[retired2007]

hope i am in the right fourm. was inquiring if the Pentax 1.4x HD PENTAX-DA AF Rear Converter works with the k1 and the newer lenses, 70-200 2.8 ?? ect?
thanks
also i have saw a lot at cheaper prices on e bay from japan , are they worth the extra savings??

[Adam]

The DA teleconverter is not designed for use on full frame, and will cause vignetting.

There's nothing wrong with getting the same unit for less on ebay (if you don't expect a warranty), though.

If you want autofocus in a teleconverter for FF, this one would be my recommendation until Pentax releases a proper one:
Tamron-F 1.4X Pz-AF MC4 Lens Reviews - Miscellaneous Lenses - Pentax Lens Review Database

[WPRESTO]

You might also search EBAY for the long-discontinued Kenko AF converter. Only screw-drive, but the IQ is pretty decent. However, they aren't common in K-mount.

[retired2007]

The DA teleconverter is not designed for use on full frame, and will cause vignetting.

There's nothing wrong with getting the same unit for less on ebay (if you don't expect a warranty), though.

If you want autofocus in a teleconverter for FF, this one would be my recommendation until Pentax releases a proper one:
Tamron-F 1.4X Pz-AF MC4 Lens Reviews - Miscellaneous Lenses - Pentax Lens Review Database

will the tamron work with the k1?

[Adam]

will the tamron work with the k1?

Yes it's full frame.

[tduell]

The DA teleconverter is not designed for use on full frame, and will cause vignetting.

Yes, it does cause vignetting, but it may be quite minimal and acceptable.
I use the DA converter with the D FA 150-450 on the K-1 and the results are quite acceptable for me.
It may be useful to see an example of the vignetting with the lenses you have in mind.

Cheers,
Terry

[gatorguy]

You could also watch for the full-frame Pentax 1.7AF which appears from time to time in the Marketplace. I have both it and the Tamron 1.4 and don't notice any particular image quality differences. They are also very "stackable" with a faster telephoto like the *200.

I also have the full-frame 2X Kenko from back in the day but haven't had as much success with it.

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Last edited by gatorguy; 09-24-2017 at 08:10 AM.

[Des]

If you are looking at 3rd party teleconverters, you should note that there are models that seem to have a similar name, but are quite different, and models that have completely different names that are actually the same. For example, I have the Kenko pz_AF 1.5x Teleplus SHQ. There are two versions of this very model, one (the one I have) which magnifies 1.4x and another which magnifies about 1.6x: Teleconverter magnification comparison. (5 imgs): Pentax SLR Talk Forum: Digital Photography Review And it seems the one I have is the same as the Tamron-F 1.4x Pz_AF. The "pz" designation indicates that the TC will (theoretically) drive a lens with HSM/SDM autofocus, although it must be said that user reports of the effectiveness of this combination seem to range from fair to unusable. But I only use mine with screw-driven AF lenses, and it is quite good.

The Pentax DA 1.4x is the only K-mount TC that is weather-resistant, works with all AF systems used on Pentax and third-party K-mount lenses (screw-drive, DC, SDM/HSM and PLM), and is the only one that communicates the effective focal length to the camera (for EXIF and SR purposes). Many people have lamented that Pentax have not made a model with FF compatibility.

[retired2007]

If you are looking at 3rd party teleconverters, you should note that there are models that seem to have a similar name, but are quite different, and models that have completely different names that are actually the same. For example, I have the Kenko pz_AF 1.5x Teleplus SHQ. There are two versions of this very model, one (the one I have) which magnifies 1.4x and another which magnifies about 1.6x: Teleconverter magnification comparison. (5 imgs): Pentax SLR Talk Forum: Digital Photography Review And it seems the one I have is the same as the Tamron-F 1.4x Pz_AF. The "pz" designation indicates that the TC will (theoretically) drive a lens with HSM/SDM autofocus, although it must be said that user reports of the effectiveness of this combination seem to range from fair to unusable. But I only use mine with screw-driven AF lenses, and it is quite good.

The Pentax DA 1.4x is the only K-mount TC that is weather-resistant, and the only one that communicates the effective focal length to the camera (for EXIF and SR purposes). Many people have lamented that Pentax have not made a model with FF compatibility.

here's what i have , a k1 with the 70-200 2.8, i also have the old 55-300 which on a clear day is a great lens. i have a k20d that i am using the 55-300 on and it just isn't there . would like the converter for both the k1 and am looking in to a k3ii.

[Des]

here's what i have , a k1 with the 70-200 2.8, i also have the old 55-300 which on a clear day is a great lens. i have a k20d that i am using the 55-300 on and it just isn't there . would like the converter for both the k1 and am looking in to a k3ii.

I assume you mean the DFA 70-200 f2.8? That one uses DC autofocus, rather than screwdrive. I tried my DA 18-135, which also has DC AF, with the Kenko (with the pz contacts) and it does work. I'm not sure that a TC without the pz contacts will work with any AF lenses other than ones with screw-drive AF. Other people will be able to confirm that.

As for the 55-300, the screw-drive versions (not the PLM version) will work with any AF TC. But you need to bear in mind that a 1.4x TC will cost you one stop of light - so the maximum aperture of f5.8 at 300mm becomes, in effect, a little narrower than f8. Not to mention that that lens benefits from stopping down, especially at the long end, so you may need to be somewhere in the region of f11 or so. And if you are using it for moving subjects like birds, where faster shutter speeds are also required, you will need good light to allow these settings. (Maybe the K-1 would be better than the K-3 series in this regard, because of its superior high-ISO performance.) On most cameras the autofocus is likely to be unresponsive or hit-and-miss at such narrow apertures when the light is less than excellent. And of course a TC is only as good as the lens it's used on - I also have the 55-300 and while it's very good for a consumer zoom, it's no match for my FA*300 f4.5. Personally, when it comes to using a TC with the 55-300, I wouldn't find the game worth the candle.

Nevertheless, a number of people have successfully used the 55-300 with a TC. If you search the forums you will find plenty of examples. By all means try it, but don't expect it to work well every time.

[Unregistered User 8]

Hi Lee. The HD DA 1.4x rear converter will work beautifully on the K-3 II should you get it, but I am curious why you want a 1.4x converter with your K-1 as it has 1.5x crop mode with no loss of light or resolution.

[retired2007]

i am sorry but not a professional, just a hobbyist, are you saying that if i use my crop sensor lenses on the k1 i will still get the crop factor, my 55-300 on the k20d is equal to a 450mm, so if i put on the k1 i will get the same 450 equivalent? i would like to get a long lens but cant swing right now.

[aslyfox]

i am sorry but not a professional, just a hobbyist, are you saying that if i use my crop sensor lenses on the k1 i will still get the crop factor, my 55-300 on the k20d is equal to a 450mm, so if i put on the k1 i will get the same 450 equivalent? i would like to get a long lens but cant swing right now.

have you seen this:

Pentax K-1 Review - Introduction | PentaxForums.com Reviews

[Unregistered User 8]

i am sorry but not a professional, just a hobbyist, are you saying that if i use my crop sensor lenses on the k1 i will still get the crop factor, my 55-300 on the k20d is equal to a 450mm, so if i put on the k1 i will get the same 450 equivalent? i would like to get a long lens but cant swing right now.

HI Lee, no apologies needed as most of us are " hobbyists." But yes, using the crop mode on your K-1 will give you the field of view of a 450mm lens. Give it a try and see what you think of the results.

[surfar]

I own both early versions of the 55-300,(Not the PLM version)...i dont own the DA1.4x TC.However, the Sigma and Kenko(lots of other names) 1.4x TCs work fine in good light.
A word of warning though, theres a TC by Sigma that is restricted to a few Sigma lenses.Read all the reviews of TC 1.4x AF and you will get an idea of whats out there.

The Pentax is the only one with WR.