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03-30-2020, 06:33 AM   #1
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Pentax 645Z lens aperture control

Hello
I am planning to buy a Pentax 645Z and various lenses, including the 25mm f/4. I would also like to use the Pentax 645 lenses on a Sony A7Rii via the Fotodiox Pro TLT ROKR - Tilt / Shift Lens Mount Adapter for Pentax 645 (P645) Mount SLR Lenses to Sony Alpha E-Mount Mirrorless Camera Body.

I can't see an aperture ring on the lens, so is there any way that I can change the lens aperture when using this or other 645Z lenses on the A7Rii?

Thank you for your assistance!

Trevor

03-30-2020, 07:46 AM   #2
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Looking at images of the lens, I would agree with you, certainly the older 645 lenses have an aperture control ring, my 28 - 45 doesn't either, but all the other lenses I have do including the 80mm - 160 / 45mm - 85mm. You could opt for the 35mm instead, this has an aperture ring.
03-30-2020, 09:09 AM   #3
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Yes, some of the newer lenses don't have aperture rings anymore. Pity....
03-30-2020, 10:22 PM   #4
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Some of the new lenses have an electric diaphragm to eliminate aperture control issues. That solution eliminates the possibility of aperture rings

03-31-2020, 12:00 AM   #5
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QuoteOriginally posted by chrism888 Quote
Looking at images of the lens, I would agree with you, certainly the older 645 lenses have an aperture control ring, my 28 - 45 doesn't either, but all the other lenses I have do including the 80mm - 160 / 45mm - 85mm. You could opt for the 35mm instead, this has an aperture ring.
Thank you. Is there an older version of the 25mm f/4 lens for Pentax 645 that does have a physical aperture ring?
03-31-2020, 12:12 AM   #6
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QuoteOriginally posted by TrevorA Quote
Is there an older version of the 25mm f/4 lens for Pentax 645 that does have a physical aperture ring?
Neither the DFA or the DA version of the 25/4.0 have an aperture ring.

Your next best option is the DFA645 35/3.5, which is a really nice wide angle lens too. Just not ultra wide....

There is of course a multitude of 24mm lenses you can adapt to your full frame Sony - many of which will be faster, smaller, cheaper and probably better for that format.

Last edited by Sandy Hancock; 03-31-2020 at 12:18 AM.
03-31-2020, 11:48 PM   #7
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Sandy
Thank you for this information and advice.
Trevor
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