Originally posted by Fotorix I need suggestion btw best one or two from the following lenses:
Pentax HD DA 40mm
Pentax SMC DA 40mm
Pentax DA 20-40mm
Pentax DA 70mm
If I didn't already have the DA 35 Limited Macro
and the DA40 Limited (SMC variant), I would be looking very closely at the 20-40. Little babies are excellent subjects for a normal lens (which the 40mm FL is on a crop sensor), but as she grows bigger and more mobile you will feel the need to "zoom out" a little.
Of the lenses you have selected, the DA20-40 would therefore be my choice for practical reasons. The only downside I perceive is that this isn't a constant-max-aperture lens (it'll be a stop slower by 40mm). It also may not have enough reach at the long end for wedding work.
If compactness and ease of handling is everything to you (and it may be if you're trying to dangle a toy in front of your daughter to grab her attention while you shoot with the other hand), the DA40 is king. But then you lose the flexibility of zoom, and it becomes less about wedding work and more about a lens with which to photograph the hell out of your little girl (with which there is nothing wrong!!).
It also depends on what else you have at the long end (error - I meant Wide end) to give you flexibility if you decide to get a prime.