I just bought a nicely-preserved pre-owned Canon EF 24-105mm f/4L lens, from a local camera store. I am attending a 40-hour forensic photography class this week, at the county sheriff's academy, and learned that my preference for an ultra-wide zoom for shooting crime scenes is not really a best choice; there is now more of an emphasis on capturing scene images from a "normal" angle of view, meaning about 50mm for full-frame cameras, and about 28mm for 1.5x and 1.6x cropped-frame-sensor cameras.
I also learned that my employer, a very large city police department, had recently purchased Canon EF 24-105mm f/4L lenses for the Crime Scene Unit officers, an upgrade from the lesser kit lenses used in the past. As a patrol division officer, I am not provided with a DSLR ; there is a point-and-shoot available for me to sign-out for the duration of my shift, but the court system expects DSLR-quality images, so I use my personal photo equipment. (It is normal practice, in the USA, especially in the South and Southwest, for police personnel to provide much of our equipment.)
Well, this afternoon, I saw this lens at Houston Camera Exchange, in like-new condition. I did not have a camera body with me, so asked to try the lens with a pre-owned 1D-series body. The results, especially its pleasing minimum focusing distance, seemed good enough to make the purchase, and bring the lens home to try on one of my 1D Mark II N cameras. True to its reputation, this lens acquires focus quite readily, even doing so in an amazingly low level of light, as the sun went down. It also performs quite well with flash.
This lens had not been on my wish list, but I had done some research in the past, and known it was considered a quite reliable, competent lens by a significant number of working professional photographers, even if the techno-enthusiast-guys tended to be critical. I has also noticed that quite a few nature photographers were winning awards with images created through this lens. Fortune smiled on me today, so I did not waste the opportunity. I may now have to sell a lens or two, or something else, to compensate my budget, but that is OK.
Notably, my pair of 1D Mark II N cameras, originally acquired to shoot images of birds in bright daylight, are proving quite nice for night-time evidentiary shooting. Good lenses and flashguns keep these 2005-era cameras relevant, in spite of their relatively poor performance at high ISO.
Canon 5Ds R/7D2/7D/5D/40D/1D2N; Nikon F6/D3s/D700/FM3A/Coolpix A. Lens selection undergoing changes; some favorites: Zeiss 2/135 APO Sonnar, Canon 100mm f/2.8L Macro IS and 135L, Nikkor 14-24/2.8G and 200/2 VR.