Sunday, October 28, 2007

White Balance

I realized the other day that I've mentioned white balance (also known as color balance) a couple of times, but never explained it. Getting a proper white balance basically means balancing out the colors so that they are true to life, instead of distorted by the lighting conditions. You know how regular indoor light bulbs often give everything a yellowish tint, and fluorescent lights tend to give a bluish tint, but your eyes/brain adjust so you know what the colors really are? When you have proper white balance in a photo, you compensate for this tint. Your whites look white and all your other colors look accurate. What got me thinking about this? I was photographing a sweater I'm working on, and the first photo came out looking like this:

Ick. (This is one reason I love digital photography - when something is wrong in your photo, you know right away.) The problem was that my camera was still set to white balance for Shade conditions, from some pictures I'd been taking previously. In the D40, there are eight different white balance settings. Six of them correspond to the type of light you're shooting in:

Incandescent (most regular indoor bulbs)

The other two are Auto and Pre. Auto is what it sounds like it should be (automatically adjusts based on what it thinks the light source is), and Pre is used when you want to get a really accurate reading. Basically, you take a preliminary picture of a colored (often grey) card (like this one, for example) and the camera uses that data to get an accurate color balance in the following pictures. (I've never actually done this...never really needed to for the photos I take...)

You can certainly just leave your camera on Auto and forget about it. The software seems to be sophisticated enough that most images will turn out okay. Here's the Auto version of the purple sweater:

It's much better than the Cloud-balanced shot, but still not quite accurate. I was taking these pictures inside near a window (generally the best indoor place to take pictures of knitting, assuming it's sunny outside), and from previous attempts I knew that setting the camera to balance for Sun would probably work best:

Yep. It captures the color of the purple very well, and the white collar looks white, not blueish or cream. Just for kicks, here's what it looks like when set on Cloud:

Close, but not quite. Both on the camera's LCD screen and on my computer, the Sun-balanced shot looks the best.

The Auto is good enough on my camera that I usually leave it on Auto for snapshots, or when I'm going to be in multiple different light conditions in a short time period. However, if I know my lighting will be consistent for awhile, like when taking knitting photos or taking pictures at an indoor sporting event, I'll set the white balance to match the lighting. It only takes a few clicks, and it's usually worth it. My old point-and-shoot has white balance settings as well, although by the time I learned what it was, I already had my dSLR, so I haven't played around with it much. Point is, if you have a digital, you can probably adjust the white balance. Try it out. Let me know how it goes. =)

To learn more about white balance, you can check out:
Ken Rockwell
Cambridge in Colour

A related topic is monitor calibration. I know pretty much nothing about this, as I cannot afford a monitor calibration system. Based on the tests at that site, I think mine's okay, and I'm not too concerned since I just take pictures for fun. =)

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Saturday, October 20, 2007

Shutter Speed, and Bubbles!

Note: I've created a photography glossary in the sidebar with links to definitions of terms I use often, like exposure, depth of field, aperture, etc. I feel silly linking to the same things over and over again, so if you see a term you're unfamiliar with that isn't linked, check out the sidebar! =)

So, a few posts ago I talked about aperture and how it affects depth of field in addition to exposure. (In my mind, the exposure effect is intuitive; the depth of field one is not.) Today, a similar discussion on shutter speed...

Again, in my mind the effect of shutter speed on exposure is intuitive: the faster the shutter speed, the less time there is for light to enter the lens, the darker the picture. A slower shutter speed would then lead to brighter, more exposed pictures. The non-intuitive effect of the shutter speed is its effect on capturing motion.

This is more intuitive than depth of field...follow along with me...warning: science and math!

A basic formula of the physics of moving things (aka kinematics) is that:

speed = distance / time

We can rewrite this as:

distance = time * speed

For the purpose of most of the things we take pictures of, the speed is relatively constant, so we don't have to worry too much about that term. What we can control is time, via shutter speed. A faster shutter speed corresponds to a shorter amount of time. This corresponds to a smaller term on the right-hand-side of the second equation, and thus, since the right- and left-hand-sides must be equal, the left-hand-side must be correspondingly smaller. But the left-hand-side is distance, and so in our shorter time span, our moving object moves a shorter distance. So we have

fast shutter speed -> shorter time -> less distance

The same reasoning works for slow shutter speeds:

slow shutter speed -> longer time -> more disance

The distance the object moves is the effect we see in photos. Fast shutter speeds "freeze" moving objects, while slow shutter speeds lead to blurrier motion. Either of these effects can be exploited to get the photo you want, using the shutter-priority or full manual modes.

I was taking some photos tonight for my knitting blog (for a post on blocking and its magical effects) and decided to play around with my shutter speed as I was taking pictures of the "fill the sink with water" step. Check this out:

Bubbles!!! (Reminds me of this guy!) The shutter speed is 1/320, with my maximum aperture of f/3.5. (For an explanation of the numbers of shutter speed, click here.) I had to turn a flash on (it's dark outside and I was too impatient to wait until daytime to take pictures...). Since I was shooting in full manual, I could adjust the flash level, a dSLR feature that I love. Normally I adjust it down, but for some reason I decided to play with adjusting it up. (This picture was shot with the flash at +1.0.) Since I had the flash on and up, I could use a pretty fast shutter speed, and still get a bright image. Want a closer look?

Here's another fun one, same camera settings as above:

I like how the motion of the water is frozen into the wave forms. (I'm taking grad quantum 1 right now...I can't get away from wave forms...)

As a counterexample, here's a photo taken with a much slower shutter speed (more time!):

See how the water is just a blurry stream? Unfortunately, I can't tell you the exposure for that one, although it was around 1/50. (In addition to playing with flash levels, I was playing with shooting in RAW. Well, it turns out that Picasa, my editing program, can't pick up the EXIF data for RAW files, so I lost the record of all the settings. I've never had any problems with JPEGs, so I will just return to that and keep my data.)

More experienced photographers than myself can do even cooler things with shutter speeds:

Slow shutter speed:

(Image used under terms of CC License. Photo by Flickr user

Fast shutter speed:

(Image used under terms of CC License. Photo by Flickr user chomp_on_that)

Neat, eh? =)

Tuesday, October 16, 2007

Monkshood... another interesting flower. They line the stream beds in the French Henry area and bloom during the second half of the summer. I like the shape of the bloom, and how it's separated from the leaves; I think it lends a dramatic flair to the flower. Does the shape of the bloom remind you of something? Like a monk, wearing his hood? (Also, they're poisonous, so don't eat them, mkay?)

As for photography, do you notice how the flower is normally lit/colored, but the background is very dark? You can see the same thing in this shot, of Mountain Bluebells:

Obviously y'all are smart enough to know that the reason for the lighting differences is flash. It illuminated the flowers, but not the relatively empty background. Now, some people are very anti-flash. I don't love it, but I don't hate it either. I generally try to shoot without it, but will turn it on when necessary. I actually really like the effect in the first photo, because I think it draws attention to the flower. I don't like it as much in the second photo, but it was too dark to get a clear shot without a flash. (Obviously I just need a better lens with a wider aperture, so I don't have to use a flash if I don't want to...or a tripod...or both...)

So are pretty, and flash isn't evil. =)

(Please forgive the lack of real content in this post, and the sporadic updates lately. Midterms stole all my time...)

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Friday, October 5, 2007

Eye-Candy Friday

This was taken one afternoon during Camp Director training this past summer. We'd had an afternoon thunderstorm, and the clouds started to clear away as the sun was just beginning to set. The effect on Tooth Ridge was awesome - it was literally glowing!

Philfolk - Don't you just love the first sentence of that Wikipedia entry? Do you think Ranger Bus Tour is an appropriate citation? =) Bonus points to whoever can name the CD in the foreground...

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Wednesday, October 3, 2007

Random Wednesday!

(Click for bigger. You can see some cool depth-of-field effects in the big one!)

This is a Sego Lily - isn't it interesting? It's one of the many flower pictures from this summer that I alluded to earlier. =) According to my Philmont Fieldguide:

Early Mormon settlers ate the bulbs of the Sego Lily when other food sources were scarce. Today the Sego Lily is the state flower of Utah. The bulbs have long been a source of food for the Navajo and Hopi Indians as well. The genus name, Calochortus, is Greek for beautiful herb.

Neat, eh?

I'd love to link you to the Fieldguide so you can purchase your very own, but it's currently not for sale, as it is being re-written (which it desperately needs!). The writers and photographer came through camp one day on a flower hunt. We'd just had a hailstorm that destroyed a lot of our flowers (including this rose!) and so I showed them the pics I had on my D40. They really liked them and asked me to submit them, for possible inclusion in the guide! Cool! Maybe they were just pretending to be interested, to humor me, but I still thought it was neat. The new guide probably won't be out for a few years, by which time I'll probably have forgotten all about it. Hopefully they'll let me know if they do decide to use anything!

Happy Wednesday! =)

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