A while back, I posted the following simple lens decentering test, using a out-of-focus LED: Simple decentering test There have been reports of this test not detecting lenses whose field curvature is not symmetric about the lens axis, but has a til component. There is no reason to think that the OOF LED test can… [Read More]
Archives for July 2016
Depth of field summary — part 1
This is a continuation of a report on new ways to look at depth of field. The series starts here: A new way to look at depth of field I’ve been derelict in publishing a summary of all my work of depth of field. I apologize. The reason is that I find it difficult to… [Read More]
A book report — press proofs
This is part of a series about my experiences in publishing a book.The series starts here. I’ve reported previously on my attempts to proof the images for the book on my Epson 4900: A book report — hard proofing There have been enough confusing communications about the images that I created for the book in Coated… [Read More]
How to decrease photon noise
Sometimes pithy photographic explanations, although valid and meaningful for the cognoscenti, can need some unpacking for most folk. Consider that Ansel Adams and others have used whole books, with charts, tables, graphs, and examples, just to say “expose for the shadows, develop for the highlights.” Thus it is — possibly, anyway — with photon noise. This post… [Read More]
Aliasing visibility and PS downsampling
I interrupt the series of posts on DOF for this one that proves a point that most of my blog readers already know: in general downsampling can cause aliasing, and in particular the downsampling algorithms in Photoshop do cause aliasing, at least some of the time. I’ve addressed this issue before, with spectral plots showing… [Read More]