Photographic meanderings

They don’t stay on all the time like incandescent lights do!

Loyde Schutte has been writing the inimitable Yosemiteblog.com since before I arrived here in Yosemite in May of 2005. Although he doesn’t live in Yosemite, his intense focus on the park is remarkable. He once remarked to me that he turned down a programming job in Seattle (was it for Microsoft?) because it would have meant moving away from Yosemite.

Loyd is going to be self employed at the start of 2010, once again giving up a job to remain close to the park.

I am always delighted when one of my images makes it to his Picture of the Day; Loyd’s taste in photography is good, and I’m always flattered when he includes my work.

Loyd is married, and has two small children. You can follow him on Twitter either as @LoydSchutte or as @THEYosemiteblog

Tonight I had the pleasure of attending a holiday concert at the Ahwahnee; Andrea Daniel was one of the performers, and had a voice like an angel. Thank you so much for the wonderful music, Ms. Daniel!

Slow shutter lens zoom image of my Christmas tree. Happy Holidays, one and all. Why yes, I *am* a commando(1) in the War on Christmas–how did you guess?

(1) Don’t. Go. There.

El Capitan from Nose to Horsetail, with Three Brothers. 6 images stitched together.

Gates of the Valley
Winter’s covered everything
Merced River slows

Last night my neighbor and fellow veteran Dave and I went out hunting the last light. We didn’t find it, unfortunately, but on our circumnavigation of The Big Ditch, we talked about light and how to shoot at night. Dave uses a film camera, and admitted that he really didn’t know much about photography in general. I got my pedant on, and tried to explain cameras as I understood it.

Consider sight; We have eyelids, retinae, pupils and irises. While we are awake, our eyelids are open more than they are closed, allowing light to pass through the pupils, and onto the retinae at the back of the eyeballs. The iris expands and contracts to adjust the size of the pupil, the little black dot in the center of our eyes. The iris is the colored part of our eyes.

Fun fact–the iris is named after the Greek goddess of the rainbow, and who also gave Her name to the flower.

A camera, on the other hand, has a shutter, an aperture, and the recording media–either film or CCD/CMOS sensor.

The shutter equates to the eyelid. The aperture equates to the pupil. The media–film or sensor–equates to the retina.

All analogies break down, eventually. The camera is not an eye. First, the shutter doesn’t stay open most of the time, like our eyelids. Secondly, the media is often much more sensitive than our retina.

On a camera, the shutter opens, light passes through the aperture (pupil), and lands on the media. The variables are how long the shutter is open, how wide open the aperture is, and how sensitive the media is.

The media collects light, and the longer the shutter is open, the brighter the image will be. Also, the wider open the aperture is, the brighter the image will be. Finally, the sensitivity of the media can be adjusted–and the more sensitive the media, the less time it will take for the shutter to be open, and the smaller the aperture has to be for an image to be captured.

Let’s start with the sensitivity of the media. ISO or for film, ASA. On digital cameras, you can set the ISO between shots–going from ISO 400 for dusk to insanely high, say 12,400. For film cameras, however, you need to choose your film ASA, and once the roll is in the camera, you’re stuck with it until you’ve finished it. In either case, the higher the sensitivity of the media, the more likely it is that you’ll get grainy or noisy images–funky speckles on the print.

The aperture, or the opening that allows light through is called the ƒ-stop. Note the pretty f? It’s pronounced “eff”, but that particular symbol is used to designate how large the hole is. I have no clue why. The size of the aperture, or opening is assigned a number: ƒ/1 is the widest opening. The biggest hole. Yeah, I know. It’s counter intuitive. The larger the number, the smaller the hole. Think of a window in your house, with curtains. If you want to peek out the window, you pull the curtain aside a little bit, making a hole you can look through. Most of the curtain still covers the window, right? Say 22 inches? ƒ/22 doesn’t mean 22 inches of the aperture blades are across the media, it’s just an arbitrary number. But the idea is sound–more curtain means a smaller hole. If you pull the curtains all the way back, less curtain covers the window, allowing more light in through a bigger hole.

Finally, shutter speed. Shutter speed means how long the shutter is open–think again of a window, this time an old fashioned one with actual shutters, or a set of doors on the outside that you have to open and close by going in and out of your house. They aren’t the same as the curtains inside. The longer the shutter is open, the more light hits the sensor or film in your camera. Oddly, the media collects light, and the effect is cumulative over time. The longer the shutter is open, the brighter or lighter a picture will be. This is why you can take pictures at night, and see things in those pictures that your eyes didn’t see when you were taking the picture.

All three of these things work together in the camera and lens to make images. How you adjust them depends on the light available. Me, I tend to get confused having to juggle three variables. I tend to set my ISO at 100 all the time, and adjust the aperture and shutter speed according to what I’m shooting. Sometimes at night, I will bump up the ISO, hoping I don’t get too much noise, or grain in the image.

One final thing: aperture affects the depth of field of your image–imagine a line of fence pickets stretching away from you into the distance. Our eyes can adjust as we look from near to far, so that they all look in focus. That’s the theory, at least. It all depends on how good your eyes are. A camera and lens can’t do that automatically. I have no clue why, but a smaller aperture means that the lens can make each picket more in focus. With a wider aperture, you have to pick which picket will be in focus. Some of them will be blurry looking.

This has been an over-simplified primer. What we haven’t covered is the actual configuration of the camera, nor have we looked at lenses for a better understanding of them. F’rex, the shutter is in the lens, but the speed is determined by the camera. The limitations of the shutter speeds available is due to the camera, not the lens. If your camera has a top shutter speed of 1/1000th of a second, changing lenses isn’t going to change that. The aperture, however, is a function of the lens. If you want a wider aperture, you can switch lenses. You don’t have to switch cameras.

I hope I’ve got all of this right. If I’ve made any glaring mistakes, please feel free to correct me in the comments. But do it politely.

Tucked away between
Two fallen granite boulders
Stretching for the sun.

A mug of spiced wine
Handel’s Messiah Playing
First Snow of Winter.

Bon Hiver, Ever’body!