focusing tilt shift for miniature with limited focus points

JC

I acquired an older EOS tilt shift lens, mostly for in focus landscapes, but I also want to use it for miniature.

I am using this lens with a 5D mark II, however, I'm really spoiled by the 14x focus assist zoom in manual focus mode on the Olympus OM-D. Focusing using live view zoomed in on the screen of the 5D is a lot harder. Easier is to manually focus through the viewfinder and wait for the focus alert, but the 5D mark II has a limited number of focus points. With a normal lens I just move the nearest focus point over my subject, focus, and then recompose, but that doesn't work for the tilt shift when there is a very particular plane of focus you want.

This last practice I tried was a hard subject- in part because to get a downward view I had to stand on a desk, and there were limited places I could stand, and the part of the image I wanted in focus didn't always line up under the focus points, but also because it was hard to switch gears mentally from a focus 'point' to a focal 'plane'.

This one came out ok, the focal plane ended up roughly over the right part of the instrument and the screens.



Adding a subject that I really want in focus made it harder, I had to recompose slightly to get the guy under a focus point, and then recompose for the spacing after finding the focus, and that moved the orientation of the plane, and it didn't end up where I wanted it.



Any suggestions for how to focus? I didn't find any online tutorials that really addressed this. I get the geometry of it, just looking for some practical advice.

Also, would appreciate any general critique of the image, and the processing. I ramped up the vibrance and applied local contrast enhancement to try to make this look like a tinker toy set or something. (The set up here, is that this is a veeeeeeeery expensive mass spec, so playing against that by making it look like a toy)

ziggy53

Magic Lantern is a firmware overlay which adds functionality to specific Canon camera bodies. Fortunately the Canon 5D Mark II is one of those cameras.

Specifically it adds two functions which you might find helpful:

Focus peaking
Magic Zoom

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Focus Peak

Focus assist function. High-contrast lines will be marked by blinking dots showing which part of the image is in focus.

Methods:

D1xy: computes first image derivative on X and Y and takes the max value. May work better in low light or on noisy sensors.
D2xy: approximates second image derivative with a 3×3 Laplacian kernel. May be more accurate in good light.
Other parameters:

Threshold: how many pixels are considered in focus (percentage).
Color: either fixed color, or a color coding according to focus intensity.
Grayscale img: if enabled, LiveView will displayed as grayscale (but still recorded as color).
To see how it works, check this article from Luminous Landscape.

Visual example of Focus peaking from the above link:

http://www.guillermoluijk.com/misc/escena1.gif

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Magic Zoom (ziggy note: Using this function turns off the Focus peaking if it's on.)


Displays a zoom box for focus assist. Can be used while recording.

Trigger modes (not all modes are available on all cameras):

HalfShutter: triggered when you press the shutter button halfway.
Focus Ring: triggered by turning the focus ring.
Zoom.REC: triggered by pressing Zoom In button while recording. If your camera has a LCD sensor, you may also cover it and press Zoom In.
FocusR+HalfS: triggered by turning the focus ring, or by pressing shutter halfway.
Focus+ZREC: triggered by turning the focus ring, or by pressing Zoom In while recording.
Zoom In (*): triggered by Zoom In button (overrides Canon's default zoom modes). To bypass magic zoom, press both zoom buttons at the same time or cover the LCD sensor.
Always On: no trigger key needed. You can use both Canon's 5x/10x zoom and Magic Zoom.
When ML believes you have achieved perfect focus, Magic Zoom will display a focus confirmation (customizable):

Green Bars
Split Screen: when the image is out of focus, the zoom box looks like a split focusing screen from old film cameras.
Split Screen with ZeroCross: will reverse the split direction whenever you achieve perfect focus.
Other parameters: size, position, magnification.

Notes:

Zebras, focus peaking and false color are disabled automatically when the zoom overlay is active.
Focus triggering only works with lenses that report Focus distance, or when you use follow focus / rack focus.
In some modes, half-pressing the shutter may temporarily hide the zoom overlay.

ziggy53

Additionally, you may wish to make some "focus targets" which are generally just a white sheet of paper/card stock with a large, black "+" sign printed on it. This gives a high-contrast target which is easy for the AF points to latch upon, or which is easier for focus peaking to discern (assuming that Magic Lantern is installed and Focus Peaking is activated).

You place these targets on stands or props at desired points of focus in a static scene, and they make your life easier to find focus with the camera.

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Another valuable technique:

You may also manually "bracket focus" on several captures, combining the best bits in post-processing. This allows you to shoot relatively blindly (if you can't see the viewfinder or LCD display very well) and still make something of the photography session.

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You may also wish to shoot the entire scene more in focus, then use Photoshop to create a pseudo-miniature image in post-production. (To be clear, I am suggesting that you use the tilt-shift lens for acquisition and using some of its capabilities, then stopping down the aperture a bit to get more of the scene in focus during image capture, then using the linked approach to finish the image to your liking.)

Qarik

I use TS lens on occasion, and my suggestion is to simply manually bracket focus around the plane of interest. It isn't very scientific but with some practice it can be fairly reliable as long as your subjects are static.

archfotos

Why not just shoot tethered to a laptop using the eos software and liveview to achieve the specific focus you want?

Sam

I have started to work with my tilt shift lenses and with the 90mm tilt shift can do pretty well with live view and zoom to achieve good focus. It's much harder with the 24mm tilt shift to see the focus.

Yes if you can shoot tethered do so, it helps a bunch.

I'm not to keen on guessing at focus and shooting multiple shots.

Try this approach, Focus on the near subject you want in focus then tilt for the subject farthest from the camera. Then return to the close subject and refocus, then back to the far subject and re-tilt if necessary. After a couple of careful back and forths you should have the most in focus that the lens is capable of. Don't randomly tilt and focus.

Not sure how to do the reverse for miniaturization.

Sam

ziggy53

Sam wrote: »

... Not sure how to do the reverse for miniaturization.

Pretty much the same as your technique, Sam, but if you get too much in focus then you add some focus blur (defocus) to the entire scene in a new layer, the add a gradient to gradually make the softer focus start a bit earlier. You can also mask objects in the scene to keep individual objects more in focus, if it helps your "vision" of the scene.

Basically just Google "photoshop miniature effect tutorial" and follow their steps to get started.

JC

Thanks for all the advice, sorry I didn't get back sooner.

I've been thinking about magic lantern for a while, never could dedicate the time to learning how to use it, might need to try now- but i really like the focus target idea too.

archfotos wrote: »

Why not just shoot tethered to a laptop using the eos software and liveview to achieve the specific focus you want?

Because I use Linux......
Because a lot of the shooting I do is way far away from power outlets, so I've just never gotten into that technique. It would work here I guess.