The Nikon SB-900 flash

The SB-900 is the most recent flash from Nikon. It has first been introduced at a much higher price than the SB-900 and many users thought that it was just positioned above the 800. But after a few weeks, the SB-800 just retired and the prices have been adapted. The SB-900 is just the successor of the SB-800 and replaces it.

The SB-900 is a very interesting upgrade vs the SB-800. The main differences are:
- better focal distance coverage
- full FX and DX modes compatibility
- better pixel based display
- temperature management
- more filters and separater filter holder
- larger omnibounce-like diffuser
- better user interface
- no optional 5th battery - works with 4 batteries
- faster reload
- more orientation possibilities (can really turn in all directions now)
- easy switch between modes via on switch/button
- firmware is upgradable via the camera body (needs to be a recent one, like D300, D3 or D700)

Cons:
- a bit less power than the SB-800 (guide number)
- huge compared to previous generations
- heavier
- the temperature management system can be a bit too quick to react, making the flash unsable for some time


Based on my personal experience, I would now recommend the SB-900 as the master of the CLS system or as your only flash if you need only one. Then you can upgrade your system by adding a number of SB-600 slaves or SB-800's (you'll have to buy them used from now on - end 2008 - since they are not available anymore).

There have been a few issues with the thermal protection. A firmware upgrade has been made available by Nikon to solve the issues. Don't forget to upgrade if you are still using the original version.