Following on from discussions on other threads here how about everyone test their camera and lens AF speed using a common testing proceedure.
The Testing method - Outline.
In order to test the AF speed a common testing proceedure is required, one that is applicable to all AF SLR's regardless of age or focusing system employed.
The proceedure is very straight forward and can be used with any AF lens and all that is required is a notepad, pen/pencil and a stopwatch.
Multiple testing for each lens and focal length will need to be employed to produce a more even result and to provide more consistent results. For this reason 7 tests per focal length will give a good level of data and population accuracy.
Two focal test points should be used, near focus and infinity. Selecting an object that is around 700-1000m distant for the infinity target would be acceptable for all but the longest supertele, in which case an object around 1500m should be used.
The objects selected as test points should be checked to make sure the lens doesn't focus hunt when aquiring focus.
A single sensor point (center) should be used to ensure maximum compatibility with both new and older SLR autofocusing systems. Multipoint focusing tests should be performed seperately.
All predictive or continious focusing methods should be disabled, so that the camera lens combination under test reflects the real capabilities of the AF system to respond to a maximum focus 'thow' situation.
The use of a tripod is mandatory.
Use fresh batteries to ensure maximum AF performance.
100 ISO shall be used as the standardised ISO rating for the test.
Each tester shall test their 'lag' time with the stopwatch by a simple test method to determine their average response time.
Tests shall be carried out in full sun and also near sunset to guage the preformance differential under good and adverse lighting conditions.
Testing method - Detail
Bring the lens to it's closest AF focal distance and disable any predictive or other focusing systems that will cause the lens to be AF active while lining up the infinity target.
Measure the time taken to focus on the infinity target.
Repeat until you have 7 readings.
Note down the aperture used (wide open value) and shutter speed so that an evaluation of the lighting conditions can be cross-compared with other cameras/lenses.
Repeat the test by focusing on the infinity target and measuring the time to focus on the minimum focus target Follow the procedure described above.
Measuring your stopwatch reaction time.
This is straight forward, click on the stopwatch and then as quickly as possible click on the stop button. Do this 7 times, noting the time taken each time. This will be used to determine your 'average' lag which will be used to bias the AF results you obtain.
--- end of test method ---
So what do you guys think? Any flaws anyone can spot in the proceedure?
If no one can find any major flaws I'll code up a web page for inputting the results and set up a statistical analysis of the data provided by the good members of Club Snap.