Frequently Asked Questions
Here are some frequently asked questions I see about some of my posts.
What is “raw”?
Short answer: “Raw” is a better photo file-format (versus jpeg) that keeps extra detail and yields higher quality. You non-digital folks can think of it as a better quality film for the camera.
Longer answer: On most compact cameras, there is only one file format you can choose: jpeg. Jpeg can yield excellent quality, but where the quality falls apart is when you start making large adjustments to your images.
On DSLRs and advanced cameras, you have another choice to save your images: raw format. Raw format saves the entire data that the camera’s sensor sees. That is very useful when there are faint details like clouds that you need to resurrect when you are post-processing your images. In the past, raw used to be difficult to deal with, but loads of programs (even free ones) can read the files now and it’s as easy as dealing with jpeg. For highest quality, you should use raw if you are able.
What is an SLR or a DSLR?
Short answer: An SLR refers to those higher-end, larger cameras with interchangeable lenses, and optical viewfinders. “D” indicates digital.
Longer answer: SLR stands for Single-Lens-Reflex and DSLR stands for Digital Single Lens Reflex. The basic criterion is that all such cameras have a mirror that reflects light from the lens into an optical viewfinder. There are four main advantages to DSLR cameras.
- Larger sensor size. This means better response to light, cleaner images, and more control over shallow depth of field.
- Capability of using raw format.
- Far greater degree of control.
- Optical viewfinder. An optical viewfinder allows you to see the scene instantaneously using your eyeball directly rather than being forced to use an LCD preview. Other advantages are greater camera stability (because the camera is closer to your body) and no issues solar glare obscuring an LCD.
What is Lightroom?
Lightroom refers to a Adobe Lightroom. It’s an amazing photo management tool combined with batch non-destructive editing capabilities. I use it much more than Photoshop because of I am able to work on multiple images at once. It doesn’t replace Photoshop and I still need Photoshop for more heavy-lifting. However, for many images I don’t use Photoshop at all.
What is this f/2.8, f/8.0, etc?
Short answer: The F number refers to how narrow the aperture is. The greater the number after the slash, the narrower the (smaller) the aperture is. Yes it’s a bit confusing but if you think of it as a fraction it will make sense.
What is aperture?
Aperture refers to the size of the “pupil” of the camera. The wider it is (smaller F number), the less of your scene will be in focus, and the shallower the depth of field.
What is Depth of Field?
Short answer: Depth of Field (DOF) refers to how much of the depth of your image is in focus.
Long answer: Shallow depth of field can be used to isolate the subject and create professional looking blurred backgrounds. Shallow depth of field refers to an image that has only some bits in focus (useful for portraits), while deep depth of field refers to an image that has most everything in focus (useful for landscapes).
Depth of field is usually a function of how narrow one’s aperture is. A narrow aperture (f/16 for example) will result in almost all of depth of the scene in focus, while a wide aperture (eg f/2.8) will result in only in the subject being in focus.
What is ISO?
Short answer: ISO controls how sensitive the camera sensor is to light.
Longer answer: By raising the ISO on a digital camera, you can take shots in less light than before without opening the aperture, or slowing the shutter speed. The downside to this is that your images will have more grain or noise than they would have if you had stuck to a lower ISO value. Better cameras will give you cleaner images with high iso settings.
The lower the iso, the cleaner the image with less noise or grain, the higher the iso, the less light you need for a photograph, but the greater the noise or grain.
What does mm refer to (eg 35mm)?
Short answer: mm stands for millimeters (duh). Millimeters (confusingly), is used to measure two main things in photography, (1)focal length and (2) film/sensor size.
Longer answer: So what does “35mm” mean? Well, by itself usually that refers to the size film, or sensor that your camera uses. 35mm is a standard (also known as full-frame). However, if one is discussing focal length, 35mm will refer to that particular focal length. Yes it can be confusing.
Why is sensor size important?
Short answer: Sensor size (or film size if analog) is important for three main reasons. (1) Larger sensors give better quality images. (2) Larger sensor sizes have wider angles of view for a given focal length, and (3) Larger sensors have shallower depths of field for a given aperture level.
Longer answer: Sensor size is important for:
- Quality of images
- As explained above, all other things being equal, larger sensors will usually yield better quality images with less noise.
- Focal length
- Different sensor sizes react differently to different lens focal lengths. The smaller the sensor size, the more “zoomed in” a particular focal length will look. Crop-factors tell you how to relate smaller sensors to the standard 35mm sensor size (full-frame). My camera has a “crop factor” of 1.6. Therefore, 18mm focal length on my camera (with a sensor 1.6x smaller than normal 35mm film) will be equivalent to 28.8mm on a full-frame SLR. On a compact camera with a sensor size 6 times smaller, 18mm would be the equivalent of a 108mm lens on a full-frame camera.
- Depth of Field
- Smaller sensors have deeper depth of field. What that means is that more things appear in focus which can be a bad thing if you want to isolate your subject or a good thing if you are doing landscapes. The crop-factor also can be used to find the equivalent aperture on a full-frame camera. F/10 on my camera (with it’s 1.6x crop factor, yields the equivalent depth of field of f/16 on a full-frame camera.