During my training courses and by email I get asked quite a lot about what camera equipment to invest in next.
Often people buy an entry level DSLR which comes with a 'kit' lens typically this is in the range 18 - 55mm and can often be bought with another kit lens say 55 - 200mm. For many this is all you ever need and will cover wide angle to medium telephoto. 18mm range is good for Landscape photography, 50 - 100mm is fine for portrait work and 200mm will get you some wildlife shots too.
These kit lenses are light, cheap and compact. They are also a compromise.
These lenses often have aperture ranges of F3.5 to F5.6, much slower that pro lenses that are F2.8. These pro lenses are heavy expensive and well built. So whats the difference and why do consumer lenses have 2 F stops, or ranges?
Consumer lenses say 55 - 200mm extend and as they do the barrel effectively becomes smaller as it does so the aperture increases and less light is available to the sensor. The impact of less light and higher aperture affects depth of field and shutter speed, both can be unwanted.
A pro 70-200mm lens costs around six times more than the consumer 55-200mm. So what do you get? Better build quality, a lot more weight but importantly a constant aperture of F2.8 from 70mm to 200mm. This is important in low light and produces a far more pleasing background (bokeh) than a consumer lens.
So what if you don't want to spend £1700 on a lens. Nikon and Canon both offer 70 -200mm F4 lenses. They are significantly lighter and cheaper and only lose one stop of light. If you want some cheaper alternatives then look at 50mm prime lenses. These often come in the 50mm range, have a fast aperture either F1.8 or F1.4 typically. These are sharp, light and offer excellent bokeh. Perfect for portraits and low light photography. You can get a used Nikkor 50mm F1.8D lens online for around £100. The latest Nikon 50mm F1.8G rivals its more expensive 50mm F1.4G and is a worthy 'next' lens.
So for your next purchase look no further than a 50mm prime lens, I don't think you will regret it and your photography will improve.