Summary ray diagrams
At `2F` (at two principal focal lengths).
At `1F` (at one principal focal length).
At greater than `2F` (at more than two principal focal lengths).
Between `2F` and `F` (between two principal focal lengths and one principal focal length).
Between `F` and lens (between one principal focal lengths and the lens).
and a summary in block format would be.
NOTE: The NO is to show that there is nothing in this triangle.
![](/images/user/base/Maths/Logarithms/Reference%20Tables/reference-log-table-1.4df6ee6.jpg)
![](/images/user/base/Maths/Logarithms/Reference%20Tables/reference-log-table-2.d516bb3.jpg)
![](/images/user/base/Maths/Logarithms/Reference%20Tables/reference-anti-log-table-1.b0b0513.jpg)
![](/images/user/base/Maths/Logarithms/Reference%20Tables/reference-anti-log-table-2.f89189d.jpg)