Two 63s: Fuji GF 63mm f/2.8 and SMC Pentax-A 645 45-85mm f/4.5

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Rob de Loe Regular Member • Posts: 153
Two 63s: Fuji GF 63mm f/2.8 and SMC Pentax-A 645 45-85mm f/4.5
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I’m not a major measurer, but I do like to know the “shooting envelope” for my gear. When I get a new lens or camera, I’ll take it to places where I can shoot scenes with which I’m very familiar so that I can get a quick sense of strengths and weaknesses. In that spirit, I also find it’s useful to compare two lenses of similar focal lengths so I can understand each one better.

I’ve been shooting a Fuji GFX 50R for about 8 months now, but only using adapted lenses. Recently I added an actual Fuji GF lens to my lineup: the 63mm f/2.8. It’s a lovely lens and I’m enjoying using it as my “walking around” lens. I honestly have no complaints. Even the supposedly-slow autofocus of this model is fine for me.

I’ve gone so long without an actual Fuji GF lens because I mostly shoot off a tripod, using my Toyo VX23D “adapter”. The lenses I use the most lately are SMC Pentax-A 645 medium format lenses. In particular, I use my SMC Pentax-A 645 45-85mm f/4.5 a lot because it covers my favourite focal lengths. It’s an old, slow, heavy zoom from the film days.

I’ve been extremely happy with my Pentax-A 645 lenses on my VX23D. However, I was very curious to know how it compares to my new Fuji lens because I frequently read claims that modern Fuji GF lenses are vastly better than old timey film-era lenses. Some even claim that using lenses like my Pentax-A 645s on a Fuji GFX 50R/S camera is a waste of the sensor.

Now that I have a Fuji GF lens, I can test that claim. To satisfy my curiosity, I put my GF 63/2.8 up against my Pentax-A 645 45-85/4.5 at the 63mm mark in a wide range of settings and let my eyes be the judge.

Importantly, these two lenses are not competitors in my setup. I use them for very different purposes. Pentax 645 lenses are for slow and steady work on my Toyo VX23D, while my new GF 63/2.8 is for hand-held photography. So the question is not “Which is lens is better?”; given how I use them, that question doesn’t make sense. Instead, I’m simply asking “Is it true that Fuji GF lenses are incomparably better than old medium format film-era lenses?”

If you don’t have the patience to wade through the rest of this post, let me just say that it’s not true – at least not in this particular comparison. My Pentax-A 645 45-85mm lens (at 63mm) is definitely not wasting the GFX sensor.

Caveat: I’m comparing one copy of the GF 63/2.8 to one copy of the Pentax-A 645 45-85/4.5 (at one focal length). It’s possible that I have both the worst GF 63/2.8 ever made and the best Pentax-A 645 45-85/4.5 to ever come out of Japan. But I doubt it. I haven’t seen any reasons to think there’s anything wrong with either lens (and I’ve checked both carefully for corner performance, performance at all apertures, near and far performance, etc.)

I compared these lenses in many settings (test charts, various standard scenes I use), but here I’m only going to show examples from my infinity scene. This is a view from “Catholic Hill” in the town where I live (Guelph, Ontario, Canada). It’s the highest point of land in the city, and is dominated by a Basicalla directly behind my shooting position. It was cold and overcast, but visibility out to my focus target was excellent. These conditions helped to ensure consistent light between lens changes.

Catholic Hill test scene. Focus is on the cell tower on the horizon, just to right of centre

At the horizon, slightly to the right of the centre of the frame, is a cell phone tower. I manually focused both lenses on that tower, and made two separate sets of pictures from minimum to maximum apertures; for the GF 63/2.8 I also made an f/4.5 picture so I could compare f/4.5 performance on both lenses. I then chose the set that was best focused on the tower. I’ve done this so often with so many different lenses that I’m very confident I nailed focus properly, meaning differences you’ll see in the files are due to the lenses rather than focusing error.

I find there’s very little useful to be learned about a lens from small JPEG images posted on forums. I am going to post some JPEG images here, so you can quickly see specific things I want to point out, but I’ve also provided links to the actual RAW files so you can judge for yourself (which is always best). Links to RAFs are at the end of this post.

All the JPEG images posted here are minimally processed in Lightroom 9.2. Unless otherwise noted, I’ve adjusted exposure using the “Auto” setting and balanced colour temperature by reading off the same neutral gray feature. I left sharpening and noise reduction at the Lightroom defaults, and I didn’t make any other adjustments that affect the appearance of sharpness (e.g., texture, clarity).

OVERALL:

  • Both lenses are excellent for their purposes. The Fuji is better for some purposes than the Pentax, and vice-versa. For example, the Fuji is useless as a shift lens while the Pentax can’t shoot at f/2.8 and doesn’t autofocus.
  • Neither lens has any magical properties that I can detect (special glows, mystical micro-contrast, indefinable 3D pop).
  • The Fuji doesn’t have a “digital” look, and the Pentax doesn’t have a “film” look. Apart from the specific differences noted before, they render in very similar ways.

Bottom-line: these are both high quality, no-nonsense professional-grade optics. They both produce consistent, high quality results in a wide range of shooting conditions. There’s no support here for the notion that Pentax 645 lenses are not as good as Fuji GF lenses.

IN DETAIL:

I mostly shoot for black and white, and that’s a good thing because the colours of these lenses are poles apart. The Fuji has a distinct bluish cast while the Pentax has a more neutral-yellow cast. Uncorrected, I find the Pentax is a bit more realistic (but this is more a reflection of my taste rather than a claim that the Pentax colours are more accurate). It’s possible to match the colours when shooting RAW, but mixing and matching colour pictures made with Fuji GF and Pentax-A 645 lenses outside of a studio will be a constant pain (especially if one shoots JPEG).

Exposure has been adjusted, but colour temperature is as shot

Resolving power and sharpness are the areas where many enthusiasts claim Fuji GF lenses walk all over alternatives. If it’s true, this should be obvious in files at 100%. I’m not seeing that in this comparison. At 100%, at f/5.6 through f/16, I call it a wash across the frame. At f/5.6, at higher magnifications, the Fuji is perhaps a bit sharper. At f/8, I don’t see any meaningful differences between them. And at f/16, diffraction seems to have softened the Fuji more than the Pentax (which works for me because I frequently shoot my SMC Pentax-A lenses at f/16).

100%

200%

400%

I have tested both lenses against a test chart with lots of fine detail, and at the close distance of my chart, the extreme corners of the Fuji need f/8 to be excellent; they’re not bad at f/2.8, and typically I wouldn’t be worrying about corners when shooting f/2.8. The Pentax is also very good wide open, and excellent at f/8.

Wide-open performance is of concern to many photographers. In terms of resolution, the Fuji is really good wide open (f/2.8). But the Pentax is also really good wide open (f/4.5); it’s not a lens that I would ever want to shoot at f/4.5, but if I had to I would.

Comparing f/4.5 for both lenses, the Fuji is definitely better at that aperture – but at f/4.5 it’s stopped down while the Pentax is wide open, so kudos to Pentax for really strong wide-open performance.

At 100% it’s hard to see any differences, so this is 200% (f/4.5 for both lenses)

Both lenses are well corrected for typical aberrations. My infinity test scene isn’t suited to evaluating distortion, but my test chart setup is, and on that basis I can say neither lens shows photographically-relevant amounts of distortion. Extremely slight barrel distortion is visible in the Pentax shots; the Fuji may show a tiny bit more.

Comparing the Fuji GF to the Pentax using my Catholic Hill infinity test scene, the Fuji lens does a very good job of controlling chromatic aberrations. There are virtually none (look at the tree branches against the sky). But the Pentax controls CA incredibly well too, and the tiny bit that you can find cleans up well. Interestingly, the aliasing in the Fuji pictures (which is visible at very high magnification and points to more resolving power for the Fuji lens) is more disagreeable to me than the tiny amount of CA in the Pentax pictures, and the aliasing does not always clean up well with Lightroom’s new Enhance Details function.

Chromatic aberration comparison. This is the extreme corner at 400%. The Fuji GF has been corrected automatically for light falloff, whereas the Pentax has not

Aliasing comparison. There's lots more aliasing in the Fuji file, which points to greater resolving power. The downside is it's ugly and doesn't clean up well.

As a side note, Fuji GF RAFs imported in Lightroom benefit from automatic lens corrections that cannot be turned off on import, whereas Pentax pictures are coming in straight. To see how much work was done on the Fuji file behind the scenes, I used Iridient X Transformer to create an uncorrected version. In the case of the GF 63mm f/2.8 lens, it looks like most of the quality is coming from the optics rather than software. A slight increase in chromatic aberration and light falloff are visible in this 400% comparison of the corners of the corrected and uncorrected versions of the same GF RAF. It’s also apparent that some pixels are “lost” in the corrected version (Left) due to distortion correction that is not applied in the Iridient X Transformer version (Right). The amount of correction seems to be very small.

Left is imported into LR with lens corrections applied. Right is converted in Iridient X Transformer (so no lens corrections)

My Catholic Hill infinity test scene doesn’t reveal anything about the quality of background and foreground blur. That’s not something I pay a lot of attention to anyway in my photography, so I don’t have any pictures to show you. However, based on some casual tests and some real world photography where I used f/2.8, I can say that the wide-open Fuji GF 63/2.8 renders out of focus areas in a way I find pleasing.

It wasn’t possible to compare resistance to flare and ghosting in this scene, but those problems were not prominent in other tests I made; coatings and internal baffles seem to be excellent in both lenses.

The bottom-line for me is that these are both excellent lenses. This post is already long enough so I haven’t addressed the other focal lengths of the SMC Pentax-A 645 45-85mm f/4.5, or the other SMC Pentax-A 645 lenses I use (35/3.5, 150/3.5). I also don’t have comparable Fuji GF lenses for other focal lengths. However, from my own comparisons the 45-85mm is just as good at other focal lengths as it is at 63mm, the 35mm is even sharper than the 45-85mm, and the 150mm is excellent almost from wide-open. Kudos to the old Pentax 645 lens designers. Even without the computing power and manufacturing techniques available today to Fuji, they made extremely high performing optics for the Pentax 645 that perform beautifully on the Fuji GFX 50R/S sensor.

FOLDER CONTAINING RAFS:

This is a Google Drive folder that contains original RAFs.

https://drive.google.com/open?id=1v26ZIVFLSTaW2zUwT3WbrcIHCm9qtpJr

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