Stanley

Stanley here again with a new topic. I have hear about filters: Neutral Density filters, polarizing filters etc. I also heard that filters can add artistic effects too. I know there is a lot of experience out there in "Ugly Hedgehog" about all things photographic. How, why and when do you use filters?

taken with Nikon D100 w/18-55 kit lens

JimH Loc: Western South Jersey, USA

I could write a book.. lol

Quick breakdown, your milage may vary:

1) Circular Polarizer (CPL) - recommended for nearly every outdoor daylight type of shot. Screws on front of lens, and then rotates withing frame. Polarized lightwaves so that reflections from shiny surfaces are cut down. Makes blue sky bluer. Works best when SUN is at 90' angle to you and scene (e.g., at your left or right side, rather than behind or in front of you) Not as useful indoors or at night.

2) Neutral Density (ND) - darkened glass, added to front of lens to cut available light, allowing for LONGER shutter speeds without over exposing whole image. Used, for example, to get that milky smooth flowing look of waterfalls and creeks,etc.

3) Graduated Neutral Density (Grad, or GND) - a filter that's dark on top, and clear on the bottom. Used to help DARKEN the top of a bright scene yet allow the darker bottom to be exposed correctly. E.g., a sunset with an interesting foreground. Cameras go crazy trying to figure out what the correct exposure is for a scene with a really bright top (like a bright sky or a sunset/sunrise) and a darker bottom , like woods or forest or something. A GND allows you to fake out the camera exposure meter and arrive at a more happy compromise. Grads are also delineated as HARD - a concise, clear, abrupt change from dark to light, and SOFT - a more gradual change from light to dark.

4) UV, sometimes called "haze" filters - opinion on these is divided. FILM was subject to, and sensitive to, Ultraviolet light. Digital sensors are not. Therefore, there is NO TECHNICAL need for a UV filter on a DSLR. HOWEVER, a WELL MADE UV filter is very nearly optically pure, so it's use will not degrade the light you need, and may help protect the front of the lens from dust, dirt, flying bugs, and the occasional tongue.

As with any other photographic accessory, you gets what you pays for. A cheap $10 CPL from Walmart will NOT have the optical purity of a $100 multi coated gem from Hoya or B+W. I know, because I've got them both. A cheap filter will end up degrading your image quality more than it will improve the light.

Screw-on filters must of course, match the front element diameter of your lens - and this could be 50mm, 58mm, 67mm, 77mm, or even more. If you look inside the front ring of your lens, it's often printed there, with a number next to a circle with a line through it.

There are, of course, other kinds of filters that add special kinds of effects, like starbursts on points of light, and different color filters like yellow or blue, but they're more often used in specific situations, and I don't use them, so I'm not going to expose myself to even further ridicule.. :) Google is your friend.

chapjohn Loc: Tigard, Oregon

Adding to JimH's good review of filters--Many people use a UV or Skylight filter all the time for all situations. They almost never remove it. It gives help by controlling most of the harmful UV light and also as a protecter of the front of the lens.

JimH Loc: Western South Jersey, USA

Chap, I may have been editing my post while you were putting yours in, but there is no technical need for a UV filter on a digital camera - the low pass filter in front of all sensors effectively blocks all UV light. Protection, yes. UV filtering, not needed.

notnoBuddha

[quote=JimH]I could write a book.. lol

Quick breakdown, your milage may vary:

1) Circular Polarizer (CPL) - recommended for nearly e................."

For what I know about it, a very concise, informative reply. This one I even made a copy of - thanks.

Stanley

Wow, a book is right. As I acquire more photographic equipment, I will defiantly add some kind of filters and use your excellent summary to guide me, thanks,
-Stanley

Kathi Loc: Pennsylvania

Fabulous and succinct summary ~ thanks!!!

abc1234 Loc: Elk Grove Village, Illinois

In the days of black and white film, I used various colored filters. Today, in the era of digital photography, I use only one: polarizer.

If the day is not bright and sunny and you are not shooting so the sun is about parallel to the front of the lens, leave the polarizer off. Otherwise, it can be a great help in darkening the sky and increasing apparent foreground contrast. However, you can still get this later with your software.

The only other time it works is to reduce reflections, inside or out.

To complicate matters, the filter makers have come out with polarizers for every day of the week now.

Good luck.

Jwilliams0469 Loc: Topeka, Ks.

abc1234- "the only other time it works is to reduce reflections, inside or out" I can't agree with the inside use of a CPL without an extreme brightened area. Unless you are taking photograph of a subject in front of a window on a bright day or something in that range. CPL's are to lighten the chance of a reflection and lower brightness and to add contrast to blues, oranges, reds, yellows, and so fourth. if you are in a regular lighted room, your photographs will be darker than intended.

Greg Loc: Maryland

Agreed. Hard GND's are more typically used on water landscape where there is generally a precise definition between Horizon and sky, where as soft would normally be used for not water landscapes where the dividing line due to tree's, etc. are not as precise.

I think most of the artistic filters are of limited use in the digital realm as you can duplicate their effects in PP, where things like ND, GND and polarizers you cannot, and their use enhances the raw images.

Finch585 Loc: Northern California

I was planning on asking the group why the CPL rotates within its frame? (so this is the perfect opportunity)

abc1234 Loc: Elk Grove Village, Illinois

The physics is such that it removes incoherent light. That is, light that is not traveling in parallel to the lens. The filter has crystals lined up in a certain direction. You have to line up the incoming light with the orientation of the crystals. You do that by rotating the filter. Some filters have a spot that you line up with the sun.

For it to work effectively, you have to have a lot of direct light, not scattered light as on a cloudy day. Rotate the filter and notice the effect. If you are wearing polarizing sun glasses, everything goes black when the two polarizers are perpendicular to each other. So, do not forget to take them off.

Hope this helps.

Reb

Jim H:

Google may be your friend, but he ain't my friend. Google limits my emails, and there is no way I have ever found to contact them, or to eliminate them. This is very annoying to me. As to filters, I don't think there are any that can be used with my Canon A-590. I would like to have a Rebel, as that is my name, but they have priced it well over the size of my pocket.

Reb

GENorkus Loc: Washington Twp, Michigan

Should you find a quality made polarizer marked with a PL instead of CPL marking on the ring, don't get it for your digital camera. The PL was made for film cameras. To a degree, it will still work but not as well.

If you are having a tough time seeing a difference while turning the filter, look for a triangle printed on the ring itself.

Turn the CPL ring so the "triangle" is pointing towards the sun's direction. That will generally gives the results you want.

(Your milage may vary.) :thumbup:

abc1234 Loc: Elk Grove Village, Illinois

PL types interfere with autofocus; CPL does not. Has nothing to do with film versus digital.