[bscott]

Do the Pentax teleconverters allow for auto focus with Pentax lens. This would be the Pentax 1.4 and 2x teleconverters.

[jatrax]

This would be the Pentax 1.4 and 2x teleconverters.

There are no current Pentax TC's. AFAIK all of the legacy ones are manual focus only except for the Pentax-F 1.7x AFA. Which is not really a TC but a auto focus adapter designed to work with manual focus lenses by having the auto focus in the TC body. It is semi-auto focus as you need to pre-focus the main lens and the AFA will finish the job.

There are a few TCs out there, Kenko, Vivitar and Sigma that have an autofocus ability but only for screwdrive, not SDM. There is at least one TC that has SDM contacts but some reports say it is not reliable. The Sigma TC's will only work with some lenses as they have optical elements that may conflict with the lens, there is a list of approved lenses on the Sigma site.

[Adam]

There's a SDM teleconverter on the roadmap which will hopefully be released this year!

[JimmyDranox]

I have a Soligor C/D4 Pz/Af 1,7 Teleconvertor. It has SDM-HSM contacts, but I don't have a SDM lens to test with it, only Sigma HSM, which are known to have problems with AF with teleconvertors. Still, Sigma 50mm 1.4 works with it in good light, but is hunting until it finds focus. With screwdrive lenses is working allright.

There are a few TCs out there, Kenko, Vivitar and Sigma that have an autofocus ability but only for screwdrive, not SDM. There is at least one TC that has SDM contacts but some reports say it is not reliable. The Sigma TC's will only work with some lenses as they have optical elements that may conflict with the lens, there is a list of approved lenses on the Sigma site.

Only available used but the Kenko 1.5 Pz-AF 1.5x Teleplus SHQ works with SDM on my Pentax 50-135. So did a Tamron 1.4 until it got jammed on a Sigma 100-300/4 and had to remove with a Leatherman tool. The plastic body wasn't enough for the weight of the Sigma. No issues with the Kenko, use it all the time.

[Canada_Rockies]

A previous post mentioned that the F 1.7x AF was designed to add AF to manual focus lenses. That is true. But the comment that it is not a teleconverter is not true. It is one of the highest quality teleconverters available. It has all the normal drawbacks, but it is optically superior to most others available. Not all, just most.

[jatrax]

A previous post mentioned that the F 1.7x AF was designed to add AF to manual focus lenses. That is true. But the comment that it is not a teleconverter is not true. It is one of the highest quality teleconverters available. It has all the normal drawbacks, but it is optically superior to most others available. Not all, just most.

Quite correct, I should have said "it`s not like other TCs". And I agree on the quality, it is by far the best I have used.

[JimJohnson]

While there is a place for TCs, for most photographic situations, the photographer is far, far better off to simply crop the digital image. And honestly, the same goes for adding diopter filters to the front of a lens for macro work, for exactly the same reasons.

[Canada_Rockies]

While there is a place for TCs, for most photographic situations, the photographer is far, far better off to simply crop the digital image. And honestly, the same goes for adding diopter filters to the front of a lens for macro work, for exactly the same reasons.

That may be true for cameras with more pixels for telephoto than my K10D, but a 10 mpx body has limited crop room. A letter size print takes 6 mpx or more. I don't see cropping at all for true macro, even if you have 24 mpx to play with.

[JimJohnson]

That may be true for cameras with more pixels for telephoto than my K10D, but a 10 mpx body has limited crop room. A letter size print takes 6 mpx or more. I don't see cropping at all for true macro, even if you have 24 mpx to play with.

I figure 'true' macro will use some form of lens extension rather than simple diopters. My point being that adding inexpensive glass behind or in front of a lens usually degrades the image more than cropping would for approximately the same final composition. And yet, adding inexpensive glass is often the first thing many folks think of doing.

I agree with your point, cropping isn't a universal panacea either, but all so often overlooked as an option.

[Canada_Rockies]

I figure 'true' macro will use some form of lens extension rather than simple diopters. My point being that adding inexpensive glass behind or in front of a lens usually degrades the image more than cropping would for approximately the same final composition. And yet, adding inexpensive glass is often the first thing many folks think of doing.

I agree with your point, cropping isn't a universal panacea either, but all so often overlooked as an option.

I must have misread. I don't use extra glass for close work. I have am M 100/4 macro and a 50mm extension tube that I use to bring the macro to 1:1. I also use it with my M 400/5.6 to come in closer than 5m / 16.5 ft. This is a surprisingly good rig for dragon flies. The field of view comes down to about three dragon fly lengths horizontally.

Closeup lenses have never cut it with me. Using a teleconverter for anything than increasing the reach way out there doesn't do macro for me, either, and I have sold my 1.4X-S recently, I use it so seldom. I have used a reversing mount adapter and M 28/3.5 to get 2:1 macro in the past.