HI All
again about hotpsots, they wil occur on the lenses which are older and have no multicoating, prime lenses are the worst (apparently).

Anyway a couple of other tips, if you want pure B&W IR, switch the camera to B&W then place a red filter behind the IR filter, this will increase the exposure times, but should shorten the wavelength you can get, upto 800nm +.  Although this is not accurate it works for me on CANON stuff, I dont know about other camera's.

You can get a Pseudo effect by leaving the camera to b&W and using a red filter,  but this will push the wavelength a little lower, some of you may like the effect, but hey its upto personal choice.

I am currently working an a long article to try and get to the bottom of IR work (including PS processing) and when it is finished I will post here or you can mail me for it, when its done.

One other thing, which is worth noting is that never shot directly into sunlight even with an IR filter on,

John