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Tilt & Shift Lenses
>Any thoughts on "shift n' tilt" lenses usage? I've never worked with and would appreciate some words of advice. (I'm particularly concerned on depth of field and exposure corrections)
Let me strongly recommend an introductory text on view cameras (maybe Adams' _Camera and Lens_ and an afternoon spent with a 4X5 camera.This will give you a good idea of what can be accomplished with swings and tilts, and the effect of shifting the plane of focus is very visible on the ground glass
>.When you go to perspective control lenses with that dinky little 35mm negative, you won't have half the control that you can get with a view camera, but you'll know what to do with it.--
>It really depends what you want to use them for, if you want to use them "correctly" i.e. to correct perspective or increase depth of field in a given plane then your best bet is to get a book like the one Sinar ( makers of 5 * 4 & 10 * 8 view cameras ) publish on the subject.If you want to use it for effects type shots i.e. most of the picture soft as you can and only a very narrow strip sharp, like the commercial I've just finished shooting, then it's probably best that you still read the book but then you just play until you get the focus effect you want.
>The exposure is pretty constant across the shiftable image with the Arri T&S lenses but drops off at the more extreme shifts with the Clairmont/CP lenses. However, the Clairmont/CP lenses are capable of more extreme effects than the Arri ones.I use these lenses a lot and don't really have a preference for either, they are both good in different areas, e.g. it's a lot easier to follow focus with the Arri lenses.As a taster and an intro to the idea you may want to try the CP swing lenses that are based on the Canon still lenses. You only have one plane to work with and therefore can get results much more quickly.
>Depth of field is best judged by eye. There really isn't any other way.Exposure correction only applies for extreme close up subjects, the best method I've found is to measure the image size in the plane of focus with the lens set flat, then apply the amount of swing and tilt desired, and apply the appropriate correction for the magnification factor, using formulae or tables. However I've only used the swing&shifts for normally composed shots on people rather than for extreme close-ups on packs etc, and I suspect the previous advice is good - do some research on view cameras and how to use them.I've used the Clairmont kit and the Arri kit.
>The Arri kit seems easier to use - has better locks and a little scale for each adjustment and better build quality - but the Clairmont kit has a wider range of lenses.They're both good though. Pulling focus is very difficult though. But you can do things like set up a plane of focus where an object will be sharp at 18" from the lens on the left of frame and sharp at 50' on the right. You can then track without pulling focus at all if you place your subject in the plane of focus. Allow plenty of time to set up your shot!
>They have become a little over-used here in the UK on commercials but they're very effective. I'd love to carry a set on a picture one day with the express idea of integrating them into the aesthetic. They're useful in a more mundane way, too - remember those in car profile two-shots at night where one actor is sharp and the other is a blob? Bring on the swing-shifts!
>Got a raking two-shot in a dark interior and can't quite make the focus split? And so on.
>Kodak has a good book called "Photography with Large Format Camera's", which although a tad brief in the lens theory area, explains it all pretty well. I've shot 4 TVC's with shift-tilts now ... all of them to make less interesting subjects a little more 'fruity'.Here in NZ, we only have access to a system manufactured by Sammy's in Australia. It's a PL-mount with a solid bracket attached, which holds the lens 'board' (actually a threaded plate) ... the lens-board is connected to the PL with a cloth bellows and can be racked in and out for focus, has lens rise and fall, shift left and right from optical centre, and of course 'swings' both X and Y axis as well.I presume most systems would be similar, though Clairmonts looks much more precise.
>The Sammy's one is not the best ... made for 35, it only mounts to 16mm cameras with some difficulty and compromise (the bracket off the PL mount hits the viewfinder optics on both Arri and Aatons unless it's oriented straight up from the lens port ... no T-Bar split). Lens selection is limited to 25, 35 and 90mm, and practically none of the adjustments can be done on the fly. Even pulling focus moves the lens (and therefore the image) too much that it's distracting.For those not familiar with shift-tilts, here's how I get my head around them.
>For a start, the lenses are not standard cine lenses. To work they have much wider coverage at the film plane ... I imagine a circle maybe 4 inches in diameter surrounding the camera's aperture at the film plane. The depth-of-field indicated by the lens can be seen as the 'thickness' of that circle. Moving the lens up or down, left or right effectively moves that circle in relation to the gate. The gate gets to look at any part of that circle of you like. Naturally there is vignetting around the edges, and the lens sharpness drops off out there too.In normal, optically centred position, the gate is at the centre of the circle. Shifting the lens down shifts that whole circle down (or the image-area the film is seeing up), and so on. Hence the perspective capability ... e.g., looking at a tall building with the camera horizontal, you can raise the lens up (do a 'rise'), to see the top of the building.You're not tilting the camera, you're tilting the optical light path!
>The film plane is still parallel to the building (it's still straight up and down as the camera is horizontal), so there's no convergence of the vertical lines!Swinging the lens takes the plane of focus away from being parallel to the film ... that same circle of light no longer strikes the film plane evenly, but cuts through it at an angle. That's how the interesting focus effects happen ... the plane of focus is not the way we're used to, and performs strangely! It's a good effect, but it's also practical as in extending focus for the car shot mentioned earlier.
>The thing is, if the driver in that car shot moved too far forward or backward, they could move out of the depth of field making for a very odd focus effect in an otherwise very 'normal' shot!OK, couple other points ... exposure correction is not necessary until you get into macro-territory, where your standard macro theory applies ... same as any bellows macro attachment. In our case (with the Sammy's unit), compensation wasn't necessary when focusing above 15" for the wider lenses, and I think 3' for the 90mm. That's pretty close.
>Can't use a Matte box ... it'd get in the way of the optics. So all filtration has to be on the lens ... ie Series 9 or similar. For the same reason, you have to really take care of flare with lensers thoughtfully positioned by the grips. Steadicam would be a nightmare I imagine.Lenses are fairly slow, even though they're primes ... T2.8 to T4.That's about all I can think of right now ... sorry about raving on a bit, but I guess someone asked!
>Shift/Tilt lenses (or bellows systems) allow you to play with some of the optical properties that are usually fixed in prime or zoom lenses.You can change the plane of focus (usually its parallel to the film plane) and/or change the geometrical appearance of any subject in the shot (shoot into mirrors without seeing the camera, correct for distortion when shooting up a high skyscraper).You can see a changed plane of focus effect in a bunch of commercials on TV these days, it has become somewhat fashionable to put part of the image out of focus. Another useful application is shooting two actors talking to each other, who are at different distances to the camera.
>If the depth of field normally does not hold both, you can angle the depth of field with a Shift/Tilt system, and get both in focus.
>Re : Exposure correction with Shift/Tilt SystemsBoth the Arri and the Clairmont systems have a ruler printed in the manual (make sure you get a manual from the rental house!).
>When you do a close up, place the ruler in the shot, aligning one end with the left frame edge.On the right frame edge you can read now the magnification ratio as well as your exposure compensation. It does not get any easier.
>but the Clairmont kit has a wider range of lenses.Not true anymore.
The standard Arri Shift/Tilt system comes with four lenses:
>24 mm T4.0 45 mm T2.8 90 mm T2.8 110 mm T2.0
>Arri have also released two more :
>18 mm T2.8 20 mm T2.8 28 mm T2.8 35 mm T2.8 60 mm T2.8 80 mm T2.8 150 mm T2.8
>In addition we have a Retro Adapter for the shift/tilt system, that allows you to mount Arri primes to the shift/tilt system "up-side down", that is the lens front looks to the camera, and the PL mount side becomes the lens front. This is great for macro cinematography.In addition we have a PL mount adapter, that allows you to mount Arri Macro lenses on the shift/tilt system. Use this for extreme close-up cinematography.
>The Arri Shift/Tilt system can be viewed at our Burbank location (818 841 7070) or at CSC in NY (212 757 0906).