For simplification I would like to use the following notations:
EF 70-200mm f/4L USM → A
EF 70-300mm f/4-5.6 IS USM → B
The main difference, besides the maximum focal length and maximum aperture, is the Image Stabilizer that option B offers over option A. Also, A produces sharper images, based on what I have read around the web. However, I have also read that some people would rather not have the sharpest image because of the fact that it is easier to make a picture sharper then it is to make it otherwise. In other words, after an image has been sharpened, it is harder to recuperate detail that was lost due to the sharpening. Is this last statement true? Could I produce with B images as sharp as the ones that A produces with the help of computer software, by sharpening the image?
I understand that both of these might not be ideal for night shooting, because of their maximum aperture, but they should be good enough for a starting photographer like me, given the high cost of others with larger apertures.
One thing that I read in the reviews for A is that it is pretty good for taking pictures of sports especially for taking pictures of batters. However, I read as well that because of A´s maximum focal length, it is not that great for taking pictures of wildlife such as birds because one would have to be within 5 to 10 feet to be able to fill up the sensor as much as possible. Is this necessarily true?
I was trying to reason for A that if placed on a tripod, it should be able to take at least the same pictures that B would take as far as images being blurred from the shaking, within the same focal range. Also, I was thinking that if wildlife watching, how often would I need to take unprecedented shots that would require IS capability? I guess whenever some animal comes out of nowhere and I am forced to move the camera fast even while on tripod to focus on it. I have always read good things about L lenses, so it makes it harder to ignore. The situations in which one would use or need an IS surpass those in which one does not?
I would like to take pictures of different kinds of wildlife. I would also like to take action pictures such as sports although this might not be often. I am also interested in night photography and portraiture as well as close up pictures of flowers. Having mentioned what I like, what are your thoughts as to what is best for me and in general for other starting photographers?
I would like to add that A has a ring USM and that B has a micro-USM. Supposedly, A is quieter than B, but I am not sure I understand how exactly this affects a soundless picture? One good thing A has is that after auto focusing has been obtained, it allows you to manually focus it without having to switch to manual mode. I am not sure if I would need this, but sounds attractive. Also, as can be seen, the size of both focusing rings in A might make it easier to handle.
Adding on, I am most likely to pair any of these with a EF-S 18-55 mm Lens.
Please feel free to expand on, clarify or correct my comments