Today’s Question: You mentioned using an 18-400mm lens in one of your Instagram posts. What do you think in general about using a lens with such a long range, which could potentially be the only lens I might need for many photo trips?
Tim’s Quick Answer: As you can probably already appreciate, using a lens with a particularly long zoom range involves a degree of compromise. You’ll gain convenience and often a lower price compared to otherwise covering the same range. However, you can generally expect lower image quality with this type of lens.
More Detail: When it comes to long-range zoom lenses, the key is to consider how the balance of advantages versus disadvantages.
The most significant advantage of a zoom lens with a long range of focal lengths is convenience. With a single lens you can cover a wide variety of situations, with the potential that you would never (or at least rarely) need to switch lenses. That also means you wouldn’t need to pack as many lenses.
In many cases a long range zoom also represents a cost advantage. Especially when you consider how much you might otherwise spend on lenses that would cover the same range, the savings can be substantial.
These benefits, however, do involve some compromises. In general, the longer the zoom range for a lens the more likelihood image quality will be lower than you could expect with a shorter-range zoom lens. And, of course, a prime lens will typically perform even better. That’s not to say that a long-range zoom lens won’t provide quality that is perfectly acceptable, but this is certainly an issue you’ll want to evaluate carefully.
In addition, you’ll often find that a long-range zoom lens is a relatively heavy lens. To be sure, such a lens will typically be much lighter than the combined weight of the several lenses you would need to achieve a similar focal length range. But the lens will still tend to be a little on the heavy side by virtue of covering such a long range. So while the lens may be convenient, it may result in a somewhat heavy camera configuration.
Of course, the issues discussed here are very general things to consider, and each individual lens will represent a different balance of advantages versus disadvantages. You will therefore need to evaluate the specifications for any lens you’re considering and be sure to read reviews to get a sense of how well the lens will suit your specific needs. Even better, use a rental service (such as LensRentals.com, https://timgrey.me/rentlenses) to rent a lens you are thinking about buying, so you can perform your own real-world test to see how the lens performs for you.