There are some beautiful - detailed shots of animals where the photo is of just the anamal's eye, where you can see the colors in the iris, or seperation in ligaments in wings....highly detailed. Now I have some good shots of my cat, but if I enlarge the photo the fur gets pixil-ized and fuzzy. Im pretty sure people are not walking right up to a polar bear with a macro lens for the fantastic close-up,.. (well maybe they can,....once), but how is it done were magnifying does not pixelize? Thanks
If you can get close, then use a macro lens - 90mm or 100mm is often used. If you can't get close, then use a lonnng lens.This where an APS-C camera really helps because of the crop factor. On Canon cameras it is 1.6. So a 300mm lens gives you an effective focal length of 480mm and a 600mm gives an effective FL of 960mm. Lots of choices out there from primes to zooms.
Your right, they are probably not walking right up to dangerous animals , and as Ray stated the main ingredient is a long lens. There is some pretty simple math here, as Ray stated your crop sensor will help out a bit because the small sensor is cropping the image from what a full frame would see with the EF lens mounted since it only sees about 2/3 of the glass. So while the images is magnified to 600mm it shows a crop similar to what you would see with over 900mm on a full frame. Is a crop sensor better for wildlife? Its not an easy yes or no, you can get better performance out of full frame sensors regarding noise and dynamic range and usually more megapixels(so you can crop in post production). Now regarding the fuzzy pixelated issue, lets assume you have a full resolution file to start with. If you set print size to 300dpi without changing the actual pixels you would get maybe something around 12x18 inches, and you could crop to something tighter and just print smaller and have a high resolution image. If you are zooming in further than this you will start to see the pixels and the image will degrade as you noticed by trying to enlarge the image. I would not recommend trying to use an image below 150-200 dpi as it will not look good printed. Bottom line is you can't introduce information that is not there in the file, the best idea is to crop and zoom using lens choice and that is what those with wildlife shots generally do, and maybe fine tune in post production a little bit.