Upload & Sell: On
I just finished doing a test to compare what happens when you hit the bare front element of a lens with a paintball, with what happens when you hit it while it's wearing a UV filter. This landmark experiment was inspired by past discussions on FM, and in particular by Herb Chong's suggestion near the bottom of the first link below:
Lens: Vivitar Series 1 35-85/2.8 VF VMC, made by Kino, M42 mount.
note: this is a parts-only lens that I bought for its clean front element, which I swapped for the scratched front element on an otherwise Mint condition version of the same lens (since sold).
Filter: Tiffen 72mm Haze-1 U.S.A.
Marker: Autococker with pump kit and J&J ceramic barrel.
Paintball: winter formula, orange paint.
Shooter: my son Trevor, member of a competitive paintball team with professional sponsorship (i.e. he's a good shot).
Setup: shooting from 25 feet; barrel velocity approx. 280 to 290 fps; lens mounted with M42 to Pentax K adapter on otherwise useless dead Pentax MX body, in turn mounted on 468MG head/055 GS tripod.
(1) Bare lens: three direct hits on the bare front element of the lens did no damage at all, except to turn the white lettering on the lens face into orange lettering.
(2) Filter in front of lens: one hit on the filter blew a hole right through it and caused significant damage to the front element of the lens beneath it.
Observations: these paintballs were hitting very hard - two near-miss hits went right through the cloth covering the 468MG tripod head; paintball splatter covered the adjacent white wall of the house to a height of about 10 feet (recently cleaned to a height of about 8 feet - stupid splatter!).
Verdict: next time I shoot a paintball tournament, I will not use filters on my 24-70L, 70-200/2.8L IS and 300/4L IS lenses (which is the same as the last two times I shot paintball tournaments).
Learning: next time I do a paintball test, it won't be so close to the white side of my house (thank goodness she wasn't at home).
For what it's worth.
1. before, you can just see the original scratch at about 9:30 o'clock
2. after, all of the white stuff is pitting and chips, many are worse than they look
3. after closeup, original scratch runs on LHS between .8 and Auto.