Latitude of Kodachrome 40 and Ektas 7250 7239

[Gareth Tucker]

Hello

 

Would anyone be able to tell me the latitudes of Kodachrome 40T, Ektachrome 7250 and Ektachrome 7239.

 

To make this request more clear (as peoples definitions of latitude tend to vary) I would like to know the number of stops from correct exposure down to solid black and up to pure white and if possible a safe working margin for highlights and shadows still retaining detail.

 

I have searched Kodak's website for one of those incredibly helpful photographs with all the f stops marked on the differnent tones but can only find them for the newer stocks.

 

Many Thanks

 

Gareth Tucker

 

student film-maker, England

[John Pytlak RIP]

All the reversal camera films are similar for latitude. You can compare the sensitometric (characteristic) curves provided in the technical data for each film, looking at the log exposure range from highlight densities of approximately 0.30 to shadow densities of about 2.80. Generally if the films will be directly projected, try to control exposure to within 1/2 stop. Reversal films are usually more forgiving of underexposure, especially if you can correct somewhat during telecine transfer or printing.

[Gareth Tucker]

Regarding what John_P_Pytlak of Kodak said -

 

Many thanks John.

 

After looking at the charteristic curves I'm certain that the information I'm after is in there the only problem is that I cannot translate the graphs into a useable form.

 

For example the chr curve graph for K40 is quite steep, implying that it records quite a narrow range (or in other words is a quite high contrast film) recording as black what might to the naked eye have a lot of detail.

 

My problem is that I want to be precise and know that if a particular area of the scene is say 2 stops down from my key light, will it still register (in the shadows) or do I need a little more light to make sure that area of the scene will record ?

 

I think my use of word "latitude" was maybe incorrect as it implies a sort of margin for error which is not what I'm after.

[John Pytlak RIP]

Perhaps the Kodak tutorial on sensitometry, exposure and latitude will help you interpret the data:

 

http://www.kodak.com/US/en/motion/support/h1/structure.shtml