My Canon 100-400 mm has always been my go to lens for wildlife photography, Unfortunately it is big and bulky and can really wear you out if you drag it around all day. I recently purchased a used 100-300 mm Panasonic Lumix lens for my g7 which is a mirrorless camera. The Canon 10–400 weighs 55,4 ounces and a Canon body, the 50d weighs 1.8 lbs. The lens and camera body together total out at 5.3 lbs. The lumix g7 weighs 12.7 ounces and the 100-300 lens weighs 1.14 lbs . The lens and camera body total out under two pounds. If you are traveling. and on foot a lot, the convenience of a lighter camera- lens combination is a major consideration.
If I were intending to make large prints I would definitely use the 100-400 Canon lens. On the other hand if am taking travel pics I’ll chose the lighter combination.
I opted to use the 50d with the Canon 100-400 because of a similar pixel count, 15.1 megapixels for the 50d versus the 16 megapixel count of the g7.
Below are comparisons of the 2 lenses. All images were raw and converted to jpg with no sharpening added. All photos were handheld and all images were taken at 800 ISO in order to get fast shutter speeds and f/stops with some depth of field. I took the photos handheld because that is the most likely way I will use both lenses.
The two images above were shot at maximum focal length. The 50d has a 1.6 crop factor making a 400 mm a 35 mm equivalent of 640 mm and the g7 has a crop factor of 2 making its 35 mm equivalence 600 mm. You will need to click on the photos to enlarge them in order to get a better idea how the lenses compare. On this image there was some atmospheric distortion due to the ground heating up from a warm sun.
The above two images are cropped to the actual pixels. Atmospheric distortion is obvious. The Canon 100-400 seems to hold up better.
Birds in flight are captured using continuous firing. The first image is full frame the second actual pixels, The image holds up better at a shorter focal length.
As you compare the canon lens you can see its a little sharper.
The canon works better for moving birds because you can track them better. With the mirrorless g7 an image appears in the viewfinder right after you shoot, blocking a live view.
Again comparing the canon and g7 the canon 100-400 has an edge.
I also did some tests using the g7 on continuous focus and continuous fire and I was relatively happy with the results. The second picture is the actual pixel crop. Again, I reiterate the ability to follow a moving target with a mirrorless camera can be quite a challenge.
In conclusion I would recommend the g7 for travel and especially for photos that didn’t require tracking a moving object. The Canon 100-400 wins out but the cost is significantly different.
I paid under $400 (used) for the Panasonic lens and $1400 for the Canon lens which was new when I bought it.