It depends, is the answer to this question. All right, I agree, that excuse requires an explanation.
In my defence, it depends on the purpose for which you intend using the kit and how tricky the conditions are likely to be. There are too many photographic gadgets and gizmos in the market to shake a financial stick at, so I am concentrating here on noise and lens glass.
Simply put, professional equipment is indispensable when the highest image quality is required under the most extreme conditions. Obtaining well exposed, sharp, saleable pictures of small, distant wildlife in almost no light is an example of this; and wildlife has a habit of being in exactly these conditions more often than we like.
The latest pro-specification DSLRs are bristling with features that sometimes make even a technophile like me scratch his head in puzzlement and wonder. However, top of my ‘important list’ as a nature photographer is the incredible ability of sensors to control noise at high ISO values in extremely low light, compared with cameras further down the food chain. This can mean the difference between getting the image and ruining it with camera shake or noise. I photographed a series of images recently of a wild lioness having her teeth checked in near darkness at ISO 20,000 and the results were gratifyingly clean.
Sometimes you simply cannot get close enough to that small animal in the gloom and to use a smaller lens just would not work. So a large ‘rocket-launcher’ prime lens is the only thing that will do. Why? Partly because of the obvious, it is very long, but also because it has a colossal lump of superb quality glass in it that gathers much more light, that is, faster shutter speeds, with less distortion than its cheaper cousins. Couple that with image stabilisation, which lengthens the acceptable shutter speed by up to a staggering 16 times without camera shake, and that is a formidable combination, albeit at an eye-watering cost.
If you can afford to buy all this first-class equipment, then this is excellent; you will see a difference in awkward conditions. But really, if you do not use your camera in challenging situations, all you are doing is making your bank manager and your spouse fall off their seats with shock unnecessarily.
Also, most entry-level and mid-priced DSLR bodies and lenses are more than capable of getting good images at moderately high ISO levels. People on my workshops have achieved superb photographs with relatively cheap cameras; the important thing to remember is that it is the photographer who takes the picture, not the camera. The photographer should know how to get the best out of the equipment, whereas the camera does not know the difference between a good photograph and the back end of a giraffe.
So, the flip side of my gear love-in above is that you should not get carried away with the thought that you need to spend vast amounts of cash to assure good photographs. Experience, technique and practice always will outdo top end equipment, undoubtedly helpful though it is. By all means, re-mortgage the house for shiny, expensive black boxes with exciting buttons and bicep-challenging bits of glass, but the gear itself does not make us better photographers.
So, returning to the question as it relates to my own photography, is pro gear really worth the money for me? My job is to sell images and clients demand the utmost quality from some very difficult situations. Therefore, I have to live with the fact that my largest lens is worth significantly more than my car and my bank manager and my wife fall off their seats in synchronised horror more often than is good for any of us.