Pentax FA 31mm on GFX?

FLM Canada · 10-01-2022, 12:42 PM - **2 Likes**

Thanks everyone, I put in my order for the FA31.
Will update with photos when I can.

FLM Canada · 10-06-2022, 02:55 PM - **1 Like**

The lens arrived today, looks very promising.
Only a very faint vignette on 4:3 GFX.
Testing over the weekend.
Thanks again

sad_punk · 03-01-2023, 07:15 AM

I love this lense, this is my favorite on K1, but no, too much vignetting as you may be willing to use it a full aperture. If you are not always shooting at F/1.8 you have better Pentax options :

- The best FF Pentax lens option around 30mm is probably the DFA 15-30mm, corners vignettes below 20mm and not sharp around 20-22mm (still usable depending on the subject), but on higher focal this is a really convincing lense as long as you donc compare it to the Fuji GF 30mm of course, wich has been built for this sensor.

- On pentax MF lenses, the FA 645 35mm is a must on GFX, which use the same sensor as the 645Z. This lense was designed for film much larger than the sensor so you don't have to worry about corner sharpness. Just note the fuji automatic white balance tend to produce yellow image with this lense, where the Fuji 30mm gives me much more natural tones. Nothing impossible to correct before, or after shooting.

If you want a FA limited lens on the GFX, but in a very different focal length, the 77mm gives me very satisfying results. The FA 645 75mm gives me better color and sharpness, which i can ofen find usefull, but the 77mm keeps all its magic alive on the gfx sensor.

FLM Canada · 03-01-2023, 07:31 AM - **4 Likes**

Actually, I found that the lens covered the GFX sensor very well, with only a very mild but pleasing vignette, which I never bothered to remove.

The FA31 was also very good for infrared, see this 720nm image shot on GFX:

When the GF20-35 came out I sold the FA31 because the GF lens has AF, covers several important focal lengths and is also excellent for infrared photography.
But the FA series is indeed special, and if I feel the need to add to my portrait lenses, I'll try the 77mm. Thanks for the recommendation.

normhead · 03-01-2023, 08:27 AM - **1 Like**

I have couple Pentax 645 lenses 55mm and 75mm.. which I got quite cheaply. Just saying.....

FLM Canada · 03-01-2023, 08:37 AM - **1 Like**

P645 lenses are great, I have the 35mm, 45-85 and the 120 Macro.
I use them mostly for architectural work, not for walking around stuff or infrared.

sad_punk · 03-02-2023, 01:40 AM - **1 Like**

Originally posted by FLM Canada

P645 lenses are great, I have the 35mm, 45-85 and the 120 Macro.
I use them mostly for architectural work, not for walking around stuff or infrared.

Not a fan of the zoom as (at least for the FA version) it is not sharp at maximum focal length/full aperture. the 35mm and 75mm are my favorite. The 120 is the lens I use to digitalize my 120 films (645/6x7). For 35mm films i use the DFA 100mm on my K1 as the 2/3 ratio is more adapted. I sold my 200mm F/4 for 6x7 and 645 as i love the Pentax 67 165mm F/2.8 that i use instead, but they give strong results for very little money.

leekil · 03-04-2023, 08:27 PM

Back when 645 film cameras were still common, the reputation of the 45-85 was that it was sharper than the FA 45. Maybe you got a bad copy?

sad_punk · 03-06-2023, 01:59 AM

Originally posted by leekil

Back when 645 film cameras were still common, the reputation of the 45-85 was that it was sharper than the FA 45. Maybe you got a bad copy?

it is possible but i can't compare to the 45mm that i have never tried..
btw the zoom is geally good at 45mm. That's at 85mm at F/4.5 that I was disappointed on GFX by comparison to other focal lenght. I didn't notice that on my 645N or D, this was maybe important for a subject when I used it on the GFX later (a show on a stage under the clouds, so max focal + max aperture to keep iso low ... artists makup and clothes were kind of blurry and it didn't looks like motion blur ... I would have given another tries if not invested on the 45-100mm since then, I still use the 45-85mm on my 645N, even if I am ofen more willing to take the 75mm )

leekil · 03-17-2023, 08:08 PM

The guy from LensRentals has mentioned that lenses used on different systems than what they are designed for could have some differences due to specifically being designed for a certain type of sensor cover (?), I don't recall the details. Potentially this coudl be an issue in your case with the GFX, but I also have not heard of anyone having a specific problem like that using lenses on another system.

sad_punk · 03-27-2023, 02:16 AM - **1 Like**

Originally posted by leekil

The guy from LensRentals has mentioned that lenses used on different systems than what they are designed for could have some differences due to specifically being designed for a certain type of sensor cover (?), I don't recall the details. Potentially this coudl be an issue in your case with the GFX, but I also have not heard of anyone having a specific problem like that using lenses on another system.

My 645 FA 45-85mm was designed for 120 film size

Abbazz · 07-24-2023, 09:24 PM

The plain old Pentax FA 35mm f/2.0 is a great lens on Fuji medium format mirrorless cameras. The extreme corners are a bit soft (we are talking about a few pixels here) but vignetting is invisible at F/5.6-8 and image quality is great. Worth a try!

Cheers!

Abbazz

03-01-2023, 07:15 AM	#18
sad_punk Senior Member Join Date: Oct 2018 Location: Paris Photos: Gallery Posts: 215	that's a no I love this lense, this is my favorite on K1, but no, too much vignetting as you may be willing to use it a full aperture. If you are not always shooting at F/1.8 you have better Pentax options : - The best FF Pentax lens option around 30mm is probably the DFA 15-30mm, corners vignettes below 20mm and not sharp around 20-22mm (still usable depending on the subject), but on higher focal this is a really convincing lense as long as you donc compare it to the Fuji GF 30mm of course, wich has been built for this sensor. - On pentax MF lenses, the FA 645 35mm is a must on GFX, which use the same sensor as the 645Z. This lense was designed for film much larger than the sensor so you don't have to worry about corner sharpness. Just note the fuji automatic white balance tend to produce yellow image with this lense, where the Fuji 30mm gives me much more natural tones. Nothing impossible to correct before, or after shooting. If you want a FA limited lens on the GFX, but in a very different focal length, the 77mm gives me very satisfying results. The FA 645 75mm gives me better color and sharpness, which i can ofen find usefull, but the 77mm keeps all its magic alive on the gfx sensor.

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10-01-2022, 12:42 PM - 2 Likes	#16
FLM Canada Junior Member Join Date: Jun 2013 Location: Ottawa, Ontario Posts: 32 Original Poster	Thanks everyone, I put in my order for the FA31. Will update with photos when I can.

10-06-2022, 02:55 PM - 1 Like	#17
FLM Canada Junior Member Join Date: Jun 2013 Location: Ottawa, Ontario Posts: 32 Original Poster	The lens arrived today, looks very promising. Only a very faint vignette on 4:3 GFX. Testing over the weekend. Thanks again

03-01-2023, 07:31 AM - 4 Likes	#19
FLM Canada Junior Member Join Date: Jun 2013 Location: Ottawa, Ontario Posts: 32 Original Poster	Actually, I found that the lens covered the GFX sensor very well, with only a very mild but pleasing vignette, which I never bothered to remove. The FA31 was also very good for infrared, see this 720nm image shot on GFX: When the GF20-35 came out I sold the FA31 because the GF lens has AF, covers several important focal lengths and is also excellent for infrared photography. But the FA series is indeed special, and if I feel the need to add to my portrait lenses, I'll try the 77mm. Thanks for the recommendation.

03-01-2023, 08:27 AM - 1 Like	#20
normhead Pentaxian Join Date: Jun 2007 Location: Near Algonquin Park Photos: Gallery \| Albums Posts: 40,451	I have couple Pentax 645 lenses 55mm and 75mm.. which I got quite cheaply. Just saying.....

03-01-2023, 08:37 AM - 1 Like	#21
FLM Canada Junior Member Join Date: Jun 2013 Location: Ottawa, Ontario Posts: 32 Original Poster	P645 lenses are great, I have the 35mm, 45-85 and the 120 Macro. I use them mostly for architectural work, not for walking around stuff or infrared.

03-02-2023, 01:40 AM - 1 Like	#22
sad_punk Senior Member Join Date: Oct 2018 Location: Paris Photos: Gallery Posts: 215	Originally posted by FLM Canada P645 lenses are great, I have the 35mm, 45-85 and the 120 Macro. I use them mostly for architectural work, not for walking around stuff or infrared. Not a fan of the zoom as (at least for the FA version) it is not sharp at maximum focal length/full aperture. the 35mm and 75mm are my favorite. The 120 is the lens I use to digitalize my 120 films (645/6x7). For 35mm films i use the DFA 100mm on my K1 as the 2/3 ratio is more adapted. I sold my 200mm F/4 for 6x7 and 645 as i love the Pentax 67 165mm F/2.8 that i use instead, but they give strong results for very little money.

03-04-2023, 08:27 PM	#23
leekil Pentaxian Join Date: May 2016 Photos: Albums Posts: 2,003	Back when 645 film cameras were still common, the reputation of the 45-85 was that it was sharper than the FA 45. Maybe you got a bad copy?

03-06-2023, 01:59 AM	#24
sad_punk Senior Member Join Date: Oct 2018 Location: Paris Photos: Gallery Posts: 215	Originally posted by leekil Back when 645 film cameras were still common, the reputation of the 45-85 was that it was sharper than the FA 45. Maybe you got a bad copy? it is possible but i can't compare to the 45mm that i have never tried.. btw the zoom is geally good at 45mm. That's at 85mm at F/4.5 that I was disappointed on GFX by comparison to other focal lenght. I didn't notice that on my 645N or D, this was maybe important for a subject when I used it on the GFX later (a show on a stage under the clouds, so max focal + max aperture to keep iso low ... artists makup and clothes were kind of blurry and it didn't looks like motion blur ... I would have given another tries if not invested on the 45-100mm since then, I still use the 45-85mm on my 645N, even if I am ofen more willing to take the 75mm )

03-17-2023, 08:08 PM	#25
leekil Pentaxian Join Date: May 2016 Photos: Albums Posts: 2,003	The guy from LensRentals has mentioned that lenses used on different systems than what they are designed for could have some differences due to specifically being designed for a certain type of sensor cover (?), I don't recall the details. Potentially this coudl be an issue in your case with the GFX, but I also have not heard of anyone having a specific problem like that using lenses on another system.

03-27-2023, 02:16 AM - 1 Like	#26
sad_punk Senior Member Join Date: Oct 2018 Location: Paris Photos: Gallery Posts: 215	Originally posted by leekil The guy from LensRentals has mentioned that lenses used on different systems than what they are designed for could have some differences due to specifically being designed for a certain type of sensor cover (?), I don't recall the details. Potentially this coudl be an issue in your case with the GFX, but I also have not heard of anyone having a specific problem like that using lenses on another system. My 645 FA 45-85mm was designed for 120 film size

07-24-2023, 09:24 PM	#27
Abbazz Pentaxian Join Date: Nov 2006 Location: Jakarta Posts: 667	The plain old Pentax FA 35mm f/2.0 is a great lens on Fuji medium format mirrorless cameras. The extreme corners are a bit soft (we are talking about a few pixels here) but vignetting is invisible at F/5.6-8 and image quality is great. Worth a try! Cheers! Abbazz