darryl walthall

With each change in the ISO, how much exposure loss or gain is created. For example, if I rate my film at a ISO of say 25 on one take and then rate my ISO at say an 8 on the next take, how does this change relate to exposure increments. Is this is a change in a stop or two ?

so how can I shoot with a 90 degree shutter angle without getting a strobe effect yet keep the sharpness and grainless image quality ?

so does a 90 degree shutter cause flicker with HMI lighting?

I like to overexpose negative stock 2/3 stops sometimes. If I close my shutter angle to 90 degrees, how do I factor in the 2/3 stops over exposure? whats the equation ?

I'm shooting a day light scene for a music video. I want the hot undifussed look of an hot summer day in Los Angeles. The director would like a slighty brown earth tone to the overrall image. I am thinking of using a light tobacco filter or even a subtle warming filter. Does anyone have experience with the tobacco filter ? How does it look or effect the overall image?

Can I achieve a sharper image, with less grain, by manipulating the shutter angle or speed ? And if so, do I open the shutter or close the shutter to help achieve a sharp , grainless image?

a cinematographer can over or under- expose a film stock in at least two different ways , correct ? He can over expose a particular film stock if he changes the asa/iso from say 800 to 400 or He can simply open up one stop on the lens from, lets say, a t4 to a t2.8 . So whats the difference in the two techniques ? Will the film stock respond in the same manner, even though the process of over-exposing the film one stop is different ? On the surface it appears that the easier way to over-expose a film stock would be to simply open up on the lens . That way you don't have to "calculate" while on the set and you could leave your mind free to focus on other things like compostion, lighting, movement or whatever. Maybe there is no difference in the two techniques and I am just over thinking the situation . Can anyone clarify ?

sorry I have asked this question before but I thought I could save the answer in my folder and it appears that the answer has been deleated from my folder. My question is this : if I lower the asa/iso is that over exposing or under exposing. If I increase the asa /iso, is that overexposing or underexposing and by how much . If a film stock is "box" rated at say 400 asa/iso and I rate it at 100 asa/iso, am I overexposing the film or underexposing and by how much ? Please clarify and this time I will transfer the answer into my notebook for safe keep and later reference . Thank you very much. Darryl Walthall

I have decided to rate my iso 1000 film stock at iso 500 ( thanks to the info provided by Dave Mullens and Dirk Dejonghe). But how exactly do I go about that ? I know I must make the appropriate adjustments on my light meter, but do I also have to make a note on my camera reports ? How will the lab know that I have not "box rated" the emulsion; that I have changed the "factory settings" in terms of the iso and that they ( the lab) should be aware of that .

can someone explain the ralationship between over and under exposing a film stock as it relates to the iso . If, for example, I am using a film stock that has an iso rating of 1000 and I rate it at 500, is that over or under exposing and why and by how much of an over or under exposure is is; 1 stop or 2 ?