Concerns are frequently expressed about lenses like the RF 100-500mm with f/7.1 being narrow and so the images must surely be noisy because high isos are necessary in dim light? Some claim the 400mm f/5.6 is superior in low light because it is 2/3 of a stop faster (or a 1/3rd faster than the 100-500mm at 400mm f/6.3). I've pointed out that the 100-500mm has the same size front element of the 400mm f/5.6 that although you need to crank up up the iso by 2/3 of a stop to maintain the shutter speed, the extra magnification of the longer lens compensates for any extra noise. Others are genuinely worried that a 2x extender needs an extra 2 stops of iso at f/14, and I've said don't worry as the R5 handles noise well and again the 2-fold gain in magnification compensates for 2 stops higher iso. To show this, I have today taken a series of images in cloudy overcast conditions at 20m distance of a magazine cover with the 100-500mm on the R5 from 1/100s to 1/6400s, increasing the iso from 160 to 10k, and in parallel with the RF 2x at the same shutter speeds and isos from 640 to 40k. The RAW images were processed using my standard procedure with DxO Photolab PL4. The noise reduction was with its DeepPRIME and luminosity at its standard 40 on the slider - this is mild and loses minimal detail. Lens sharpening was on but I decreased the global to -2 as the standard 0 is a little aggressive.
Here are the images in pairs - at 500mm and 1000mm with 2 extra stops of iso. The crops are 100% - 1 pixel of crop = 1 pixel of original. Draw your own conclusions!
Here are the images in pairs - at 500mm and 1000mm with 2 extra stops of iso. The crops are 100% - 1 pixel of crop = 1 pixel of original. Draw your own conclusions!