In this case, I framed the 3 towers: ‘Torre Caja Madrid’, ‘Torre Sacyr-Vallehermoso’ and ‘Torre de Cristal’ at CTBA with the structure of the ‘Torre Espacio’.
I used a 9-stops neutral density filter, Hoya ND400, to increase the clouds motion sensation. I had a Lee Big Stopper (10-stops filter), but I broke it. That was more versatil because it has a square 100 mm format and can be used with any lens, you only need to change your ring adaptor for your filter holder. But I think that Lee needs to improve the frame with some harder stuff.
If you check my pictures, you will see that I usually shoot with ND filters. I love them, ‘cos you get more light quality and they usually warm the colour of your images ( this is fantastic for the time around dawn or dusk). I bought a Lee Filter holder for wide angle lens and 3 HiTech ND kits at Teamwork Digital, and I am very happy with the quality and the price. Although I have 2 graduated neutral density (GND) kits – 1, 2, 3 stops – with ‘hard’ and ‘soft’ transitions, I really don’t use due to that I often shot architecture and it is difficult to have a rectilineal horizon. So if you use them in this case, you will have some buildings or other elements darker than what you eye see as consequence of the black part of the filters. This is a reason to avoid GNDs and use multiexposures techniques like HDR or DRI for architectural photography, but the textures and details can be other ones.
Cuatro Torres Business Area, Madrid (Spain)
Canon EOS 450D | Sigma 10-20mm f4-5.6 DC EX HSM + Hoya ND400 filter @ 10 mm | f11, 2s, ISO 100. HDR from 3 exposures @ [-2 EV .. 0 ..+2 EV]