The other day I was taking pictures with my Nikon D40 and I did something to it (changed some setting or another unwittingly) and now there is a graph of some kind that displays every time the picture is shown on the LCD. I assume this is some sort of color and/or light saturation graph but I cannot find anything in my handbook about it or how to turn it off.
Does anyone know what this is and how to turn it off?
Thanks.
That’s the histogram. I’m not sure how the D40 is set up, but try hitting up or down on the control pad (the circular pad on the right side of the camera) while in review mode. It might cycle through various preview modes (normal, histogram, highlight warning, etc.) depending on how it is set up.
That worked! Thanks so much.
You might want to learn how to read the histogram. It’s very useful for reviewing images because the LCD screen is too small to give you real exposure information.
Obligatory link to the most useful histogram article I read when I was learning the basics of digital photography: http://www.luminous-landscape.com/tutorials/understanding-series/understanding-histograms.shtml
I can’t live without my histogram now; I always use it to check exposure, usually after each shot, to let me know if I need to change the exposure and take another. It’s incredibly useful to know before you lose the chance to take another that you’ve under or overexposed, because while you can apply some correction later, there’s nothing like nailing the exposure the first time.
I agree, but there’s a big caveat - most cameras only display a single histogram of brightness. If the scene has a bright color, the image may have saturation in one color channel (red, green or blue) but not others. You wouldn’t know that by looking at a histogram. This is most often a problem when photographing bright red flowers or clothes.
(Though some high-end cameras display separate histograms for RGB to avoid this problem.)
Luckily, the D40 has a supersecret RGB histogram.
Wow. I hope you won’t take this the wrong way, but you sprang the cash for a DSLR and you’re not familiar with histograms?
I have a couple D40s, and I only vaguely understand what a histogram is. I’m basically a point-and-shoot kinda guy, but the SLR is my “weapon of choice”. I had Nikon 35mm SLR bodies and lenses, so the D40/D40x was a natural transition, financially- and compatibility-wise.
I didn’t know what they were for a while, until I started frequenting photography message boards. But as others have said they are very useful and really not all the difficult to read. They might look complicated but when ‘in the field’ it’s good to take a quick glance at it and make sure you didn’t blow out your whites.
DSLR’s are getting cheap and are easy to use even if you don’t know what a histogram is for. I just took 800 shots at a wedding last Saturday with a Nikon D60 that I bought on Tuesday the week before and the bride and groom were very pleased. I had to Photoshop some shots to get the brightness and contrast right and perhaps using the histograph would have helped out there.
I never would have bought a SLR camara. The use and expense of films along with making seemingly complicated settings changes on the fly was too dauting for me. A DSLR takes the initial mystery out and allows me time to learn about functions such as f-stops, exposures and histograms when I have more time. Also let’s face it, photography in the past had a certain amount of geek/snob appeal (sort of like high end audio) and developing film was a painful expense. A DSLR levels the playing field and let’s the masses enjoy and learn about photography. That’s a good thing and well worth the added expense.
I’ve owned several 35mm SLRs, in the distant past, from one where pretty well everything was manual to one which (by today’s standards) was semi-automatic. It’s not that hard to learn to use an external exposure meter, and transfer the settings to the camera, or to focus by getting things to line up in the viewfinder, but with a modern SLR, where you just switch on and push the shutter in automatic mode, you can get reasonable results very quickly.
I got the camera as a gift from my father-in-law and I have not had time to really play around with it, read the manual, do a tutorial and all that good stuff that I really need to do to understand all the features.
Wow. I hope you don’t take this the wrong way, but do you always run your gob before getting the whole story?
Yes, usually. 
I was just interested to know the reason, and lilflower has explained. Actually, the D40 looks pretty affordable - a DSLR has long been on my wish list but not at four-figure prices (and that’s four figures of sterling). One to bear in mind.
lilflower - no offence intended. Good luck with the camera and enjoy the learning curve!