1.4 Converter and Sigma Lens


brigOdon

Link Posted 20/09/2022 - 14:59
Hi all
Can anyone advise if my K5iis, Pentax 1.4 rear converter and Sigma 18 - 35 lens will all work together in perfect harmony or are there some potential pitfalls?

Thanks all

Ian

Mike-P

Link Posted 20/09/2022 - 16:44
If the 18-35mm is HSM then you will probably have problems as the Pentax 1.4x doesn't usually play nicely with Sigmas version of SDM. (having tried on the 70-200mm HSM, 85mm HSM, 24-70mm HSM and 50-500mm HSM)

Saying that when I tried it was all on a newer body so I can't be sure it would be the same
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brigOdon

Link Posted 21/09/2022 - 15:23
Hi Mike,
Yeah that's my experience too, just wondered if I was doing something daft, but apparently not.

Cheers

Ian

Mike-P

Link Posted 21/09/2022 - 15:57
The thing is when the 1.4x first came out it worked fine with Sigma lenses then Pentax released a firmware update for all bodies under the guise of "compatibility issues" with some SDM lenses and from then on it never worked properly again.

Guess Pentax wanted to cripple the competition.
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Pwynnej

Link Posted 21/09/2022 - 16:34
I guess a wide-angle zoom and teleconverter would be fairly incompatible...I doubt whether a Sigma 1.4x will work on the 18-35. I am only guessing but I suspect the front element of the Pentax TC will touch the rear element of the lens and that is the last thing you want.
Z-1p, K-1, P50
F50 1.7. FAs 24, 35, 50 1.4, 85, 135. DFA15-30, DFA24-70, D-FA*70-200. D-FA 100 (gone now!). The SMC-FA Limited Trinity.
Metz 45 CL-4, AF500FTZ. AF540FGZ.
Some Mamiya and some Nikon

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