Some lenses look quite decent on static test chart evaluation in controlled conditions but are less impressive out in the real world where lighting and other conditions are uncontrolled. I have found the RF 24-105mm STM and RF 24-240mm to be in this category.
At the other end of the scale some lenses produce very good results on the test chart and perform even better out there in the visually complex world.
The RF 100-500mm f4.5-7.1 L IS USM is one of these.
Most flat test charts actually represent a fairly easy subject for a lens. They are evenly lit and usually consist of discrete shapes, lines or bars with sharp edges. The camera and subject are both perfectly still.
But in the real world there is camera and subject movement, atmospheric distortion, specular highlights and areas with low brightness range all in the same frame. There are issues of autofocus speed, accuracy and tracking capability. Stabiliser effectiveness is critical especially when the camera is moving rapidly. Subjects with fine textural detail can be difficult to render clearly.
Add all these factors together and we soon see that some lenses perform much better than others when tested in real world situations.
Before acquiring the RF 100-500mm lens I had been using an EF 70-300mm Mk2 lens on the EOS R5 with the required adapter. In its own right the EF 70-300mm is a very good lens and represents excellent value for money.
But for subjects moving fast including birds in flight, I soon realised that the RF 100-500mm gives me a higher keeper rate with more frames in focus and more frames critically sharp.
I have been repeatedly amazed at the amount of detail which the RF 100-500mm can reveal in still or moving subjects particularly when mounted on a high level body like the EOS R5.
