I wouldn't personally go for any of them as they're not wide enough for general landscape use IMHO. Very wide primes are expensive however the Pentax 12-24 or Sigma 10-20 are both good performers. They're both slow compared to primes however that's not such an issue with landscapes as using smaller apertures is preferably anyway.

Can't say anthing about the 100 macro but I've had the 10-17mm fisheye for about a year now and I've been very impressed by it. It is very small and light and therefore convenient to carry despite not being a lens I use a huge amount. Optically it's very, very sharp with great colour rendition -the only downside I've found is a bit of CA but it's not a serious problem.

I'm still learning the best way to use if but I've certainly had some fun so far.

Lovely area - you'll be wanting something wide for all the landscapes though.

I'd definitely suggest the Pentax (or Tamron) 28-200 then. If you buy one 2nd hand on Ebay you should be able to get your cash back on re-selling it so it'd be more or less free.

Where about in Scotland are you going and when? I'm in Edinburgh so if you're in the vicinity I'd be happy to loan you mine as I don't use it much these days.

I had one of their manual focus 28mm F1.8 lenses and it was an excellent performer. I sold it when I bought a 24mm F2 but wish I'd kept it really.

I've had a few of the lower end Sigma zooms (28-80 etc) and wasn't impressed by those however the 10-20mm is very good indeed and I've got one of their 24-135mm FF2.8-4.5's and that's a decent lens.

I've been meaning to pick up one of the APO 70-300's for a while as I've seen some great results from it and the macro capability would be useful. Personally I'd prefer it to the Pentax 80-320 and definitely to the old Pentax 100-300 which I was quite unimpressed by.

Another lens to consider is the Pentax (or Tamron) 28-200. I always found it quite reasonable with film and it also works pretty well on digital as it's weakest performing areas (edge sharpness and some light falloff) and removed substantially by the 1.5x cropping factor with digital.

If you were to save up for a lens then a 70/80-200 F2.8 would definitely be one to consider. I've had one (Tokina ATX-Pro 80-200 F2. for many years now and it's been one of my most useful lenses both with film and digital. I've also had excellent results using it with a decent quality 2x 7-element teleconvertor. Yes the costs are high but worth it (IMHO) in the long run.

For less cash I'd be tempted by one of the better versions of the Sigma 70-300 as they seen to be good performers with a very useful 2:1 macro capability.

As for the FA* 24mm F2 - I used to own one of those in my film days and thought it was a great lens. I sold it when I switched to digital as its usefulness suffers badly with the 1.5x cropping factor and because I had a 20-35mm F2.8 Tokina that while not being quite as sharp or portable did add some versatility. I still mist the FA* 24mm F2 from time to time though, usually on those occasions when I still use film.

I got a Sigma 24-135mm F2.8-4.5 from the US on Ebay for under £100 (well under if I recall correctly) including postage and taxes etc. and I've found that to be a decent performer and a useful general purpose lens - it fits well with the Sigma 10-20mm I use for wide angles etc.

A lot depends on the type of photographs you take. George says above that everyone should own a decent 50mm lense and that's probably more true now that it was with film - I never used a 50mm all that much in my 35mm film days but it makes a decent portrait lens with the 1.5x crop factor of a DSLR. It's also the cheapest way to get a fast low-light lens, something that is often useful. I have a FA 50mm F1.7 that usually lives in my camera bag - it still doesn't get a huge amount of use but it's small and light and easy to keep with me for when it is needed.

With the DSLR I usually now carry the following lenses - in order of most to least use:

Pentax 16-45mm F4
Sigma 10-20mm F4-5.6
Tokina ATX-Pro 80-200 F2.8
Pentax 10-17mm F3.5-4.5
Pentax FA 50mm F1.7

With a 7-element 2x TC those cover the vast majority of my photography, in fact the only other lenses that get any significant use are an FA* 85mm F1.4 (portrait shoots or low-light) and a 55mm F2.8 macro.

With the lenses you currently have what I'd do is to sell the 28-105 and both of the 18-55's and replace them with a 16-45mm F4. That would give you a decent general range when combined with the 28-200 (which I've found quite good on digital as the cropping factor reduces problems with corner sharpness and light fall-off). I'd then try and get a manual focus 50mm cheap (an A 50mm F1.7 perhaps) as even second hand you'll be lucky to get a AF equivalent for under £100.

I've got a DS and a K10D. Unlike John I prefer the handling of the K10D to the DS. Other than that I find the extra pixel count useful when cropping and I've also found the anti-shake quite effective in low light conditions - I was at the Edinburgh Tattoo on Friday night and got some suprisingly good handheld results despite using a fairly slow zoom (16-45 F4 - I just picked up the camera bag without thinking when I should have changed the zooms for primes!).

The main advantage of the DS, which is also a great camera, is that it works with TTL flash - in fact I'm thinking about keeping mine as if I sold it I'd need to get a P-TTL replacement for my AT400FTZ and that'd probably cost more than I'd get the for DS anyway.

Pete - I'm sure you're a nice guy in the real world however your posts on here sometimes don't paint you in a particularily good light and therefore in future you might want to consider either not replying immediately to a post you think upsetting or perhaps typing your reply then pausing for reflection and review before pressing the submit button. The moderators on here have shown considerable tolerance with bad language and insults in your previous posts and I think perhaps you could reward that by focusing more on photography issues and rather less on the personal stuff.

If you want to reply directly to an individual poster then you can do so privately without sullying the forum with nonsense such as this thread. If you've got issues with posting made here then I'd suggest notifying the moderators directly with the nature of your complaint.

All the best
Steve