Filter For Light Reflections Off Cars?

[knwnasrob]

so I go to a lot of car shows that are indoors so of course there are many little circle light reflections from the ceiling lights on the cars. any way to remedy this?

 

[ann]

Polarizer should due the trick, however, you are going to lose 2 f stops of light.

 

[KmH]

A circular polararizing filter, nor any other filter, is not effective at reducing glare on metal.

 

[skieur]

A circular polararizing filter, nor any other filter, is not effective at reducing glare on metal.

At the proper angle a polarizer does reduce reflections on metal and with a good polarizer you will lose less than 2 f stops.

skieur

 

[KmH]

Light reflected off metal is not polarized.

Light reflected off of glass, rocks, leaves, water, and just about anything else is.

Note: most light reflecting of a car body is reflecting off of paint, not metal.

 

[Josh66]

Note: most light reflecting of a car body is reflecting off of paint, not metal.

And a CPL will work for that.

The OP said 'cars', not 'flat pieces of bare metal'.

edit
Also, from everything I've seen - they do work on metal... It's not like it's hard to test... Grab a piece of metal (I have a lot of metal laying around...), grab a CPL (it doesn't even have to be on a camera), look through it while rotating it and see what happens. When I do that, the reflections on bare metal move and/or disappear.

 

[Josh66]

OK, everything I read online says that it shouldn't work too...

Like this article on Wikipedia:

Light reflected from a non-metallic surface becomes polarized; this effect is maximum at Brewster's angle, about 56° from the vertical (light reflected from metal is not polarized, due to the electromagnetic nature of light). A polarizer rotated to pass only light polarized in the direction perpendicular to the reflected light will absorb much of it. This absorption allows glare reflected from, for example, a body of water or a road to be much reduced. Reflections from shiny surfaces of vegetation are also reduced. Reflections from a window into a dark interior can be much reduced, allowing it to be seen through. (The same effects are available for vision by using polarizing sunglasses.)

I also noticed that paragraph doesn't cite any references...
Anyway ... that's not the only place I read that.


I tested it with a bunch of different kinds of metal, with varying surface roughness (they were all bare though). On some, I didn't notice the CPL doing anything at all. On others, the glare reducing effect was quite apparent. I tried: aluminum (a few different alloys), steel (a few different alloys), titanium (6AL-4V), and various tools (some just tooling steel, some chrome plated).

I didn't notice anything on the chrome plated stuff, but that could have just been due to the shape. This wasn't exactly a scientific test, lol. I also didn't notice anything on some of the aluminum (it depended on the surface). It seemed to work perfectly on the steel & titanium though...


I don't know... It seems to me that "metal" is too general to just make a blanket statement that it won't work. There are a lot of different kinds of "metal" (just a rough estimate by eye-balling it, but I'd say about 80% of the periodic table is made up of metals - so yeah, there are a lot), and there are a lot of different ways to prepare the surface.

 

[RichardsTPF]

I am looking for a CPL. The CPL price ranges from $70 to $170. The most expensive one might not be the best. Read some treads here, looks like Hoya and B+W have good quality filters.
Any recommendation?

 

[Josh66]

Personally, all of my filters are B+W, with the MRC coating. I've never had an issue with them...


One tip though - you might want to pass on the 'slim' filters (especially rotating ones, like a CPL) unless you really need it. They tend to be harder to get off of the lens due to how thin they are.

edit
You also have to remove the slim filters to put a lens cap on - they don't have filter threads on the front.

 

[ann]

Well, I don't know what to say, except I and several students have used one to do that very thing. Remove reflection from a car. Never tried it with other metal surfaces so I can't address that and give any advice past a car.

 

[Big Mike]

Also, when it comes to polarizing filters to block reflections...you can only block the part of the light that is 'polarized direct reflection'. However, much of the light in the reflections will be 'Ordinary Direct Reflection', which you can't block with a filter. So it's unlikely that you will be able to remove all the reflections with just a filter on the lens.

It's not practical, but one method would be to put a polarizing filter over the lights themselves, then you could use a filter on your lens to completely remove the reflections.

The moral of the story is that care shows aren't ideal to take great photos of cars.

 

[tirediron]

Well, I don't know what to say, except I and several students have used one to do that very thing. Remove reflection from a car. Never tried it with other metal surfaces so I can't address that and give any advice past a car.

This works because, as mentioned above, the reflecting surface of the car (unless it's a DeLorean) is a painted surface, not a metal surface.

 

[Josh66]

Even if it were a 'metal' surface, from what I have seen it may still work, depending on a number of factors. "Metal" is a pretty general word.

I just don't think this situation is simple enough to make such broad sweeping statements. All I can really say is, if you don't believe me - go test it for yourself... Really, you should anyway - just so you'll 'know' and not have to take the word of 'some random guy on the internet'.