Hi--

>Thanks for the response. I suppose I'm still confused about something
>and that is the perspective each lens gives. I can appreciate that a
>15 will cost more because it is practically half the focal length of
>a 35, but as you (and I) know both the 8 and 16 provide the same 180 angle
>of coverage in the image field. I presume that the 8 will have
>different perspective to the 16 or else why would anyone bother
>with it (aside from the fact that the 16's image circle is
>cropped by the 35mm frame)? Is this assumption correct? Does the 8
>produce a greater "bulge" effect? Put it another way, if I were to
>take pictures of identical subjects using the two lenses, what
>differences would I see other than magnification and cropping?

Absolutely none (unless it is the OP fisheye), BUT, there is a difference
in the feel: the spherical perspective fits nicely into the full circle,
but often awkwardly into the rectangular frame (same is true of the 8mm
plus 1.4x, but having the larger image while maintaining the full 180
degrees is useful sometimes - I always wanted to try a 6mm f2.8 on a
2x converter!).

>For quite some time I've been very attracted to the 16 but I've
>hesitated. Recently I saw some pics done with an 8 and the circular
>image is really impressive. I might go that way instead but it's
>likely that I'll have to purchase the Sigma since the Nikkor's
>price is very prohibitive. Does the Sigma have built in filters?

No - you split the lens in half to place them inside (awkward, and
I fear decentering those tiny optics, so I never use filters with it
[unless I tape gels on the rear]). I would recommend a used 16mm f3.5
(may need to be AI'd) rather than the 8, since you will almost certainly
find it more useful (the 8mm film area is VERY small), and that particular
lens is VERY sharp, and, well, 16's are FUN! (I also use it commercially,
which causes occasional consternation on the client's part.)

David