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EdZ
Professor EdZ
   
Reged: 02/15/02
Posts: 12569
Loc: Cumberland, R I , USA42N71.4W
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Resolution Testing and USAF Res Charts
10/29/05 12:27 PM
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Binocular Resolution Testing Using 1951 USAF Line Pair Charts
In addition to test results for about a dozen binoculars, this thread shows some comparative results for a very good semi-apo 80mm telescope. Also included is a discussion on how to use the charts and links to web access for the charts and tables.
See the chart and the tables in my gallery here
USAF 1951 Resolution Chart and Table of Constants
It is extremely important that the chart be exactly sized.
The caution here is the user must know exactly how to size the chart.
You will find sizing notes below in this post and also in my gallery.
Source for commercially available resolution charts
Edmund Optics
Conflicting Arcsecond Test Results Explained
an excellent discussion explaining the differences in various arcsecond resolution values posted various places around the internet, and how to interpret them. This discussion is relevant to understanding how to use the USAF resolution charts and how the values determined by using them is so different than point source resolution. It explains why resolution values determined by the USAF charts are significantly closer than can be achieved observing point sources.
Understanding Resolution
a comprehensive technical report on the various criteria affecting resolution
Double Stars for Binoculars - a list of doubles for all sizes from 7x35 to 40x100
a list of double stars from which you can select observation targets providing you with good indications of the maximum visual point source resolution of your instrument.
Quote:
Lens Resolution Testing
and a link to a USAF 1951 Chart with the Table of Constants.
Chart with Table of Values
I find it interesting that few if any current web links provide ALL the information necessary to use these charts.
Using this table of values linked here which shows the constants for the Groups and Elements of the Line Pairs Chart,
the forumula is 8121 / (D x LPM) where D is the distance to your target measured in inches and LPM is the value from the Constants.
The constants are the actual number of line pairs per mm for the mimimum you can see.
For instance a 10x binocular used at a distance of 125 feet that can see line pairs in Group-1, Element2 has a value of 0.561. Therefore it's resolution is 8121/(125x12x0.561) = 9.65 arcseconds.
Line Pairs Resolution CANNOT be directly compared to point source resolution. See the forum discussion.
It is extremely important to have the target sized properly. See the discussion in the forum thread.
Binocular Resolution Testing Using 1951 USAF Line Pair Charts
included is a discussion on how to use the charts and links to web access for the charts and tables.
It is extremely important that the chart be exactly sized. As a check, the three bars and two spaces in Group-2 Element 1 should measure exactly 10mmx10mm. Both the sets of bars in G2-E2 and the solid black square top center should measure 9mmx9mm.
This page was originally accessed from
http://medfmt.8k.com/mf/resolution.html
Lens Resolution Testing by Robert Monaghan
which has posted the following notation along with the information
[My understanding is that the USAF chart etc. is in the public domain as it is a government produced chart and related documentation...]
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