This subject is discussed quite often. MegaVision's PhotoShoot™ software gives you the option of 3 different intensity scales to use .... 0 to 100, 255 to 0 and Zone System.
The correct answer is: The one that works the best for you!
Sound like a copout? Not really--let me explain. As we all know, each photographer has his / her own work flow and has developed many different tricks or tips to make his or her situation the most beneficial for themselves.
While it may seem like a simple choice (and it is), some customers develop strong loyalties to their choice.
A little about each....
0-100 is probably the most popular at this time as the majority of our cameras (at this time) are in commercial studios where the images usually end up on a printing press. Since most of these photographers must deal with either printers or separations houses, the 0-100 scale makes a lot of sense. If a photographer makes a test and receives feedback from the graphic house / printer, corrections or advice will most likely be given in a percentage value. For example: "your highlight is about 6 or 7% too magenta", or " your shadows are too blocked up, open it up another 10% or so". Obviously when using the 0-100 scale 7% = 7 points. Corrections or set ups can be easily done. 0 means "nothing" as in no dot or no value --- a 0 reading means there is nothing there to print, pure white or paper white as the case may be. 100 is "blocked" or a solid dot -- too much data to print with any detail, it will be the pure black on the press. Most work for Web presses will require you to hold at least a 7% value in any area you wish to have a dot or detail...nothing over a 95% will "hold" or maintain detail, and often less than 90% maximum dot percentage.
255 to 0 is most commonly used by photographers who have Photoshop experience. Using this scale has no advantage or disadvantage -- it's simply personal preference. This scale can be more intimidating than the other two choices to a novice for the simple reason of math. A quarter-tone on the 0-100 scale is 25--easy math. A quarter-tone on the 255 scale is 191; not as easy to calculate. However, someone who uses this scale (or any) on a regular basis will learn which numbers correspond to the important values. This scale is a reverse from the 0-100, as the largest number, 255, represents the end of the highlights. 255 signifies no dot, or value -- completely white, while 0 on this scale represents total block, or solid black. Most separation houses or printers understand and in most cases use the scale in some part of their work.
Zone System-- this scale is finding a following among people whose images remain in the RGB color space, although it can be used for any application. Based on the Zone System as developed by Ansel Adams, it uses the same 0 to 10 scale, where 0 represents absolute black, 10 represents pure white. This scale is easy to learn and use from a photographer's viewpoint.... keep in mind that your separator or printer will not understand it and you will have to translate. You will find on this web site a guide to using the Zone System written by our own Richard Chang. Please read it for tips and further information on how to best use this system.
So back to the original question.... which should I use? Again, the one you feel the most at home with is probably the best choice... learning to use all 3 scales simultaneously has great advantages and is probably the best choice in the long run.
For further help or questions regarding this issue or any other, check out the Tips section, the FAQ's and as always, contact your friendly MegaVision Rep.