Polarizer on a cloudy day?

[cjtinkle]

I normally leave my polarizing filter on all the time; (yes I'm a newb) but we happen to be in CT at the moment and it's been fairly overcast and cloudy. Should I take the polarizer off and replace it with a UV filter, or just leave it on?

[Belmondo]

I am definitely NOT speaking from an authoritative position, but here's what I've been doing.

I have a UV filter that stays on all the time as a protection for the primary objective on the lens. I don't think it has much impact on image, and doesn't impact light-gathering to any meaningful degree.

Because the polarizer does slow the lens down, I use it on a 'case basis.' Generally, on very overcast days, it does very little and stays in the bag. On days with broken overcast, it can be very useful for giving definition to the cloud formations.

Also, if I'm having a problem with reflections, regardless of the sky conditions, I'll use it.

In short, I use the UV filter for lens protection, and the CP to enhance photos only when needed. The UV filters never come off the lenses except for cleaning.

Disclaimer: I have no idea what I'm talking about. You will get other opinions, I'm sure.

Good luck.

[minicooper]

^ I second that! a polariser can bring your exposure down by about 2 stops, so you may have some difficulties if you leave it on all the time. Thats what a skylight/UV filter is for.

[openspace]

Even with diffused light (cloudy day) a polarizer can make a difference by removing some of the haze from the sky. But it really depends on the exact light conditions. Even in full sun, depending on the angle and direction of the shot in relation to the sun, a polarizer can make a huge difference or none at all.

In the case of a cloudy day, before put my polarizer on, I'll hold it up to my eye and spin it. If it appears to make no difference, then it goes back in the bag.

As far as UV / skylight filters go, they really do very little - other than perhaps adding a bit of warmth. For most people, their only real value is as a lens protector. After all, if you really need to filter the light, you'll grab the polarizer.

John Fielder, a famous landscape photographer based in Colorado admits to regularly using a lens with a "hideous scratch" on the front element. And it makes absolutely no difference in his photos. Since no lens can focus anywhere near the plane of the front element a scratch on the lens has no real effect.

But the same cannot be said of a filter. Anytime you place any piece of glass in front of the lens, you risk degrading the image - including affecting contrast.

This is why many photographers including Fielder have long since chucked their UV and skylight "lens protectors".

But it is a personal decision. I shoot at high altitude (above 10,000 feet) regularly where the UV rays are intense. And for years I used a high end coated UV filter whenever a polarizer wasn't needed, primarily as protection, but also because I thought it was really making a difference. But then I ran some film tests. And you know what? The filter went in the drawer. But I'll admit I still get nervous anytime I'm shooting in extreme conditions and I see that front lens element sitting out there exposed to the wind and rain and dirt.

So it's up to you.

[cjtinkle]

I keep forgetting about the polarizer slowing the lens down, I have UV filters for each lens though. I admit to being terrified of ruining one of my lens without some protection on it, but even a newbie like me can see the difference in the pictures with NO filter on, they're much better, and I bought good filters too.