A ring has two size markings in millimeter such as 28mm-37mm, 49mm-52mm, 77mm-72mm and so on. The first number is the size of the thread that is closer to the camera lens (i.e. , the male thread), while the second is the size of the thread of the farther end (i.e. , the female thread). Therefore, a step-up ring with marking 43mm-49mm means the male and female thread sizes are 43mm and 49mm, respectively.
Some forms of ordination analysis, classical or canonical, are widely used by palaeolimnologists. as tools in the handling, summarisation, and interpretation of palaeolimnological data, either modern assemblages or. core fossil assemblages.
Power analysis. The figure shows the six variables involved in a power analysis. They are interrelated such that if any five of them are specified, the sixth one can be estimated. Normally, the power analysis is used to estimate sample size. But if that is fixed (e.g. only 20 subjects are available) then it can be used to estimate the signal or the power of a proposed experiment.