using more than one filter

Joined: 18 Jun 2004 Posts: 189 Location: Huntington, WV

I was wondering if people use more than 1 filter at at time, such as a UV filter along with a polorizing filter?

Posted: Fri Aug 19, 2005 5:13 pm

I have been known to screw in a closeup filter or two on top of my UV.

Posted: Fri Aug 19, 2005 5:18 pm

I read somewhere that you shouldnt use more than two filters at any one time..

Posted: Fri Aug 19, 2005 5:38 pm

Be extra careful not to let the light hit the front of your lens. If the filters are not multi-coated (most are not) you will set up reflections between the two filters and lose a lot of contrast.

Posted: Fri Aug 19, 2005 5:39 pm

I do not take my UV filter off for anything... and I often use a polarizer with it... never experienced any problems.

Joined: 08 Jul 2005 Posts: 147 Location: Watertown, NY

You can use two filters at once, but keep in mind when using wide angle lenses you can get vignetting from stacking them.

Joined: 10 Aug 2005 Posts: 21

If you want to use other filters with your UV, i'd advise taking out the uv and just using the filter. No matter what people say, if you're not careless, you're better off without a UV filter anyway (the uv filter's main function is to block out UV rays, but they probably won't reach the sensor/film anyway because of the complexity of most lenses, since they can have up to 18 elements or more, the other function would be to see through fog, but what it does is, in my experience, just make things a tad more clear, so unless u're shooting in foggy conditions... lose the UV :D).

However, if you need to use 2 or more filters you need to know a few basic things:
1. Each filter will cost you image quality. Wheather it's contrast or brightness, blurr or who knows what, it's very probable that the quality will be diminished with each filter you add.
2. As it was said, depending ofc on the thickness of each filter and the rings you use, you might experience vignetting (dark spots at the edges of your photo)
3. Lens flares probability increases with the number of filters u're using, because you have more lenses, thus u get more refletions, and so on.

The main problem is, however the fact that the glass quality of the filter is probably lower than the lenses', even if you're not using professional lenses, therefore you'll get lower quality. However, if the filter(s) is/are good, the loss of quality will be less noticeable.

If i were you i'd experiment a few photos with one filter and then some with 2 or more, in different lighting conditions, and then compare. One roll of film should be enough. If you're using a digital then your problem is solved... just take pics.

Edit: I'm talking mostly out of personal experience, so if i'm wrong, please excuse me.

Posted: Fri Aug 19, 2005 9:02 pm

The reason I never take off the UV filter is because I view it as cheap insurance against damaging my actual lens. I have seen more than one lens that was dropped and saved by having a UV filter.

As for the image quality, consider this....
for 1 shot, yes the UV filter makes you shoot through more glass, and in many cases lower quality glass... However, over time, you can clean and clean and clean your UV filter worry free because you can replace it for cheap. Without it, you will have to touch the glass on the lens to clean it.... the lens glass is much more expensive, and more sensitive, and not really replaceable. Dust on your glass is inavoidable... but cleaning the actual lens you risk much more than by cleaning a UV filter.

Joined: 10 Aug 2005 Posts: 21

You're right, that's why I said "if you're not careless" I never dropped my lenses, really, when i mount a new one i just do it over my bag so if it falls it falls into the soft-bottomed bag (and besides, if you drop your lens so hard that it would crack the UV filter it might crack some lenses on the inside too so there's not much help there). And I try not to touch my lenses so there are very few fingerprints, and i only clean them for dust like once a month and I'm careful with that too. It may sound like being "too" careful but it's not really, just put the lens in the bag when u take it off and don't touch the glass. Easy. :)

And i had some very unpleasent experiences with UV filters... The first one i used was made of very low quality glass, and I didn't notice the quality difference untill I shot a nice waterfall, with and then without filter. I threw it away as soon as i got my photos processed. The second one was my girlfriends' and i used it on a foggy morning, and every time there was the possibility of flare, it would happen. So that really made me angry at UV filters... that's why I'm so against them.

Posted: Fri Aug 19, 2005 11:14 pm

maybe i'm just used to shooting in "harsh" conditions... I have to brush off dust and specs of lint, etc almost daily.

and I guess I don't view it as careless to take my camera hiking on rocks, or to shoot a baseball game at field level, or out in the rain, etc... after all, that's why i have a camera... so that I can capture those special things. I guess when you're shooting for journalism, you have to be willing to take some risks with your gear... so I find it a good idea to minimize those risks. Afterall, "Sh*t happens".

Don't get me wrong... I also LOVE shooting for art, but because my camera comes out in all conditions, I think it is wise to give it a little extra protection and sacrifice a little in raw image quality... especially since it is so easy to make up in processing.

EDIT: to me the UV filter's main function is not to block UV rays... any physicist will tell you that plain glass does this anyway... the main function is to protect your expensive, coated glass. And speaking of physics... microscopic particals of dust stick to glass... all the time... even in the cleanest of clean environments. These microscopic particals are too small to see, but they are big enough to refract and reflect the light bouncing off of your subject through the lens, detracting from your image quality. So allowing these to build up on your good glass is no different than allowing them to build up on your cheap glass... except that you can periodically replace your cheap glass to start fresh. The principle that talks about particals sticking to glass is...Van-der-Waals forces

Posted: Sat Aug 20, 2005 4:59 pm

In my opinion, UV filters (and Skylight filters) are sold by retailers as a method to increase the sale and improve profitability. The retailer is the primary beneficiary of this transaction.

If you replace your lens cap when you are not actually shooting, in most cases you will not have to clean your lens more than once a month.

I shoot in the studio mostly and I can go many months with nothing more than a shot of compressed air once in a while. I can't remember when I had to clean my studio lens last.

I place a UV filter on my camera when I venture above 8,000 feet of elevation. By my recommendation that is the only condition that requires a UV lens.

If you shoot motocross or auto racing and there is a lot of dust you might be able to justify it. If you do, get a first rate filter (multi-coated) and not the junk that is sold with most cameras (which is not much better than window glass).

Posted: Mon Aug 22, 2005 8:01 am

Hi, most things have been said already, may be some more personal experience helps you decide whtat to do:

1. UV filters are not necessary to cut-off UV light, except on the highest mountains or on a very sunny day at the beach (I have never experienced problems with UV at sea level myself and also not up to heights of about 4500 meters)
2. UV light is cut-off by the glass in your lenses anyway - if your pics are blueish, because of let's say snow etc., use a correction filter instead, like a 81A
3. UV filters can be used as a protective surface, to shield the front element of an expensive lens - if you are going into a shooting situation, where damage/dirt is to be expected (climbing, skiing, beaches etc.)
4. Cleaning a lens carefully, i.e. with compressed air or a dedicated brush etc (NOT RUBBING THEM WITH A HANDKERCHIEF) and occassionally will not damage the lens. Modern multi-coatings are so called "hard" caotings and this is true.
5. almost all UV filters and ofcourse most other filters too will degrade your image quality, because these fliters are called "polished", which means, they have never got an optical polish, but were "flame polished", just melting the rough surface, to smooth the roughness. The result is like the surface of a calm pond - a farc cry from a "polished" surface, as we would expect them
6. very expensive filters get a real surface polish with a guaranteed maximum roughness. They also receive a good multi-coating and very few filters get a slightly curved surface (optically ofcourse "null"), so that reflections will not reflected into the lens, but to the outside

7. combining several filters will degrade image quality massively. Let's say, you add to filters with a 90 % image quality, your result will be a mere 81 % quality left.

8. combining several filters will produce additional reflections and annoyingly so, if you shoot somewhere near the sun. Especially if you don't combine multi-coated filters

9. a UV filter need not be combined with any other filter, because any other filter (except cheap plastics) will act as a UV filter anyway

10. a bit of dust on the lens will virtually have no effect on the image quality, unless it's greasy. So there is no reason, to protect the lens from any bit of dust (a rough calculation shows, the contrast loss begins, when more than 15 % of the surface of an optical train will be blocked... That is adequate to "dust" in coin size.

11. dust on the front lens can induce more stray light by scattering - a good lens hood will minimize this -, but it also needs to be more, than the dust that accumulates in a normal household.

My experience is: In most sitautions (hiking, mountaineering, normal walking), I don't need a UV filter to protect my lenses. A substantial lens hood protects the lens instead and is a necessary gadget anyway. If not in use, the lens cap will keep away the dust.

I protect some of the very expensive lenses with an adequately high-quality UV filter, when circumstances afford that: shooting near salt water or in the spray at cliffs or on beaches, because the salt water can damage the coatings on the lenses. Also in heavy rain or snow, a UV filter is fine for me, because I need to wipe the front surface dry so often (which is ofcourse not what I meant aboave as careful cleaning).

regards, René