Instead of answering this week's Monday Mystery Photo question myself, I'm going to let one of our readers answer it for you. Samantha hit the nail on the head with the answer she left in the comments section.
Here's what Samantha had to say:
So I think it needs to be a slow shutter speed to create the blur, and the only other thing I have learned is that if you go below 60 it should be on a tripod to prevent blur. So somewhere from 60 below. Am I close?
Yes, Samantha. You are VERY close. Great job and thanks for playing the game.
The shutter speed for this shot was 1/30th of a second. I did not use a tripod. The slow shutter speed allowed the sensor to pick up the motion of our model who was standing up quickly from just fixing her shoes. More on that in a bit. For now, I want to focus on shutter speed. What is it exactly?
The shutter speed is the amount of time the camera's shutter stays open. The longer the shutter stays open (slower shutter speed) the more motion the camera's sensor will record. Slow shutter speeds allow the sensor to record not only your subject's motion but also (unfortunately) the photographer's motion (referred to as camera shake - usually from unsteady hands). The result is either an intentionally blurry image, or an unintentional blurry image. The quicker the camera's shutter opens and closes (faster shutter speeds), the less time the camera's sensor has to record all that motion. The result is a sharper image.
Samantha hit on one more important factor. If you want your image to be super sharp and you know you are going to have to shoot at a slower shutter speed, it is important to use a tripod (and encourage the subject to remain still). In this week's Monday Mystery Photo, the image displays motion because the subject itself was in motion - not because I didn't have my camera mounted on a tripod. The slower shutter speed was chosen for the purpose of capturing the subject's movement.
Samantha also mentioned the criteria for when you should mount your camera on a tripod. She has learned (in order to limit blur from camera shake) you should mount your camera on a tripod whenever you are using a shutter speed slower than 1/60th of a second. While this is a great point, it is not entirely true. Let me explain:
The general rule of thumb for whether or not you need to use a tripod is as follows: You want to make sure that your shutter speed is higher than the largest focal length of your lens. That number will change for each lens you use.
For example, if you are using a 24-70 mm lens, you should use a tripod for shutter speeds slower than 1/100th of a second (You'll go with the closest corresponding shutter speed to the largest focal length number which is 70.). For a 50 mm lens, a shutter speed slower than 1/60th of a second will require the use of a tripod.
I love my 70-200 mm lens, but it's not the first lens I'm going to grab if I'm shooting at sunset and do not have my tripod with me. Why? I know that with the 70-200 mm lens, I need to keep the shutter speed higher than 1/200th of a second if I want sharp images while hand-holding the camera.
There are exceptions to this rule of thumb.
Photographers who have many years of experience - who have developed very steady hands - may be able to shoot hand-held at much lower shutter speeds than the novice photographer. Conversely, if a shooter knows they have shaky hands, they would be wise to increase their shutter speed above the suggested minimum to accommodate for their weakness. This comes into play for me when shooting with the 70-200 mm. I've learned that I get much better results if I keep the shutter speed above 1/250th of a second when using that lens. It's a dang heavy lens! And I have teeny-tiny wrists and hands. Because of this, I've learned to accommodate for my lack of strength by using higher shutter speeds.
Okay, that's all shutter speeds and tripods. Let's get to the TRICK I was talking about in this week's Monday Mystery image. Is a slow shutter speed the ONLY thing I needed to create that arc of motion?
NOT AT ALL! It's really quite simple. Yes, I chose a slow shutter speed to allow the camera more time to record the motion. But, the more important factor is that THERE WAS MOTION TO RECORD in the first place. The model was moving in an arc from the ground (changing her shoes) up (back to standing position). Had she been standing still while I pressed the shutter, the image may only have been blurry due to the slow shutter speed. There would have been no sense of MOVEMENT and MOTION at all.
That's the trick. That's it.
An easy place to try this trick out for yourself is at the local park. Grab your favorite little tyke (or your favorite kid at heart) and put them to work swinging on the swing set. Take a picture with a fast shutter speed (usually a shutter speed of 1/250th is enough to freeze this type of motion). Then take a picture with a slow shutter speed (around 1/30th or 1/15 of a second). While you'll get sharper results with a tripod, it isn't at all necessary for this assignment. Your goal is to simply get a feel for the difference.
Now, take a look at both images. Which do you prefer? Maybe you are creating a scrap book for your child. You may just want one of each. Use that faster shutter speed shot to capture the look of overflowing joy on their face while cropping in close to capture those tack sharp sparkly eyes. Use the slower shutter speed to capture that arc of motion to put the emphasis on the swinging motion - on the childhood favorite activity.
There are all sorts of uses for this little trick. (Your son running track, your daughter dancing in her ballet recital, the dog chasing a ball, a stream of headlights traveling down the highway...) You get the picture.
No, really. You need to get out there and GET the picture. Have fun with it!