my uncle lives on Vancouver island, so we're going to visit him and his new family. I can't wait, Its the most beautiful place I've ever been.

I've hand held my 200m M series prime on a 2x TC (400mm F8 ) with a pretty good success rate, it just lacks some contrast. I also have a walking stick with a camera thread on the top for some much needed support, so hand holding would literally be for when its that or nothing.

I'm still torn between the 170-500 which fits right on the top end of my lens collection, and the 135-400 which I feel I can reasonably hand hold throughout its range.

I am going to Canada for a holiday next Easter,

this is still a way off but my finances demand that I start saving for these things early!

Basically I am concious that the last time I was there 320mm was not always long enough. Since then I have gone to a *ist DL2 with 50-200 as my longest truly good lens. Technically I could mount the 80-320 but the 50-200 is so much better that it's not really worth it.

So I am thinking of adding to my current twin lens kit. The current contenders are

Sigma 135-400 - Perhaps a little short, but the cheapest option
Sigma 170-500 - focal length right on the money
Sigma 50-500 - a bit pricey but from its reputation, just wow!

Any alternative suggestions would be greatfully received, but keep in mind that I am not a rich man and the above are already pushing the limits of what I can justify, the 50-500 particularly.

Does anyone have any experience of the above or similar lenses? I need something that can be hand held at need, and which can be carried around all day. I am no stranger to carrying heavy lens kit bags but I like having two shoulders the same height off the ground if you see what I mean!

that deffinitly supports the theory that this is solely to provide the juice for the SSM then, sensible I suppose since there is already the provision on the mount.

thats basically my line of thinking too. Still at least it will keep me from being tempted by the new lenses!

Oh and Pentax do (or did, I guess probably not anymore) make both M42-K adaptors and 645-K adaptors. My M42-K ring is a genuine Asahi Pentax item.

The thinking might well be that those who want DA* lenses probably have a K10D anyway, and they are probably right.

I'm guessing its another Pentax/Tokina joint project. I am also interested if these lenses will work with the older bodies. I suspect the reason Power Zoom has been resurected on the K10D is to provide power for the SSM, so nothing in the consumer MZ or *ist series will be able to power the new motors (though perhaps the Z series will??), but will there be some sort of pass through to allow focus drive by the old method?

The Nikon USM lenses don't work with old Nikon AF bodys, but Pentax backward compatibility has always been a cut above Nikon so who knows.

thanks for the link, I have been thinking about replacing my 18-55 for a while (though not too desparatly as Pentax saw fit to give us the best of the "kit" zooms) and these two are both on the list of possibles

Since you already have the Tamron which has a great reputation and gives you better reach and speed than the Sigma can manage, I really don't think theres a contest here. The 16-45 wins hands down, with better wide angle and pretty much unparalleled image quality from what I hear.

It might also be worth thinking about something really wide like the Pentax 12-24 if you can afford it. That way you aren't doubling up on focal lengths in the same way as you will with the 16-45 28-75 pair. edit: oops just saw your £200 max, thats pretty much out of the question then!

just to jump on the bandwagon here, I am also interested in this Sigma and also its bigger brother the 170-500.

It is a long range sure, but I've never seen a sharper lens with the possible exception of my SMC-A 50mm 1.7. The DA 50-200 beats my Tamron SP 90mm Macro and SMC-M 200mm F4, I only use the primes for speed or (in the case of the macro) close focusing.

Such quality in such a small light package and at such a price is rare.

nice choice of camera and zoom pair, you wont be disapointed with that little kit. I'm quite green with envy.