The difference between 300mm and 400mm isn't that great, but bear in mind that the 400mm prime will almost certainly be sharper than the 70-300. As somebody said in a another thread, the angle of view of the 400mm lens will be 300/400 = 3/4 of the angle of view of the 300mm. This is a great tool.
The 400mm focal length of this lens is ideal for many field based sports such as soccer (football) and rugby as it's not too long, such as a 500mm for example, but at the same time it's gives more pull than a 300mm.
So what are telephoto and superzoom lenses, like a 70-300mm, used for? They're best when you want to get close to a distant subject. It could be a building on the horizon or a face in a crowd. They're perfect for wildlife photography, where you can't get close to the animals you want to shoot.
In wildlife photography, the 400mm is the king at teaching this concept. You will have to zoom with your feet to get the image size you desire often shooting with the 400mm. Watching your subject to learn what to do and not do in approaching a critter is a vital lesson that you will learn with this lens!
MM: “Every safari photographer should have a telephoto zoom lens, such as 100-400mm or 200-500mm. These focal lengths are critical to capture the action that occurs within a certain range from the vehicles. There are times the wildlife is further away, but the majority of the action is within 200-400mm away.”
A 300mm lens is enough for wildlife and bird photography. With a lens of this focal length, you'll be able to capture detail from a distance, even when focusing on small subjects like songbirds. Look for a lens with a fast speed to make sure that you can capture a moving subject without blur.
Here is an example: For a 300mm lens, divide 300 by 50 to get 6x magnification. Or divide 300 by 100 to get 3, then multiply 3 x 2 to get 6x.
However, if you are buying the lens entirely for shooting surfers, I agree the 400 5.6 is a better choice, due to smaller/lighter, and faster focusing with better tracking. Image quality in the center is very similar. corners are much better on the prime.
On a full-frame camera, with a 400mm lens, you can reach up to 8x zoom and on a crop-sensor having 1.5 crop factor, you can get results of up to 600mm lens with the same 400mm lens. If you mean how far it can shoot, then you can shoot as far as you need.
Focal lengths such as 300mm or 400mm would be a large, heavy telephoto lens for taking photos of birds or airplanes. Just remember - a small number is wide, a large number is telephoto. Two numbers together, e.g. 35-105mm, means that the lens zooms from one focal length to another.
A lot of folks recommend 400mm as a minimum focal length for quality bird photography. But even at this range, you'll still need the bird to be quite close to you for your subject to fill the entire image frame. However, we consider a 400mm lens to be the ideal focal length in terms of overall capability.
At 600mm, photographers are sure to capture some incredible close-ups of wildlife in action. The image stabilizer is also very reliable, which helps this lengthy lens produces sharp images even when photos are taken from a handheld position.
The Canon 100-400mm lens is best used for wildlife and sports, although it's also very good for photographing portraits, landscapes, and airshows. It's designed for full frame Canon cameras, but functions perfectly with "crop" cameras too.
Zoom simply means that the focal length (apparent magnification) of the lens can be changed, ie, it looks like it can look at things either closer up or further away by adjusting it. Telephoto, roughly, means that the lens has a relatively narrow field of view, thus it can be used to look at things further away.
At 300mm the lens will have the equivalence of a 450mm lens on a 35mm film camera or Nikon FX (Full Frame) digital camera. Many P&S cameras will say they have a 8x or 12x zoom, that just means that the longest focal length is 8x or 12x longer than the widest focal length.
This 4x telephoto zoom lens is ideal for the budget-conscious photographer with an interest in shooting sports, wildlife or portraiture. In common with other telephoto lenses, the EF 75-300mm f/4-5.6 III compresses perspective and allows the photographer to restrict depth of field.
On a full-frame camera, at focal length 200mm, the diagonal angle-of-view is about 12 degrees. At 300mm, it is about 8 degrees. In other words, at 300mm, the image captures a narrower part of the scene compared to at 200mm.
Your shutter speed should be quite fast—1/2500, 1/3200, or even higher if light allows. If there is not enough light or you are shooting slower subjects, drop down to 1/1600 or 1/1250 if necessary, though you'll have to accept that you may have a lower percentage of sharp images.
If I had to photograph animals, landscapes, and everything in between, the Nikon 70-300mm would be very high on my list. It is light, it can zoom, and it has very capable VR for a lens at this price point. If you want a reliable lens for wildlife photography for cheap, I would definitely recommend the Nikon 70-300mm.
It's a great lens for wildlife, especially on DX (crop sensor) Nikon bodies where it yields an equivalent focal length of 105-450mm. It is light and relatively small, which is helpful if you are panning with flying birds, or otherwise needing to hold it up for long stretches.