Smoke from the South Fork Lost Creek Fire rises above the Swan Range approximately 40 miles southeast (bearing approximately 130°) of Kalispell on the evening of 13 August. The Hammer Creek Fire in the Bob Marshall Wilderness is 70 miles from Kalispell and on almost the same bearing.
Forty miles is quite a distance on a hot, moderately hazy summer evening, so I shot the image through a Hoya 72 infrared filter on a 4-element Nikkor-Q 200mm f/4 mounted on a Nikon D50 APS-C digital camera. Exposure: 1.6 seconds at f/11, ISO 200. Focus: infinity marker opposite the IR dot. I adjusted the contrast with Adobe Photoshop.
If you don’t have an IR filter, try using a polarizer, then using just the red channel of your RGB image. That won’t cut the haze as well as an IR filter, but it will help.
I prefer shooting IR with manual focus prime lenses with hard infinity stops and IR marks. The more elements a lens has, the higher the probability of IR hot spots (excluding lenses designed for IR, of course), so I prefer simpler lenses. Cameras matter, too. Many older digital cameras have relatively weak IR cutoff filters, making them better suited for IR photography. Bjørn Rørslett rates the IR performance of many Nikkor lenses. His ratings match my experience, but there are so many variables involved that each lens/camera combination must be tested.