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03-03-2017, 09:53 AM - 1 Like   #1
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How do Pentax K1 pixel shift images compare with Fuji GFX images?

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I have a Pentax K1 and just love it. My pixel shift images absolutely blow me away. I think my K1 will be my main camera for years to come - I don't see myself changing to another system anytime soon.

On the Internet we're all reading lots of chatter about the newly released Fuji medium format, 51MP camera the "GFX 50S". I'm sensing lots of excitement about it. I know long time Nikonians who are selling their D810s and moving to the Fuji GFX 50S.

It's certainly too early to expect comparisons of this new medium format camera to other cameras, but I'd hope that in the near future someone does a direct comparison of Pentax K1 Pixel Shift images to Fuji GFX images. I would be very interesting in seeing how K1 pixel shift images compare to GFX images.

The GFX does not have pixel shift, therefore, I might expect from a perceived sharpness standpoint, the two might be fairly close. However, being a medium format camera, I expect that the Fuji GFX would likely better the K1 in dynamic range and 3D-like rendering at wide apertures.

Also, I expect that you Pentaxians with Pentax's medium format digital cameras would love to see comparisons between your Pentax medium format digital cameras and the Fuji GFX too.

If any of you do see such comparisons posted on the Internet somewhere, please do share the link with all of us here at the Pentax Forum.

Meanwhile, I'd be interested to hear your take on the Fuji GFX (will you buy it, how do you think it will compare with your cameras, etc.).

Thank you...



Last edited by Fenwoodian; 03-03-2017 at 11:28 AM.
03-03-2017, 10:44 AM - 5 Likes   #2
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If you compare that actual image data collected by the two camera's the K-1 kills the GFX:

Fuji GFX:
* 12.75 million red-sensitive pixels with big gaps between them in both rows and columns
* 25.5 million green-sensitive pixels with holes
* 12.75 million blue-sensitive pixels with big gaps between them in both rows and columns

K-1 w/ PS:
* 36 million red-sensitive pixels with no gaps or holes
* 36 million green-sensitive pixels with no gaps or holes
* 36 million blue-sensitive pixels with no gaps or holes

Anyone horrified by the use of digital zoom on low-end cameras should be horrified by what demosaicing a Bayer filter image is really doing.

As for "perceived sharpness", that's a tricky issue because the typical demosaicing algorithm often fills in the missing data for each color using measurements in the other colors. Thus, for example, if the green pixels show a sharp edge, the software assumes there's probably a sharp edge in missing red and blue pixels, too, which may not be a bad assumption for a higher percentage of subjects and lighting conditions.

As for dynamic range, the added pixels of data collected by PS create finer-grain noise which translates into finer resolution of high-DR scenes plus PS collects two samples of green for every pixel which enhanced DR in that channel.

And as for "3D-like rendering at wide apertures" there's the issue that one can generally get larger aperture lenses for the K-1.
03-03-2017, 10:44 AM - 2 Likes   #3
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Fuji just reuses the now semi old sensor as used in the Pentax 645Z for some years now.

From a sheer pixel peeping perspective there is little to no difference to a K-1:

Studio shot comparison: Digital Photography Review

I'd say the pentax K-1 with pixelshift even is on top of the pack, with the Pentax 645z following closely and the best Canon, Sony, Nikon equipment following behind.
The Fuji will perform about as good as the Pentax 645z (assuming they sometime produce better lenses than the meh 65mm types that are now floating around with at best mediocre results).

Lets not forget the Pixelshift image has 36 MPx information in all 3/4 colors, while a 50 MPx image only has 12,5 Mpx information with the rest just computer guesswork.
03-03-2017, 11:27 AM   #4
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I should clarify, I'm of course referring to the Fuji GFX "50S" model. The one with the 51.4MP CMOS medium format sensor.

---------- Post added 03-03-17 at 12:35 PM ----------

QuoteOriginally posted by photoptimist Quote
If you compare that actual image data collected by the two camera's the K-1 kills the GFX:

And as for "3D-like rendering at wide apertures" there's the issue that one can generally get larger aperture lenses for the K-1.
Agreed.

Any comparison between the K1 and the GFX 50S would necessitate the use of different lenses.

Right now there are only 3 Fuji lenses available for the GFX 50S - two are f/4 lenses and one is f/2.8.

I was of course thinking of a comparison using lenses set to the same aperture. Using faster K1 lenses at a wider aperture would of course skew the results in favor of the K1.


Last edited by Fenwoodian; 03-03-2017 at 11:37 AM.
03-03-2017, 01:04 PM - 1 Like   #5
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I think all the replies above are fully aware of the comparison. 51 Mpix with a Bayer filter means 8256 x 6192 pixels = 51121152 pixels of which 1/4 are sensing red, 1/4 are sensing blue and the remaining half are sensing green (RGBG pattern).

Therefore:
12780288 red pixels
12780288 blue pixels
25560576 green pixels

The K1 in PS gives 7360 x 4912 = 36152320 pixels for each colour (with green double sampled)

In a straight fight between a K1 in PS and the Fuji GFX 50S, the K1 would technically win the colour resolution competition. However, in real life how many subjects do you photograph using:

1. A tripod
2. Have no significant motion

I can't say I've used PS very often, though when I have used it for macro shots of motionless items, the results have been stunning.
03-03-2017, 01:50 PM   #6
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PS = Drool.
03-03-2017, 03:26 PM   #7
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QuoteOriginally posted by phoebus Quote
. However, in real life how many subjects do you photograph using:

1. A tripod
2. Have no significant motion
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The majority of what I shoot with my K1 are motionless subjects with my K1 on a tripod.

Also, I own dozens of lenses, and not one has auto focus! Don't need AF and don't want AF.

Obviously, there are many types of photography and photographers out there.


03-03-2017, 04:09 PM   #8
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Someone should organise a comparison shoot-out of the K-1 with all the current MF's with the Sony 51 MP sensor - ie the 645Z, Fuji GFX 50S, and Hasselblad X1D. And include the Phase One IQ3 50MP [actually 51MP] CMOS back, which is also likely the same Sony chip. And for good measure, throw in a comparison with the Canon 5DSR.

I wonder if any updated 645Z (645Z II?) will offer pixel-shift? That would be interesting.
03-03-2017, 05:15 PM - 1 Like   #9
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Well, I would choose a 645Z before a K-1 any day when it comes to image quality. It is medium format and even though the PS is nice, it does not compare to the true MF 3D feel. Also being able to handhold shooting with the 645Z vs tripod K-1/PS is one more advantage or if the subject is moving in any way the PS is not really worth the trouble. Love my K-1 but it can do only so much. Also love my 6x7 for the really, really big image surface.

I really like the Pixel shift but I use it less and less due to the more or less cumbersome work flow. And I can't say I see much difference when printing around A4 to A3+.
03-03-2017, 06:32 PM - 2 Likes   #10
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QuoteOriginally posted by Tjompen1968 Quote
Well, I would choose a 645Z before a K-1 any day when it comes to image quality. It is medium format and even though the PS is nice, it does not compare to the true MF 3D feel. Also being able to handhold shooting with the 645Z vs tripod K-1/PS is one more advantage or if the subject is moving in any way the PS is not really worth the trouble. Love my K-1 but it can do only so much. Also love my 6x7 for the really, really big image surface.

I really like the Pixel shift but I use it less and less due to the more or less cumbersome work flow. And I can't say I see much difference when printing around A4 to A3+.


I agree with this statement. I love my k-1 but i find myself taking the z with me more. Although p/s is nice it has too many limitations.

Also ive done my own tests between the k-1 and the z due to curiosity. There are two phrases that i love hearing about full frame, it has a medium format feel, and you can get the same image. Both are funny, first quote, the only camera that feels like medium format is medium format. The second quote cant be farther from the truth. As far as what i saw: Dof-can be replicated, lighting-can be replicated, how the subject fills the frame and how everything behaves within the frame-couldnt replicate it. No matter how many times the different formats get compared, you can not get the same results between formats. Each format serves their own purposes.


03-03-2017, 08:20 PM - 3 Likes   #11
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QuoteOriginally posted by Tjompen1968 Quote
Well, I would choose a 645Z before a K-1 any day when it comes to image quality. It is medium format and even though the PS is nice, it does not compare to the true MF 3D feel. Also being able to handhold shooting with the 645Z vs tripod K-1/PS is one more advantage or if the subject is moving in any way the PS is not really worth the trouble. Love my K-1 but it can do only so much. Also love my 6x7 for the really, really big image surface.

I really like the Pixel shift but I use it less and less due to the more or less cumbersome work flow. And I can't say I see much difference when printing around A4 to A3+.
Give Raw Therapee v5 a try.
Its a game changer wrt pixel shift processing.
Fast, smart, customize-able masking.

I'm now churning out pixel shift files as if they are normal RAWs, with RT.


Oh... and it can load LR camera and lens profiles.

Last edited by pinholecam; 03-03-2017 at 08:38 PM.
03-04-2017, 12:58 PM   #12
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QuoteOriginally posted by Tjompen1968 Quote
Well, I would choose a 645Z before a K-1 any day when it comes to image quality. It is medium format and even though the PS is nice, it does not compare to the true MF 3D feel. Also being able to handhold shooting with the 645Z vs tripod K-1/PS is one more advantage or if the subject is moving in any way the PS is not really worth the trouble. Love my K-1 but it can do only so much. Also love my 6x7 for the really, really big image surface.

I really like the Pixel shift but I use it less and less due to the more or less cumbersome work flow. And I can't say I see much difference when printing around A4 to A3+.
I have both cameras, and I'd say that the K1 is an excellent backup camera to the Z, and for some things (certain types of quick documentary work I've had to do at work lately...) *maybe* the first choice (although the real reason I've been using it for this at work lately is that I've got a UWA for it which I need for the interior shots I'm having to do, and the IBIS is coming in handy in order to preserve the dark lighting w/o using a tripod/monopod... but this is very specialized work in a curious museum setting). But mainly for me the Z is still the star and my first choice for my most serious work. I don't see that changing. I'm glad I have the K1 as a backup in case my Z has to go to the shop.
03-04-2017, 04:26 PM   #13
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QuoteOriginally posted by pinholecam Quote
Give Raw Therapee v5 a try.
Its a game changer wrt pixel shift processing.
Fast, smart, customize-able masking.

I'm now churning out pixel shift files as if they are normal RAWs, with RT.


Oh... and it can load LR camera and lens profiles.
Is there a guide on how to deal with PS images in RT? I've poked around it a bit, if it makes the workflow easier than Silky pix into lr, I'd give it another go)
03-05-2017, 03:47 AM - 2 Likes   #14
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QuoteOriginally posted by awscreo Quote
Is there a guide on how to deal with PS images in RT? I've poked around it a bit, if it makes the workflow easier than Silky pix into lr, I'd give it another go)
Here's a try...

Access the pictures via selecting the directory (as any other software)
I've found that as long as the directory is not choke full of files, RT works fast, so I will split files into a few folders to keep things going fast.


For PixS files, the Demosaicing tab is where we can select the algo used (so select "pixelshift" as shown here)


I've found that leaving Motion Correction as Automatic often works very well with v5 of RT (it was less so on the v4 PixS branch of the software)
There is a Show Motion checkbox that is checked to show what the program thinks needs to be masked (ie. it will use only 1 layer for those parts)

I'm tending towards just leaving on Auto, checking that the mask is not masking off too much and thats the end of it wrt me doing any PixS actions. (because v5 on auto works well in most cases)


Selecting "Custom" opens up all the masking options.


As you can see, there are loads of options. (but I am finding less need to use them since v5)

Forum user "heckflosse" who works on the RT gave very good info on them here :
https://www.pentaxforums.com/forums/190-pentax-k-1/324925-pixel-shifted-imag...ml#post3917471

"Currently the 3x3 new (we should find a better name for it, I just chose this name because it was new at that time) is the way to go for motion correction in rt imho. It's the only method which allows the options 'Fill Holes', 'Blur' and 'smooth transitions'. For pixel shift images without motion it may be better to choose 'Motion correction off' and for images with very little motion you should try to disable 'check red/blue cross' to get as much details as possible"


If you have LR or can get hold of the camera profiles, it can be used by RT.
This is the tab to do it (under Color Management ) :




Similarly, LR Lens Profiles can be loaded here:




You can save all the settings as Custom Profiles, so that you load them with all the settings that you want at a click.
For Example,
I'd often use a custom profile set as "Pixel Shift -Landscape -auto" - which has the Pentax "Landscape" color profile, Pixel Shift, custom curve/sharpening/other adj

Last edited by pinholecam; 03-05-2017 at 03:55 AM.
03-05-2017, 06:00 AM   #15
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You do not buy a medium format camera for pixel count alone. Get an ALPA with Live View Phase One back and you have 100MP today and 200MP tomorrow - all RGB, or get a monochrome back, ... Fuji has some 50MP single shot. Price and form factor are similar to top 35mm gear, but pixels cover more area, focus perfromance is quite different as well as lens selection.
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