Lytro is a revolutionary camera. It captures the "light Field" entering the lens instead of just a flat 2D image. The information contained in the light filed allows for post capture image manipulation that is quite unique. For example, focussing can be done after capture. Also, 3D images can be created from a single light field, captured with a single lens. And, there's much more to come in the future.
The notes below are an attempt to "calibrate" a prototype camera so that I understand the limits of its capabilities. You can't just pick up the camera, take a shot and expect to get a "perfect" light field image that can be infinitely refocussed. In general, the light field effect extends from the minimum focussing distance (DFmin) to infinity. However, beyond a certain distance, everything is focussed to infinity and so the camera will not adequately refocus beyond a certain maximum distance (DFmax). Also, the camera has depth of field (DOF) around a focus point which varies with zoom factor (like a regular camera).
The camera has two modes - normal and creative. In normal mode you just point the camera and shoot. Pictures can then be refocussed afterwards, between DFmin and DFmax. In creative mode you have the opportunity to "assign" a focus point, on a particular subject, prior to shooting. The picture can then be refocussed around this point, up to some limit. Creative mode is handy for situations where you want a particular subject to "stand-out" (background and foreground are out of focus) or to focus on a subject that may be difficult to refocus in normal mode due to distance from the camera or some other limitation. In normal mode, the zoom range is from (approx) 43mm to 146mm. In creative mode the zoom range is extended from 43mm to 333mm. In total, it looks like an 8X zoom.
First tests are measuring DFmin:
NORMAL Mode
Zoom Focal(mm) DFmin (in)
0% 43 2.5
25% 61 7.0
50% 76 10.0
100% 146 60.0
CREATIVE Mode
Zoom Focal(mm) DFmin (in)
0% 43 <.5
25% 81 1.0
50% 126 6.0
100% 333 28.0
As for DFmax, it looks like anything over 6-10ft (@43mm) or approx 20ft (full-zoom) is either not refocusable or is already out of focus. I guess I should measure this more precisely but, for now, it's clear that this camera is for shooting close in. The greater the zoom factor, the more noticable is the "out of focus at infinity" effect. In the extreme, taking a picture with full zoom of distant objects will result in everything being slightly out of focus.
So, the question is what kind of pictures work? When should I used normal mode and when should I use creative mode?