Although I have a preference for super fast, ultra high quality, prime lenses there are times when zoom lenses become a necessary evil or better put totally preferable...
I like to use prime lenses as they are fast - typically around f1.8, f1.7, f1.4 or f1.2 and are of very high optical quality even when used wide open. Thus they allow me to work in very low light at the lowest ISO's for maximum iQ and also allow me to make photos with pronounced subject isolation if desired. Plus they encourage me to move around, zoom with my feet if you like, to find the best possible framing of my images and not simply be static and stand in one spot zooming in and out.
Then there are however many circumstances where either your surroundings prevent you moving about or where it is inconvenient for you to carry a lot of of equipment or you need to work quickly and you cannot change lenses quickly enough or you are working in a hostile environment where swapping a lens would allow ingress of damaging material into your camera body. Then, typically, zooms come into their own.
For these sorts of occasions I have three such zooms lenses:
- Olympus M.Zuiko 14-150mm f4-5.6 II
- Lumix G Vario 100-300 f4-5.6 II Power OIS
- Lumix G Vario 7-14mm f4 Asph
The 14-150mm is my go everywhere super zoom travel lens and also the one I use for events like steam galas where there is fast action with no time to change lenses, crowds to be avoided so tight cropping may often be needed and movement can often be quite restricted so having to stand in one spot and being able to zoom in and out can be a boon rather than evil.
The 100-300mm is my tele zoom as the focal range implies and the one I use for shyer creatures like garden birds and animals like squirrels and such. It is also useful with some scenics for compressing apparent perspective.
The 7-14mm is my wide angle zoom giving me everything from a super wide to a moderate wide angle of view useful for interiors, architecture and some scenics.
Each lens is of moderate speed to minimise bulk and weight thus maximising mobility. One other thing they all have in common is convenience, so I understand their popularity. As for optical quality? Well they are really pretty decent, though one end of the zoom range is always a bit softer than the other I find.
Are they as good as the primes? Well all I will comment about them is that being slower, you end up quite often at higher ISO settings than an equivalent prime lens for a given focal length and you often have to do a bit more work in post processing to bring out a quality image compared to a prime lens, by introducing tools like Topaz AI, for example, into your standard workflow.
Using that good testing tool the Mark 1 eyeball then e.g. images from say my 20mm f1.4 are visibly nicer out of the camera than those from my 14-140mm set at 20mm especially taken in low light but then one is a Pro prime and the other a super zoom. Having said that, the images from the super zoom are still surprisingly good just don't put them side by side with one from a Pro prime. Mind you having worked the extra magic in post, it become much harder to tell the difference.
Thus we come the old hoary question, which is best? Well from me you will get the old hoary answer, "Neither" or maybe better still, "Both". They are tools each appropriate to their time. place and application. Given the opportunity I will always opt for my fast prime lenses but when circumstances dictate I will always prefer my flexible zooms.
Actually zooms aren't a necessary evil after all, they are often simply the right choice.