Upgrades over the kit 50-200 lenses?

Hello again been lurking because 95% of the time I've no idea what I'm doing so let the experts do the talking and just read

I recently bought a Sigma 10-20 f3.5 after noticing it seemed to be the lens of choice for MTB photographers because put simply you don't need a flash or have to run miles off the trail to get the shot composed!

The downside is, now the kit lenses seem a bit, mehhhh, not as sharp, not as bright colours?

I've also got some older Pentax-M lenses (28mm f/2.8 and 50mm f/2.0) which I like so I'm happy around those sorts of focal lengths for now. But was keen on the Sigma 50-150 F2.8 but that's been discontinued. Anything else I should be looking for? I'm not a huge fan of the 200mm end anyway so losing that isn't a worry.

Lenses will be used for everything, but needs to be small enough to fit in a small-ish bag for cycling, and not so expensive that I'd be crying for weeks when I or it endure a high speed gravity induced technical malfunction on the bike! The 10-20 f/3.5 is probably on the limit for all 3 (big, weighty, expensive).

Happy to look 2nd hand, but can't find any of the 50-150 f/2.8 on ebay or by googling.

There's a very nice Pentax DA* 50-135mm f2.8 weather sealed zoom in the Classifieds (shameless plug)

Very nice, but to stretch to that might need a couple more paydays.

[edit] got confused between the sigma lenses, there's an old and a new 50-150, I was looking at the old one (definitely can't afford the new version!)

Th 50-135 is an outstanding lens, but pricey and relatively heavy given your requirements.

The standard 'upgrade' from the 50-200 kit lens would be a DA 55-300 - great lens for the price. It's a bit bigger, but still relatively light for carrying around with you, and MUCH lighter than the 2.8 options (sigma or Pentax). You can get v. good deals on second hand of the old version ( MikeP has one in the classifieds at the moment) and folk report the optics on the old version are just as good as the new WR version.

It is on the long side though, if 200 is already too long for you

The DA18-135 is very useful and gives great results, it's compact, light, WR and you can normally pick a 2nd hand one up cheap enough!

I wouldn't say 200 (or 300) was too long, but in the compromise between weight, speed, size and focal length, it's the thing I'd not miss. I'd put high speed over everything else, no point having a light compact lens that's easy to carry up hills if it doesn't do the job once up there.

Small's relative too, anything that doesn't come with it's own tripod mount would be compact enough to fit in the bag.

The 18-135's definitely a consideration, it was more expensive than the 18-55 & 50-200, is it enough of an upgrade to be worthwhile?

EYes.

if you are wanting something to cover wider than 50 (and not just a straight upgrade of the 50-200) and dovetail with the Sigma 10-20, then this is definitely worth serious considertion. I've a copy and found it a really excellent general purpose lens, with much better IQ than the kit lens.

But it's not a 2.8 if high speed is a must.

I was skeptical of the 18-135 but found an unbeatable deal on one and must say I am actually pleased with it.
It is a nice little lens that does everything you ask of it well.
People complained it was a little soft wide open, but to be honest, I am almost always shooting portraits when wide open at any focal length and this lens is plenty sharp in the centre and that softness near the edges is pleasing in portrait so no real loss there. I also have some rather sharp, rather fast primes if I wont to swap lenses so there's no downside to this lens as far as I'm concerned. I say it has CHARACTER, not flaws.

I agree the DA18-135 is worth a look. It's my lens of choice for tramping in the mountains. Light, compact and fast focusing. The DC motor seems to be robust, never heard of anyone having problems with the autofocus drive. Nice lens for landscape use with a very good range that means I won't need to change lenses all day. Even with WR there are times when you don't want to be opening the front of your sealed camera!

The DA16-85 is also a good lens. It is sharper than the 18-135 but it is also bigger and heavier. It also has a DC autofocus motor. This is the lens I use when I'm not going to be carrying it up and down a mountain all day but am not going out to do 'photography'.

The 50-135 is the bees knees in terms of image quality but it is a big lens and it would seem the SDM motors have a certain fragility. (Mine is waiting to be repaired at the moment). I think you might find it a bit heavy on the bike.

My gallery has plenty of mountain pics taken with the 18-135 some more recent non mountain ones with the 16-85.