[Gerrys]

I am very confused about filters, specifically UV's. I have a K10D. I know that the filter makes for better colors, but you also need to compensate for the loss of light. Is it worth all the trouble? I Am hearing both pros and cons on this. I have a circular Hoya and I am not even sure how to rotate it for best results. I also have a skylight filter that i keep on all the time. Do I need a lens cap to keep on when not in use? Seems like a pain taking it off and on. Please don't think I am a dodo as I am a little new to all this.

thanks

[jots]

For my DA lenses, I don't put any filter in front; only the cap when not in use.

I have UV or Skylight filters on all my classic K lenses. I don't want anything to touch the front element. I also keep a cap on the filter during storage but will keep the cap off in between shoots. Once in a while, I will remove the filter for critical shoot, or to put an polarizer on.

For your circular polarizer, you view through the lens with the filter, while you rotate. And when you see the effect you want (usually removal of reflection) then you take the picture.

With digital photography (esp. with post processing SW) I don't use other types of filters any more. Other people still might use them for special effects.

[sevenarrow]

jots already explained how to use the polarized filter.

Have you ever worn polarized sunglasses outdoors and noticed how much prettier everything looks when you're wearing them? The same thing happens when you use a polarized filter on your camera lens.

The only time you're going to be using the polarized filter is when you're outdoors under sunny conditions. Therefore loss of light is not an issue. There should be plenty of light. There is very little benefit to using polarized filters under cloudy skies.

I'll also add that the polarizer increases color saturation and improves contrast (because glare and haze is removed). So you stop rotating the filter when contrast and color saturation appears ideal such as the desired saturation of blue color in the sky. It is also useful for scenes containing water. It eliminates the glare or reflection of that surface resulting in a much more pleasing picture.

I've never seen any reason for using a UV filter. A polarized filter is much more effective.

I've never believed in placing a UV filter permanently on the lens to supposedly protect it from damage. It doesn't make sense to spend all that money on a high quality lens only to put an optically inferior UV filter on top of it. You're canceling out all that optical quality.

So... use filters only when you really need them ... when the final image will be better than if you hadn't used the filter.

[kevinschoenmakers]

I don't think many people actually buy UV filters to block out UV, rather everyone uses them to protect their lenses. You can leave these on all the time and just click your frontcap into the filter.

[Gerrys]

Thank you all for some helpful hints. One more thing; I meant skylight filter, not UV. Should I be leaving that off as well?

[code4code5]

Thank you all for some helpful hints. One more thing; I meant skylight filter, not UV. Should I be leaving that off as well?

When I first got my camera, I had a "Skylight" filter on the lens. I found that there was a slight change to the color cast in the photos that I was getting and the focus seemed soft, so I ended up taking it off. I suppose if I had better quality filters, it wouldn't have been so much of an issue, but I usually leave my lenses naked now.

[sevenarrow]

A skylight filter reduces excessive bluishness in outdoor scenes especially in open shade under a clear blue sky.

A UV filter absorbs the ultraviolet rays which reduces haze in the scene thus improving contrast and maybe color saturation.

In my opinion a polarized filter does the job of both skylight and UV filters and much more effectively. I have the same opinion as before about using any filter mainly as a lens protector.

[roentarre]

Moved to accessories section.

[Ben_Edict]

Code4code... - we had some very recent threads with basically the exact same questions - so you may find the search facility helpflu.

Generalle the use of UV filters is open to debate (and hotly debated), because their filtering properties are of low value, unless you photograph under excessive UV light (at more than 2500m height, under extremely dry and sunny conditions with snow/ice around, sometimes at the sea shore under really bright blue skies).

It is clear, that ANY aditional filter in front of the photographic lens will degrade image quality. This is a physical necessity. It is NOT so clear, if a really high quality filter degrades the image quality VISIBLY. In my experience a first rate filter does not degrade image quality visibly, if used wisely:
- remove filters, when shooting directly into a light source (sun, bright lamps etc.), as the filter will produce additional reflections, ghosting, flaring - even if it has a fancy multi-coating
- remove filters indoors, unless you need one for colour conversion (which you don't with a DSLR)
- remove the filters for night shots, as (see first line) any filter will increase flaring and ghosting.
- ALWAYS use a good (aka the right) lens hood, with a filter, to minimize additional reflections/flare.

Then there are still applications for a UV filter as a lens protector:
- in very windy conditions and sandy/dusty environments
- near the sea with salt spray around
- when shooting dirt track and similar events
- when small children are around, whose natural curiosity might lead them to probe your lens with their fingers (yes, I had that with completely strange kids), which just clutched a messy ice cone...

Skylight filters have a slight pinkish tint, to make images (in film days) taken under overcast skies a bit warmer and more pleasing. I never quite understood, why anybody would use a Skylight as a protective filter, when the colourless UV is available.

Polarizers are helpful to reduce unwanted reflections on non-metallic surfaces (car paint, windows, foilage etc.). This gives better colour saturation and better colour contrast. As Polarizers remove part of the light (the part that matches the polarization level of the filter), they actually reduce overall brightness contrast, especially as the bright sky usually contains the highest amount of polarized light. Brightness contrast and colour contrast are two different things.

Even in digital days I find two other kinds of filters very helpful, as they cannot fully or only with extreme time-consuming computer sessions imitated during post-processing:

1. the Neutral Density (ND) filters. These simply block part of the light and do not influence the quality of the light (colour or contrast). This is extremely helpful, when shooting in bright light, but wanting a wider open aperture to reduce depth of field. Sometimes you may also simply want a much longer expsoure time, which you cannot achieve without additional ND filters. I personally use them mostly when shooting portraits under bright light, to keep my aperture wide open.

2. the Graduated Grey filter (ND Grad), to reduce excessive contrast between very bright parts of an image (usually the sky, sometimes sand on a beach or snow) and the less bright rest of the image. There upper part is grey and gradually the density of the grey vanishes, until the lower part is completely clear. The idea of the graduation is, that the transition between the grey and the clear part of the filter should not be visible in the image.
GRADs should be used in a filter holder (Cokin, HiTech, Lee etc.), which allows to rotate the filter to the desired angle and to shift the filter up and down in the filter holder to place the transition as you prefer.

With layers and masking you can to some degree imitate the action of NDs and Grads in Photoshop, but I rather use the filter (cost: 1 minute or so), then sitting half an hour per image on the screen. Especially blurring the background in a portrait, because the aperture was stopped down to much, is a pain somewhere and suddenly mounting a ND filter really looks so easy...

Ben

[Class A]

... [great info on the use of filters] ...

Your explanations are so good, you could submit them as a forum article on the use of filters.

[Ben_Edict]

Your explanations are so good, you could submit them as a forum article on the use of filters.

Thanks, so much. I have no idea how to that and sure I would need to extend that topic quite a bit, as there are some interesting other applications (IR for instance).

Ben

[soccerjoe5]

Nobody "needs" filters to take great photographs. They can however enhance your photos if you know what you're doing.

Here's a great write up on filters, probably the best one out there: Filters by Thom Hogan

[Ratmagiclady]

Skylight filters generally incorporate UV filtering, too, by the way: the little bit of warming really isn't generally noticeable with the 1A, (stronger with a 1B) but it's generally-superfluous in digital, (auto white balance'll just tend to want to correct it out anyway, for instance,) ...part of why you don't often see them much anymore. I didn't even prefer them for film, but the effect's negligible in black and white, anyway.

I put UVs on lenses with particularly vulnerable elements, and generally keep some old ones around for use in crappy conditions.

Many, a deep round rigid hood offers plenty of protection for: often the wider ones, or that require a shallower hood get the UV's. At the other end of the spectrum, if you take a lot of long shots, particularly with teles, at high altitudes, or at the ocean, the actual extra UV cutting would be of use. (basically, the air scatters UV and can appear as a faint haziness when you're looking through more of it.) Though I believe most digital sensors do this to a degree, anyway, compared to films.


Basically, if you put a good UV on your lens, it can't do you any harm, (do use the cap in your bag or whatever) ...just bear in mind it can be a weak link in your optics.

[OregonJim]

I put UVs on lenses with particularly vulnerable elements, and generally keep some old ones around for use in crappy conditions.

Personally, I put HEPA filters on my lenses - helps to keep dust off the sensor.

[mikeSF]

i've been wanting to know this about coated lenses and non-coated lenses: if you add a multi coated filter to a non-coated lens, are you getting similar flare reduction and color improvement as if you were using a multi-coated lens to begin with? or will the outer element (of the lens) still create flares although the filter glass will not?

for example, i do not believe there is a coating of any sort on the Cosina 55mm 1.2 and it flares like crazy. If i affix my Hoya HMC CPL filter to that lens, will there be some flare reduction attributed to the filter?