I have long been thinking about a longer, telephoto range zoom lens, as this is perhaps the main technical bottleneck in my topic selection currently. After finding a nice offer, I made the jump and invested into Sigma 150-600mm/5.0-6.3 DG OS HSM Contemporary lens for Canon. It is not a true “professional” level wildlife lens (those are in 10 000+ euros/dollars price range in this focal length). But his has got some nice reviews on its image quality and portability. Though, by my standards this is a pretty heavy piece of glass (1,930 g).
The 150-600 mm focal range is in itself highly useful, but when you add this into a “crop sensor” body as I do (Canon has 1.6x crop multiplier), the effective focal range becomes 240-960mm, which is even more into the long end of telephoto lenses. The question is, whether there is still enough light left in the cropped setting at the sensor to allow autofocus to work reliably, and to let me shoot with apertures that allow using pretty noise-free ISO sensitivity settings.
I have only made one photo walk with my new setup yet, but my feelings are clearly at the positive side at this point. I could get decent images with my old 550D DSLR body with this lens, even in a dark, cloudy winter’s day. The situation improved yet lightly when I attached the Sigma into a Viltrox EF-M Speed Booster adapter and EOS M50 body. In this setup I lost the crop multiplier (speedboosters effectively operate as inverted teleconverters), but gained 1.4x multiplier in larger aperture. In a dark day more light was more important than getting that extra crop multiplier. There is nevertheless clear vignetting when Sigma 150-600 mm is used with Viltrox speedbooster. As I was typically cropping this kind of telephoto images in Lightroom in any case, that was not an issue for me.
The ergonomics of using the tiny M50 with a heavy lens are not that good, of course, but I am using a lens this heavy with a monopod or tripod (attached into the tripod collar/handle), in any case. The small body can just comfortably “hang about”, while one concentrates on handling the big lens and monopod/tripod.
In daylight, the autofocus operation was good, both with 550D and M50 bodies. Neither is a really solid wildlife camera, though, so the slow speed of setting the scene and focusing on a moving subject is somewhat of a challenge. I probably need to study the camera behaviour and optimal settings still a bit more, and also actually start learning the art of “wildlife photography”, if I intend to use this lens into its full potential.