@Ascensci, if I understand you correctly, you’re taking photos with a setup where you have your subject at the center of a turntable, and you’re rotating the turntable a little bit between each frame. Is that correct?
The lightfield photo app is set up with the assumption that you’re moving the camera linearly from left to right, rather than rotating the subject. I think that could explain why the focus tool causes your images to look blurry – the way the tool works under the hood is that it grabs a portion of each image and assembles them to make a quilt. The tool knows that the subject is shifting position in the frame from one photo to the next, because the camera is moving from one side to the other. The ‘Focus’ value tells the software to shift the region that it’s cropping from each image by a few pixels for each image in the sequence, in order to keep the subject centered in the frame. Changing focus changes how much you shift the crop region as you move through the sequence.
This is really hard to write about without pictures – I’ve been thinking about writing a series of illustrated tutorials on camera techniques for capturing lightfields – I have some spare cycles in the coming days and will see what I can do.
But yeah – the focus knob isn’t going to work well with rotation, because your subject is always in the same position in the camera frame. Focus is going to change its position in the camera frame and make it appear blurry. For a rotated picture, you basically just want to tile each of your images together into a quilt. This tool won’t do it for you, but you can do it in illustrator/photoshop pretty quickly.
The style of image where you rotate the subject is interesting – it doesn’t really feel 3D to me, because each of my eyes are seeing a different rotation of the subject, which is different than what my eyes see when I look at an object in the real world – in the real world, my eyes are shifted left/right by a few cm, so I see the object skewed slightly from a different perspective, but not rotated. When I’ve done experiments rotating a subject, I get the illusion that, as I move my head left/right in front of the looking glass, the subject appears to rotate. This feels really interesting to me, but if I keep my head still, something feels not-quite-right about the image, and that’s because the subject is rotated differently for each eye. It’s subtle, but it just doesn’t feel quite right in my brain.
I’ve been doing a bunch of experiments with shooting real-world lightfields, and I’m of the opinion that there is no right or wrong way to shoot it. There is a technique for filming that I call realistic-perspective, which is (roughly) where you move the camera from left to right along a line while pointing straight ahead, and the left/right distance is the same as the distance from the center of the line to your subject. This tends to make little objects in the Looking Glass that feel like they are really there – it matches the perspective of a real-world object on the table next to the Looking Glass.
There are a bunch of other techniques that play with perspective in the Looking Glass, from moving the camera larger or smaller distances that affect the field of view of the subject, to doing stuff like rotating the subject or gently rotating the camera as you move it. None of these are right or wrong, in the same way that a fisheye lens for a camera isn’t any more right or wrong than a portrait lens. They just create different effects, all of which are interesting to play with.
In your case, I really recommend tiling your images together into a quilt, and just viewing that quilt in the Looking Glass with the Quilt Viewer program – I think that’ll give you better results than the Photo Viewer, which isn’t going to work well with turntable images. If you’re interested in that, let me know and I can help walk you through it.