Help with finder

I have a Hummingbird 859 I believe. I am slowly figuring it out. I noticed that in the settings there is an option for switch fire and also on the beam selector there is a choice of 200 and maybe 83. Does anyone know what these features are supposed to be for?

Youtube has a lot of information on your questions. Hope this helps you.:twocents
http://www.fishtec.co.za/cone%20coverage%2001.jpg

https://www.youtube.com/watch?v=ydFqx-igMfU

https://www.youtube.com/watch?v=KTacpPjjWiU

Switchfire:

https://www.youtube.com/watch?v=q_bANSg00Vg


https://www.youtube.com/watch?v=kPXomXW6ioE

A good rule of thumb for SwitchFire ... (only affects the 2d image) ..

*Use SwitchFire Clear in less than 10ft of water and adjust Sensitivity up to an acceptable amount of clutter ...
*Use SwitchFire Max in deeper than 10ft of water and adjust Sensitivity down to an acceptable amount of clutter ...

scrat gives good links for explainations ...

Rickie