Is DoF an optical, perceptual or a hybrid property ?

Started 1 month ago | Discussions thread
ForumParentFirstPrevious
Flat view
Le Artiste Regular Member • Posts: 129
Is DoF an optical, perceptual or a hybrid property ?
1

Spin off from https://www.dpreview.com/forums/post/65136361

There appears to be a popular notion that the circle of confusion used to calculate the DoF of a given photo should be calculated for a given print size viewed from a given distance, usually the distance equal to the focal length.

I think this is problematic, since it would follow that:

Changing the print size or viewing distance is equivalent to changing the aperture stop during capture.

Cropping the image whether in camera, in post-production or on paper alters the DoF of the remaining image.

I always thought of the DoF as an intrinsic property of the optical capture system that cannot be altered by crops, reproduction size or viewing distance - the fact that this property can sometimes be masked by output magnification and viewing distance does not make them equivalent similarly to how digital exposure correction or ISO change is not equivalent to actually changing the exposure.

It appears that at least Fujifilm is aware of the discrepancy as its cameras offer the choice of 'film format' vs 'pixel' as the basis for the DoF scale in manual focus mode, the film format option presumably uses traditional APSC film CoC radius whereas the pixels one is based on the pixel pitch - the later is more sensible to me even though it results in much narrower DoF bands and a longer hyperfocal distance for a given aperture but it guarantees that things that are 'in focus' are in focus regardless of the output size, method and viewing distance used.

ForumParentFirstPrevious
Flat view
Post (hide subjects) Posted by
ForumParentFirstPrevious
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark MMy threads
Color scheme? Blue / Yellow