Filter filter

May 30, 2006 6:06 AM

I shot a roll of print film (Kodak Gold 200) using the wrong filter (80a instead of polarizing). Can it be fixed in the developing — like when you push b/w film — or later, in the computer?
posted by LeLiLo to sports, hobbies, & recreation (7 comments total)

An 80A filter is actually 2 stops vs 1 1/2 stops for most polarizers - you'll be off by 1/2 a stop which isn't really that much. You can fix it in developing by telling the lab that you underexposed by half a stop.
posted by jedrek at 6:25 AM on May 30, 2006

Oooch. Since a polarizer interacts with something other than the color of light, its effect is almost impossible to replicate after the fact. If you've got some big skies you want to darken, though, in Photoshop you can switch to LAB color, make a new layer, select the L channel only, apply image, and apply the B channel in either overlay or darken mode. Change the opacity of that layer to mute the effect. If there's a lot of other blue things in the photo that you don't want to darken, perhaps you could use the A channel -- dark A = green, and the sky actually is closer to cyan than blue.

On preview, I may have missed the point, and jedrek's gor it.
posted by notsnot at 6:28 AM on May 30, 2006

I am guessing that you meant to use the polarizer outdoors and used the 80A instead. Oh man are your skies going to be blue, as is everything else a little bit Did you use an SLR with through the lens metering? If so, exposure is fine. If not and the exposure is off by one half stop this really is not significant with Kodak Gold 200. As for the blue from the filter, the color can be corrected somewhat in printing, although you may need to go to a custom lab to get that level of attention. The automatic printers will do some color correction anyway so if these were portraits they may very well just correct them for you.
posted by caddis at 7:16 AM on May 30, 2006

caddis is spot-on
posted by matteo at 8:14 AM on May 30, 2006

I am guessing that you meant to use the polarizer outdoors and used the 80A instead.

Yeah. I drove 370 miles to shoot this wedding for a friend, but of course once I got there I saw all these people I hadn't seen for years, and I was barely on time anyway, and when I realized the ceremony was starting I just grabbed the filter out of my bag... and was shooting away when I realized what I'd done. So I kept going to the end of the roll to keep things consistent. It was an SLR with TTL metering.

I was more worried about the bride being blue than about the exposure. I figured I could fix things in Photoshop and print the best ones myself, but wondered how I might make that easier.

Thanks for the replies. (The other six 36-exposure rolls survived without incident.)
posted by LeLiLo at 8:37 AM on May 30, 2006

So are you normally shooting a polarizing filter without turning it for maximum effect? Do you just put it on the lens and shoot? Because the 80A doesn't rotate, and you would have noticed this, no?
posted by weapons-grade pandemonium at 11:01 AM on May 30, 2006

Because the 80A doesn't rotate, and you would have noticed this, no?

Interesting question (sorry for the delay in replying, I've been driving back across New England). Actually, it did rotate, which is one thing that helped confuse me. It was attached to a 55mm to 62 mm step-up ring, which I guess was actually the thing rotating.

I assumed rotating = polarizing filter. And, when the rotating didn't really change anything through the lens, I thought that maybe because the sun was directly overhead, not coming from an angle, it wouldn't affect the polarizing that much. (Plus, with the 80A the sky did get more blue.)

It all made a kind of dumb sense at the time. (I wasn't thinking clearly, obviously, which is how mistakes happen.)
posted by LeLiLo at 8:55 PM on May 31, 2006