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PENTAX AF ADAPTER 1.7X

Mike-P
Posted 30/03/2023 - 13:43 Link
For sale is my Pentax 1.7x adapter. I recently purchased this to use on my Irix 150mm macro lens but for some reason it doesn't attach which is very strange as it's fine on every other lens I own.

Comes as pictured, even has the manual which is very unusual to find. 225 incl UK postage.

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Lubbyman
Posted 30/03/2023 - 18:45 Link
I've been through the same head-scratching exercise and did work out why it doesn't attach. Can't remember now, though, except that the Irix mount differs from the current K mount in a subtle way that doesn't matter with Pentax digital cameras or the Pentax 1.4x converter but does for this adapter from the F-series era. Thankfully, the Irix wasn't the only reason why I got the adapter .

The adapter also won't attach to the Laowa 25mm 2.5-5x macro, but I tried that just out of curiosity rather than thinking it might be even remotely useful!

Steve
Mike-P
Posted 30/03/2023 - 19:29 Link
After a bit of thought I did get it on the Irix using one of the small extension tubes in-between but it seems the lens is also missing a pin which means through the viewfinder it's really dark and so impossible to focus.

As you say though, it's fine with the 1.4x
Lubbyman
Posted 30/03/2023 - 20:25 Link
Just checked the lens and 1.7x and remembered why they don't attach. The reason is in a new thread in the 'Lenses for Pentax cameras' section in case it's useful to anyone. In a nutshell, Irix didn't bother with ensuring compatibility with equipment that pre-dated the 'crippled K-mount' (introduced with later film cameras). Pity.

Steve
davidwozhere
Posted 03/04/2023 - 00:26 Link
Well stick an A series 50mm macro lens on it. You get a stunning AF 85mm result. Or a 100mm macro for that matter. Then you won't need a fancy 180mm Sigma.
Both the *istDS and the K5 are incurably addicted to old glass

My page on Photocrowd
Lubbyman
Posted 03/04/2023 - 20:00 Link
Mike-P wrote:
After a bit of thought I did get it on the Irix using one of the small extension tubes in-between but it seems the lens is also missing a pin which means through the viewfinder it's really dark and so impossible to focus.

As you say though, it's fine with the 1.4x

davidwozhere wrote:
Well stick an A series 50mm macro lens on it. You get a stunning AF 85mm result. Or a 100mm macro for that matter. Then you won't need a fancy 180mm Sigma.

Or you can attach the 1.7x to the camera, then the 1.4x, and finally the Irix 150mm to give a 357mm f7.1 macro. It works - even the AF. Here's the proof of principle. 30cm from front of lens to eye, the white of the eye is 6mm diameter. Please don't try to judge the IQ of the stacked TCs from this image. The camera was on a tripod with wireless trigger and 3 sec delay but the tripod was on a carpet and I know from other shots that some vibrational blur can sometimes be seen.

One thing is clear, though - the DOF is very, very thin. Anyone care to try it handheld ?

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Are you still wanting to sell the 1.7x, Mike-P ?

Steve
davidwozhere
Posted 04/04/2023 - 00:48 Link
Blessed daft things we try!
Both the *istDS and the K5 are incurably addicted to old glass

My page on Photocrowd
Mike-P
Posted 30/04/2023 - 16:57 Link
Sold subject to payment.
Mike-P
Posted 30/04/2023 - 20:13 Link
And paid for.

Thanks for looking.
Cayman
Posted 04/05/2023 - 16:56 Link
And arrived - very well packaged and in beautiful condition and exactly as described. Thanks Mike!
Mike-P
Posted 04/05/2023 - 18:36 Link
Thanks for letting me know Rod, hope you get more use out of it than me

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