FZ200 Diffraction Limit - Panasonic Tech Service

Started Aug 27, 2013 | Discussions thread
Stephen Barrett Contributing Member • Posts: 683
Factor of 2 Found

Thank you Detail Man for drawing my attention Jimmy's post. It is certainly worth reading in detail.

Quoting from that same post:
"the following image which shows crops from the DPR test charts for FZ30 and FZ50 both with an assessed resolution of 1800 LPH."

LPH means lines per picture height (meaning LINE WIDTHS per picture height)
LPPH also means "lines per picture height" (meaning LINE WIDTHS per picture height)
LP/PH means line pairs per picture height

So there is my factor of 2. I thought LPPH meant line pairs per picture height, but it doesn't unless there is a slash in it: LP/PH.


Line pairs or lines?
All MTF charts and most resolution charts display spatial frequency in cycles or line pairs per unit length (mm or inch). But there are exceptions. An old standard for measuring TV resolution uses line widths instead of pairs, where there are two line widths per pair, over the total height of the display. When dpreview.com recommends multiplying the chart values in its lens tests by 100 to get the total vertical lines in the image, they refer to line widths, not pairs. Confusing, but I try to keep it straight. Imatest SFR displays MTF in cycles (line pairs) per pixel, line widths per picture height (LW/PH; derived from TV measurements), and line pairs per distance (mm or in).

Revision of Standard to Avoid Confusion


The following table and explanation will be part of the upcoming revision of ISO 12233 and was created by Don Williams.

LW/PH = Line width per picture height
LP/mm = Line pairs per millimetre
L/mm = Lines per millimetre
Cycles/mm = Cycles per millimetre
Cycles/pixel = Cycles per pixel
LP/PH = Linepairs per picture height

 Stephen Barrett's gear list:Stephen Barrett's gear list
Canon PowerShot SX30 IS +3 more
Post (hide subjects) Posted by
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark MMy threads
Color scheme? Blue / Yellow