Category Archives: Discussion

Slightly Off-Topic: Photographers’ Rights

This isn’t really about how to take better pictures, but it’s important enough that I want to share.

Yesterday, while walking through San Francisco’s SOMA neighborhood, I spotted a sign in a bookstore window. The sign reminded me of something, so I pulled out my phone and took a picture of it. Just as I finished taking the picture, one of the store’s employees came up to the window and gestured to indicate that I wasn’t allowed to do that.

I didn’t push the issue, but he happened to be dead wrong. In the US, I have every right to photograph the exterior of a commercial building, so long as I am doing so from public property. If I’m on private property, the owners of the property have every right to ask me to refrain from taking photos, and I must do so.

Every photographer should read the following information on photographers’ rights.  It’s even provided as a printable PDF, so that you can keep a copy in your camera bag.  In our current social climate, photographers are being hassled more and more in the name of security, and it’s important to know your rights, responsibilities, and restrictions.


Filed under Discussion

Two interesting photos

I’m a big fan of the Day in Pictures on SFGate — the photos are generally quite interesting, they’re well-captioned, and the editor likes to play amusing games with proximity.

Today’s set had two photos that are excellent illustrations of the things you can do if you understand exposure. This one shows an elderly man praying in the middle of the road, with cars whizzing by on either side of him. The blur of the cars is worrisome– you’re sure he’s going to get hit at any moment– but it shows his conviction.

The second one shows a landscape with a closeup of poppies in the foreground. The poppies are crisp and sharp, and the background is reasonably sharp as well.

Take a moment to think about how you might shoot those two photos.

Got it? OK, here’s my take.

The first one requires a slow shutter speed in order to capture the motion of the cars. If we look closely, we can see that everything is sharp as far as the eye can see. This suggests that the photographer used a very narrow aperture and a slow shutter speed, and probably a low ISO as well. We don’t know how fast the cars are moving, but let’s guess, oh, 30MPH. We can ask Google and find out that’s 44 feet per second. I’d guess that the shutter speed was somewhere between 1/2 second and 1 second. I’d guess that the photographer also used a neutral density filter (something I haven’t talked about, but it’s basically a piece of grey glass that reduces the light coming into the camera) to get a slower shutter speed.

The poppies were clearly shot at a fairly small aperture, since the background was mostly in focus. The shutter speed is indeterminate, but was probably “whatever it takes”.

Whenever you see an interesting and unusual picture, take a minute to see if you can figure out what the photographer did to get it. This is excellent practice for figuring out your own shots when you’re trying to get a specific effect.

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Filed under Discussion, Exposure

Why are there spots on my picture?

Dusty Flower You might notice it in the blue of the sky or the white of a wedding dress. Maybe, as often happens with me, it’s the petals of a flower. Whatever the image, someday you’re going to look closely at a picture and see that it’s full of little spots. These often look like little dark spots ringed by a color that’s slightly lighter than the background, and they show up in the same place on every picture you take.

These spots usually come from dust on your sensor. You won’t see them too often at large apertures, but when you stop the camera down they start to become visible. They particularly stand out in areas that have large expanses of a single light color, but you can often see them in other areas of the image as well.

This flower was taken at f/32, which as we all know is a very tiny f-stop. It’s not a great photo, but because of the small aperture it shows every little piece of dust on the sensor. You can’t really see it at the small size, but if you were to look at the full-resolution image you’d see lots and lots of little bitty spots all over the photo.

Sensor DustOn the right is a collection of full-size crops taken from the same image. These spots become highly-visible and quite annoying when the image is enlarged.

There’s an easy way to test to see if you have noise on your sensor. Find a brightly-lit white or light-colored wall, or a piece of plain white paper. Set your camera to manual mode, shutter speed of about two seconds, and the smallest aperture your lens will do. Point the camera at the white surface and take a picture, moving the camera around just a little bit so that the background becomes blurry.

Transfer the image to your computer and look at it full-size. Chances are good that you’ll see at least a few little specks, and if you’ve never cleaned your sensor before it may be pretty bad.

This image originally came from Flickr user djwudi, and I thank him for allowing me to use it. He works in a camera shop, and a customer came in complaining about spots on his photos. This is what the sensor looked like at f/32 before cleaning. I’ve personally never seen one this bad, but dust can start making your pictures ugly long before this point.

If you change lenses, and sometimes even if you don’t, getting dust on your sensor is inevitable. However, there are a few things you can do to reduce the amount of dust that your sensor collects:

  • Never store the camera without a lens or other protective cap
  • Minimize the number of times you change lenses, and minimize the amount of time the lens is off the camera
  • When you change lenses, make sure the body of the camera is pointed down and the camera is turned off
  • Try not to change lenses in dirty environments

My procedure for changing lenses is to turn the camera off (though sometimes I forget), then take the rear cap off of the new lens and get it ready to go. As soon as it is, I point the camera straight down, remove the lens, and put the new one on as quickly as possible. I then put the rear cap on the old lens and store it in my camera bag.

Do you have dust?  Don’t worry!  Here are SSA!’s instructions for cleaning your sensor.


Filed under Discussion, Equipment

Shooting Through a Fence

In the last lesson, I talked about shooting at the zoo under difficult circumstances and how to break the problem down into manageable pieces. One of the problems that TJ faced was that there was a fence between him and the subject. I promised to take a few sample shots through a fence and show what effects different apertures had on the image.

The following images were all shot with a Canon Digital Rebel XT and the Canon 50mm f/1.8 lens, also known as the nifty fifty. I chose it because I wanted to be able to open up the aperture in order to blur the fence as much as possible. Here are three sets of images that show how the fence looks from different distances at different apertures. I apologize for not finding more interesting subjects, but these were taken during a quick stop at the Port of Oakland when I was late for work.

In the first set, the camera is just a couple of inches from the fence. The camera was in aperture priority mode, and the four shots were taken at f/2, f/4, f/8, and f/16. As you can see, at f/2, the fence blurs so much that it’s essentially invisible. At f/4, you can start to see the fence blurring parts of the image. At f/8 the fence is quite visible, and at f/16 it’s almost sharp.

Close f/2 Close f/4
Close f/8 Close f/16

This time, I’m standing about an arms length away from the fence.  At f/2, the fence is just a blurry grid.  At f/4 it starts to look like a fence, at f/8 it’s clearly a fence, and at f/16 it’s fairly sharp.

Medium f/2 Medium f/4
Medium f/8 Medium f/16

In the final set I’m standing about five feet away from the fence, and also at a slight angle.  At f/2 the fence is a blurry mess, at f/4 it starts to sharpen up, and at f/8 and f/16 it’s sharp enough to work as part of the image rather than being a flaw.

Far f/2 Far f/4
Far f/8 Far f/16

Conclusion: if there’s a fence in your way, figure out what you want to do about it and adjust accordingly.  If you want to make the fence disappear, get as close to it as you can, and open up your aperture as wide as possible.  If you want to use the fence as part of the image, back up a bit and stop down.


Filed under Discussion, Lesson, Question

What do you want to know?

I need to go shoot some examples before I write the next couple of lessons.  Unfortunately, I’ve been spending painfully long hours in the office this week and haven’t had time to get out and shoot.

In the meantime, what do you want to know?  My plan is to fill out the basics of aperture and ISO, and then do… something.  What should I write after that?  Do you have questions about what I’ve written so far?


Filed under Discussion