[David&karen]

Hi everyone! What are the best options for a 1.4 to 1.7 tele-converter for the DA* 300mm? I see Pentax makes them on their webside, is that a good choice? Thanks for all your input!

David

[Lowell Goudge]

Hi everyone! What are the best options for a 1.4 to 1.7 tele-converter for the DA* 300mm? I see Pentax makes them on their webside, is that a good choice? Thanks for all your input!

David

I am a little confused by yout post, and even went back to see on the pentax site they list teleconverters, and cant find one.

I do know that they still reportidly are making the SMC-F 1.7x AF converter, which is a teleconverter with movable elements providing AF capability for manual lenses.

I have an origonal one from the 1990's which works very well with my SMC 300F4 lens, and would work equally well with any newer pentax 300 mm lens.

Note that this converter will leave the lenses autofocus disabled, making it a semi AF lens, where you manually focus to a close focus and the converter does the rest.

the big plus with this converter is it has sufficient electronics to report hte true aperture back to the camera, a must for using P-TTL flash.

[David&karen]

Actually the Pentax 1.4 tele-converter is on their webstore for lenses, page 4 link:PentaxWebstore smc Rear Converter A 1.4xL

[steve1307]

The rear converter listed in the webstore is manual focus only when you see the "features" tab.

The Pentax F 1.7 AFA works with any Kmount for AF. You can't use it for "catch in focus" because it hasn't got an AF/MF switch
The Kenko 1.5x PZ_AF Teleplus SHQ has the contacts which allow SDM to work. Opinion is divided on how well or how reliably it locks focus. You can use it for "CIF" because it is using the lenses SDM which can be switched AF/MF.
The Sigma APO "DG" TCs which are the current ones don't work. I'm not even sure they fit.

There is one expert on TCs for Pentax long lenses over at the other forum dpreview. There are many posts on this topic by Ron Brandon aka "brandrx". He has about 16 different TCs in his collection.


by Tapatalk

[GaryH]

I have the DA*300 and can report that both the Kenko and Tamron 1.5, 1.4x teleconverters with the PZ contacts will focus after 3 or 4 button pushes. That was not acceptable to me and I ended up with the Pentax AFA 1.7x. It was expensive but it works great. You have to prefocus manually then the AFA takes over . Sounds like a hassle but it works very well. The image quality using the AFA is nice too. Right now the AFA seems to be the best teleconverter solution for the DA* lenses.

[Lowell Goudge]

I have the DA*300 and can report that both the Kenko and Tamron 1.5, 1.4x teleconverters with the PZ contacts will focus after 3 or 4 button pushes. That was not acceptable to me and I ended up with the Pentax AFA 1.7x. It was expensive but it works great. You have to prefocus manually then the AFA takes over . Sounds like a hassle but it works very well. The image quality using the AFA is nice too. Right now the AFA seems to be the best teleconverter solution for the DA* lenses.

Actually, for anyone who uses a 300+ lens for wild life, the AFA is a great option because it gives you a focus range, and the AFA is very fast to focus if the subject is in the AF range. it is great for isolating the subject against confusing foreground and background because the AF simply can;t go and focus on the out of focus things.

[cem.kumuk]

You have to prefocus manually then the AFA takes over . Sounds like a hassle but it works very well. The image quality using the AFA is nice too. Right now the AFA seems to be the best teleconverter solution for the DA* lenses.

Can you please share some images that you take with Pentax AFA F/1.7x? Also, when you’re saying “pre-focusing” do you mean turning the AF/MF function of the lens into MF and manually focus in the object with focusing ring of the lens and fine AF adjustment is done by the AFA? If so, it sounds like its an operation something in between MF/AF. I’m very curious about the image quality especially in difficult light conditions. I’ll appreciate very much if you may share some samples.

[GaryH]

Can you please share some images that you take with Pentax AFA F/1.7x? Also, when you’re saying “pre-focusing” do you mean turning the AF/MF function of the lens into MF and manually focus in the object with focusing ring of the lens and fine AF adjustment is done by the AFA? If so, it sounds like its an operation something in between MF/AF. I’m very curious about the image quality especially in difficult light conditions. I’ll appreciate very much if you may share some samples.

regarding the focusing switch. I generally turn the lens switch to MF but the AFA converter will work with it either on or off. The AFA actually moves its lens elements to focus and cannot move enough to focus a large lens through its entire focus range. You have to prefocus manually and the AFA will sharpen up the focus then you half press the shutter button. Sounds a little complicated but actually becomes second nature rather quickly. Generally I set the manual focus of the lens to infinity and I don't have to do much after that, the AFA will be able to bring the subject into sharp focus from there.
I originally bought the AFA 1.7x to use on our vacation with the DA*60-250 and I was pleased with the results with that lens. Now I am wondering if the DA*300 and afa 1.7x combo might be good enough for me to use that instead of my Bigma..

Here are some shots.

[cem.kumuk]

Thanks a lot for the very helpful answer Gary. I've sold my Bigma a week ago in order to buy something better. In the quest of such a lens finally I decided to go for DA*300mm. I made very nice shots with my Bigma as well but my performance with that lens was not consistent enough due to the difficult handling of the lens from the point of dimension and weight. Now I beleive I'll get rid of these problems with my new DA*300mm.

[GaryH]

I tend to agree with you. I have been contemplating selling my Bigma also. The DA*300 is one fine lens.