tele converters
telephoto. Your better off with a 1.4 to 1.7x
for telephoto. Which lens is it for?
Half Man... Half Pentax ... Half Cucumber
Pentax K-1 + K-5 and some other stuff
Algi
Shouldn't really use a teleconverer on any lens over f/4 really.
PPG Wedding photography Flickr
Concert photography
Currently on a Pentax hiatus until an FF Pentax is released

phill
k1 k5iis superA
8mm fisheye pentax da 12-24 sigma 15mm tamron 17-50 tokina 20-35 pentax fa 24-90 tokina 28-70 atx pro
Pentax A 135 sigma ex dg 100-300 f4 pentax fa 50 1;1;7 pentax A 501;1;4 pentax A200f4 sigma 70-200 apo ex 2.8 sigma af 400mm pentax 1.7 af adapter
Pentax af aw 1.4 rear converter and a flash
It's also manual focus only so wouldn't give you auto-focus on the FA 80-320mm.
Generally speaking the 7 element converters are better than the 4 element ones, and amongst the 7 element ones I have generally had good results with the Teleplus MC7 and my best results have been with the Pentax A 2X-S. The Pentax A 2X-S was designed by Pentax for lenses up to a focal length of 300mm (there is a 2X-L for 300mm+ lenses). I did own a Macro Converter a long time ago but replaced it with Macro lenses soon after.
Quality does tend to reduce the longer the lens (as milamber said - used with a 50 they are very good) and with a zoom the top end is quite often not as good as the shorter end anyway even without a converter.
LennyBloke
Results with my mirror lenses have certainly proved better for distant work. I've had both 500mm & 600mm mirror lenses, while neither were a patch on the Bigmos (Sigma 150-500) they cost less than the TC your after, and I suspect are about the only reasonable way you'll get beyond 320mm without paying a fortune...
Mike
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Pentax:K5ii, K7, K100D, DA18-55, DA10-17, DA55-300, DA50-200, F100-300, F50, DA35 AL, 4* M50, 2* M135, Helicoid extension, Tak 300 f4 (& 6 film bodies)
3rd Party: Bigmos (Sigma 150-500mm OS HSM),2* 28mm, 100mm macro, 28-200 zoom, 35-80 zoom, 80-200 zoom, 80-210 zoom, 300mm M42, 600 mirror, 1000-4000 scope, 50mm M42, enlarger lenses, Sony & micro 4/3 cameras with various PK mounts, Zenit E...
Far to many tele-converters, adapters, project parts & extension tubes etc.
.[size=11:].Flickr• WPF• Panoramio
I do not have experience with the teleconverters listed above but have a Super Paragon mf 2x converter.
With shorter focal lenses (as mentioned above) it may on a good day be described as ok (maybe) and with my telehoto lenses it is not good in my experience.
It may be that I just can't use it correctly - it may be that it is not a great example of a teleconverter and I have no idea how many elements it has.
However, if you live or find yourselef anywhere near Wrexham we could meet up and try it out if you want to.
Incidentally, it's not an item I intend to list for sale as I doubt it's true worth is much more than (or maybe less) than a decent bag of fish and chips

Regards
Stu
K10D, K5 plus plenty of clueless enthusiasm.
My Flickr site link
A friend at work has the Vivitar Macro Focussing TC, but doesn't use it very much. I would guess it is similar in quality to the 7 element Teleplus MC7 that I own; this is a good quality TC but must be used with prime lenses (I've had excellent results with a 50mm and a 105mm Macro, but it's totally useless with my 55-300). The one you describe is massively overpriced at £85; I would guess it's worth nearer the £40 mark?
Regards
David
Flickr
Nicola's Apartments, Kassiopi, Corfu
Some cameras, some lenses, some bits 'n' bobs
Hi Simon
A friend at work has the Vivitar Macro Focussing TC, but doesn't use it very much. I would guess it is similar in quality to the 7 element Teleplus MC7 that I own; this is a good quality TC but must be used with prime lenses (I've had excellent results with a 50mm and a 105mm Macro, but it's totally useless with my 55-300). The one you describe is massively overpriced at £85; I would guess it's worth nearer the £40 mark?
Regards
David
I was going to say the same in my post, David, but when I checked on Ebay this is a PK A converter, not the usual PK one. 40 pounds would be about right for the PK. Haven't seen a PK A before so 85 might be the going rate?
Still isn't the right converter for the job, though
Regards
David
Flickr
Nicola's Apartments, Kassiopi, Corfu
Some cameras, some lenses, some bits 'n' bobs
PPG Wedding photography Flickr
Concert photography
Currently on a Pentax hiatus until an FF Pentax is released

champywoo
Member
Macclesfield, Cheshire
I don't have available cash for a Sigma 50-500 or 150-500 so thought about a tele converter. One of these are for sale on ebay for £85 or best offer. The seller has described it as having 7 elements in 7 groups, which reading another thread was suggested as being reasonable unlike cheap tcs that only have 4 elements.
I am aware of the two pentax 1.7x converters on ebay, but can't stretch to the price of them.
Any comments wil be greatly appreciated.