I recently started playing with HIE, and need a bit of advice. I rate the film at 400 and bracket +/- a stop. I shoot through a red (25A) filter and develop in HC-110 for 5 minutes. Although I'm getting white foliage as expected, I'm not getting black skies. Could it be that it just wasn't sunny enough and there wasn't enough IR about, or could it be something else? The filter, maybe? Any help appreciated. Mike.