[reh321]

I want a teleconverter that turns an APS-C lens into full frame at the same time as it adds magnification.

This will, of course, be the opposite of a ‘booster’.
The same amount of light would be spread over more area, resulting effectively in a ‘larger’ {numerically} aperture than the lens is set for.

[davesofnj]

The same amount of light would be spread over more area, resulting effectively in a ‘larger’ {numerically} aperture than the lens is set for.

But this happens whether or not the teleconverter is FF. And experience with the current offering says that the results are perfectly acceptable. The issue as I see it is how much more expensive would the glass be to make a FF teleconverter. If it existed, I would take it out with my 300mm prime lens and use it at 420mm for my bird photography. While the 150-450 gives 630 mm, it is so much heavier and often provides more zoom than I need (although there are times when it's the only choice due to the distance of a bird; but in those cases, it's rare to get a really useful photo other than for documenting a rare sighting).

Dave

[mlag]

I can't find info about how well this set focuses with such low effective aperture. Can anyone share?

Recently acquired the 150-450. Out of curiosity, I tried it with 1,4x TC and was amazed how swift both tc+lens focused, no hunting in low light, much better than with my old 55-300 f5.8 WR. Even in the current, grey winter weather..... pictures also quite decent, even in low light conditions of cloudy rainy days. I need time and good weather to investigate furter - lower iso than 3200 and shorter shutter time than 1/15 (handheld) should improve my first pictures- but it was above expectations and very promising.

On k3 II.

[gatorguy]

Curious if anyone has personal experience with trying to pair the Pentax Rear Converter-A 1.4x-L and 150-450? I know it works well with the *200, but not the *300. I've seen no comment whatsoever on the DFA150-450

[davesofnj]

Curious if anyone has personal experience with trying to pair the Pentax Rear Converter-A 1.4x-L and 150-450? I know it works well with the *200, but not the *300. I've seen no comment whatsoever on the DFA150-450

I've used the combination with my K-1 II for years. Works well except for the vignetting, but most of the time I crop that out anyway. That's why I was so interested (earlier in this thread) in a FF teleconverter.

Dave

[gatorguy]

I've used the combination with my K-1 II for years. Works well except for the vignetting, but most of the time I crop that out anyway. That's why I was so interested (earlier in this thread) in a FF teleconverter.

Dave

So performance is good? Probably pushing my luck to ask, but have you compared images with the far newer Pentax HD1.4?

[davesofnj]

So performance is good? Probably pushing my luck to ask, but have you compared images with the far newer Pentax HD1.4?

I didn't realize there'd been more than one version of the 1.4x. As far as I know, the HD 1.4x is the one I'm talking about. I recall paying close to $600 for it soon after it became available. It's under $400 these days.

The metric I used, albeit somewhat subjectively, was that if the same quality could be achieved by simply enlarging the image by 40% in Photoshop then there was no point in buying the teleconverter. It was clearly superior so I regarded it as a very good buy. In those days, I had a K-3, so the APS-C limitation wasn't a big deal. But then I got a K-1 and FF became desirable.

Dave

[joehenryd]

In the days of manual focus, there were the 1.4x-l and 1.4x-s as well as 2x-l and 2x-s. The L versions were for the F* 300 2.8 and F* 600 4. The front elemnets on the L stuck above the mount. This was done to decrease the distance from the rear element on the lens that was recessed and the converter lens. Joe

[wadge22]

The L versions were for the F* 300 2.8 and F* 600 4.

They were usable with more lenses than just those two. From the database entry for the 1.4x-L TC:

Supported Lenses:

• SMC Pentax-DA* 200mm F2.8
• SMC Pentax-FA* 200mm F2.8
• SMC Pentax-A* Macro 200mm F4
• SMC Pentax-A* 300mm F2.8
• SMC Pentax-FA* 300mm F2.8
• SMC Pentax-A* 400mm F2.8
• SMC Pentax-A 400mm F5.6
• SMC Pentax 500mm F4.5
• SMC Pentax-F* 600mm F4
• SMC Pentax-FA* 600mm F4
• SMC Pentax-A* 600mm F5.6
• SMC Pentax 1000mm F8
• SMC Pentax A* 1200mm F8
• SMC Pentax 135-600mm F6.7
• SMC Pentax F* 250-600mm F5.6
• SMC Pentax FA* 250-600mm F5.6
• SMC Pentax 400-600mm F8-12

They are manual focus only, and if used with an autofocus lens like an F, FA, or DA series lens, will make it work the same as an A series lens (manual focus only, no exif data or focal length communication).