Canon 300 f4 is
Canon 300 f4 L is
Official name: Canon 300 f4 USM L IS
Focal length: 300mm
Optical construction: 15 elements in 11 groups
Exotic lens elements: 2 UD lens element
Filter size: 77 mm
Close focus distance: 1,50 m
Focus limiter: 1,5 or 3 m
The lens built like a tank. The built-in-hood the best solution according to my preference. The weight positioning is different than the 400 f5,6L: The 400 feel well balanced: the weight is proportionally distributed along the lens body, the 300 seems that weight is centered around the units “neck part”, but this is not really problematic in usage, on a 30D camera a difference is not big. The stabilizer makes some noise usually not disturbing, but for example in wildlife photography with a close subject perhaps can be too loud. The usual agreement of this lens stabilizator helps with 1,5-2 stops gain, compare to the newest 4 stop units. The lens is perfectly hand holdable with its approximatly 1200 gramm weight. The stabilizator has on/off and panning function.
This lens is very good optically, nice saturated colours, fine detail and sharpness. This is a real professional lens, with excellent qualities. If someone want better optical quality must pay lot more and has lot more bulk and weight to deal with it (Canon 300 f2.8 is). I think the Canon 300 f4 is is a very fine lens.
What is this lens good for:
Almost everything what requires this focal length. Wildlife/bird/sport/action photography portraits from a distance, macro, fine details of anything.
Compare to other primes:
The obvious candidates for comparison the Canon 200 f2,8L, the Canon 400 f5,6L and the canon 300 f 2,8L. First start with the easier one: compare to the 300 f2,8L is: The 300 f2,8 is one of the sharpest lens in the canon lineup, much sharper than the 300 f4. Let’s see the facts: The f2,8 lens’s optics has a diameter of 128mm, and the whole lens is significantly bigger (1,2 kg vs 2,5kg.) The 300 f2,8 L is is a real monster compare to this lens, that invites much more interest from people.
Compare to the 200 f2,8L and the 400 f5,6L: The 200 is sharper, the 300 f4 is sharper than the 200 with the 1,4 converter, between the 300 and the 400 there is no big difference in reality although on paper the 300f4 has bigger resolution, even with the 1,4 converter. The 300f4 with a teleconverter is not far from the 400, but overall the 400 is better.
300f4L is or 400f5,6 L ?
It depends. For hardline bird shooters 400f5,6 L, because of the longer focal length, faster autofocus operation at 400mm. If somebody wants to use the lens for macro work, prefer f4 aperture, like to make lots of bug, butterfly picture, or use the lens frequently on a boat than the 300 F4 is. The main difference of this two lens is the focal length, 3,5m vs 1,5m minimum focus distance, the stabilizator, and f4 vs f5,6 aperture. The f4 is not so sharp at f4 as the 400 at f5,6. In close distances the 300 at f4 quite sharp see pic below, but longer distances more visible that the lens not “tack” sharp wide open.
See below 300 f4 wide open sparrow female, distance app 4m.