Relative Light Index for photocameras

I have developed a mathematical formula to compare the light sensitivity for photo camera lenses.

A twice as high value means that the lens will receive twice as much light. The formula and equation are linear.

The relative light index of a camera can be calculated as followed:

RLI = ( 1/lens mm ) * (F^2) * ISO value

This initial formula doesn`t correct for VR or OS (whatever name you prefer).
Therefore I adapted the formula to compensate for this

RLI = ( 1/lens mm ) * (F^2) * ISO value * VR (if not, 1  | if yes 2)

Because these values are very small (below 5) its recommended to multiply them with 1000 to create a  more easy to read value.

Linux Kernel 2.6.39 installation guide for Ubuntu Linux

This short walkthrough describes how to get the latest linux kernel working under Ubuntu Linux without having to compile it yourself.

This tutorial should work with the latest version of Ubuntu Linux (10.04 LTS, 10.10, 11.04 and 11.10) and most distributions based on these versions of Ubuntu Linux like Mint.

The included kernel files have been compiled using the generic ubuntu configuration.
Note: nVIDIA ForceWare drivers are automatically installed using DKMS, if you have these installed and up-to-date.

Installation Guide

  1. Download the kernel headers package;
  2. And the appropriate package for your system
    I386: linux-headers-2.6.39-020639-generic_2.6.39-020639.201105190911_i386.deb
    AMD64: linux-headers-2.6.39-020639-generic_2.6.39-020639.201105190911_amd64.deb
  3. And the accompanying compiled kernel;
    I386: linux-image-2.6.39-020639-generic_2.6.39-020639.201105190911_i386.deb
    AMD64: linux-image-2.6.39-020639-generic_2.6.39-020639.201105190911_amd64.deb
  4. Install the files in the same order (else it won`t work!)
  5. In the terminal run:
    sudo update-grub
  6. Reboot and select the kernel from the bootloader menu
    If it`s not there check all steps (and of course for errors)

The source can be found on

Bye Bye Hyves, Bye Bye FourSquare

I have just deleted my hyves account (dated 2006) and FourSquare account (2009) .

Why I deleted my Hyves account:

  • Slow
  • Copies all ideas from Facebook
  • Facebook is better

Why I deleted my FourSquare account:

  • What`s the point of checking in?
  • Facebook Places

Pro CSS for High Traffic Websites

Apress has just released a book called “Pro CSS for High Traffic Websites”, written by by Antony KennedyInayaili de Leon (ISBN-13: 978-1-4302-3288-9 –  400pp ).

The book covers the development processes required to smoothly set up an easy-to-maintain CSS framework across a large-volume website and to keep the code reusable and modular. It also looks at the business challenges of keeping branding consistent across a major website and sustaining performance at a premium level through traffic spikes and across all browsers. Defensive coding is considered for sites with third-party code or advertising requirements. It also covers keeping CSS accessible for all viewers, and examines some advanced dynamic CSS techniques.

What you’ll learn from this book:

  • The value of process
  • Making reusable, robust, and modular CSS
  • How to maximize the performance of your site
  • Integrating with third parties
  • How to keep branding consistent
  • Best practices for cross-browser and accessible CSS
  • Dynamic CSS techniques

Who this book is for:

This book is for Web developers building and maintaining premium, successful, high-traffic websites using web standards. This book will also help team leaders responsible for code that will be shared over multiple projects, as well as project managers with a high churn of contract staff.