Originally posted by manooti What would be a decent telephoto with zoom for wildlife shots? scared of the crop with 16mp
Ahaha, beware ! That where you could spend all your money.
As savoche said, the 55-300 is a nice consumer zoom for wildlife, portraiture outdoor, architectural details, sports and so own. You can buy a very innexpensive version of it (DAL) for a very good price used. Or go for the WR version that is going to cost more money for exactly the same optical quality.
You must understand this is a consumer tele zoom. It will do wonder in a zoo, or if you shoot big animals not too far away. Or general use. It will need good light to perform well. And you'll not crop anything out of it even if you had a 36MP body (that doesn't exist on APSC) simply because the sharpness is so-so at 300mm.
Many that really shoot wildlife spend lot of time hunting for it with very expensive stuff (several thousand dollar of it) and their are not even sure to get one good shoot each time they go out. This is just to say you have to understand it. There nothing bad and no risk with that 55-300, but you might soon find you need more reach for birds, or want more sharpness, light overall, and then it just kill your wallet. This is the kind of practice that cost a lot. Either you have the money and love then that's ok, either you'll better limit yourself.
Overall, that K50 + sigma/tamron 17-50 f/2.8 + 55-300 + DA50 seems like a very nice starter kit, covering all kind of usage with a nice compromize in term of price and quality.
You said your photo where not all good with your previous gear. That's mean it is likely not only the gear fault as a a good photographer would have manage some great shoot anyway. The next step is then to train, take lot of photos, learn from your errors, read, train more...