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05-27-2020, 09:39 AM   #1
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Pentax 67 400mm F4 + Pentax DA 1.4x or 1.7x

Hi Guys,
Pentax 6x7 400mm F4 + 67 to K adapter + DA 1.4x converter on Pentax K1

Pentax 6x7 400mm F4 + 67 to K adapter + FA 1.7x adapter on Pentax K1

Will any of the above combos be able to provide AF?
Has anybody tried any of such?

Thank you in advance for your comments/thoughts.

Vasyl

05-27-2020, 09:46 AM   #2
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QuoteOriginally posted by Vasyl Quote
Pentax 6x7 400mm F4 + 67 to K adapter + FA 1.7x adapter on Pentax K1
This combo (with the FA 1.7x) should, in theory, provide a bit of AF support. You'd have to manually focus the lens to the right general area, and the TC can then focus within a range there. It will also lose 1.5 stops of light, effectively turning the 400 into a 680mm f/6.3. You can read some reviews about it here: SMC Pentax-F 1.7x AF Adapter Reviews - Pentax K-mount Teleconverters and Adapters - Pentax Lens Reviews & Lens Database
05-27-2020, 09:55 AM   #3
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QuoteOriginally posted by bertwert Quote
This combo (with the FA 1.7x) should, in theory, provide a bit of AF support. You'd have to manually focus the lens to the right general area, and the TC can then focus within a range there. It will also lose 1.5 stops of light, effectively turning the 400 into a 680mm f/6.3. You can read some reviews about it here: SMC Pentax-F 1.7x AF Adapter Reviews - Pentax K-mount Teleconverters and Adapters - Pentax Lens Reviews & Lens Database
Thank you. I thought so, but I was not able to find any information about such combo.
Talking about the 1.7x adapter...Does the adapter do the AF by moving elements inside or does it push and pull the lens mounted on it?
05-27-2020, 09:59 AM - 1 Like   #4
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QuoteOriginally posted by Vasyl Quote
Thank you. I thought so, but I was not able to find any information about such combo.
Talking about the 1.7x adapter...Does the adapter do the AF by moving elements inside or does it push and pull the lens mounted on it?
I don't have the teleconverter myself, but it focuses by moving the elements inside the converter. It's a pretty neat device, able to give some sort of AF capabilities to all sorts of lenses.

05-27-2020, 10:38 AM   #5
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QuoteOriginally posted by Vasyl Quote
Hi Guys,
Pentax 6x7 400mm F4 + 67 to K adapter + DA 1.4x converter on Pentax K1

Pentax 6x7 400mm F4 + 67 to K adapter + FA 1.7x adapter on Pentax K1

Will any of the above combos be able to provide AF?
Has anybody tried any of such?

Thank you in advance for your comments/thoughts.

Vasyl


The P67 lenses are all manual focus. The only mechanism for focusing the lens is turning the focus ring with your hand.

But my 645z will provide focus confirmation in the viewfinder with any manual-focus lens—you turn the ring, and a green light appears when the focus spot detects proper focus. The K1 is probably the same. That would work with any adapted lens or converter.

Rick “as long as there is enough light” Denney
05-28-2020, 03:43 AM   #6
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Umm I have the lens and that 1.7 and 1.4 converter, I can double check tomorrow how they function, however as others have said, you can prefocus to a general area and the 1.7 will do the focusing from there. Still need to meter manually or use the green button for exposure and use the aperture manually.
05-28-2020, 04:12 AM   #7
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Are we talking about the new Pentax 67 400 mm f/4 ED or the old Takumar 400 mm ?
05-29-2020, 02:02 AM   #8
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QuoteOriginally posted by RICHARD L. Quote
Are we talking about the new Pentax 67 400 mm f/4 ED or the old Takumar 400 mm ?
The newer 400 M* 67

05-29-2020, 03:20 AM   #9
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I've never tried the 1.7x adapter but it was originally only suitable for lenses f/2.8 or faster (back in the day) - unless you already have the lens & 67 adapter there must be easier/cheaper/lighter ways of getting to 5-600mm* (the 1.7x AF adapter usually attracts 'premium' prices these days)? AF is far less important than auto-aperture, and a smaller/lighter lens (with fewer adapters) is going to be much easier to handle.

When I use my 67 500/5.6 on the K-1, AF is the least of my worries...

* If you're shooting that long, a shorter lens on an APS-C body or K-1 in crop mode is likely to give better results with much easier handling (less bulk, weight, vibration etc) and you can use the DA 1.4x converter for AF.
05-29-2020, 08:30 AM   #10
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I guess I never knew that Pentax made an internally focusing teleconverter. From reading about it, the contacts may have to be shorted to work with adapted lens.

I adapted a Takumar 500/4.5 to my Canon a while back just to see what it was like. Heavy, is what it was like. Crew of native bearers heavy. NEVER allow the camera to bear the full weight of the lens off the front heavy. But it worked.

Rick “an equally slow small-format equivalent to the 67-lens-plus-converter might work better, Af or not” Denney
05-30-2020, 12:22 AM - 1 Like   #11
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Well here goes K1 FA 1.7XAF teleconverter with the M* 400mm 67 lens with pentax 67 K adapter

Like all lenses the AF converter cannot do the whole focal range, you need to pre focus manually to a zone and then the AF does the fine focusing. I was surprised how well it worked, naturally close up subjects take more manual focusing to get it in the zone, however from 10 meters onwards very little manual focusing was needed. The bokeh and sharpness seemed acceptable to me, I was using the combo on a monopod rather than a tripod, so there may have been a little camera shake.





Then I tried pre focusing on a fence pole then taking a series of shots just using the AF and seeing how far the lens could AF











overall I found it wasn't hunting for focus and I think I will actually use the combo in the future.
Each fence post is about 10 feet 3 metres apart and it covered a range of 40-50 feet which I found pretty good in a usable range
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