Digital photographyWe round up the month's most interesting questions about digital photography, ranging from use of a polariser and face recognition to Picasa 3, plus the best reader tips.

Where Are My Photos?

Picasa 3 seems to have lost a bunch of my photos. Is there any way I can recover them? Are they on my hard drive? Alyn McConnaha

First, let me come to Picasa's defense, Alyn. Picasa is unlikely to have lost your photos.

It's important to remember that photo organisers like Picasa, Windows Live Photo Gallery, the organiser in Adobe Photoshop Elements, and others don't actually store your photos. Instead, they point to wherever your photos are located on your computer.

When you start using an organiser for the first time, it will scan your hard drive, locate all your photos, and generate small thumbnails to represent each image. When you choose one of those images, your organiser finds the photo, still nestled away where you originally stored it.

The moral of the story is that you should never think "Picasa is storing my photos now, so the originals are duplicates" and try to delete them. If you do, you'll be deleting the only copies of your photos from your computer.

So what happened to your photos? The most likely explanation is that you deleted the photos accidentally, either in Picasa or in Windows Explorer. To be sure, you can search your computer for the photos. Hopefully you store your photos in the My Pictures folder (in Windows XP) or Pictures folder (in Windows Vista), which will make them easy to find. You can also search your PC for any JPEG files (Select Start, Search and try *.jpg).

Photography news, reviews and tutorials

Understanding the polariser

I'm finding the effect of my polarising filter to be subtle to the point of invisible. It doesn't seem to reduce reflections at all. Can you explain? Jerry Heiss

Ordinary light, unpolarised, causes reflections in glass and water, and contributes to low contrast, hazy-looking skies in your photos. You can use a polariser to reduce or eliminate reflections and punch up the skies.

A polariser is a circular polarising filter that you screw onto the front of your camera lens. You can spin it around, and it has a variable effect depending upon its position. The effect on your photos is based on a number of other factors, including where the sun is and the angle you're making with respect to the reflections or the sky. To get the right effect, you need to consider all of these factors when you frame your photo.

Next page: face recognition and readers' top tips >>

See also:

Tutorial: Master digital SLR photography

Photo FAQs: improve your digital photography

Camera reviews

We round up the month's most interesting questions about digital photography, ranging from use of a polariser and face recognition to Picasa 3, plus the best reader tips.

Face recognition

I recently saw an ad for Apple that says it can help organize photos for you based on face recognition. How long will it be before something like that is available for Windows users so that I can better organise my photos? Kathleen Diehlmann

Apple might be actively advertising face recognition (and to be honest, I haven't seen those ads myself), but rest assured that there are several programs for Windows with face recognition technology built in.

Right now there are three programs you can try for a taste of face recognition. Picasa Web Albums can recognise the faces in the photos you store on the Web. PicsMatch is a fully featured desktop photo organiser with face recognition, and Windows Live Photo Gallery has some limited face recognition features as well.

Face recognition is one of the last frontiers of digital photography, Kathleen; I think we'll see a lot more of this sort of thing very soon.

Photography news, reviews and tutorials

More clever camera tricks

Recently, I wrote about six clever ways to use your camera, and a lot of readers couldn't resist sending me their own unconventional uses for digital cameras and camera phones. Here are the best reader tips.

I use my camera to take photos of preexisting damage to rental cars on business trips. I try to also shoot the odometer or other surroundings that document the date. On the rental agreement, I note that I took photos of existing damage. I haven't had a problem since! S Calabrese

On vacation, I'll often see a public map. Paris has many of these as you exit the subway, for example. I quickly snap a photo of the map and refer to it as we tour to stay on track and avoid getting lost. Once we have left the city I simply erase the picture and retrieve the camera space. Rob Schenk

Take pictures of your luggage before you check it. If lost or damaged, you can give them a picture, which is better than a description. If the luggage turns up damaged, you can use the photo to prove they did the damage. Lester

I've got a tip for the do-it-yourselfer: If you take something apart to repair it, a photo of the gadget in different stages of disassembly can help you get all those darn pieces go back together in the right order, with no missing pieces at the end. Charlie Bress

Traveling abroad? Keep a digital picture of your passport on your camera. If you should lose your passport, the data on the picture will speed a replacement passport. jaygeecee

See also:

Tutorial: Master digital SLR photography

Photo FAQs: improve your digital photography

Camera reviews

PC World