How does focal length affect the shutter speed you need?
Asked 1/14/2014
11 views
2 answers
0
I’m new to photography and trying to understand whether lens focal length and camera shutter speed are directly related. Does using a longer focal length change the exposure, or does it mainly affect how fast a shutter speed I need to avoid blur from camera shake? I’ve also heard about the 1/focal length rule—how does that fit in, and when does it not apply?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
12y ago
2 Answers
12
There is no direct relation between the two. However, there is an observation that with longer focal length you need faster shutter (keeping ISO the same) in order to avoid blur from camera shake. Quoting:
The rule of thumb for a sharp picture, free from the effects of camera shake, is to use a shutter speed which is at least as fast as 1 divided by the focal length of the lens. So if you are using your zoom set at 100mm you should use a shutter speed of at least 1/100 of a second. If you are using a 50mm lens you will get a sharp picture at 1/50th of a second.
Now this rule is modified by VR (vibration reduction), and similar solutions, so you gain a few stops so your shutter speed can be decreased by that.
This rule does not apply if the camera is on a tripod, or you have a steady hand, etc.
It also does not help removing blur from people moving, etc.
Originally by user24785. Source · Licensed CC BY-SA 4.0
user24785
12y ago
0
Generated from our catalog & community — verify before relying on it.
Focal length and shutter speed are not directly linked. Focal length affects angle of view and magnification; shutter speed is part of exposure.
Where they do relate is camera shake: the longer the focal length, the more visible small movements become, so you usually need a faster shutter speed when hand-holding. A common rule of thumb is to use a shutter speed at least as fast as 1 divided by the focal length: for example, around 1/50s with a 50mm lens, 1/100s with a 100mm lens, and 1/400s with a 400mm lens.
This is only a guideline. Image stabilization/VR can let you use slower shutter speeds, while high-resolution cameras or large enlargements may require faster speeds. The rule also doesn’t matter if the camera is on a tripod, though subject movement can still cause blur.
Also, some zoom lenses have smaller maximum apertures at longer focal lengths, which can force a slower shutter speed for the same exposure unless you raise ISO. That’s due to aperture changes, not focal length itself.
Recommended products
UniqueBot
AI12y ago
Your Answer
Related Questions
How should shutter speed be chosen for handheld macro photography, and does image stabilization still help?
Should I always use the fastest shutter speed in good daylight?
Do you apply crop factor when using the NPF rule for astrophotography?
How can I estimate the shutter speed needed to freeze subject motion?
How does hand shake at 1/250s affect image sharpness?