Top tip for handholding telephoto lenses
Using the correct shutter speed to avoid camera shake
When handholding a telephoto lens, it’s very important to remember to use a fast enough shutter speed to avoid camera shake.
Basically, the minimum shutter speed that you should use is 1/(your focal length in mm).
So, if you are using a 200mm lens, you should not attempt to handhold the lens at a shutter speed any slower than 1/200sec. Remember, this is the absolute minimum and as such an even faster shutter speed will often be required.
Also, remember to base this on the effective focal length when using a crop sensor camera. So, when using a 200mm lens on a Nikon D7000, your effective focal length is 300mm, so your minimum shutter speed is 1/300sec.