Adapting Rz67 lenses on the gfx100s

[NicktCundari]

Im extremely confused on this topic, im trying to understand how an rz67 lens will perform on a gfx100s with an adapter.

Specifically, what the crop factor is and how to calculate that difference in size from 6x7 film to the fuji sensor. I've asked around, and the answer I got was that the crop factor would be 1.60 ( 87.32/54.78) as the 6x7 film frame is larger than the sensor, turning an rz67 65mm to a 104mm. Im not sure if any of this is correct. My main worry is buying an adapter to have my lenses perform like a telephoto which is what I don't want as I tend to shoot wide.

 

[JimKasson]

Im extremely confused on this topic, im trying to understand how an rz67 lens will perform on a gfx100s with an adapter.

Specifically, what the crop factor is and how to calculate that difference in size from 6x7 film to the fuji sensor. I've asked around, and the answer I got was that the crop factor would be 1.60 ( 87.32/54.78) as the 6x7 film frame is larger than the sensor, turning an rz67 65mm to a 104mm. Im not sure if any of this is correct. My main worry is buying an adapter to have my lenses perform like a telephoto which is what I don't want as I tend to shoot wide.

The frame of a 67 camera is 56mm high. The GFX 100S sensor is 33 mm high. So, for the same vertical angle of view, multiply your 67 lens focal length by 56/33 or 1.7.

--
https://blog.kasson.com

 

[Bashir Lunat]

Yes, RZ lenses are excellent. 50mm ULD is fantastic and widest except the fisheye 37mm.

 

[Rich42]

Im extremely confused on this topic, im trying to understand how an rz67 lens will perform on a gfx100s with an adapter.

Specifically, what the crop factor is and how to calculate that difference in size from 6x7 film to the fuji sensor. I've asked around, and the answer I got was that the crop factor would be 1.60 ( 87.32/54.78) as the 6x7 film frame is larger than the sensor, turning an rz67 65mm to a 104mm. Im not sure if any of this is correct. My main worry is buying an adapter to have my lenses perform like a telephoto which is what I don't want as I tend to shoot wide.

Nick,

I've used Pentax 67 (and 645) lenses on the GFX 100S and they worked, although other than the 645-A 120mm macro (which is great), showed their age and heritage, performing significantly below similar native GF focal lengths. They were very highly-regarded lenses on my 67 and 645N and I had high hopes for them but tried them once and put them away. Modern optics, they were not.

The only way to know the image quality of the RZ lens on the 100S is to try it.

Your 65mm lens fits firmly in the "Normal" range for the GFX. It will give you slightly less FOV on the 100S than it did on the RZ67. Adapting the lens to the GFX doesn't "turn it into" some other focal length. It's a 65mm lens on the RZ67 and it will be a 65mm lens on the 100S, with a slightly more narrow FOV than you had when you used it with film.

About the same FOV as a 105mm lens has on the RZ. Is that a "telephoto" effect? Yes to some, not so much to others.

I'd be interested to know if the Mamiya lens fares better than my Pentax lenses.

--
Rich

 

[DavidMillier]

Rich

Your comments about your experiences with older Pentax lenses (for example) are a bit of a blanket statement. Can you be more specific about where you found deficiencies compared to native GFX lenses?

 

[Rich42]

Rich

Your comments about your experiences with older Pentax lenses (for example) are a bit of a blanket statement. Can you be more specific about where you found deficiencies compared to native GFX lenses?

Hi,

I had the 67 105mm f/2.4, 200mm f/4, and 165mm f/2.8.

I also had the FA 645 75mm f/2.8.

I got the SMC Pentax-A 645 f/4 Macro after selling all the other lenses and hearing about it here on the forum. I was about to get the GF 120/4. I'm glad I didn't. The Pentax is a stellar performer at Macro up to 1:1.

I had very high hopes for the 105/2.4 as it was a "star" among other lenses on the 67 and 645N. But it was quite soft at all apertures with harsh bokeh. I tested a LOT of lenses on the 100S and my Micro Nikkor 105/2.8 easily outperformed it, although with a little vignetting.

Of course, with the GF 110/2 there was no need to even try to make the 105 work. The GF 110 is simply in its own league.

The 200 and 165 lenses were just disappointing and easily outperformed by my Nikkor 180/2.8 which is close enough to either focal length.

The FA 645 75/2.8 was ok, but certainly not remarkable and when I had a chance to sell the other lenses, it went, too. I'll be getting a GF lens in that range eventually.

--
Rich
"That's like, just your opinion, man." ;-)

 

[NicktCundari]

The adapter is coming in tomorrow so ill update it with results

 

[TomB23]

I have the 55/4, 90/2.8, 200/4 and had the 105/2.4 too, based on some testing I did, I found them all to be quite sharp. However the faster and older lens design of 1052.4 required some more stopping down. 200/4 was sharp from f/4 but with high contrast subject a bit too much of purple fringing.

Although well usable, important drawbacks of adapted manual MF lenses of P67 system I found these lenses are 1) there heavy weight, enhaced by the weight of the Kipon adapter I use, with some 400 grams additional weight. 2) the lack of exif data and 3) the cumbersome effort to focus first and then set the aperture to desired value, with all the risk of adjusting focus unwantedly. I guess this would be no different for RZ67 lenses.

 

[JimKasson]

I have the 55/4, 90/2.8, 200/4 and had the 105/2.4 too, based on some testing I did, I found them all to be quite sharp. However the faster and older lens design of 1052.4 required some more stopping down. 200/4 was sharp from f/4 but with high contrast subject a bit too much of purple fringing.

Although well usable, important drawbacks of adapted manual MF lenses of P67 system I found these lenses are 1) there heavy weight, enhaced by the weight of the Kipon adapter I use, with some 400 grams additional weight. 2) the lack of exif data and 3) the cumbersome effort to focus first and then set the aperture to desired value,

On the GFX cameras, I usually focus manual focus lenses at taking aperture.

with all the risk of adjusting focus unwantedly. I guess this would be no different for RZ67 lenses.

 

[Rich42]

I have the 55/4, 90/2.8, 200/4 and had the 105/2.4 too, based on some testing I did, I found them all to be quite sharp. However the faster and older lens design of 1052.4 required some more stopping down. 200/4 was sharp from f/4 but with high contrast subject a bit too much of purple fringing.

Although well usable, important drawbacks of adapted manual MF lenses of P67 system I found these lenses are 1) there heavy weight, enhaced by the weight of the Kipon adapter I use, with some 400 grams additional weight. 2) the lack of exif data and 3) the cumbersome effort to focus first and then set the aperture to desired value, with all the risk of adjusting focus unwantedly. I guess this would be no different for RZ67 lenses.

Tom,

I had forgotten about the excessive purple (and green) fringing. I was able to remove that in Photoshop, but in many cases, had to be extremely careful as the extreme settings needed of the sliders resulted in bizarre colors in other parts of images.

Setting the appropriate lens data in the camera's "Lens Registration" section of the "Mount Adapter Setting" gets all that information into the Exif data, except the camera has no way to know the aperture being used.

 

[TomB23]

@Jim: thanks for the advice, I hesitated to do it that way since the focal plane is better defined with large aperture. However some lenses have some spherical aberration making the focal plane change, perhaps it may be better in thoses cases to focus with closed aperture. I will try.

@Rich: yes, purple and green fringing is very pronounced. 105/2.4 is extreme when full aperture is used.

Talking about colors, getting colors right is actually another topic for adapting lenses, especially if you change lenses on similar subjects, differences to native lenses are easily visible.

 

[weihaowang]

I can echo what Rich said. I have the same set of P67 lenses, plus a few others. Previously I tried them on FF cameras, P645z, and GRX50R. They are all terrible in today's standard in terms of sharpness Some still cannot get close to native GFX lenses after substantial stopping down. I figured if I reached such a conclusion on 645z and 50R, I should not bother to put them on my GFX100S.

I think you will have better luck with P645 or Mamiya 645 lenses. Most of them can be quite sharp wide opened, in the frame center. In the edges, they are still terrible compared to native GFX lenses though.

Rich

Your comments about your experiences with older Pentax lenses (for example) are a bit of a blanket statement. Can you be more specific about where you found deficiencies compared to native GFX lenses?

Hi,

I had the 67 105mm f/2.4, 200mm f/4, and 165mm f/2.8.

I also had the FA 645 75mm f/2.8.

I got the SMC Pentax-A 645 f/4 Macro after selling all the other lenses and hearing about it here on the forum. I was about to get the GF 120/4. I'm glad I didn't. The Pentax is a stellar performer at Macro up to 1:1.

I had very high hopes for the 105/2.4 as it was a "star" among other lenses on the 67 and 645N. But it was quite soft at all apertures with harsh bokeh. I tested a LOT of lenses on the 100S and my Micro Nikkor 105/2.8 easily outperformed it, although with a little vignetting.

Of course, with the GF 110/2 there was no need to even try to make the 105 work. The GF 110 is simply in its own league.

The 200 and 165 lenses were just disappointing and easily outperformed by my Nikkor 180/2.8 which is close enough to either focal length.

The FA 645 75/2.8 was ok, but certainly not remarkable and when I had a chance to sell the other lenses, it went, too. I'll be getting a GF lens in that range eventually.

 

[JimKasson]

I think you will have better luck with P645 or Mamiya 645 lenses. Most of them can be quite sharp wide opened, in the frame center. In the edges, they are still terrible compared to native GFX lenses though.

That's not true of the Pentax 645 120 macro. At 1:1, it's better by far than the GF 120 with 45mm tube. At 1:2 it's not quite as good, but close.

--
https://blog.kasson.com