[zobeleye]

Hi guys,
I am considering going Fuji in MF as an alternative to the 645Z, with my eyes on the upcoming 100MP camera.
Does anybody already use Pentax glass with adapters for Fuji ?
what about lenses that don't have the aperture-ring, like the DFA line, 35,90, 28-45 ?
Can they be stepped down with the adapter ?
I am thinking Kippon a.t.m.

any thoughts ?

cheers
Stephan

[Adam]

The adapter would need to have an aperture ring if the lens does not. Seems the adapter you mentioned wouldn't be good for DA lenses, therefore.

Also, the D FA 35mm does have an aperture ring because it's basically the FA lens with updated coatings.

[Andrea K]

The adapter would need to have an aperture ring if the lens does not. Seems the adapter you mentioned wouldn't be good for DA lenses, therefore.

Also, the D FA 35mm does have an aperture ring because it's basically the FA lens with updated coatings.

the DFA 35mm has a different AL element, a different coatings and the rounded blades.

[Gerd]

I have been using the GFX 50s for nearly two years with Pentax 645 lenses. This works very well.

There is a Fotodiox Pro Adapter LINK: The lens without aperture ring controls - also works pretty well.

With the GFX 50s can also be quickly focused manually.

However, the native Fuji G mount lenses are much better than most Pentax 645 lenses. In my opinion, are also better than the HD lenses.

With the upcoming GFX100s, most 645 Pentax lenses will probably not work as well. The GFX100s has a pixel pitch of 3.74 micron. These are very high requirements. The native Fuji G mount lenses are already designed / calculated for 100 MPix.

Greeting Gerd

[2351HD]

Seems to be a lot of Pentax MF users moving to Fuji. So much gear for sale.

Pentax have a lot of work to do.

[zobeleye]

Hi Gerd,
When you say it works very well with the adaptor, what about
"• If your lens does not have a manual aperture control ring, it will stop down to its smallest f/stop by default."
Does this mean you have to use the lever on the adaptor to open the aperture up, once you connect it, or everytime after taking a picture?
And when you say lenses are not as good as the Fuji, which ones are you referring to ? Its hard to imagine a sharper lens than the 90 DFA makro...
Cheers and thanks for your time
Stephan

[Gerd]

Hello Stephan,

Subject Aperture ring:
I had set in my post above a link for an adapter that controls Pentax 645 lenses without aperture ring.
(Https://www.fotodioxpro.com/collections/lens-mount-adapters/products/p645a-gfx-pro). The adapter captures the apature fork and controls the position via an aperture ring on the adapter. So you can take all Pentax 645 lenses without restrictions (except the two old Leaf Shutter lenses).

Subject Fuji G mount lenses quality:
I refer to all Pentax 645 lenses. The Fuji 120mm F4 Macro is sharper than the Pentax HD DFA 90mm. Look at the MTF charts at Fuji. (http://www.fujifilm.com/products/digital_cameras/gfx/fujinon_lens_gf120mmf4_...specifications). The Fuji can also show 1: 1 on a fully electronic extension ring.

The Fuji 110mm F2 is also sharper with the aperture open than the Pentax HD DFA 90mm. And it has F2.

I have the DFA version of the Pentax 645 25mm F4. If I compare that with the Fuji 23mm F4, then the Pentax 25mm does not even come close to the 23mm Fuji.

The Pentax DA 28-45mm F4.5 is at a similar level to the Fuji GF 32-64mm F4. The Pentax 28-45mm is much more expensive, it has a smaller zoom range and it has more CA's.

The Fuji GF 250mm F4 with stabilizer is much better compared to the Pentax 200mm F4 or the Pentax 300mm F5.6. With the 1.4 tele converter the Fuji reaches 350mm F5.6.

But you also have to be fair and look at it from a purely technical point of view. When the Pentax lenses were designed the requirement was not that they need to work on a 44x33mm sensor with 100 Mpix and a pixel pitch of 3.74 micron. The Fuji lenses had exactly this requirement from the beginning.

What I wrote does not mean that the Pentax lenses are bad - quite the contrary. Only the Fuji lenses are, in most cases, even better.

I hope this helps you further.

Greetings Gerd

[chicagonature]

Hello Stephan,

Subject Aperture ring:
I had set in my post above a link for an adapter that controls Pentax 645 lenses without aperture ring.
(Https://www.fotodioxpro.com/collections/lens-mount-adapters/products/p645a-gfx-pro). The adapter captures the apature fork and controls the position via an aperture ring on the adapter. So you can take all Pentax 645 lenses without restrictions (except the two old Leaf Shutter lenses).

Subject Fuji G mount lenses quality:
I refer to all Pentax 645 lenses. The Fuji 120mm F4 Macro is sharper than the Pentax HD DFA 90mm. Look at the MTF charts at Fuji. (FUJINON GF120mmF4 R LM OIS WR Macro | Lenses | FUJIFILM X Series & GFX – Global). The Fuji can also show 1: 1 on a fully electronic extension ring.

The Fuji 110mm F2 is also sharper with the aperture open than the Pentax HD DFA 90mm. And it has F2.

I have the DFA version of the Pentax 645 25mm F4. If I compare that with the Fuji 23mm F4, then the Pentax 25mm does not even come close to the 23mm Fuji.

The Pentax DA 28-45mm F4.5 is at a similar level to the Fuji GF 32-64mm F4. The Pentax 28-45mm is much more expensive, it has a smaller zoom range and it has more CA's.

The Fuji GF 250mm F4 with stabilizer is much better compared to the Pentax 200mm F4 or the Pentax 300mm F5.6. With the 1.4 tele converter the Fuji reaches 350mm F5.6.

But you also have to be fair and look at it from a purely technical point of view. When the Pentax lenses were designed the requirement was not that they need to work on a 44x33mm sensor with 100 Mpix and a pixel pitch of 3.74 micron. The Fuji lenses had exactly this requirement from the beginning.

What I wrote does not mean that the Pentax lenses are bad - quite the contrary. Only the Fuji lenses are, in most cases, even better.

I hope this helps you further.

Greetings Gerd

Hi, Gerd,

1. Thank you for the very thoughtful and thorough review. Im considering buying the GFX 100 or upcoming 100s and I own the older Pentax-A 120mm macro lens and the FA 55-110mm from the film days.

2. When the Pentax lenses are stopped down, does the quality difference narrow between Pentax and Fuji. I shoot highly detailed landscapes at high f-stops, like f22 and often f32.

[Anil Kumar K]

Wonder why anyone would use apertures like f22 and f32 on a medium format Pentax lenses with Pentax 645z. To my experience going beyond f11 reduces the sharpness very drastically due to diffraction. Diffraction is a curse to high resolution digital cameras.

[TDvN57]

Wonder why anyone would use apertures like f22 and f32 on a medium format Pentax lenses with Pentax 645z. To my experience going beyond f11 reduces the sharpness very drastically due to diffraction. Diffraction is a curse to high resolution digital cameras.

Will appreciate your comment....

#1 - Full pic 645z + FA 200mm f/4 @ f/32 1/8 sec ISO 100

#2 - 100% crop

#3 - 100% crop

-

[kaseki]

The circular aperture diffraction point spread function first nulls are at 2.4 x lambda x f/no. wide, but the 50% points are a bit more than half this. So at f/32, and a yellow wavelength of 0.5 micrometers, we would get a ballpark value of 20 microns. This is larger than the 645Z pixel size (around 5 microns), but may not be as noticeable as one might expect given that the focal plane is color sparse, and the Bayer filter has to interpolate between pixels of any particular color. Also, the "granularity" of the scene is a factor. If one looks at the power spectral density of a real world scene, the energies at the highest frequencies of interest are going to be relatively low, rock fractures notwithstanding. More defects would be seen imaging a USAF resolution chart.