On Mon, 19 Oct 1998 20:58:02 +0800, "Patrick Mok" wrote:

>I am in trouble to decide which lens I should buy:
>1)Sigma Micro 105mm f/2.8
>2)Nikorr 85mm f/1.8
>Both lens cost me HKD $2600
>I want to buy these kind of lens because I want to take portrait photos but
>I can't afford the long focal length small f-number lens.
>Nikorr have shorter focal length but a smaller f-number, while Sigma have
>longer focal length lens but larger f-number.
>I would like to know which lens have a narrower depth of field since I use
>it for portrait.

Um, since these lenses are very close in FL (especially since the
macro lens almost certainly shortens its FL as part of its focusing
scheme), you can go on f-stop alone, though about one stop difference
in speed won't make much difference in the appearance of the DOF at
the same focus distance...