# Some general questions about lens filters for a 35mm SLR **URL:** \ **Category:** Factual Questions\ **Created:** [January 6, 2005, 4:37pm UTC](https://boards.straightdope.com/t/some-general-questions-about-lens-filters-for-a-35mm-slr/283406 "2005-01-06T16:37:46Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Zebra](https://avatars.discourse-cdn.com/v4/letter/z/c0e974/32.png) [@Zebra](https://boards.straightdope.com/u/Zebra)\ **Post date:** [January 6, 2005, 4:37pm UTC](https://boards.straightdope.com/t/some-general-questions-about-lens-filters-for-a-35mm-slr/283406/1 "2005-01-06T16:37:46Z")
I basically know nothing about lens filters. So, How do I know what size filter to buy for the lens. I know it’s not the same at the lens size but is the number written somewhere on the lens? What sort of lens should I be using for general outdoor photography. Frequently the sky is really washed out and I would like to avoid that. Can a filter do that? I know I need to use T (tungsten) film for indoor or use a filter. What kind of filter and why? Thanks ---
**Author:** ![Phlosphr](https://avatars.discourse-cdn.com/v4/letter/p/c68b51/32.png) [@Phlosphr](https://boards.straightdope.com/u/Phlosphr)\ **Post date:** [January 6, 2005, 4:54pm UTC](https://boards.straightdope.com/t/some-general-questions-about-lens-filters-for-a-35mm-slr/283406/2 "2005-01-06T16:54:34Z")
I have a Nikon D70 Digi SLR - and the filter diameter is printed on the “lip” of the lens that came with the camera. However, on my 300mm lens it is printed on the opposite end. You can also use a ‘step-down’ ring if the filter you choose is too small. Most people choose the appropriate UV filter for their lenses by their fav make or model. What type of camera do you have? ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [January 6, 2005, 4:57pm UTC](https://boards.straightdope.com/t/some-general-questions-about-lens-filters-for-a-35mm-slr/283406/3 "2005-01-06T16:57:15Z")
> [@Zebra](#): > > How do I know what size filter to buy for the lens. I know it’s not the same at the lens size but is the number written somewhere on the lens? It’ll be the size listed on the lens in mm, for instance 52mm. The other important number is the f-number, or focal ratio. That’s a measure of how “fast” a lens is. The smaller the number, the faster the lens. > [@Zebra](#): > > What sort of lens should I be using for general outdoor photography. Frequently the sky is really washed out and I would like to avoid that. Can a filter do that? A circular polarizing filter can enhance the sky nicely. the light from the sky is polarized, but the light from the clouds and msot foreground objects is not. Rotate the filter until you get the best result in the viewfinder. > [@Zebra](#): > > I know I need to use T (tungsten) film for indoor or use a filter. What kind of filter and why? If you use daylight film indoors without a filter, your photos will look yellow-orangeish. To offset this use a blue daylight filter. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [January 6, 2005, 5:00pm UTC](https://boards.straightdope.com/t/some-general-questions-about-lens-filters-for-a-35mm-slr/283406/4 "2005-01-06T17:00:57Z")
> [@Zebra](#): > > How do I know what size filter to buy for the lens. I know it’s not the same at the lens size but is the number written somewhere on the lens? It’s usually written on the lens cap somewhere. If not, look up the specs for the lens - the “filter size” should be listed. It’s probably on the manufacturer’s home page. Or just take the lens to the shop. > [@](#): > > What sort of lens should I be using for general outdoor photography. It’s entirely up to you. > [@](#): > > Frequently the sky is really washed out and I would like to avoid that. Can a filter do that? A clear blue sky can be darkened with a polarizing filter. Note that most autofocus cameras need a “circular polarizer” filter instead of a standard polarizer. There’s no way to darken an overcast sky with a filter. > [@](#): > > I know I need to use T (tungsten) film for indoor or use a filter. What kind of filter and why? That’s only true for slide film. Incandescent light has a warmer (red) color so if you use normal slide film without a filter, the picture looks too red. With print film, the color balance is corrected when printing. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [January 6, 2005, 5:04pm UTC](https://boards.straightdope.com/t/some-general-questions-about-lens-filters-for-a-35mm-slr/283406/5 "2005-01-06T17:04:50Z")
> [@scr4](#): > > With print film, the color balance is corrected when printing. IME, although that’s technically true, the color still looks off unless a filter is used. Unfiltered prints do come out looking more natural than slides, but they still don’t look quite right to my eye, even at more costly processing places. Maybe I’m just picky. 🙂 ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [January 6, 2005, 5:15pm UTC](https://boards.straightdope.com/t/some-general-questions-about-lens-filters-for-a-35mm-slr/283406/6 "2005-01-06T17:15:27Z")
> [@Q.E.D.](#): > > It’ll be the size listed on the lens in mm, for instance 52mm. I think I confused myself here. The number on the _front_ of the lens is usually the focal length, not the filter size. 50 mm is a common focal length for general-purpose 35 mm film photography. If you’re going to get a single, good lens for most situations, allow me to recommend a good zoom lens, covering the range of about 30-120 mm. This will get you by in most situations you’re likely to encounter normally. ---
**Author:** ![AncientHumanoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ancienthumanoid/32/278_2.png) [@AncientHumanoid](https://boards.straightdope.com/u/AncientHumanoid)\ **Post date:** [January 6, 2005, 5:23pm UTC](https://boards.straightdope.com/t/some-general-questions-about-lens-filters-for-a-35mm-slr/283406/7 "2005-01-06T17:23:44Z")
Even with colour negative film, it’s best to get as close to a nuetral colour rendention as possible before printing, either by using supplemental lights/flash or by filters. There are so many things filters can add to your photographic enjoyment. [Look here.](http://www.bauser.com/lens-filters/) [And here.](http://www.photographic.com/accessories/177/) Also, experiment yourself. Film is cheap and filters are relatively inexpensive (compared to bodies and lenses), so you really have little to lose. Enjoy! ---
**Author:** ![AncientHumanoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ancienthumanoid/32/278_2.png) [@AncientHumanoid](https://boards.straightdope.com/u/AncientHumanoid)\ **Post date:** [January 6, 2005, 5:28pm UTC](https://boards.straightdope.com/t/some-general-questions-about-lens-filters-for-a-35mm-slr/283406/8 "2005-01-06T17:28:17Z")
> [@NoClueBoy](#): > > Even with colour negative film, it’s best to get as close to a nuetral colour rendention as possible before printing, either by using supplemental lights/flash or by filters. Unless, of course, you are going for a certain look or feel. That’s what’s so fun about photography as an art, hobby, or past time. The variables are almost endless. Sometimes a mistake turns out to be beautiful. Read all you can about it, talk to others about it, but most of all, just get out here and do it. It’s very rewarding. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [January 6, 2005, 5:30pm UTC](https://boards.straightdope.com/t/some-general-questions-about-lens-filters-for-a-35mm-slr/283406/9 "2005-01-06T17:30:19Z")
> [@Q.E.D.](#): > > IME, although that’s technically true, the color still looks off unless a filter is used. True, it still looks reddish. I think of it as a natural incandescent color but I can see it bothers a lot of people. One other point: the above is true if the indoor shot is lit only with incandescent lights. A flash has a more white (more bluish) color. And I won’t even get into fluorescent lights… ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [January 6, 2005, 5:35pm UTC](https://boards.straightdope.com/t/some-general-questions-about-lens-filters-for-a-35mm-slr/283406/10 "2005-01-06T17:35:18Z")
> [@scr4](#): > > And I won’t even get into fluorescent lights… Ugh. I always hated photographing under fluorescents with color film. I tried some filters once (they make different ones depending on the color balance of the lamps) meant for fluorescent lighting, but the result is never really all that good, though it is an improvement over raw lighting. ---
**Author:** ![pulykamell](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pulykamell/32/3166_2.png) [@pulykamell](https://boards.straightdope.com/u/pulykamell)\ **Post date:** [January 6, 2005, 5:48pm UTC](https://boards.straightdope.com/t/some-general-questions-about-lens-filters-for-a-35mm-slr/283406/11 "2005-01-06T17:48:14Z")
> [@Q.E.D.](#): > > Ugh. I always hated photographing under fluorescents with color film. I tried some filters once (they make different ones depending on the color balance of the lamps) meant for fluorescent lighting, but the result is never really all that good, though it is an improvement over raw lighting. You really need a color temperature meter if you want to balance fluorescents accurately. Those filters help, but it’s always a guess at the amount of color correction. Then you gotta gel your strobes accurately, yadda yadda yadda. The ability to manually white balance in digital cameras makes life so much easier. (Although strobing will still be tricky.) OK, lens for general outdoor photography/sky washed out– Depends on what you’re shooting, of course. For landscapes, I tend to use anything from the 20mm-35mm range. I would recommend a 24or 28mm. I think overall the 24mm will prove more useful in the longrun. The reason you’re getting washed out skies is because your film can’t handle the wide range of contrast between land and sky. The easiest solution to this is to use a neutral density graduated filter. They come in a number of ranges, the most common being one or two stops. What they are is a square piece of glass with a gradient that goes from gray on top to clear in the middle. It does not not affect the color of your picture (although you can get colored ones as well), but simply knocks down the brightness of the sky a couple of stops. [Here’s what one looks like](http://www.singh-ray.com/grndgrads.html), with an example of its use. This is a very very useful filter if you’re into landscape photography. In fact, the only filters I use are a UV filter (as protection for the lens more than anything), a graduated filter, and very very occassionally, a polarizer. If you pay attention next time you see a movie, look at all the landscape scenes. Chances are, a graduated filter is being put to use. Look for the tell-tale dark-to-bright gradient. ---
**Author:** ![picker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/picker/32/13969_2.png) [@picker](https://boards.straightdope.com/u/picker)\ **Post date:** [January 6, 2005, 5:49pm UTC](https://boards.straightdope.com/t/some-general-questions-about-lens-filters-for-a-35mm-slr/283406/12 "2005-01-06T17:49:14Z")
> [@](#): > > There’s no way to darken an overcast sky with a filter. Not true. Use an ND (Neutral Density Filter). or a Graduated ND. It will allow you to compensate for out-of-gamut exposure differences between very bright and and very dark sections of a framed shot. ---
**Author:** ![pulykamell](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pulykamell/32/3166_2.png) [@pulykamell](https://boards.straightdope.com/u/pulykamell)\ **Post date:** [January 6, 2005, 5:55pm UTC](https://boards.straightdope.com/t/some-general-questions-about-lens-filters-for-a-35mm-slr/283406/13 "2005-01-06T17:55:05Z")
> [@picker](#): > > Not true. > > Use an ND (Neutral Density Filter). or a Graduated ND. > > It will allow you to compensate for out-of-gamut exposure differences between very bright and and very dark sections of a framed shot. A straight ND will not do much of anything except require you to shoot a longer or wider exposure. It tends to be used in situations where there’s too much light for the aperature or shutter speed you need, and you have to knock down the exposure two or three stops to achieve it. Also, if you’re doing black & white photography, there’s a lot you can do with colored filters to darken the sky, or increase the contrast between sky and clouds. Generally an orange or red filter will make the sky appear darker, as these filters only allow orange or red light through. Since the blue sky doesn’t have much orange or red light in it, the filter effectively blocks it out making the sky appear darker. ---
**Author:** ![Carnac\_the\_Magnificent](https://avatars.discourse-cdn.com/v4/letter/c/ccd318/32.png) [@Carnac\_the\_Magnificent](https://boards.straightdope.com/u/Carnac_the_Magnificent)\ **Post date:** [January 6, 2005, 5:55pm UTC](https://boards.straightdope.com/t/some-general-questions-about-lens-filters-for-a-35mm-slr/283406/14 "2005-01-06T17:55:55Z")
> [@Q.E.D.](#): > > Ugh. I always hated photographing under fluorescents with color film. I tried some filters once (they make different ones depending on the color balance of the lamps) meant for fluorescent lighting, but the result is never really all that good, though it is an improvement over raw lighting. I’ve got an old, trusty SLR with many lens and filters. My question: do the professional digital cameras, which I’ve never used, require filters, or does the camera compensate without them? Do the digitals even TAKE polarizing or “warming” filters or, again, is this done digitally? ---
**Author:** ![pulykamell](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pulykamell/32/3166_2.png) [@pulykamell](https://boards.straightdope.com/u/pulykamell)\ **Post date:** [January 6, 2005, 6:02pm UTC](https://boards.straightdope.com/t/some-general-questions-about-lens-filters-for-a-35mm-slr/283406/15 "2005-01-06T18:02:25Z")
> [@Carnac the Magnificent!](#): > > I’ve got an old, trusty SLR with many lens and filters. My question: do the professional digital cameras, which I’ve never used, require filters, or does the camera compensate without them? Do the digitals even TAKE polarizing or “warming” filters or, again, is this done digitally? Polarizing, no. I can’t see how a camera could simulate polarization. It requires extra information (direction of light) that the camera doesn’t record. For the rest, the answer is more-or-less yes. Colored filters you can always simulate in post. Otherwise, the high-end digital cameras allow you to dial in light temperature in Kelvin to white balance. For example, daylight is generally around 5500K. If you set white balance to 7000K, you will achieve a slightly warmer look. Set it to 3200K and it will be as if you’re shooting with Tungsten film (which imparts a strong blue cast to daylight). In the next tier of digital cameras, you usually have the ability to set white balance manually by pointing the lens at a neutral gray or white card and pressing the shutter. You can buy cards that are slightly warm or cool to give you a white point that isn’t neutral. In most digital cameras, you will at least have automatic white balance presets: for tungsten, for fluorescent, for cloudy days, for daylight, etc… Setting white balance on cloudy on a normal day will give the picture a warmer look. Setting it on tungsten will make it blue. ---
**Author:** ![nesta](https://avatars.discourse-cdn.com/v4/letter/n/a4c791/32.png) [@nesta](https://boards.straightdope.com/u/nesta)\ **Post date:** [January 6, 2005, 6:02pm UTC](https://boards.straightdope.com/t/some-general-questions-about-lens-filters-for-a-35mm-slr/283406/16 "2005-01-06T18:02:46Z")
> [@Zebra](#): > > What sort of lens should I be using for general outdoor photography. For a general outdoor walking-around lens, you will probably want a zoom in the range **Q.E.D** mentioned, or a prime 50mm or 80mm. For landscapes, though, you might prefer a wide angle somewhere between 20mm and 30mm. > [@Zebra](#): > > Frequently the sky is really washed out and I would like to avoid that. Can a filter do that? Polarizers are good for the blue sky, and some other color tweaking. If your primary concern is landscapes where the sky is washed out or the ground is too dark, you might want to consider a [graduated](http://www.bhphotovideo.com/bnh/controller/home?O=productlist&A=details&Q=&sku=121050&is=REG) filter. They are square filters that you hold in front of the lens to compensate for one side of the frame being brighter than the other. You can get them in graduated color or neutral density. ---
**Author:** ![AncientHumanoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ancienthumanoid/32/278_2.png) [@AncientHumanoid](https://boards.straightdope.com/u/AncientHumanoid)\ **Post date:** [January 6, 2005, 6:02pm UTC](https://boards.straightdope.com/t/some-general-questions-about-lens-filters-for-a-35mm-slr/283406/17 "2005-01-06T18:02:54Z")
> [@Carnac the Magnificent!](#): > > I’ve got an old, trusty SLR with many lens and filters. My question: do the professional digital cameras, which I’ve never used, require filters, or does the camera compensate without them? Do the digitals even TAKE polarizing or “warming” filters or, again, is this done digitally? Both. And depends. Programs such as Photoshop have the tools to allow you to change many things, subtle and gross. Also, polarisers will almost certainly have to be of the “circular” type, since a non-circular polariser can affect the exposure, autofocus, and perhaps the imaging. (Not real sure aboiut that third thing.) Check your manuals and search for websites of users of your camera. There are thousands out there. ---
**Author:** ![Zebra](https://avatars.discourse-cdn.com/v4/letter/z/c0e974/32.png) [@Zebra](https://boards.straightdope.com/u/Zebra)\ **Post date:** [January 6, 2005, 6:12pm UTC](https://boards.straightdope.com/t/some-general-questions-about-lens-filters-for-a-35mm-slr/283406/18 "2005-01-06T18:12:21Z")
Sorry, I didn’t mean lens for outdoor photography but filter. Lens, I know, Filters I don’t. I own a Canon T-90. Yes, I still use film. I almost sold it and was going to use the money to get a digital but I took it out, dusted it off and took it on a trip to Paris and I remembered how much I loved it and film today is much nicer than the film I was buying 15 years ago. I have a small family of lenses that I’m using and I’m constantly watching E-bay for more. I have a 35-70 zoom on the way to me right now and I a 28, a 50, a 100 and a 135. I also have a 500mm mirror lens for when I want to play spy. If I am using a filter how does that affect my exposure. The T-90 has a great TTL (through the lens) metering system so if I left the exposure on auto it should be fine. But what if I ‘go crazy’ and set the exposure manually? ---
**Author:** ![AncientHumanoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ancienthumanoid/32/278_2.png) [@AncientHumanoid](https://boards.straightdope.com/u/AncientHumanoid)\ **Post date:** [January 6, 2005, 6:17pm UTC](https://boards.straightdope.com/t/some-general-questions-about-lens-filters-for-a-35mm-slr/283406/19 "2005-01-06T18:17:52Z")
You’re still metering thru the lens, thus thru the filter. Without TTL metering, the filter will have a filter factor, indicating how much extra exposure may be needed. With polarisers, this is often anywhere from 1.5 to 2.5, most of us simply use 2.0. the filter factor will be listed in the little peice of paper that came in the filter’s tiny box. You know, the generc instruction sheet. 🙂 Adjust accordingly. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [January 6, 2005, 6:20pm UTC](https://boards.straightdope.com/t/some-general-questions-about-lens-filters-for-a-35mm-slr/283406/20 "2005-01-06T18:20:55Z")
> [@Zebra](#): > > If I am using a filter how does that affect my exposure. The T-90 has a great TTL (through the lens) metering system so if I left the exposure on auto it should be fine. But what if I ‘go crazy’ and set the exposure manually? Color-balancing filters won’t generally affect your exposure. Neutral-density filters , of course, will, but it’s easy to compensate, since they are rated in stops. For example, an ND-2 will decrease your exposure by 2 full stops, so to compensate, you can increase your exposure time by two stops, or open your aperture by two stops, or increase your exposure time by one stop AND open your aperture by one stop, depending on factors like depth of field and whether you’re photographing moving objects and such. [Next page](https://boards.straightdope.com/t/some-general-questions-about-lens-filters-for-a-35mm-slr/283406.md?page=2)