Currently, I own the kit 18-55 and the 50 1.4 for my K100D, and being a low budget teenager with not great amount of experience (though I have been reading many a review and topic on lenses) I was wondering whether anyone could suggest a lens or two that would be worth investing, and are a relatively cheap price.

At the moment i'm looking at the 10-17 Pentax fisheye, or the 10-20 Sigma lens, which although is cheaper, is not fisheye (which quite interests me)

Also on the "wanted" list would be a lens around 90-150mm, probably a prime, maybe 105 or 135? Any suggestions?

Feel free to tell me the lenses I want are pointless, as long as you suggest a better option Also, if anyone could suggest an online shop which sells used lenses also, then I would be quite interested - Im not too keen on spending a lot of money, especially at this stage in my life where photography to me is not professional.

Thanks, Rob.

Thats awesome
Might take a trip there sometime, if I'm ever up in Scotland, and nearby.

Personally, I dont think I've ever had to edit out CA from my photos, and I use the kit 18-55, and the 50mm F/1.4 lenses.
It all depends on what your shooting, but from what I have seen, edges of dark/light boundaries, in usually natural light, is where it occurs most?
Even though it is an annoyance, unless you have images of trees with CA, or something else complicated, it is quite easy to edit it out.

Oh, and Niblue, where is that photo of the lighthouse taken? Is incredible

The topic of light is pretty much completely open ended, since light has to enter the lens
So unless someone submits an image with their lens cap on, it follows the theme heheh

Yes, I have found that my favourite pictures taken with my 10-17 are ones that dont include straight lines and therefore, no distortion, just incredible wide angles to fit in my subject

Oh I completely agree, I didnt set out taking the shot knowing I was going to correct it, it just seemed to work when i did!

And as for fisheyes being not the easiest to use, its certainly different, you have to look at things with a complete new attitude - thinking about the 170 (its 180 diagonal) degree effect.

Although, why would I want to crop out that forground plant, and distort it more?
And would I really want the horizon dead centre?

Plus Id say the zooming effect of the clouds on the corrected one looks pretty good

I did infact not take the shot thinking of having it corrected, so that is why - i just did it for the sake of it. But when you can see a straight horizon, i personally dont like the fact the world is round

I shall be taking a trip into the city (Liverpool) tomorrow, and taking some building shots with it, so ill keep this thread updated with some corrected versions?

I too tried out PTlens - the trial is good though it took me 3 tries out of the free 10 to get something right

Here is a comparisson between fully post processed, distortion corrected (left), and fisheye (right)

My 10-17 should appear on my doorstep tomorrow, if the order stated the truth - I shall post some images on this thread to show you what I think of it when i have the time.