15Bit Offline Upload & Sell: Off
|
I think in the consideration of whether to use a filter you need to carefully look at the application, the risks to the lens and the properties of the components. Things to consider here:
- The front element of the lens generally has much higher ultimate strength than a filter (with respect to cracking)
- The front element of the lens generally has slightly better scratch resistance than a filter (but not much)
- A filter and a front lens element have similar chemical resistances
- The front element of the lens is probably a fair bit more expensive than a new filter, but for some cheaper lenses the price difference might not be so great
- Lens hoods are usually plastic, and can deform and break to absorb a lot of energy without damaging the lens (they just snap off at the bayonet mount). They also provide protection against objects approaching the lens from oblique angles. Replacement lens hoods are generally of a similar price to a protective filter or less.
Thus for some sorts of risk a filter is a bad choice, as it will break under conditions which the front lens element would survive fine, producing sharp and hard glass shards which cause damage that would have been avoided if the lens was bare. Examples of this sort of circumstance would be impacting objects that are soft but possess a lot of kinetic energy. The paintballs are an excellent example, as would be a number of children's toys.
In contrast, objects with sharp edges and low impact energy (i.e. those that will tend to scratch rather than break) favour the use of a filter, as it has similar scratch resistance to the lens element and is cheaper to replace. Nice examples of this would sandy or gritty conditions on a windy day. Cold fine snow is also a surprisingly good abrasive, and i tend to use protective filters when skiing in very cold weather. For sandy and gritty conditions a filter is also easier to clean - you can rinse it off under the tap when you get home and thus reduce the risk of incurring scratches when cleaning.
For hard and sharp objects with significant kinetic energy (flying stones etc) you are probably screwed whether you have a filter or not, but there is a kinetic energy window where a filter doesn't break, but damage to the lens element would have occurred in it's absence. Using a filter makes sense in these conditions, as even if it does break some damage to the front element would have occurred anyway. Not using your camera at all in such conditions makes even more sense to me though
In cases where there is the possibility of chemical damage (i work in a research lab), a filter makes a lot of sense.
In all cases a lens hood will provide improved protection, whether a filter is fitted or not. It will also provide protection in the event that you drop the camera.
I would comment that i rarely use protective filters, but do use the lenshoods a lot. I have had flare problems with filters, and i tend towards the opinion that i didn't spend a lot of money on a high grade lens in order to degrade the image by adding extra bits of glass in front. Also, for most of my use i just don't need the extra protection: The only front element damage i have experienced was when i dropped my 70-200mm f/2.8 in a carpark (in a padded lowe-pro bag, with camera attached) about 12 inches with the front element landing flat on the asphalt. No scratches (it was in a lowe-pro bag), but the energy was enough to dislodge the front element from it's mount (and crush the lens cap) and cost me half the price of a new lens to get fixed (new element + norwegian labour prices). A filter would not have helped, it would just have made the accident even more expensive by breaking the filter in addition. For this kind of impact a lens hood is what i needed, but i was just getting everything out the car so it wasn't fitted.
|