What filters are good and why?
This is an attempt to summarise the widely-held opinions of photographers in general.
I believe this is a fair distillation of views.
- Adding any filter risks adding lens flare and reducing sharpness
- The effect of most filters can be reproduced in post processing
- The only filter which cannot be adequately reproduced in post is a polarising filter (particularly when used to remove / reduce reflections / glare).
- Neutral Density filters are sometimes necessary. For example: when the photographer wants to reduce the amount of light entering the lens to allow a wide apperture and a long exposure (for example, when photographing flowing water).
- UV Filters:
- Many photographers feel that it is worthwhile to put a UV filter on the front of every lens, on the basis that this will protect the front lens element - from dust, scratches and catastrophic damage if the lens is dropped. In other words, it is a kind of insurance policy against lens damage. I understand that Scott Kelby takes this position.
- Many (other) photographers believe that this practice is not worthwhile: they may feel that the reduction in image quality (actual or potential) is not justified by this "insurance policy". I have heard Scott Bourne articulate this belief.
I hope this is a fair and sensitive summary ;)
Filters that are useful for digital photography:
Polarizing filter. This will cut through haze and reduce glare. Useful for landscapes as this will darken the sky by cutting out polarized light and also reduce haze making objects in the distance look clearer. Technically you need a circular polazrizing filter if you want automatic focus and metering (most filters are this type).
ND filter. Simply cuts out light, useful for increasing the shutter speed for artistic effects or flash sync or allowing wide apertures in bright daylight. Also available as a graduated filter (i.e. one that starts out clear and gets progressively darker, useful for taming scenes with high dynamic range, such as bright skies).
Infrared filter. Technically a visible light blocking filter. Allows infra-red photography using a standard DSLR. Requires very long exposures due to the camera's built in IR filter cutting out most of the incoming light, but can have spectacular results.
Whether you should buy any of these depends entirely on what sort of photography you plan on doing and what your budget is!
Other popular filters for film use such as coloured filters have limited use in digital photography, see this question for more details: Are there reasons to use colour filters with digital cameras?
"So why should I buy a UV filter or any other filter for that matter?"
You don't need to buy a UV filter, or any other filter, here is why you would want to use a UV filter specifically:
Now I'd say 99% of people who put a UV filter on their lens aren't doing it because of that, they're using it as a layer of protection for the front element of the lens. Its true, it'll prevent fingers jamming into the element and children's sneezes from getting all over it but there are also downsides which are illustrated in that wikipedia article. Namely flaring and quality degradation.
Me personally? I don't use UV filters as all-the-time protection on my lenses anymore (don't want flaring etc), I got a stack of them collecting dust on a shelf. I bust one out if I'm taking the lens to the ocean or something and anticipate spray but thats about it.
At the least, I get a clear filter (Hoya usually, sometimes Nikon) just to help protect the lens from surprises that include:
- Accidental spraying (Happens more than you'd think)
- Dusty environments
- Work where you have to go through heavily wooded areas
It puts one cheap peace of glass in front of much more expensive glass. A friend of mine had a $500 prime bite the dust when a passing car kicked up a small rock. What are the chances?? But it does happen.
As for the other filters, it depends entirely on what you are shooting. I usually carry a warming filter, a grad, and maybe a UV depending on what I'm doing. Most of the time, I just leave them at home, with the exception of the clear / protective filter.
Again, its not so much the body, but the lens and the conditions you are shooting in.
If you get a screw-on filter (e.g. a polariser) then you should get a good quality coated one. With digital cameras, the sensor is very reflective, so light entering the camera has a tendency to bounce off the sensor and back off the filter, causing a ghosting effect. This is reduced/eliminated with a coated filter. Note also that a polariser also acts as a 1-2 stop neutral density filter so you will need wider apertures or slower shutter speed/ISO to counter the effect.
Neutral density graduated filters are also very useful, as even though the effect can be reproduced in PP, you will retain more detail in highlit areas using the physical filter. Recovering a blown sky in post risks a weird 'grey border' effect, where saturated highlights that were originally blue become pure white, and when darkened in post turn an incongruous grey. I'm a big fan of getting it right in camera as much as possible, but that's not to say you should NEVER make adjustments afterwards.
There are no "must have" filters. In fact I would recommend that you don't get any. If you are a new photographer you have a lot to learn in terms of exposure, how to operate your camera.
It's all too easy to think that the next piece of gear will allow you to get great shot. But the gear is just a tool. You need to learn the tools and be good at using them. And getting too many tools at the same time just adds to the confusion.
So instead I would recommend spending the money on books helping you in the learning process.
I'm gonna go out on a bit of a limb and say there are no filters that you must have!
I personally think UV filters are a waste of money, if you think you need it for protection, just be more careful...
I have a circular polariser that I use more than anything else, but to be honest, I only use that for photos of water and clouds etc which I find to be the most boring photos anyway.
Save your money for some nice glass :)
I'm with the no filter crowd. I prefer the higher quality you get without a filter. Glare reduction with a polarizing filter may be the only exception. Darkening of the sky with a polarizing filter can be achieved often by use of various layer modes in Photoshop, etc.
As for protection. I've dropped a $1800 70-200 2.8 IS lens and the lens hood took the hit with no damage to the lens. I have lens hoods on all lenses, but no filters.
Just a clear filter for protection and to allow you to clean it without having to touch the actual surface of the lens. That's my advice.
Get a high quality one, perhaps Hoya and it's really all you need for the vast majority of cases. The only one I would say is work keeping in your bag perhaps is a graduated Neutral Density for darkening skies.
For effects, I now do all my work in Lightroom/Photoshop:
Neutral density filters have been mentioned because their effect is arguably not possible to be added in post-processing. The polarizer has also been mentioned because its effect is not possible to be added in post.
For completeness, another filter whose effect can arguably not be replicated is the graduated neutral density filter. A graduated neutral density filter is clear on one end and a ND filter on the other, allowing the photographer to modify only a portion of the scene. This is particularly important because it can allow the camera to record an otherwise blown-out area of the scene, and therefore can't be fixed in post -- if detail wasn't recorded, it can't be improved.
The result of using a graduated ND filter can be recreated in post by taking several exposures and combining them in Photoshop, though the result typically ends up looking a little more like tone-mapped/HDR results.