Lens choice is a very personal thing. For the top shot I was using a 300mm with a teleconverter, thus its the equivalent of a 500mm lens.
The portrait of the lovely Charlotte was taken with a 70-200mm f/2.8 zoom set to 90mm.
This shot with the highly selective depth of field was a 50mm f/1.4
There are a lot of lens out there, and for my SLR I have the whole range from 12mm to 300mm plus teleconverters. Its only now that I start to realise that I could successfully rationalise my lens choice.
First lets talk wide angles. Personally I feel a wide angle starts at 24mm (for 35mm full frame), and goes to 20mm. Any wider then this and we are talking super wide angle and they are very hard to use.
I would go for a 24mm, not too wide to be hard to use but still a real wide angle.
For standard lens then a 35mm and a 50mm go well. I use both and it depends what mood I am in. Often I find myself shooting black & white with a 35mm and colour at 50mm.
Next we have the short telephoto, and here I currently use a zoom the trusty 70-200mm. I fully intend to add a 90mm lens to my Leica.
Then long lens, this is where budget comes into play. If you shoot MicroFourThirds its much cheaper then full frame. I have a 300mm f/2.8 but with cameras getting better and better at high ISO then a 300mm f/4 is the cheaper option.
Users of SLR’s tend over the years to build up large kits and leave most of their lens at home, thats where rationalising comes in and knowing what you shoot.
For most people a 35mm and a 90mm would suit 90% of their photography.
If your into medium format then its easy to get into systems where the lens cost £5k each. At this kind of money ask yourself what do you shoot. If your a landscape kind of guy then the medium format equivalent of the 35mm and 90mm is likely the option to go for. If your a studio shooter then this is also a good starting point with the 35mm handling groups and the 90mm head and should portraits.
Wildlife photographers would go for maybe a 100mm micro and the longest lens they could afford.
If your into architecture and especially if you shoot indoors then you may need to go for 20mm, 24mm tilt and shift and a 35mm.
When you boil it down and really look at it you can get a way with about two lens and maybe one speciality lens. That is until the GAS (Gear Acquisition Syndrome) kicks in.
I currently have 24mm, 35mm and 50mm for my Leica and look to add a 90mm. This should do but then you start to look at lens character. The Leica 28mm f/5.6 has a wonderful look to it and having a selection of f/1.4 lens for character and f/2.8 for portability sounds like a good option. Unfortunately GAS never seems to stop.