[cwood]

I apologize for starting a thread on an issue that has probably been re-hashed over and over but I still find contradicting information around the internet so I'm looking for some help to clarify.

I have the Pentax FA*300mm F/2.8

Which teleconverters WILL work with this and maintain autofocus? And which ones are any good?

Does the Sigma 1.4x even fit on this lens?

Does anyone here have this lens or something similar (DA*300mm) that can share their thoughts. As usual we have the problem with Pentax that I can't just go down to the local store and try things out - I have to order things in (from Japan sometimes) which makes getting things right the first time very important.

While trying to balance the boosted zoom with image quality I'm looking at staying away from the 2x TC's and staying with the 1.4-1.7x range.

To contradict the general consensus I do shoot sports photography professionally with a Pentax setup and I'm not willing to sacrifice much in the way of image quality

Thanks for any help in advance

[Richard Day]

I apologize for starting a thread on an issue that has probably been re-hashed over and over but I still find contradicting information around the internet so I'm looking for some help to clarify.

I have the Pentax FA*300mm F/2.8

Which teleconverters WILL work with this and maintain autofocus? And which ones are any good?

Does the Sigma 1.4x even fit on this lens?

Does anyone here have this lens or something similar (DA*300mm) that can share their thoughts. As usual we have the problem with Pentax that I can't just go down to the local store and try things out - I have to order things in (from Japan sometimes) which makes getting things right the first time very important.

While trying to balance the boosted zoom with image quality I'm looking at staying away from the 2x TC's and staying with the 1.4-1.7x range.

To contradict the general consensus I do shoot sports photography professionally with a Pentax setup and I'm not willing to sacrifice much in the way of image quality

Thanks for any help in advance

The Tamron 1.4x AF TC works with the FA*300 f2.8 and f4.5. However I believe it's not available any more. It is generally regarded as the best of the 1.4x TC's if you can find one. I have one that I used with my FA*300 f4.5, I sometimes now use it with my FA50 macro to give me slightly more reach.

The new Kenko 1.5x DG TC also works on the FA* 300 lenses. I've heard that it's pretty decent.

Neither the Tamron or Kenko TC's work properly with the DA* with SDM, the Tamron does allow the SDM to function, but it is hesitant and sometimes fails to lock. Some (all?) of the Kenko 1.5x DG TC's don't seem to have the SDM power contacts in place, so the SDM doesn't work at all.

The Tamron and Kenkos will of course work in manual focus of course.

The Earlier Pentax 1.7x AF TC will also work with your FA*300 f2.8 as it has it's own AF system, you will need to put your FA*300 into the MF setting.

I don't know if the Sigma 1.4x will work with the FA*300's or the DA*300. I do know that it protrudes into the rear of the lens so it may foul the rear elements. I don't know if it has the SDM power contacts either.

If you are using a DA*, I would suggest that you wait for the upcoming SDM rear converter to come out from Pentax.

[Eaglerapids]

I have the DA* 300/4 and a A 2X-S converter. This converter works ok, not awesome, with the 300, manual focus of course, IF you can set up to avoid camera shake. I haven't taken any photos with this setup handheld that satisfy me. For me a tripod and MLU are required, I can't imagine shooting sports with it. I will buy the new Pentax converter as soon as it's available but for some reason Pentax seems to hate me and has decided to punish me by making me wait for the converter as long as they made me wait for the dang 300/4 itself:-).

[John Kovarik]

To (somewhat) echo Richard's comments the Tamron 1.4 is a very good TC; I find it also works with SDM - others will confirm this. There is a performance price though I regard it as a small one but you have to have the right model which is discontinued and not easily found. I have a Kenko 1.5 which also produces very good IQ and which will function with SDM but not as well as the Tamron. A recent entry on the market is the Promaster 1.7 which is very good but will not do SDM. I think it is around $70 -80.............

[cwood]

"Pentax seems to hate me and has decided to punish me by making me wait for the converter as long as they made me wait for the dang 300/4 itself"
True enough. If/When this exists I may get it. For now I need something available.

"There is a performance price though I regard it as a small one"
If I can make a better poster by using a TC than by cropping an image taken without a TC then I don't consider there to be a performance price. Hopefully one of these will help me achieve this goal as I am not in the market for a new $9000 600mm f/4.

"I haven't taken any photos with this setup handheld that satisfy me"
With ~10lb of lens, body, battery and TC I don't plan on doing a lot of handheld. I can only imagine the images would come out a little blurred if I tried.

Thanks everyone for their input. I'm going to see what I can dig up for a Tamron or Kenko