Pages: [1] 2   Go Down

Author Topic: Pentax 645z vs Fuji GFX  (Read 3780 times)

michaelbiondo

  • Full Member
  • ***
  • Offline Offline
  • Posts: 126
    • http://michael@michaelbiondo.com
Pentax 645z vs Fuji GFX
« on: July 15, 2017, 06:30:35 PM »

Hello,
I have been shooting architecture with the Pentax 645Z for the past few years. Most of the time I work with the 28-45 zoom and I feel that this camera & lens combo works pretty well for my style of photography. I am very curious about the GFX for several reasons. First, to me, size matters. The Pentax with the 28-45 is a beast of a camera. If the Fuji with the 32-64, or possibly wide angle Nikon or Canon glass was significantly smaller or lighter, I might be tempted to switch for that reason alone. Secondly, for times when I am un-tethered and off-tripod, I really like to see a live histogram in the viewfinder. So having that in the EVF with the Fuji is a big plus. Finally, the versatility of the Fuji, with lenses and tech camera options is also a very attractive feature.
The two questions I have are 1) are the current Fuji GFX users finding the GFX to be reliable? For the past two years of heavy use I have found the Pentax to be bulletproof and I am interested in the Fuji users experience so far. Second question concerns image quality, hard to tell from inner web example and I will only know until I test for myself, but it appears that the Fuji out performs the Pentax when it comes to high ISO performance and sharpness. Could that be true or am I just trying to rationalize a "new toy" purchase. Very interested in what you all think.
Thanks,
MB

Phil Indeblanc

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 2011
Re: Pentax 645z vs Fuji GFX
« Reply #1 on: August 17, 2017, 03:40:37 PM »

I have heard from other users that the focus of the Fuji is amazingly great and fast, as they complained about the Pentax focus being iffy.
Logged
If you buy a camera, you're a photographer...

Jim Kasson

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 1852
    • The Last Word
Re: Pentax 645z vs Fuji GFX
« Reply #2 on: August 17, 2017, 03:52:52 PM »

Hello,
I have been shooting architecture with the Pentax 645Z for the past few years. Most of the time I work with the 28-45 zoom and I feel that this camera & lens combo works pretty well for my style of photography. I am very curious about the GFX for several reasons. First, to me, size matters. The Pentax with the 28-45 is a beast of a camera. If the Fuji with the 32-64, or possibly wide angle Nikon or Canon glass was significantly smaller or lighter, I might be tempted to switch for that reason alone. Secondly, for times when I am un-tethered and off-tripod, I really like to see a live histogram in the viewfinder. So having that in the EVF with the Fuji is a big plus. Finally, the versatility of the Fuji, with lenses and tech camera options is also a very attractive feature.
The two questions I have are 1) are the current Fuji GFX users finding the GFX to be reliable? For the past two years of heavy use I have found the Pentax to be bulletproof and I am interested in the Fuji users experience so far. Second question concerns image quality, hard to tell from inner web example and I will only know until I test for myself, but it appears that the Fuji out performs the Pentax when it comes to high ISO performance and sharpness. Could that be true or am I just trying to rationalize a "new toy" purchase. Very interested in what you all think.


WRT sharpness, the GFX is sharper than you'd expect a 33x44mm sensor with a 5.3 um pitch to be. The reason is the small micro lenses.

http://blog.kasson.com/the-last-word/discovering-the-fujifilm-gfx-50s-microlens-size/

My copy of the 32-64 is the sharpest zoom I've used. It has low LoCA, fairly low focus shift, and is not far from parfocality:

http://blog.kasson.com/?s=32-64

It's not quite the equal of the 63/2.8 at the apertures the two lenses have in common, but it's close.

I have had no camera or lens failures. The firmware has been very solid, and Fuji has been quick to correct most of the initial complaints with FW revs. There are tricks to getting reliable manual focus. At some apertures, and some lenses, the AF is not completely accurate, but the errors are small enough that many will not even see them.

It's a camera with a few gotchas, but in general, I am extremely impressed. The lens line is superb, with the exception of the 63, which is merely very good. The quality of the lenses was the biggest surprize for me.

Jim




hubell

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 910
Re: Pentax 645z vs Fuji GFX
« Reply #3 on: August 17, 2017, 07:20:09 PM »

WRT sharpness, the GFX is sharper than you'd expect a 33x44mm sensor with a 5.3 um pitch to be. The reason is the small micro lenses.

http://blog.kasson.com/the-last-word/discovering-the-fujifilm-gfx-50s-microlens-size/

Jim

I read that blog entry three times expecting it to contain some revelation about the significance of the smaller microlenses that Fuji used in its version of the Sony sensor. I never found it.
Logged

Jim Kasson

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 1852
    • The Last Word
Re: Pentax 645z vs Fuji GFX
« Reply #4 on: August 17, 2017, 07:40:23 PM »

I read that blog entry three times expecting it to contain some revelation about the significance of the smaller microlenses that Fuji used in its version of the Sony sensor. I never found it.

I'm going to assume that there's a question in there. If I'm wrong, ignore the rest of this post.

I'll give you the "See Spot run" version:

Sharper than you'd think by looking at the pixel count.
More aliasing than you'd think by looking at the pixel count.

Jim

hubell

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 910
Re: Pentax 645z vs Fuji GFX
« Reply #5 on: August 17, 2017, 09:47:45 PM »

I'm going to assume that there's a question in there. If I'm wrong, ignore the rest of this post.

I'll give you the "See Spot run" version:

Sharper than you'd think by looking at the pixel count.
More aliasing than you'd think by looking at the pixel count.

Jim

I defy anyone to read that blog and infer an analysis and a deductive conclusion from it that demonstrates that the Fuji lenses are sharper because of the smaller microlenses. I suppose it's possible that it's true, but I certainly wouldn't infer it from that blog entry. Over the years, I have developed a keen appreciation that the difference between people who are really good at what they do and those that are not is the ability to explain complex concepts in an understandable way to those who are not experts in the subject matter. Surely an explanation ought to offer more than a conclusory statement  that the "effective fill factor of the GFX 50S is around 76%."
Now, to be clear, I have actually shot the GFX with the GFX zoom and compared the files side by side against the X1D with the 30mm and 45mm lenses. The GFX zoom is impressive in its own right, but once the X1D files were properly sharpened, the files with the X1D lenses were sharper. Not surprising, as I was comparing a zoom with primes. What struck me, however, was that the GFX files seemed as if they were already sharpened right out of the camera, whereas the X1D files were not and could be improved very significantly with good deconvolution sharpening.
« Last Edit: August 17, 2017, 09:56:53 PM by hubell »
Logged

pschefz

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 321
Re: Pentax 645z vs Fuji GFX
« Reply #6 on: August 17, 2017, 10:24:36 PM »

another vote for the GFX, great camera, great system, amazing lenses....
it is still the same sony sensor, so IQ is proven, IMO great up to 800, i try not shoot anything over....AF is pretty amazing for "medium format" but nothing special in comparison to smaller mirrorless....
pretty incredible package all around, price, size, weight, and incredible lenses for very reasonable price (compared to all others including canon and nikon)...

thanks again Jim for doing all the work and showing us in numbers what the eyes see.....
Logged
schefz.com
artloch.com

Jim Kasson

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 1852
    • The Last Word
Re: Pentax 645z vs Fuji GFX
« Reply #7 on: August 17, 2017, 10:25:19 PM »

I defy anyone to read that blog and infer an analysis and a deductive conclusion from it that demonstrates that the Fuji lenses are sharper because of the smaller microlenses. I suppose it's possible that it's true, but I certainly wouldn't infer it from that blog entry. Over the years, I have developed a keen appreciation that the difference between people who are really good at what they do and those that are not is the ability to explain complex concepts in an understandable way to those who are not experts in the subject matter. Surely an explanation ought to offer more than a conclusory statement  that the "effective fill factor of the GFX 50S is around 76%."
Now, to be clear, I have actually shot the GFX with the GFX zoom and compared the files side by side against the X1D with the 30mm and 45mm lenses. The GFX zoom is impressive in its own right, but once the X1D files were properly sharpened, the files with the X1D lenses were sharper. Not surprising, as I was comparing a zoom with primes. What struck me, however, was that the GFX files seemed as if they were already sharpened right out of the camera, whereas the X1D files were not and could be improved very significantly with good deconvolution sharpening.

The blog post says nothing about the sharpness of the Fuji lenses. Indeed, the test results for the curve fitting were done not with a Fuji lens at all, but with an Otus 85/1.4. The blog post is about the extra sharpness over a standard 100% fill-factor sensor caused by the small microlenses in the GFX.

So, I would defy anyone to read that post and "infer an analysis and a deductive conclusion from it that demonstrates that the Fuji lenses are sharper because of the smaller microlenses. " Just like you.

We are in agreement on the facts.

By the way, I did not write the blog post. It was written by an engineer whose qualifications are summarized on the post as:

"Brandon Dube is a senior optics student at the Institute of Optics, University of Rochester.  He works in Dr. Jannick Rolland’s Optical Diagnostics and Testing Lab (ODALAB), as well as the Center for Freeform Optics (CeFO) at the institute, and is also the Director of Metrology at Olaf Optical Testing, which many readers know as Lensrentals, as Olaf is heavily featured on the LR blog.  This summer, he has been working at JPL on the cameras for the Mars 2020 rover.  Earlier this year, he received the Kevin P. Thompson prize, the highest award given to undergraduate optics students.  You can read his resume here."

Jim


hubell

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 910
Re: Pentax 645z vs Fuji GFX
« Reply #8 on: August 17, 2017, 10:55:30 PM »

The blog post says nothing about the sharpness of the Fuji lenses. Indeed, the test results for the curve fitting were done not with a Fuji lens at all, but with an Otus 85/1.4. The blog post is about the extra sharpness over a standard 100% fill-factor sensor caused by the small microlenses in the GFX.

So, I would defy anyone to read that post and "infer an analysis and a deductive conclusion from it that demonstrates that the Fuji lenses are sharper because of the smaller microlenses. " Just like you.

We are in agreement on the facts.

Jim

Well, here's what you said:
"WRT sharpness, the GFX is sharper than you'd expect a 33x44mm sensor with a 5.3 um pitch to be. The reason is the small micro lenses." Sure sounds to me that you were claiming that the smaller microlenses in the Fuji version of the Sony sensor are a special sauce responsible for an exceptional level of sharpness in the output compared to the output from the same sensor in Pentax, Phase and Hasselblad systems. And you cited the blog entry as evidentiary support for that assertion.
Logged

Jim Kasson

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 1852
    • The Last Word
Re: Pentax 645z vs Fuji GFX
« Reply #9 on: August 17, 2017, 11:06:02 PM »

Well, here's what you said:
"WRT sharpness, the GFX is sharper than you'd expect a 33x44mm sensor with a 5.3 um pitch to be. The reason is the small micro lenses." Sure sounds to me that you were claiming that the smaller microlenses in the Fuji version of the Sony sensor are a special sauce responsible for an exceptional level of sharpness in the output compared to the output from the same sensor in Pentax, Phase and Hasselblad systems. And you cited the blog entry as evidentiary support for that assertion.

What you said was: " I defy anyone to read that blog and infer an analysis and a deductive conclusion from it that demonstrates that the Fuji lenses are sharper because of the smaller microlenses."

The post says nothing about the sharpness of the Fuji lenses, although they are quite sharp. The post is about the properties of the sensor stack in the GFX, in particular, the microlenses.

I agreed with you that you couldn't draw any conclusions about the Fuji lenses from that post.

I am saying that the exceptional sharpness of images from the GFX sensor -- as measured against the same lenses used on other sensors -- is due to the small micro lenses.

This is not without undesirable side effects, such as increased aliasing.

We saw with the D800/D800E that deconvolution sharpening could compensate to a large degree for an AA filter, at a cost of SNR. So, by extension, it should be possible to sharpen files made with micro lenses that are close to 100% in effective fill factor and make them look very much like the GFX files.

TANSTAAFL.

Jim

hubell

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 910
Re: Pentax 645z vs Fuji GFX
« Reply #10 on: August 18, 2017, 12:07:59 AM »


I agreed with you that you couldn't draw any conclusions about the Fuji lenses from that post.

Jim

I would go a step further and say that I couldn't draw any conclusions about anything of real world significance from that post.
What would be instructive to me at least is to take the same Hasselblad lens and mount it on both the GFX and another camera that uses the Sony sensor like the H6D50 or the X1D, turn off all of the baked in sharpening in the raw file and then sharpen them as effectively as possible in Iridient Developer or Photoshop.
Logged

Paul2660

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 3707
    • Photos of Arkansas
Re: Pentax 645z vs Fuji GFX
« Reply #11 on: August 18, 2017, 08:33:05 AM »

I don't agree on the theory of baked in sharpening. For raw files.

I do agree the Fuji possibly has a different filter array over the sensor with smaller micro lenses. Fuji made a point about the fact the they had Sony make a different array for them.

Just open the GFX files in C1.  As C1 has no native support for the files any baked in sharpening would be defeated. Files are plenty sharp. Are the sharper than the X1D I can say as I don't have one. But if they were any sharper I feel the images would appear too sharp.

Images from either camera should be excellent.

Fuji should have stepped up to the plate better on the software support for raw. LR support is lacking and the native Fuji software is worthless. Hasselblad and Phocus is a much better platform.  Being able to back door use C1 is very important for me.

Paul Caldwell
Logged
Paul Caldwell
Little Rock, Arkansas U.S.
Photography > http://photosofarkansas.com
Blog> http://paulcaldwellphotography.com

Jim Kasson

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 1852
    • The Last Word
Re: Pentax 645z vs Fuji GFX
« Reply #12 on: August 18, 2017, 09:35:43 AM »

I would go a step further and say that I couldn't draw any conclusions about anything of real world significance from that post.
What would be instructive to me at least is to take the same Hasselblad lens and mount it on both the GFX and another camera that uses the Sony sensor like the H6D50 or the X1D, turn off all of the baked in sharpening in the raw file and then sharpen them as effectively as possible in Iridient Developer or Photoshop.

The post explains why the GFX images with top lenses are so much sharper than you'd think. In many cases, they are sharper than they would be with a perfect, diffraction-limited lens on a 100% fill factor sensor. The post does not even attempt to show the visual effect of the increased sharpness. There are plenty of images that do that elsewhere on my blog.

I've talked about the difficulties of the test that you suggest in this forum before. I have not found an HC lens that challenges the GFX sensor on-axis, and I expect that the same will be the case with the X1D. There is no way to use the Fuji lenses on the X1D. There is no way to use the X lenses on the GFX. There is no way to use FF lenses like the Otus ones on the X1D -- no shutter.

In any event, I have sold all my HC lenses, and my Hasselblad bodies.

Jim

Jim Kasson

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 1852
    • The Last Word
Re: Pentax 645z vs Fuji GFX
« Reply #13 on: August 18, 2017, 09:38:35 AM »

Fuji should have stepped up to the plate better on the software support for raw. LR support is lacking and the native Fuji software is worthless. Hasselblad and Phocus is a much better platform.  Being able to back door use C1 is very important for me.

Have you tried Iridient X-Transformer as a front end to Lr? It allows some control that is missing from Lr, like defeating distortion correction profiles.

Jim

Paul2660

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 3707
    • Photos of Arkansas
Re: Pentax 645z vs Fuji GFX
« Reply #14 on: August 18, 2017, 09:44:45 AM »

Hi Jim:

I need to look at it again.  I tried it early on and did not like the color I was seeing in the dng.  But I love the x transformer for x-trans files.

The C1 files to my eyes are a bit cleaner especially past ISO 400, than LR, but I will take another look at the x transformer.

Paul Caldwell
Logged
Paul Caldwell
Little Rock, Arkansas U.S.
Photography > http://photosofarkansas.com
Blog> http://paulcaldwellphotography.com

Jim Kasson

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 1852
    • The Last Word
Re: Pentax 645z vs Fuji GFX
« Reply #15 on: August 18, 2017, 10:24:06 AM »

Hi Jim:

I need to look at it again.  I tried it early on and did not like the color I was seeing in the dng.  But I love the x transformer for x-trans files.

The C1 files to my eyes are a bit cleaner especially past ISO 400, than LR, but I will take another look at the x transformer.

There are a lot of XT options, so be patient when you first use it.

Jim

hubell

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 910
Re: Pentax 645z vs Fuji GFX
« Reply #16 on: August 18, 2017, 04:06:49 PM »

"The post explains why the GFX images with top lenses are so much sharper than you'd think."

Seriously? Explains to whom? An optical engineer?

"In many cases, they are sharper than they would be with a perfect, diffraction-limited lens on a 100% fill factor sensor. The post does not even attempt to show the visual effect of the increased sharpness. There are plenty of images that do that elsewhere on my blog."

You mean the ones comparing GFX files with Sony files using the same lens that is non-native to both platforms?

"I've talked about the difficulties of the test that you suggest in this forum before. I have not found an HC lens that challenges the GFX sensor on-axis, and I expect that the same will be the case with the X1D. There is no way to use the Fuji lenses on the X1D. There is no way to use the X lenses on the GFX. There is no way to use FF lenses like the Otus ones on the X1D -- no shutter."

Why not mount the same HC lens on both platforms? That you can do. That would presumably isolate the effect of the magic microlenses on the output, assuming you can turn off any baked in sharpening and then sharpen them the same, or just sharpen them as effectively as possible.



« Last Edit: August 18, 2017, 04:16:10 PM by hubell »
Logged

Jim Kasson

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 1852
    • The Last Word
Re: Pentax 645z vs Fuji GFX
« Reply #17 on: August 18, 2017, 04:19:36 PM »

The post explains why the GFX images with top lenses are so much sharper than you'd think.
Seriously???? Explains to whom??? An optical engineer?
In many cases, they are sharper than they would be with a perfect, diffraction-limited lens on a 100% fill factor sensor. The post does not even attempt to show the visual effect of the increased sharpness. There are plenty of images that do that elsewhere on my blog. 
You mean the ones comparing GFX files with Sony files using the same lens that is non-native to both platforms?

I've talked about the difficulties of the test that you suggest in this forum before. I have not found an HC lens that challenges the GFX sensor on-axis, and I expect that the same will be the case with the X1D. There is no way to use the Fuji lenses on the X1D. There is no way to use the X lenses on the GFX. There is no way to use FF lenses like the Otus ones on the X1D -- no shutter.
Why not mount the same HC lens on both platforms? That you can do. That would presumably isolate the effect of the magic microlenses on the output, assuming you can turn off any baked in sharpening and then sharpen them the same, or just sharpen them as effectively as possible.


Well, it's clear that it doesn't explain it in a way that works for you, so why don't you just stop trying. There are plenty of other more visual ways of looking at the issue on my web site, particularly the side-by-side comparisons with the a7RII, which has a 100% fill factor. (unfortunately for precise comparisons, the resolution and pitch of the s7RII are different from the GFX).

None of my HC lenses gave the sensor on my GFX an image that was sharp enough for the difference in fill factor to affect the final result. There was so much softness in the lenses that they were the long pole in the tent, not the sensor.

You must have missed this up above: "In any event, I have sold all my HC lenses, and my Hasselblad bodies." So I can't do the test even if I thought it would be useful.

Jim

Jim Kasson

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 1852
    • The Last Word
Re: Pentax 645z vs Fuji GFX
« Reply #18 on: August 18, 2017, 04:54:39 PM »

WRT sharpness, the GFX is sharper than you'd expect a 33x44mm sensor with a 5.3 um pitch to be. The reason is the small micro lenses.

There are people here for whom the link I posted is too detailed and technically challenging. They should ignore this post. For those who are interested in still more details of the search for the secret of the GFX microlenses, here's a link chock full of engineering debate:

https://www.dpreview.com/forums/post/59813210

Short version: Jack Hogan (who is s sometime contributor to LuLa) attacked the problem with a methodology that differs from that employed by Brandon Dube. Jack found the microlenses to be even smaller than Brandon's estimate.

jim

hubell

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 910
Re: Pentax 645z vs Fuji GFX
« Reply #19 on: August 18, 2017, 05:57:28 PM »

There are people here for whom the link I posted is too detailed and technically challenging. They should ignore this post. For those who are interested in still more details of the search for the secret of the GFX microlenses, here's a link chock full of engineering debate:

https://www.dpreview.com/forums/post/59813210

Short version: Jack Hogan (who is s sometime contributor to LuLa) attacked the problem with a methodology that differs from that employed by Brandon Dube. Jack found the microlenses to be even smaller than Brandon's estimate.

jim

I can't believe you have so much difficulty understanding the problem with your post. The post only addresses one part of your argument as to why the magical microlenses are so so revolutionary in achieving superior levels of sharpness with the same lens, namely the size of the microlenses. The second part, which I expected to see discussed but never was, is WHY smaller microlenses make a difference in sharpness that cannot be achieved with the "regular" microlenses and highly skilled sharpening techniques. If you had to explain to a group of people who are not engineers why the Fuji microlenses are so significant, would you just trot out Brian Dube to deliver his scientific paper as it was written?
What makes me so skeptical about the magical microlenses thing is that I actually tested the GFX against another camera with the same sensor but with "regular" microlenses. Yes, if you just took GFX files into LR and applied the default sharpening in LR, they looked very sharp. However, they couldn't handle much additional sharpening without becoming crunchy. The X1D files did not look as sharp with the default sharpening in LR, but as soon as the settings were changed to achieve optimal sharpening in LR, the X1D files looked sharper. The same thing was observed by turning off LR sharpening, bringing the files into PS and using the same Focus Magic settings. Moreover, there are some really smart people working at Pentax, Phase and Hasselblad, and none of them reengineered the microlenses. Were they all just asleep at the switch? Or is there a tradeoff in using the magical microlenses that they considered a poor design choice? Soon enough we will know, as the next iteration of the 44x33 medium format Sony sensor will be released next year. We shall see if they all use the same size microlenses.
So, if I understand what you are saying about the HC lenses, the comparison I suggested wouldn't work because the HC lenses suck so bad. The magic microlenses only show their stuff with certain lenses but not others?
I did see your tests with the HC lenses on the GFX. I agree that the leaves on the trees at a distance looked bad. But to be candid, the leaves on the trees in all your tests look really bad to me. Last weekend, I photographed a tree at a long distance with the HC 210 and 300mm lenses and enlarged the files to 300% on the screen and the leaves did not look nearly as bad.
Logged
Pages: [1] 2   Go Up