Tilt Shift

Put on the 90mm Tilt Shift lens last night -- goal was to really try out the Live View remote shooting via a tether on the 1DsIII (for my 5D setup, see Shooting Tethered with Lightroom and How to Install and Shoot Tethered with Canon and Mac). With Live View remote on the computer, you can actually see what the camera sees and do all adjustments (except remote focus) from the computer. Gonna be great for studio/product work.

However, though the goal was to test Live View, I thought the resulting comparison photos of the tilt shift were interesting. If you are not familiar with Tilt/Shift lenses, they basically allow you to change the plane of focus coming from the lens -- typically the plane is parallel to the camera and lens, but a tilt shift allows you to rotate, tilt, and shift the plane so you can basically line it up with objects in the frame for better front-to-back focus.

In other words, you can "lay" the plane of focus on a flat object, like a blanket to get stuff sharp at angles you typically can't do with a normal lens.

An example with a still life in the studio. For this shot, pretend we are selling light meters, and the goal is to make the Sekonic light meter as much in focus as we can, while leaving the rest of the objects slightly soft and out of focus. We want to call attention to our light meter "product"

1) We start with Image #1) f/5.6 with no tilt (a normal macro lens for example). We focus on a point on the lightmeter, in this case the words ISO 1 A. So notice that the words and label in the front, and the Sekonic brand name are out of focus. This is what you would expect with f/5.6 -- a shallow depth of field with stuff blurred in front and back of the focus point.


2) With a normal lens, one option is to increase depth of field -- we could adjust to f/11 for example. We see the result of this in image #2 -- f/11 with no tilt -- the plane of focus is still parallel to the camera, but we still have softness in the front and back words.

We could continue on using f/16, f/22, etc, but that would render more and more of the other objects in focus. With everything in focus, we'd not be sure what the real product was.

3) Let's go back to our f/5.6 aperture now, and apply some tilt. With the Tilt Shift lens, I tilt the front glass element forward and down, so it becomes more parallel to the surface of our product. In the case of the Canon T/S lenses, the most they can tilt is 8 degrees. 8 degrees doesn't sound like much, but you can see that the writing in the meter has improved. There is still softness, especially towards the front of the meter, and I could have played around with focus a bit more to adjust, but given this equipment, this is basically a depth of field issue.

Also, comparing images #2 and #3, they are very similar. There are some subtle differences when you begin to blow these up to 100% (or in print), but basically the focus in the lettering in the T/S version is slightly more consistent front to back.

4) If the lens tilted more, we could have used just a bit more tilt to smooth out some of the focusing issues. Alternatively, we could have raised the camera a bit more so it was looking down at more of an angle, but that could lead us to unwanted composition issues. Alternatively, we could also buy a $20-30K+ medium format camera with better controls over plane of focus....

In image #4, I lived within the constraints and upped the depth of field by closing the aperture. Overall, we have a good in-focus coverage of the meter (product) from front to back, and in addition, we have kept just enough openness in our aperture to blur the surrounding objects to tell our brains what not to focus on.

There is probably some additional tweaking to be done here, but remember that I was playing with the new Live View feature! Without that, I would have been looking through the viewfinder, and with my bifocals, focus would have been all over the place!

(Update: I did go back and tweak the tiltshift, aperture, and lighting. Used the rotation feature of the lens to rotate and align the focal plane to better match the lighmeter. Also bumped up the aperture to f/16. The better alignment allowed me to keep most of the surrounding space out of focus while giving me better depth of field on the lightmeter. As for lighting, went with a 580EX flash in a white umbrella, and used a handheld white reflector to add some detail to the right hand side...)