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Originally posted by pbskarpy I use tripod so asuper fast focusing is not very important I think.
I think any of the 55-300 versions will do well. I'm very happy with the optical quality of my old SMC DA 55-300. It can be a bit slow focusing (and noisy) for wildlife shooting, but as you say, that's not a problem in landscape photography. I'd go for the one with the lowest price. Quick shift and WR might be nice, though.
A quick summary from memory, should be taken with a grain of salt
SMC DA L: no WR, no quick shift focus
SMC DA: no WR, but has quick shift
HD DA: WR, new lens coating, quick shift
HD DA PLM: WR, new lens coating, quick shift, fast and silent focus motor, slightly less light transmission (4.5-6.3 vs 4-5.8 for the older ones)