New Lens

I'm Looking at getting a new lens in the 16/17- 50/70 F 2.8 range.
Your thoughts would be most welcome.

I see from your signature that you have (had?) a Pentax 18-135. What is it you are looking for in a new lens that would be different from that lens?

For the F 2.8
I’ve a early Tamron 17-50 which I’m looking at replacing.

Okay, that makes sense

Might be worth considering one of the older Pentax 16-50 F2.8 SDM lenses - particularly if you don't mind a screw-drive converted model (the SDM motors were prone to failure after some time), I still have mine that I use on a K5IIs and have always been very happy with the IQ and the weather sealing. These lenses used to be quite expensive but used good condition copies have come down in price over the last few years.

Sigma do one....

Here's one on FLEABAY

According to the REVIEWS it's a good lens.

Would also like it to be WR.

PM'd

The best option is the HD DA 16-50mm f/2.8 - it's very expensive but your only option if you need WR. Avoid the old SDM one as the motors are very dodgy and the optics sub-par. That leaves the Sigma 17-50mm f/2.8 which is a wonderful lens though not WR. The Tamron rquivalent is also good but with worse build quality, screw-drive AF and QC problems, so check focusing and de-centring if buying. If a slower lens is an option then the DA 16-85mm is excellent - great range, very sharp, good colour and contrast.

Can't agree on the optics of the SDM 16-50/2.8 being "sub-par"! They may not be up to the standard of the newer version but the results I have had have been excellent, many shot at maximum aperture too

Can't agree on the optics of the SDM 16-50/2.8 being "sub-par"! They may not be up to the standard of the newer version but the results I have had have been excellent, many shot at maximum aperture too [/quote]
Couldn't agree more. the older and much maligned by some (maybe a bad copy unluckily) DA* 16 50 is a super lens and renders beautiful Pentax colours and richness in many types of disciplines
All this talk of edge sharpness and such is insignificant when the image captured is of a high standard, it will positively glow
very good prices for used examples and even cheaper if you buy one with SDM failed and convert to screw drive yourself