Would I use a fast prime lens?

In one of the focal length exercises, the aim was to isolate a subject by using depth of field. This was relatively difficult with the two zoom lenses that I use where the maximum apertures are relatively high:

- Nikon 18-70mm f 3.5 to f 4.5

- Nikon 70-210 mm f 4 to f 5.6

This set me to wondering whether I would use a fast prime lens for some subjects where I needed a shallow depth of field. Two broad options appeared feasible :-

- A "standard lens" 35 to 50 mm with f 1.4 to f 1.8

- A "macro lens" 50 to 105 mm with f 2.8

A friend from Guildford Photosoc offered to loan me his Sigma 105 mm macro lens to try out for the past week. He is particularly interested in nature photography and he uses this occasionally for its macro capabilities. In contrast, I tried the lens in a variety of situations, some of which I compared with the zoom lens set at a similar 100 mm:

- Close up pictures of fruit in a bowl

- Garden pots

- Self portraits

- Street scenes

- Pictures of football players in a local park

In most cases, I was using the lens at f 2.8 because I wanted to see what was the effect of having a faster lens.

At full aperture, the Sigma lens did blur the background more than the zoom lens. However, the 1 stop difference did not have as much effect as I had expected. The lens was good for taking pictures of people and street scenes e.g. a busker playing in the High Street. It was necessary to move around quite a lot to photograph footballers as the lens has quite a narrow angle of view. The lens was very good for taking high magnification photographs beyond the range of the close up lens that I have. Macro photography is not at present a significant interest, however.

I would now like to try a "standard" lens for comparison. The extra stop of speed and the broader angle of view might suit my style of photography better.