There have been many arguments in chase lore over which still camera film is the best for overall storm documentation. Each brand has its prejudices, given the same film speed; and I agree that certain films are better in certain situations (e.g., brightly lit towers versus menacingly dark storm base versus fiery mammatus at sunset).
In spring of 1995, I did extensive slide-film trials, using 3 brands popular with chasers and one new brand, under a wide variety of storm situations. [Note: I have used the same films on several occasions in the years since, with no significant changes in performance of any brand.] Each brand shot pictures of at least one supercell from ahead of the rear flank (with respect to storm motion), so this subjective comparison should emulate similar common conditions about as much as you can expect in one chase season. Also, each brand had at least a handful of sunset and nighttime lightning shots.
For consistency, all slides were shot at 100 speed (my usual speed anyway), in the same Pentax MG camera, with the same set of lenses. [Velvia is a 50 ASA film, easily pushed to 100 ASA.] All were developed at the same photo lab, except for Kodachrome (which had to be sent to a regional processing center in Dallas). Multiple rolls of each brand were used, to detect and minimize effects of inherent quirks of individual film rolls within the same brand. No "expired" film was used. Finally, all were judged by the same pair of experienced chaser's eyes -- mine!
I acknowledge that there was still room for inconsistencies that were out of my control (e.g., subtle differences in chemicals or handling in processing from roll to roll); but I reduced the number of variables as much as reasonably possible. I also evaluated long-term durability of brands that have been around for many years, based on my experiences with the NSSL slide archives.
Here were the results:
Ektachrome (Kodak), 3 rolls: Similar to Sensia but not quite as bold in the warm bands. Can't see why people bash this film beyond its only real weakness: bold bright colors in medium to bright light. Great with cold colors and gray/on/gray shadings, including shadowed storm structure, "mean" looking black/dark blue-gray clouds, and cloud-bases. The best lightning film. Minimum 15-20 year lifespan of original colors under good care.
Kodachrome (Kodak), 2 rolls: Somewhat better with bright/warm colors than Sensia and Ektachrome, but not as bold as Velvia. 2nd most versatile all-purpose film. Main disadvantage is non-photographical: remote processing (not E-6!) with risk of loss. However, this is the best long-term archive film. Several photog rags I've read tout its durability (when slides are stored properly out of persistent light), with slides 25+ years old looking like they were shot yesterday. Personal comparison of Kodachrome and Ektachrome slides from the 1970s (while managing the NSSL slide archives in the late 80s) showed this durability markedly.
Sensia (Fuji) (3 rolls): Excellent overall film, handles warm colors well but strongest with differentiating shades of cool colors, such as blues and grays. Thus, best for under-the-storm shots, including most bases & mesocyclone/tornado situations. Excellent lightning film as well. Most versatile of all the films. Also quite inexpensive (I paid $4.50 for 36-exposure rolls at Wal Mart). A new film - no idea about its slides' long-term lifespan - so there is a risk involved here. I will be using a lot of this one from now on. NOTE: Film price has increased since its introduction in late 1994/early 1995!
Velvia (Fuji) (2 rolls): Best for sunsets, brightly-colored backlighting, colored mammatus, or any situation with lots of warm colors. This film is superior for reds, yellows, and oranges. Better for "storm structure" pictures out away from the storm, especially if the storm is strongly front-lit or the backlighting behind the silhouette is bright. Bleeds and/or color-offsets some lightning; magnifying-glass inspection reveals undesirable thin color bands on the edges of the closer/brighter CGs. Risk waiting 20-25 years to judge slides' long-term durability.
NOT TESTED: Fuji Provia or any of the Ektachrome or Kodachrome professional slide films.
That's my $.02 worth based on many slides taken of many storms that spring -- no commercial endorsement intended. Individual rolls of any of these films may vary in quality for your purposes, depending on film age, speed, camera specs, development procedures, subtleties in manufacturing of each parent batch, and your personal preferences.
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