects are profound and even F11 is not enough to get every subject, however focussed, sharp throughout. But it generally works pretty well, if not quite as well as I'd expect or require. Click here to see a 4000 pixel wide version, equivalent to viewing on-screen at about 50%. But be kind, I processed this in a hurry on a laptop with nothing but Lightroom, in the front seat of my hire car...

Tip: use the Lloyd Chambers technique to focus in LV: Set up a custom Picture Control with sharpening at maximum. Of course, you're shooting RAW  so this won't affect your image, but it will make the LV easier to focus.

Tip: if the shot matters, shoot tethered, or immediately review on a laptop to make sure you've got it right.

So, is the lens 'good enough'?

Not really, no. If I were serious about this sort of work I'd keep my technical camera for now (actually I have, but the IQ180 back is for sale. I might get a used P65+ or IQ140 for this sort of work) because this lens is unpredictable and inconsistent and that spells danger for professional use. And don't forget, this trial was only using one of the facilities this lens should be able to offer...

A top-flight technical camera lens that plays nicely with the latest generation of high-end backs can set you back as much as £7,000 so on that basis, I strongly advise Nikon, or one of their competitors, to make a Nikon fit wide angle perspective control lens that knows how to behave. And don't worry what it costs to make - even if it sells for over £5,000 the math will be right for a lot of people. I'd buy it.

EDIT: 12th July 2012

Since posting this yesterday, and after well over five hundred visitors in less than a day, it's clear that a lot of people are interested in this topic. Of those who have direct experience with this lens (and it must be said that most of them are on cameras other than the D800) quite a few have said that they have found similar effects. Conversely, an approximately equally number have defended the lens and said that they haven't seen any odd 'field effects' in its focus behaviour. I've been asked by many of these people to post an example. The following image will, if clicked, load a 4000 pixel wide downres of the slightly cropped original. That's equivalent, roughly, to looking at 50% view on screen or making a 180 DPI print. Look very carefully at what is in focus and what isn't. Focus was using the confirmation dot on the centre of the triangle on the facade, just under the statue's feet. Look at how almost the entire facade is in focus but how the people at the top of the steps are far less sharp than the 'lady in red' bottom left. Imagine the image with a 'thirds' grid applied and look inside the central, lower 9th of the frame. Most everything here is OOF, at whatever distance from the camera, whereas at the sides everything is in focus, whatever the distance from the camera.. I think I know what is happening here and I will run further tests and post again. If I am right in my theory, it could help present a further way to work more happily with this key lens.

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