Hello


first of all, the 70-200 non IS isn't weathersealed! Be carefull it's only with the IS-versions.


Furthermore the choice of lens depends mostly on your needs. And of course what you think will improve.


Both lenses are probably better with IQ then your 55-250, but... maybe you don't even really notice that difference.


What is it excactly that you don't like about your lens or need to improve? Your picture will not get better with any of both lenses. The image-quality will probably. I must say the 70-200 f4 is a beast of a lens for such bargain, but you might miss the IS a lot. You need a bit of light when shooting at 200mm with 1/200 minimum speed and f4 minimum. At least if you don't want to pump up your iso.


I would recommend that you try and turn off the IS on your 55-250 and see if you like it and you could work with it. If so, definitely buy the 70-200! If not, take a closer look at the 70-300 and see if you think it would suit you more than your 55-250.


Also take a look at the review of the 55-250, there's at least one mouse over with all 3 lenses you mentioned.


Good luck picking!


Jan