Tamron Zoom + Tele Converter - is this bad ?

Hi, just joined the Pentax zoo, just bough a used K10D and my first question is about Tamrons. I have been offered a Tamron 70-350 F4 constant ( its the model before 05A ) If the Adaptall website was working properly, i could post the exact model, but its glitched at the moment.
Anyways, i was wondering if i could use a Tele Con with this lens. Should i only use TC's with a prime lens ? There appears to be several Tamron TC's and i'm getting confused on which is the quality models, and which would or would not work with this lens.
For example there are SP x TC, F system , Non SP standard, so its a bit tricky to know where to start.

Actually its F4.5 constant .. !!

And i think this post might be in the wrong section, but the only other place i saw was Pentax Lenses, and it isnt about a Pentax lens ?

Confused already !

Hi and welcome!

You can add a TC to your lens. However the quality will degrade over just using the lens on its own. Also with the lens, you will only be able to use the meter in manual mode (something I have found with my old tamron 80-210). You will have to go into the menu system on the K10D and make sure you set it to use lens on other than 'A' setting.

I found my old lens lacks a bit in contrast and suffers some fringing compared to the modern lenses.

Hope that helps

Andy

We might pull a few tricks now and then But ZOO, Welcome to the family.

Andy, thanks bud. Yup, i'm with the program on degradation etc. I read and read and keep reading as much as poss all round the net re. Pentax cams and lenses and TC's etc.

I was thinking perhaps that i'd keep the TC down to a 1.4x so as not to lose too much, but the minefield of TC's out there has me foxed, especially the several Tamron models, and whether to choose a Tamron or something else. I presume only Tamron TC's will fit a Tamron lens ? And presumably they go inbetween the K mount adapter and the lens ?

Hi ttk, only kidding. This place looks great. Thanks for the welcome mate.

Pete

Any Pentax K-mount TC will go between the lens K-mount and body (except Ricoh ones which IIRC have a pin, and/ or electrical contacts that are different and can damage the camera). I don't have much experience of TCs myself, however I do recall that in the distant past Tamron made a specific TC that would fit between the Tamron mount and the adaptall mount!

I am sure someone else will be along to give further advice!

Andy

Noted Andy, thanks.

By the way, the Adaptall website is working again, and although looking for my lens is a link to elsewhere, it appears to be working again

http://translate.google.com/translate?hl=en&sl=ja&u=http://www.tamron.co.jp/data...

The Tamron 2x TC is quite nice quality (for a 2x TC), but since that will make your zoom F9 constant you may find it unusably slow. Also some lenses "mind" being teleconverted more than others. I generally only consider a TC when I'm using prime lens of the highest quality (my Tamron SP 90mm and 300mm lenses get the 2x treatment occasionally), but if this is a particularly good zoom then a 1.4x (tamron made one but I don't know how good it is) may produce decent results.

On the metering issue, there is a KA version of the adaptall mount. They are becomming increasingly hard to get and every time I see one for sale the price has gone up, but if you can get one they work nicely with the K10D.

Cheers for that.

Well, reading about Tamron TC's, i havent yet found the definitive answer. On old Tammy brochures, available to view on the Adaptall website, they reckon a Tam TC is best over 90mm. Yet they also state some particular lenses are ok with a TC. EG, the later version 70-350 05A of the lens i'm after. Presumably it has to be used at focal lengths over 90mm but they dont mention this bit. The previous 70-350 model i'm talking about, has no mention of compatibilty with any Tam TC.