I had only very faintly glimpsed M97 a few times over several years in my 5" catadioptric, during passages or large dry air masses, and only when very high above the horizon. It was kind of an unresolved issue; this shell nebula is not dim, I should have seen it better than that.
Then I tried again with the serious 12" after seeing the M82 supernova in the same constellation, under good urban conditions, dry air, pretty high in the sky, but no hint of the nebula. So I didn't bother with the broadband filter and went immediately for the narrowband O-III in a 24mm Hyperion (62x). Star-hopped to where Sky Atlas 2000 shows it and bingo, immediate sighting!
Finally seeing it was less surprising than how easily I saw it: no need to search the field with averted vision and such, it was, bold, round, large, as a Messier showpiece should be. The 13mm (115x) made some darker feature visible, with no clear hint of its size, shape and location within the nebula, but better conditions (no Moon in the countryside) would surely put the two large dark eyes of the Owl at their rightful place in its face.
Bottom line, get an O-III filter; chasing emission nebulae from the city without one is asking for disappointment.
My neighbor's angora cat just walked on the keyboard while I was typing this, and wrote this ominous +666 sign. Funny coincidence as cats are said to be linked to the supernatural, I hope it's not a curse.
But seriously, after locating M97 with the Baader O-III filter, I tried again with an Astronomik UHC broadband filter; the nebula was much less detached from the glow. However when chasing galaxies in Virgo and Coma, the larger bandwidth helped.
Galaxies were a bit fainter but the glow was even more so; the overall view was better, as testified by more stars showing up. After about a half-hour of galaxy viewing with the UHC filter, I tried again with no filter and Ugh! The dirt! Not only the unnatural orange tint, but a sick dirty feel to the field, I realized it's really pollution, as disgusting as chemicals and soot.
O-III and broadband filters are standard arsenal for a good reason. They not only improve contrast, but also remove the ugly from the city.
TS 8x40 Wildlife, 10x50 Marine/Fujinon 16x70/TS 80mm triplet, 6x30 finder, EQ-3 mount, TS 2" 99% diagonal/Celestron C5+ and 6x30 finder, DIY tripod/5" Bahtinov/12" GSO dob, 8x50 finder/Meade 2" 24mm 82°/Hyperion 24,13,10mm 68°/TS Expanse 17mm 70°/SW 7mm Panorama 82°/Ultima 2x barlow/Astronomik UHC-E filter/Baader O-III/Astro Solar 5" & 80mm filters/Sky Atlas 2000/Rükl's Moon Atlas/Canon 400D/5mW green laser