What lens?

[Marc1548]

Hi I would consider myself a beginner. I bought a complete dlsr kit about a year ago, second hand, but immaculate & hardly used for a steal.
Nikon D90 which came with 2 lenses 18 105 f3.5 5.6, the kit lens, & a better quality 24 120 f3.5 5.6. + some useful accessories remote shutter release, ND filters, polarising filters, spare battery + a few other bits. I bought a nice Manfretto tripod with ball head.
& recently an SB600 speedlight.

I’m really getting into my photography but these 2 lenses are very similar. I don’t really limit myself to a particular genre of photography but would like to add to my lenses for more versatility.
Could anybody recommend a good telephoto lens?
Is it worth sticking with Nikkor lenses or are other manufacturers Sigma etc just as good & compatible with auto focus, metering, & VR etc?
Is it worth keeping both the lenses Iv got? I can’t imagine I would get much for them if I sold.
Thanks for any advice or on any other useful equipment to add to my kit.

 

[Mike.P]

When you say telephoto lens what do you intend photographing as there are zooms all the way up to 600mm and beyond. Obviously you won't need that length for a lot of things but for wildlife the longer the better most of the time.

Also, what's your budget?

 

[scott199]

As above budget and reasons are the main consideration.

Ask yourself
What do I need my current glass can’t offer ?