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	Introduction
	Why all the excitement
	Not really that heavy
	The true meaning of ergonomics
	The controls
	The command dials
	The small nuances
	The incredible shutter
	The auto focus and focus tracking
	The exposure metering system
»	The power packs
	The lenses
	Why it remains an interesting alternative

There are three speed winders for the F4: the MB-20, the MB-21 and the MB-23. The MB-22 is in fact an external AC power regulator. 
 

The main function of this packs is to wind and unwind film at different speed rates. -- ADVERTISEMENT -- .

The F4 is the basic body with the MB-20 battery pack, holding 4 AA alkaline batteries in the right hand grip, providing a firing rate of 4 frames per second. This is the lightest configuration.	..
The F4s is the basic body with the MB-21 speed winder, instead of the MB-20. This battery pack holds 6 AA alkaline batteries, three in the right hand grip and three in the grip extension on the bottom of the camera body. The firing rate goes up to 5.7 fps. This is the configuration made popular in the US.
The F4e is the basic body with the MB-23 power pack, also holding six AA alkaline batteries as the MB-21 and providing the same firing rate of 5.7 fps, but it can take the MN-20 battery pack. This is the configuration favored by the pros.
For the first time, a very convenient vertical shutter button on both the F4s and the F4e is provided in both the MB-21 and the MB-23 power packs. A word of caution on AA lithium batteries for the F4: Not recommended by the factory because of the original voltage on these batteries when new and their tendency toward voltage fluctuations can indeed hurt the camera and shorten its life. (Ok, John Shaw doesn't seem to mind, but remember he can replace his anytime)