Archived posting to the Leica Users Group, 1998/06/25
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]The closest focus has the smallest DOF so focus errors will be most obvious. A constant positional error (i.e. a misalignment) will however give the largest error at infinity. I am surprised that there is an obvious error at 1m, but there is no observable error at 2m. At 1m a focus offset of 10cm represents a huge error. The most likely explaination for this is incorrect focus on your part. Test photography can be useful to determine the behaviour of the camera/lens and/or photographer. It is important to devise tests which minimise the influence of "one off errors". In the case of your test I would recommend photographing at 1m, 2m, etc. then returning to 1m and repeating the tests. This would give two well seperated focusings at each distance. An equal error on the two photographs at the same distance would then more clearly indicate an equipment problem. Note that focussing at 1m then rephotographing immediately afterwards is not as strong a test as seperating the two focussings. Richard Urmonas rurmonas@senet.com.au