I am currently using 3 Canon digital single lens reflex camera bodies. The majority of my shots are taken with either my Canon 1D Mark IV or my Canon 7D Mark II. The 1D Mark IV body provides the advantages of an outstanding auto focus system and the ability to be able to shoot bursts of up to 10 frames per second. The 7D Mark II, with its higher pixel density resulting from a 20 megapixel sensor and the 1.6 crop factor, can be an advantage when maximum focal length is needed, and it also has an outstanding auto focus system and can shoot at 10 frames per second.
When I bought the original 7D several years ago, even though it is not the most expensive camera body that I’ve owned, it, more than any other camera that I have owned, opened up new wildlife photographic opportunities for me. With its high pixel density, it allowed me to use smaller and lighter lenses, which, in turn, gave me more mobility, and that increased mobility gave me more opportunities to get shots than I had never had before. Now, the 7D Mark II provides the same advantages, and it has an improved auto focus system and other improvements over the original 7D.
One of my most frequently used wildlife lenses has been my Canon 500/4 IS. It is an extremely capable lens, and it loses virtually nothing when I add a 1.4x teleconverter.
In 2007, I acquired a Canon 400/4 DO lens. I had considered the lens for some time, but had hesitated because of mixed reviews about it. I could not be more pleased with the lens. If it isn’t as sharp as my 500/4, it is so close that I can’t tell the difference. Complaints of others centered around poor contrast, especially in less than ideal light. I’ve used the lens in very cloudy conditions, and I’ve seen no problems with contrast. It takes a 1.4x converter very well, and, at about 4 pounds, it is a pleasure to use for hand-held shooting. The lens has become a wonderful smaller and lighter weight long lens choice, especially when used with the 7D Mark II or the 7D. The 7D Mark II used with the 400 DO has easily become my favorite body and lens combination.
Often, I will go out with either the 500/4 or the 400 DO on one body and my 70-200/2.8 IS on the other body.
I also had a Canon 400/5.6 lens. While it can be an incredibly sharp lens, I rarely used it. For my shooting, the lack of image stabilization severely hampered the usefulness of this lens. Since much of my shooting is handheld and in marginal light at dawn or dusk, maintaining the shutter speeds needed to hand hold the lens becomes very difficult. Thus, when I realized that it was lens that I was never going to really like, I sold it.
Another lens that I have owned is the Canon 100-400 zoom. While it was one of my favorite lenses, when I got the 400 DO, I found that I could cover the same range with the 400 DO and the 70-200, and the 100-400 became redundant.
For much of my shooting, I will use a 1.4x teleconverter with the 500/4 or the 400 DO. Occasionally, I will use a 2x converter with the 500, but I try to limit the use of the 2x, both because there is a greater loss in image quality and because the light loss with the 2x, which must be stopped down, makes it difficult to get the shutter speeds needed to shoot anything but a relatively static subject.
While I don’t use them often for wildlife shooting, my other lenses include the Canon 135/2, 85/1.8, 50/1.8, 24-70/2.8, and 16-35/2.8.
By now, Canon has replaced many of the lenses that I own with newer versions. While it would be nice to own the newer versions, the very marginal improvements in image quality of the newer versions makes it hard for me to justify the quite steep cost of upgrading from still outstanding lenses. In the case of my 500 mm lens, it would be very nice to have the decrease in weight that comes with the Mark II version of that lens, but, again, the image quality of the original 500 mm lens is outstanding, and it is difficult to justify the upgrade cost.