Doc talk:2.4/Tutorials/Composite Nodes/Setups/Depth Of Field

Defocus Node?

Someone should update this to mention the new Defocus node. -- Jtuttle

Humbled

Author humbled by 17-year old contributor to Blendermag#7; section being Simplified using Z-Combine.--Roger 22:32, 29 November 2006 (CET)

Done. good job everyone. (claps)--Roger 00:49, 30 November 2006 (CET)

A question

In all my years of photography, I always thought that the 50mm lens, aka the "natural prime" was closest to he human eye for a full frame 35 mm camera (not a cropped digital SLR). I don't know why Blender has 35 mm as a default but it can't be to the human vision and a 35 mm camera at the same time. --iaminnocent 23:35, 5 September 2008 (UTC)

I agree that I like pictures taken with the 50, and have my default camera set to 50. As soon as I get the basic camera kit, my first lens is like a 28-135 macro zoom, and the 35 basically stays in the case as a backup. The Blender 35 default goes back decades and is probably just because of convention that the 35mm SLR is the most popular lens out there. Even though, technically, I am told that a Blender 35 Lens does not produce a physically accurate 35mm SLR Lens, but hey, it's close enough in my book. I should note (and will edit) that the field of view of the human eye is almost a fish-eye (hold your fingers out to the side at arms length and you will see that your field of view is darn near 170 degrees, it's just that we process core (vs peripheral) vision in a central region. --Roger 14:14, 6 September 2008 (UTC)

Note that for 16mm film, the 35mm lens is the "35mm film / 50mm lens" equivalent. This was underscored for a lot of people when they bought the Canon 7D, thinking it had a 35mm sensor for moving pictures, and bought a 50mm lens to go with it, which probably remains happily unused most of the time. (They should have bought a 35mm lens, e.g. as the 7D is closer to 16mm when shooting moving pictures) I'm newbie-ish to blender, but I've never found any way to adjust the "film back" of the camera -- change it from 35mm to 16mm, e.g. Is that possible? Other 3D apps allow for it, so I thought it might be buried in there somewhere.... -- Begeun 04:00, 31 January 2010 (UTC)

The issues are many in making a render look like what we see, either in reality or in film.

• First, the film back, the actual film plate or the sensor, is flat. The back of the eye, our "back" is curved. So, that right there introduces a barrel type of distortion.
• Second, the reception surface for the eye is round, and a film back is square, and images are square, so there is cropping of the field of view. Whe and how much to crop introduces a difference
• The film back has a size, and those sizes vary from camera to camera. 35mm is an inch wide, but sensors are much smaller. Thus, the way the light falls and overlaps onto that surface is different, hence two cameras with two different size backs will take different pictures. If I am not mistaken, Blender assumes that all light focuses on a single point, not a flat (or spwerical!) surface.
• Lenses: as noted above, the f-stop, outside size and curvature of the lens, coatings, all the elements, zoom level, etc all affect the appearence of the picture, and it impractical to write an algorithm for each combination.

So, all of these are issues when dealing with CGI over a back plate, but don't expect an magic solution any time soon. My Lynda.com tutorial and book offer a really good step-by-step solution for matching up a plate to Blender's camera. --Roger/PapaSmurf 18:58, 31 January 2010 (UTC)