Old & New Lens for Pentax

Hello i have a Pentax k100d, and I want buy a tele/telezoom for this camera but I have not too much money.

Taking advantage of my Camera´s possibilities, to mount any old lens for pentax, and the cheap price of these, im interested in Screwmount lens, as in bayonet K cheap lens, manual or autofocus system.

I listed some lens and the prices that I have obtained of the same one. I hope your recommendation. Thank you Very very very much!!!

Asahi SMC Pentax-M 80-200mm f:4.5 u$ 70
Takumar-F 70-200mm f:4-5.6 u$ 140
Super Takumar 200mm f:4 u$ 90
Tamron 70-210MM f:3.8-4 adaptall u$ 80
Tamron AF 70-300MM f:4-5.6 tele-macro u$ 75
TOKINA AF 75-300MM f:4.5-5.6 u$ 80

SMC Pentax FA-J 75-300mm f:4.5-5.8 AL u$ 160
SMC Pentax DA 50-200mm f:4-5.6 ed u$ 280 new
Sigma 70-300 f:4-5.6 DG APO Macro u$ 230 new
Tamron AF 75-300mm LD Macro u$ 150
Tamron AF 70-300mm f:4-5.6 Di LD Macro u$ 185

All prices include aprox u$35 of postage and handling.

And Does someone know the performance of these lenses above?

SMC Pentax A 80-200mm 4.5-5.6
SMC Pentax FA 80-320mm 4.5-5.6
SMC Pentax FA 100-300mm 4.7-5.8

Thank you very much!

The only one I can comment on is the SMC Pentax FA 100-300mm 4.7-5.8 and I'd recommend giving that one a miss.

The only one of those listed that I use is the Tamron 70-300 f4-5.6 Di LD Macro. I don't use long focal lengths very often so I was loath to spend a lot of money on one (the Tamron retails for £119 over here) but I'm certainly not disappointed with it.

It's not the best lens I own, at 300mm and wide open it's a little soft but if it's stopped down to around f8 and used at the 200mm mark then it's actually a very good performer! The macro, whilst not true 1:1, can also come in handy when magnifying small items with a reasonable stand off.

It feels well built (in a plastic-type way of course) and is relatively light to carry - the only minor gripe would be the rotating front element when focussing; if you're the sort who uses circular polarising filters then you may wish to look elsewhere.

All in all, you get a lot of lens for your money and it's certainly capable of producing excellent results once you learn to work within its limitations. Would I buy the same lens again? In a heartbeat!

Just to back up what I said above, a picture taken with the Tamron on my K10D earlier this week.

This was shot at 260mm / f5.6 / 1-180sec / iso800 and has had no adjustments other than to be converted into jpeg in CaptureOne and then "saved for web" in Photoshop.

Despite this not being taken at the "sweet spot" of the lens I don't think it's too bad...

I have the Pentax FA 80-320. At 320 wide open it isn't that good, but backed off and stopped down a bit it's capable of some pretty good results. I've never used any of the others to compare it to.

I got the SMC Pentax FA-J 75-300mm f:4.5-5.8 AL.

Overall I'm very pleased with the performance so far. AF is very fast - but a bit noisy...

Compared to the price - you get a lot.