Message posted by lone wolf on June 29, 2004 at 7:46:47 PST:

For long distance photos shot with IR, you don't really get a B&W negative (Wood) effect. That is, the foliage doesn't go white, though the sky does darken. The IR film does help with haze, but it is not as dramatic as you might expect. If you take into account the film will be 4 times slower, you run into camera shake problems. I've shot IR from Tikaboo, but thus far the best images I've got have been with Fuji Provia 100F slide film.

In theory, B&W film will have less grain. In practice, this is not the case. First thing to note is that B&W film has more lattitude than color slide film. This is achieved by having a narrow (small dynamic range) on the film, and then expanding the dynamics when printed, or in photoshop. The problem is photographs taken over 26 miles will have very little contrast, i.e. compressed dynamics, so you need to expand the dynamics for both the film and the loss of contrast due to the atmosphere. All this expansion magnifies the size of the grain. Color slide film doesn't have this problem since it requires no dynamic expansion for a "good" photograph, and less dynamic expansion for the Tikaboo shots. With color slide film, you are only compensating for the atmosphere effects.

The Macophot 820c has the finest grain I have ever seen in B&W film and about half the lattitude of normal B&W film, so in those respects it will show less grain than regular B&W film.

The grainy color telephoto shots you have seen most likely came from color negative film, which suffers the same grain magnification as B&W negative film.

Some clever person may point out that negative film and slide film are really the same except for the reversal process in slide film development, so the grain should be the same. However, look at the situation where the same film is used as both a negative and transparency. This is the case with Kodak TMX 100, which can be processed as either a normal negative or as a transparency using kodak's reversal kit. When TMX 100 is used as a tranparency, the speed is reduced to ISO 50 and the dynamic range is nearly tripled. The increase in dynamic range of the film means less grain enhancement when scanned or printed, so yes the same film can have different grain.

In Reply to: Re: IR Scan Of Mystery Jet Reveals Pulse Detonation Engines? posted by Raven on June 29, 2004 at 3:45:34 PST:

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