Morocco Photo Tour

August 29 - September 10, 2023

burden for you.

Super telephotos are very expensive, and they are inhibiting in one imporant regard. The fixed focal length means you don’t have the flexibility of a zoom. On occasion when I was using my 500mm f/4 lens, at a particular distance an animal made the perfect composition. However, if it approached too close to the vehicle I was shooting from or the blind I was using, I had to switch to a shorter focal length lens. The picture on the next page of a mother and newborn baboon is an example. I had been shooting them with the 500mm f/4, and the mother walked up to our Land Rover and sat down. I had to add one extension tube between the lens and the body to allow me to focus on the two animals. The minimum focusing distance of the 500mm lens I was using is 14.5 feet and the baboons were closer than that.

The Canon 100-500mm lens I now use is much, much lighter, it’s smaller and takes up a fraction of my backpack compared to the 500mm f/4. It is much less expensive, and most importantly it has a fantastic zoom range. This gives me tremendous compositional freedom. In addition, it focuses very close. The minimum focusing distance is only 35.4 inches (90 cm).

The very relevant disadvantage is that it is an f/4.5 - f/7.1 lens. For bird photography, when shooting in diminished light like diffused sunset, below, that’s a big deal. That means when it’s set to 100mm, the maximum aperture is f/4.5. At full extension to 500mm, however, the largest aperture available is f/7.1. That’s 1 2/3 f/ stop smaller than f/4.

To put this in practical terms, this light loss is the difference between using 400 ISO versus

1200 ISO, or 3200 ISO versus 10,000 ISO. With respect to shutter speeds, it’s the difference between using 1/3200th of a second versus 1/800.

In order to use super fast shutter speeds especially in low light environments or to use small lens apertures for increased depth of field, the ISO has to be raised. The guinea fowl picture below, for example, was taken from a blind in South Africa at dawn with artificial light mixing with the dim ambient light. I shot this with the Canon 100-500mm lens plus a 1.4x teleconverter giving me 700mm of focal length. The teleconverter cost me one full f/stop of light, so now the maximum aperture was f/10. That pushed the ISO to 12,800!

Had I been using a fixed focal length lens with a maximum aperture of f/4, the teleconverter would have made the effective aperture f/5.6, and the ISO in that case would have been 4000.

That’s a significant difference.

However, in our favor now is the remarkable post-processing tools like Topaz DeNoise AI and Topaz Sharpen AI. If it weren’t for the ability to mitigate noise and to sharpen images that need it, I would not be enthusiastically endorsing the Canon 100-500mm zoom. But we do have these tools, and in my own work they have saved hundreds of pictures that needed technical help.

Every photographer wants super sharp images that are free of noise. The two routes to get there are 1) use and carry super expensive and heavy lenses along with a sturdy tripod, or 2) use a much less expensive zoom lens that is significantly smaller and lighter and has an incredible minimum focusing distance, and in post-processing address the issues of that degrade the photographs. §