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wrotniak.net: Micro Four Thirds Lenses [wrotniak.net]
List and specifications of lenses for Micro Four Thirds system cameras, mostly by Olympus and Panasonic
photography  lens  µ4/3 
19 hours ago by ddffnn
Large Format Lens Test Review
Theoretic diffraction limits at f/22 for green light is 68 lines/mm.
By comparison a lenses f/32 diffraction limit is 47 lines/mm. If you look at the test results for all the lenses tested at that f-stop they very nearly ALL perform at that limit. This I take to be the limit at which manufacturing differences can influence the performance of a lens. And this is very important because it says a person can purchase a pretty aweful lens and still get decent results if they shoot at f/32!
filmvsdigital  resolution  lens  lenses  reference  largeformat 
6 days ago by bwiese
Large Format Lens Tests (pdf)
ref: https://www.arnecroell.com/equipment

Arne Cröll 2007-2012. All rights reserved. This version is from November 18, 2012
Below are the results of some tests of large format lenses I did over the years. The best way to test a lens would be to use an MTF
measurement setup like the Zeiss K8, but since this is not an option for me, I made test chart images and evaluated negatives, similar
to the tests by Chris Perez and Kerry Thalmann (http://www.hevanet.com/cperez/testing.html), but with a different target and setup.
Of course, one has to keep in mind that all these tests test the whole system, from film holder to development procedures. To get any
meaningful data on one component of this system like the lens, one needs to be very diligent in keeping everything else as constant
as possible. Possible error sources range from film holder problems to ground glass alignment, parallelism of the object, lens, and film
planes, to development temperature and agitation. In addition, numbers from different test setups should not be compared!
My present setup is the following*: As test object I chose the Norman Koren lens test chart
(http://www.normankoren.com/Tutorials/MTF5.html) which allows a judgement of performance at two contrast levels, 50% MTF, and
10% MTF. It is different from a pure bar chart, and gives slightly worse results in lp/mm for the 10% MTF than a standard USAF bar
chart. The text at the linked web site is worth reading to understand the concept. I printed out seven of these charts, and mounted
them on a flat door indoors, one in the center, and the remaining six in three pairs for sagittal and tangential orientation in two
corners and at one intermediate position. Note that in the “upper” corner the tangential structures are on the outside, whereas in the
“lower” corner they are inside, and vice versa for the sag
lens  lenses  largeformat  reference  sharpness 
13 days ago by bwiese
Geometric optics | Physics | Science | Khan Academy
Online classes for geometric optics, and derivation of the thin lens equation.
optics  engineering  lens  lenses  elearning  e-learning 
14 days ago by sparky989
Antique and Classic Cameras - Heliar
Heliar lens. The Harting design was essentially a modification of the Cooke Triplet, with two additional elements and a symmetrical layout. These changes helped address the Triplet's short comings of longitudinal aberrations while still allowing for a wide (fast) aperture. The lens had a speed of f/4.5 and covered 50 degrees. Its large aperture made it suitable for portraiture and instantaneous work.
heliar  lens  history  largeformat  reference  lenses  portraiture 
17 days ago by bwiese
Lens focus Depth of Field White paper
Depth of Field in Depth
By Jeff Conrad for the Large Format Page. Referenced by Wikipedia DOF page.
Photography  lens  optics  depth-of-field  dof  camera  equation  equations  reference  online  engineering  focal-length  hyperfocal-distance 
18 days ago by sparky989

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