> Scenario > -Incident light meter for a portrait > - Tungsten light > -Shooting slides so that we can not change the result in printing > -Highlights are at f11 > -Shadows are measured at f4 i.e a 8:1 ratio > -It is then suggested that the shooting f stop should be 1/2 way between the > highlights and the shadows i.e. f 5.6 plus 1/2 stop This lighting ratio is WAY too high for chrome film, you may as well be shooting at 64:1.. I personally would suggest 3:1 as being on the edge of the usefull range for chromes. > Yet when learning about incident light metering, we learned that when the > subject is brighter than average we are supposed to close down the f stop > some ( the opposite of a reflective meter, where you would open up in that > situation). This is a very odd method of using a light meter which measures the quantity of light falling on the subject and a method I would not advise unless you are trying to achieve a manipulation or change the representation of the subject - ie make a dark skinner person look white (why would one want to do that ??) I understand that the caucasian face is not all that brighter > than a grey card and we might not change the metered reading, but I do not > understand opening up (overexposing the highlights) nor should you, again, it is poor advise when dealing with positive fims. It is correct if you were using a reflected meter, but you are not. Sounds like the person teaching you this is a tad confused. > I do not understand doubly because with a 8:1 ratio, the mid point betwen > highlights and shadows is 1 and 1/2 stops. but for a 4:1 ratio it would be > only 1 stop and for a 2:1 ratio it would be only 1/2 stop. There is no > consistency with the amount we overexpose the Highlights. yet again, the recommendations you have heard are dubious at best. > Then we light and meter the white background to be 1 stop more than the > shooting f stop i.e. f8 and 1/2 stops. that will make the background white, and is probably the only bit of what you describe that makes any sense. > If you say that's just the way its done O.K. > But if you can help me with a rational that would be great only the person who taught you this could justify it (!) I'd look at first altering the ratios to give you detail in both the shadow and the highlights, for your personal benefit I suggest you do a series of trial shots yourself to determine the appropriate exposure (lighting ratio) for the film you're using. Start with a 1/2 stop diference and work your way to a 4 stop difference - you'll see the effect ;-) Do it yourself and you'll never forget the results, they will be ingrained into your photographic mind.. reading this stuff is OK but without the benefit of experience you wouldn't be able to distinguish between fact and fiction :-/ Back to the task at hand. Once you have established the lighting ratio (and with all your lights on), take an exposure reading for the part of the subject that is lit appropriately for your subject. That is to say the bit that you want exposed to appear 'normal'. Not the bit that has a hot highlight, not the bit in the shadow, that's irrelevant and taken into account already when you established your lighting ratio.. just the bit that you want to look exposed correctly. Done this? good, now set the light on your white background for one stop brighter (if you want white) - recheck your exposure with the ambient flash meter to make sure the exposure on your subject hasn't changed. If it has, make appropriate modifications to the lighting or alter your exposure accordingly. shoot. evaluate the results. become a better photographer :-) good luck! karl
