Originally posted by jusfun21 Hi everybody,
I have a question. I want to know what wide aperture prime lenses will work well for portraits and weddings? I already have the pentax 40mm and 70mm limited and the sigma 50mm f/1.4 lenses. A co worker told me it would be a good idea to have some large aperture lenses f/2.0 or wider to work better in low light situations. what do you guys think?
I would have to go with CWOOD's recommendations. The difference between 2 and 2.8 is only one stop and the zooms will add a boat load of convenience when you are shooting the wedding, where changing lenses can be a bother. The lenses you have are a great start and add the zooms for candids and the ceramony (where you may not be able to use flash).
Although it seems like the faster lenses are a thing of the past, they are still quite necessary if you look into lens sharpness. A lens, generally, is sharpest at 2 stops down from its widest opening. And no one get nit-picky with me here, I said GENERALLY. This means an f2.8 lens is sharpest at about f4.
Next, diffraction starts taking place at about f16 (again, generally) which also reduces sharpness. With an f2.8 lens, you have f4, f5.6, f8 and f11, 4 stops of pretty good to excellent sharpness.
Now look at an f5.6 lens. 2 stops down is f11 and f16 starts giving you diffraction again. You have ONE stop of good sharpness. An f4 lens gives you 2 stops. To put it in golfing terms, the wider the maximum aperture, the bigger the sharpness "sweet spot" to work with!
Have fun!
BD