In today’s post I discuss the use of memory cards and histograms.
Ensure that you always have sufficient memory capacity for your digital camera.
But how do you know how much is enough?
As a quick rule of thumb JPEG files are generally half the size of the sensor capacity. With my 18-MP Canon EOS Rebel T3i camera each JPEG will be about 9 MB. This means a 1GB card will hold about 113 photos.
Since memory cards are now relatively inexpensive, buy more memory capacity than you anticipate needing and ALWAYS carry a spare.
Just like any kind of technology, memory cards can fail. If you just use one giant card, and that card fails, you just lost all your photos! I use a 4MB card and ALWAYS carry a 4MB spare.
Tips for avoiding memory card problems:
- Format a new memory card as soon as you get it. Even if your memory card came “preformatted,” it’s still a good idea to format the card again with your own camera.
- Use multiple small cards, instead of one big one. With the huge memory cards available today, it’s tempting to buy one with a large capacity. But, what if your 128GB card fails? Then you just lost thousands of photos!
- Format your memory card after each download. Formatting your memory cards is sort of like resetting them, and making them fresh again. It will help correct any disk errors that may have occurred during your last shoot.
- Store your cards in a safe place. It’s important to protect the contacts on your memory cards, because the smallest piece of dust can cause reading/writing problems and ultimately loss of photos. Always store them in their plastic case.
A histogram is a graphical representation of the light values of the image. Yeah, I know, that really helps. A histogram display is actually one of the most useful features you can have on a digital camera.
The histogram is a tool that provides instant feedback about an image. Having your camera set to show histograms during the view process will tell you how your image is exposed. The histogram shows, in graph form, the distribution of the tones in an image. You can see at a glance whether portions are blown out or underexposed.
Represented as a graph, a histogram looks like a mountain range. The left side depicts the darkest parts of the photo and the right side depicts the lightest. Anything beyond the left edge is pure black and anything beyond the right edge is pure white—both are outside the range of the image sensor.
Every histogram will be different and there is no right or wrong shape.
Depending on which is more prevalent in your photograph—shadows or highlights—the histogram visually may favor one side or the other. By checking the histogram, I’m able to analyze the amount of dark tones (on the left), bright tones (on the right), and all the mid-tones in between. I like my histograms to stretch 80% to 90% of the way to the right end, but not all the way, to avoid blown-out highlights.
The above illustration and following explanation is courtesy 500th.net, website of photographer Martin Joergensen.
Each histogram has been overlaid with a line that indicate its general shape. The middle one shown is a so-called perfect histogram. All tones fall within the edges and we have a fairly even distribution of tones.
Above that is a contrasty image. This has a saddle-shaped curve, and the danger here lies in loss of both dark details and highlights.
Below you will find a dull image with little contrast. That has a narrow curve with few tones.
Histograms shifted too much to the left means dark images and danger of underexposure and loss of dark detail and curves shifted too much to the right is a warning of a light picture with possibly burnt-out highlights.
You have a tool that helps you nail those exposures—use it!
Photography is like making cheese. It takes a hell of a lot of milk to make a small amount of cheese just like it takes a hell of a lot of photos to get a good one.