Teleconverter for DA* 300mm

Hello

I'm in the market to buy a 1.4 teleconverter for my DA* 300mm f.4.

BUT which one is best ? that is which converters work smoothest with the lens, and which gives the best picture ?

I write smoothest because, some converters doesn't allow for AF, and Sigma's doesn't work with the glass elements ???

SO, hope I didn't confuse everyone, but myself..

As I can se, there's

1. Sigma 1.4
2. Tamron 1.4
3. Tenko 1.5
4. Tokina ?

but which should I choose for my 300mm ?

Hi Leech - I don't have a huge amount of experience with teleconverters but I have a DA* 300 and have often thought about trying to extend it a little...

I believe that the Sigma TCs are designed to exclusively work with sigma lenses so you may find that is not the best choice.

You'll need to check the specifications of the candidate TCs in detail... The DA* lens is an SDM lens so if you want to retain autofocus you will need a TC which supports SDM focussing... and you'll also need one with the contacts in it to enable the automatic aperture control as the lens has no aperture ring. If you look up the relevant TCs on the web (e.g. on the Tamron webpage, Sigma webpage etc.) you'll probably find the details of what lenses the TC is compatible with and whether it is 'dumb' or not..

Don't know if that helps much - am sure others here will know more than I...

Regards

Mat W

The Pentax 1.7 works a treat!.......

Sigma 1.4 will not work (SDM)
Tamron 1.4 will work if you get the one with the correct contacts and is pretty good.
Don't know anything about the Tenko 1.5
As far as I know the Tokina is 2x and maual focus.

Don't forget the Pentax AF 1.7x .. best of the bunch IQ wise in my opinion.

If you really want a top notch TC for that lens try looking for the Pentax 1.7 Adapter. Its a fantastic one and will extend your 300mm into 510mm. This Adapter will also convert MF lenses into AF, but you will have to nudge it first closer before it then AF for you.

Only problem is they are a bit expensive, if you can find them.

Hope this helps, but I am no expert so others might be able to give you a better advice on this

Hi Leech, I have the DA*300/4 with several TC's, the Sigma 1.4 EX does not support SDM at present. I've been using a Kenko 1.5x SHQ (rebadged Teleplus) with good results and also a Teleplus 1.7x SHQ with the subsequent loss of a little sharpness and contrast. Both support SDM, quite often the combination hunts either side of the subject but locks on nicely after a manual tweak using quick shift. I heard the Tamron 1.4x was better, but performs in exactly the same manner regarding AF. I must stress I was using the lens hand held, AF seems more accurate/positive from a good tripod. Overall I'm pleased with the results, however the camera (K20D) still assumes you have a 300mm f/4 mounted therefore SR is not optimal. IMHO there's no substitute for a fast shutter speed when shooting wildlife anyway! The following was taken with the DA*300/4 and 1.5x TC:

https://www.pentaxuser.com/photo/kingfisher-17187/large

John

I have the DA*300 and a Tamron 1.4 Pz-AF.

The SDM is absolutely spot on without the TC, but with it, it will hunt a lot and actually lock on probably no more than 1 in 4 attempts even on bright subjects. The IQ seldom matches a crop from the lens alone or a shot with my Sigma 150-500.

I'm quite happy with the IQ of the combo, you're comment on the Sigma 150-500 is of interest as I need something longer than 300mm, hence the use of TC's. I was seriously considering the Sigma 120-400 APO HSM but have some reservations, I'd really like a Sigma 400/5.6 APO Tele Macro, but they're hard to come by. What I'd really like is a Pentax SDM 1.4x TC or DA*400/5.6, nothing faster as I can't afford it

John