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Author Topic: My journey into MF digital, starting with a P45+ on a Hasselblad 555ELD  (Read 48035 times)

ErikKaffehr

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Guy,

Thanks for chiming in, always nice to hear from you ;-)

Just a few observations...

I'm not really interested in high ISO work. Almost anything I shoot I always use base ISO.

Regarding C1 and LR4, the way it is I am pretty much aligned to LR4, not because it is best but because I haved used it since 2006 and also because I am much into parametric workflow. I have bought C1 some time ago, and I am using it in parallell.

I am aware that P45+ is an older sensor and also that it uses a Kodak sensor.



Erik

Couple quick notes the P45plus is a older back with pretty much a outdated sensor comparing it to the new breeds of the Dalsa lets say and even your new Sony and Nikons. So the DR will probably will not be as wide open lets say as the newer sensors thats a given as I tested this a long time ago with the P65 Plus and P40 Plus. It still is a great sensor and it does have that Kodak color and saturation that it is known for compared to the Dalsa which has more DR and a more neutral color palette. Not that one is better than the other but there is a difference and some folks like one over the other for sure. I had the P25, P30 Plus backs and used the P45plus back pretty often. They are pretty much the same Kodak breeds of sensors but than I moved on to the Dalsa via the P40, IQ 160 and IQ 140 which I liked better but that is my preference in the end was the Dalsa. What the P45 plus is good at is very long exposures good ISO noise levels up to maybe ISO 200 but after that shadow noise will come into play with the higher ISO's. So if you use it within its limitations its a great back. Use it outside of them you may have some disappointment. But I encourage you to use C1 as in the past Lightroom sucked on those backs, not sure about today and there newer versions since I dont even have it on my machine anymore. But if I am bias than C1 is my raw processing machine and I use that on every cam it supports or i wont buy a system it does not support. You will get better results that I can tell you as the Phase engineers specifically work C1 for there backs which makes perfect sense.

BTW I was passing by and glad to see you finally jumped in. MF is fun and the results are worth it IMHO. Also go have some fun, testing gets pretty damn boring even for a engineer. Be well
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Erik Kaffehr
 

ErikKaffehr

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Hi,

I think those are valid points. I know that Doug works with color reproduction at DT, or at least DT has a division working in that area.

Doug is probably right in some aspects. On the other hand I would guess that some other experts, like Jeff Schewe may have other opinions, but Jeff is working with an other company making imaging software. Jeff suggests that noise reduction and tone mapping functions in Lightroom are superior to Capture 1: http://www.luminous-landscape.com/forum/index.php?topic=79446.msg640785#msg640785

I would still suggest that reproducing a color checker is a good thing. It is the closest thing to a reference available to everyone. It is an old stalwart of the industry.

I also think that color profiling in LR is working differently than the impression Doug has. As far as I know, each new sensor is measured with a monochromator at some lab working for Adobe. When you build a DNG profile you are tweaking the original profile. So it still based on monochromator data but individually tuned.

Best regards
Erik
 


Quote
In particular the color tests you've done don't really correlate to creative image making. Such delta-e color accuracy charting is of great value for art reproduction. But the flash and daylite profiles in Capture One aren't meant for art reproduction. They are meant to balance accuracy and pleasantness of color. If you wanted to minimize delta-e believe me you could hit some insanely tight performance requirements (our Department of Cultural Heritage does it all the time as measured by FADGI and METAMORFOZE compliance). But this won't necessarily make your pictures prettier (better than even odds in my experience that it won't). The Colorchecker Passport is a nice consumer-grade profiling system but
1) it's usually brought up in conversation when the default LR profile is pretty awful as it is in this case for the P45+
2) it increases accuracy, but with no human touch to the pursuit of making pleasant color (as is the case when the color gurus at Capture One sit down and tweak profiles for dozens of hours per back to really make the color sing in as broad of situations as is possible)
3) it isn't nearly as accurate as a more professional profiling system (more patches, more constraints on production, more fine tuning steps)


I am citing this post because it should not go unnoticed.
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Erik Kaffehr
 

yaya

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Hi,

I think those are valid points. I know that Doug works with color reproduction at DT, or at least DT has a division working in that area.

Doug is probably right in some aspects. On the other hand I would guess that some other experts, like Jeff Schewe may have other opinions, but Jeff is working with an other company making imaging software. Jeff suggests that noise reduction and tone mapping functions in Lightroom are superior to Capture 1: http://www.luminous-landscape.com/forum/index.php?topic=79446.msg640785#msg640785

I would still suggest that reproducing a color checker is a good thing. It is the closest thing to a reference available to everyone. It is an old stalwart of the industry.

I also think that color profiling in LR is working differently than the impression Doug has. As far as I know, each new sensor is measured with a monochromator at some lab working for Adobe. When you build a DNG profile you are tweaking the original profile. So it still based on monochromator data but individually tuned.

Best regards
Erik

Eric Chan might want to chime in and tell you how the profiles for LR are made

As regards colorcheckers etc. the standard one for reproduction is the SG one with far more tones than the 24-patch consumer-grade one. Also when generating profiles one should be using a linear curve and adjust exposure (on the camera) accordingly or otherwise you're compressing the gamut

Yair
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Yair Shahar | Product Manager | Phase One - Cultural Heritage
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jerome_m

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Hi,

I think those are valid points. I know that Doug works with color reproduction at DT, or at least DT has a division working in that area.

Doug is probably right in some aspects. On the other hand I would guess that some other experts, like Jeff Schewe may have other opinions, but Jeff is working with an other company making imaging software. Jeff suggests that noise reduction and tone mapping functions in Lightroom are superior to Capture 1: http://www.luminous-landscape.com/forum/index.php?topic=79446.msg640785#msg640785

I would still suggest that reproducing a color checker is a good thing. It is the closest thing to a reference available to everyone. It is an old stalwart of the industry.

I also think that color profiling in LR is working differently than the impression Doug has. As far as I know, each new sensor is measured with a monochromator at some lab working for Adobe. When you build a DNG profile you are tweaking the original profile. So it still based on monochromator data but individually tuned.

Measuring a sensor with a monochromator is not difficult and would give direct information about the primary filters. It should be the preferred method.

But this is not what Doug said. Doug believes that accurate color reproduction is not what the manufacturers are aiming to. This is also my opinion. And if the manufacturers are not designing their back for accurate color reproduction, measuring the accuracy of color reproduction is futile.
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torger

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Measuring a sensor with a monochromator is not difficult and would give direct information about the primary filters. It should be the preferred method.

But this is not what Doug said. Doug believes that accurate color reproduction is not what the manufacturers are aiming to. This is also my opinion. And if the manufacturers are not designing their back for accurate color reproduction, measuring the accuracy of color reproduction is futile.

The possibility to produce accurate color is bound to the sensor response. Final image color output is much bound to software, ie capture one and its profiles (or phocus/hasselblad and their natural color system). I don't know how much influence the back manufacturers have on bayer filter array design, I'd guess more for the newer exclusive sensors than what it was back for the P45+, for the KAF39000 I would guess the digital back manufacturers was not involved at all in sensor design (?). I'd guess Phase One has more influence on sensor design than Hasselblad has.

Anyway if you just can get the raw data you can tune the color any way the bayer array filters allows. As far as I know DxOmark measures raw data response in their color tests, ie they don't use any manufacturer provided raw converter and profiles, so they measure the sensor's ability to reproduce accurate color in some standard lighting condition, not the color you'll get if you use the manufacturer provided raw software and default profiles.

What's important is the sensor's ability to differ between nearby/similar colors, which DxOmark does measure. As long as it can do that you can tune the color in any direction you want and different colors will still be different colors. If similar colors are registered with the same RGB raw values no profile in the world can make them differ.

For me that aspect is a key performance indicator of a sensor. It's a bit difficult to evaluate though if you just get a single metric, as the sensor may be bad at separating greens but good at separating skin color, and thus may produce better results for you than a sensor good at greens but slightly less good at skin color, if your main subject is skin. A landscape photographer may prefer the sensor that is better at separating greens.

Color separation is reduced in the shadows, and I'm not sure about this but it seems to me that it's a bit separate from dynamic range, ie you can measure quite good dynamic range but still lose more color separation than another sensor which on paper has worse dynamic range. Some sensors get quite monochromatic in the shadows (usually towards green) before noise gets too bad.

To summarize, what we should be interested in and measure is "color separation" rather than "color accuracy". Different colors registered separately can be tuned, different colors registered as a single color cannot. In technical terms we want a "low metameric error". In general terms the Dalsa sensors have lower metameric error than the Kodaks, but I don't know how performance is in specific color ranges.
« Last Edit: June 26, 2013, 04:09:59 am by torger »
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ErikKaffehr

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Hi,

Interestingly DT (the company Doug works for) also refers to this document: http://www.dtdch.com/page/fadgi-image-performance-report

As I recall they have a DeltaE avg of 2.0 (or so)
Erik
Best regards


Measuring a sensor with a monochromator is not difficult and would give direct information about the primary filters. It should be the preferred method.

But this is not what Doug said. Doug believes that accurate color reproduction is not what the manufacturers are aiming to. This is also my opinion. And if the manufacturers are not designing their back for accurate color reproduction, measuring the accuracy of color reproduction is futile.
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Erik Kaffehr
 

jerome_m

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It seems to me that people on this thread are trying to reinvent the wheel. Quite a lot has been written on the subject of color reproduction accuracy in the context of document digitization. Reading books and standards on the subject would seem the thing to do first.
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ErikKaffehr

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Hi,

Just a short comment on metameric error. If you refer to the one used by DxO it is essentially based on Delta E measured on the 16 color fields of the color checker.

It is described here: http://www.dxomark.com/index.php/About/In-depth-measurements/Measurements/Color-sensitivity

According to Tim Perkin, there is a good correlation between the SMI and his color preferens, that is high SMI -> good colors.

P45+ -> 72
Pentax 645D -> 75
Nikon D800 -> 78
IQ180 -> 80
Sony Alpha 99 -> 85
Sony Alpha 900 -> 87

Best regards
Erik





Hi,

Interestingly DT (the company Doug works for) also refers to this document: http://www.dtdch.com/page/fadgi-image-performance-report

As I recall they have a DeltaE avg of 2.0 (or so)
Erik
Best regards


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Erik Kaffehr
 

torger

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According to Tim Parkin, there is a good correlation between the SMI and his color preferens, that is high SMI -> good colors.

Tim is a landscape photographer and as far as I know works very actively with colors, ie tuning individually per image in Photoshop. What you need then is a malleable raw file, ie good color separation (low metameric error, which leads to high SMI). What the colors actually are out of the box is less important. So I'm not surprised there is a good correlation.

I would not trust it that much though, I had a Canon 7D (APS-C) which I think did not have that malleable files, but it still has 78. I would guess part of the problem is that DR is not factored in, ie poor color accuracy in darker colors won't show in the SMI. Looking at the DxO charts the P45+ has less noise covariance in dark colors than that 7D, despite lower SMI. Modern Sony cameras excel in DR too though, which contributes to the malleability. The 7D has apart from quite low DR really bad banding noise further reducing subjective DR.

As far as I understand the MFD has mainly gained its color reproduction reputation from the default settings in the manufacturer-provided raw converter, and then mainly looking at skin color in studio flash photography, as humans are most sensitive to skin, and studio flash photography is a much more common(?) use case for MFD than for example landscape photography. If you work very actively with color in your files and don't depend so much on the provided tools the raw sensor performance means more and tuned defaults less.
« Last Edit: June 26, 2013, 06:47:21 am by torger »
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Doug Peterson

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Doug believes that accurate color reproduction is not what the manufacturers are aiming to. This is also my opinion. And if the manufacturers are not designing their back for accurate color reproduction, measuring the accuracy of color reproduction is futile.

This is in fact not what I said.

I said "But the flash and daylite profiles in Capture One aren't meant for art reproduction. They are meant to balance accuracy and pleasantness of color."

The design of the digital back is almost exclusively geared towards producing excellent image quality, including color. They design the back to provide incredibly good raw files for everything from fashion to product to art reproduction.

The ability for an IQ180 to distinguish between extremely subtle color variation has been noted by many users here and on other forums. The ability for an IQ180 to accurately show the transition from a strongly saturated deep shadow to a strongly saturated hot highlight has been likewise noted. We've noticed this improved even further with the IQ2 generation (see this test of the IQ260 vs P45+ for instance).

The default profiles in Capture One are good for art reproduction, but they aren't perfect. They must, inherently, provide some accommodations to ensure that the back produces pleasant color in a variety of situations (fashion/weddings/portrait/landscape/architecture/product/etc).

Since the back has an excellent sensor, and the software allows for both arbitrary-ICC input (meaning you can generate a profile out of any standards-based profiling software) and a really excellent ICC-editor (Color Editor) it's really very easy (with the proper expertise) to generate a profile for Cultural Heritage or Art Repro situations which exceeds the strictest international guidelines for color accuracy in preservation environments. Again, this is not theoretical; we do this as routine business with our Cultural Heritage clients.

You'll get pretty close for art repro purposes using the default flash profile and high quality flash illumination. But you'll do better with a profile geared exclusively for art reproduction. Which is easy to do yourself if you have a background in profile creation, or if you work with a value added partner like us.

jerome_m

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This is in fact not what I said.

Indeed it isn't and you did talk about specific profiles. My apologies.

Now, allow me a question. ISO 17321 specifies a way to measure a metameric index. Some MF backs are relatively low on that metric, compared to other cameras with a smaller sensor. Wouldn't that mean that their sensor will be less capable of accurate color than these other cameras, even with a perfectly tuned profile?
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Doug Peterson

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Indeed it isn't and you did talk about specific profiles. My apologies.

Now, allow me a question. ISO 17321 specifies a way to measure a metameric index. Some MF backs are relatively low on that metric, compared to other cameras with a smaller sensor. Wouldn't that mean that their sensor will be less capable of accurate color than these other cameras, even with a perfectly tuned profile?

I'd be glad for references (feel free to email me) regarding this information (who did the testing, under what conditions, which backs are being described etc).

But in general I prefer to examine real world testing. In nearly every image quality category a numerical representation of performance fails to fully describe the strengths/weaknesses of a given system. For instance dynamic range can ostensibly reduced to a single number for direct comparison between two systems, but in reality I've found you must consider a variety of factors like what kind of noise is created (is it pretty or ugly, uniform or clumpy) and whether color is consistent along quarter tone transitions and highlights (especially important for portraits in high contrast light among other things). The result is that two cameras which are (carefully and honestly) measured as having the same numerical dynamic range have very different abilities to reach into highlights/shadows and pull out photographically useful and aesthetically pleasant image content. So it's just so much more meaningful to take and compare actual pictures.

In my real world experience with profiling many kinds of cameras and working with those profiled cameras with some very demanding clients to capture real world objects I can say quite confidently the modern Phase One backs are exceptional at this work.

I would be glad to explore with you the underlying mechanics of this real world performance vis a vis metameric index measurement. But it would be purely an academic conversation. Feel free to email me.

ErikKaffehr

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Hi,

This is discussed in the DxO-mark article here: http://www.dxomark.com/index.php/About/In-depth-measurements/Measurements/Color-sensitivity.

So the measurement is based on the 18 color fields of the Color Checker. Leaves a few questions. One is that I don't think it can be based on unprocessed raw data, so color conversion matrix is involved.

A note is that of all cameras I have checked the Sony Alpha 900 is on top regarding SMI, and that camera is said to have very good color by some authors. The IQ180 has high SMI while the P45+ has quite low SMI.

As a side issue, Miles Hecker posted samples from Pentax 645D (low SMI) and Nikon D3X (high SMI) where I think both he and I preferred the Pentax rendition.

I will post some samples from Sony Alpha 99 and P45+ tonight or tomorrow, those are real world shots and I tried to process the image in both C1 and LR.


Best regards
Erik


I'd be glad for references (feel free to email me) regarding this information (who did the testing, under what conditions, which backs are being described etc).

But in general I prefer to examine real world testing. In nearly every image quality category a numerical representation of performance fails to fully describe the strengths/weaknesses of a given system. For instance dynamic range can ostensibly reduced to a single number for direct comparison between two systems, but in reality I've found you must consider a variety of factors like what kind of noise is created (is it pretty or ugly, uniform or clumpy) and whether color is consistent along quarter tone transitions and highlights (especially important for portraits in high contrast light among other things). The result is that two cameras which are (carefully and honestly) measured as having the same numerical dynamic range have very different abilities to reach into highlights/shadows and pull out photographically useful and aesthetically pleasant image content. So it's just so much more meaningful to take and compare actual pictures.

In my real world experience with profiling many kinds of cameras and working with those profiled cameras with some very demanding clients to capture real world objects I can say quite confidently the modern Phase One backs are exceptional at this work.

I would be glad to explore with you the underlying mechanics of this real world performance vis a vis metameric index measurement. But it would be purely an academic conversation. Feel free to email me.
« Last Edit: June 27, 2013, 01:31:40 am by ErikKaffehr »
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Erik Kaffehr
 

ErikKaffehr

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Some more samples
« Reply #53 on: June 27, 2013, 01:04:25 am »

Hi,

Here are some samples I shot yesterday and processed Quick & Dirty:


Above: P45+ processed in LR4.4. Full size: http://echophoto.dnsalias.net/ekr/Articles/MFDJourney/Samples/Forsmark/20130626-CF043214.jpg

Above: P45+ processed in C1. Full size: http://echophoto.dnsalias.net/ekr/Articles/MFDJourney/Samples/Forsmark/20130626-CF043214_C1.jpg

Above: Sony Alpha 99 processed in LR4.4. Full size: http://echophoto.dnsalias.net/ekr/Articles/MFDJourney/Samples/Forsmark/20130626-_DSC2169.jpg

These images are not included in the article yet. C1 is still in the works.


P45+ LR4.4 above:

P45+ C1 above:

Sony Alpha 99 LR4.4 above:

These images are not included in the article yet. The LR4.4 processed images have gradient filters on water and sky. C1 is still in the works.


Best regards
Erik
« Last Edit: June 27, 2013, 01:30:35 am by ErikKaffehr »
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Erik Kaffehr
 

ErikKaffehr

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Hi,

I think this samples are impressive, especially the 1:1 crops.





Raw data is here: http://echophoto.dnsalias.net/ekr/Articles/MFDJourney/Samples/Stendorren/20130628-CF043276.iiq

Best regards
Erik
« Last Edit: June 28, 2013, 05:21:04 pm by ErikKaffehr »
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Erik Kaffehr
 

ErikKaffehr

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Small update: diffraction
« Reply #55 on: June 29, 2013, 05:37:43 pm »

Hi,

I just shot a diffraction series: http://echophoto.dnsalias.net/ekr/index.php/photoarticles/76-my-medium-format-digital-journey?start=11

This is LW/PH MTF 50 for P45+/Sonnar 150 without sharpening at different apertures:



In short. Diffraction limit sets in around f/11 and is significant at f/16.

That said, f/22 and f/32 may be OK, but use medium apertures for optimal sharpness.

f/8f/22

Best regards
Erik
« Last Edit: June 30, 2013, 12:20:45 am by ErikKaffehr »
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Erik Kaffehr
 

ErikKaffehr

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Another observation: C1 and me, we are no friends...
« Reply #56 on: June 29, 2013, 05:50:47 pm »

Hi,

It has been suggested that Capture One gives superior results to LR4 with Phase One backs. I have tried Capture One and we make no friends. The more I use it the less I like it.

This is just my experience. C1 is a fine product, for sure. It has advantages, like it produces less Moiré and aliasing artefacts and may have a more aggressive sharpening by default.

Best regards
Erik
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Erik Kaffehr
 

Bart_van_der_Wolf

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The measurement of DR is almost always controversial and the value useful to photographers is not the ISO defined version.  I recommend you try shooting a transmission step wedge and using imatest software to get data more reliable than comparing histograms.

Hi Eric,

Sorry, but shooting a step-wedge is not more accurate, although may be closer to variable conditions real live shooting situations (partly due to veiling glare), depending on the lens and lighting situation used. For a fair, unbiased review one usually tries to avoid as many variables (such as lens / lighting conditions used) as possible. Ignoring things like these variables is exactly what makes comparisons controversial.

The DxO Mark evaluations seem to be pretty accurate though.

Cheers,
Bart
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== If you do what you did, you'll get what you got. ==

Bart_van_der_Wolf

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A wasted test shot is much better than a missed opportunity.

Hear, hear.

Chears,
Bart
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Bart_van_der_Wolf

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Stouffer wedge shots in a week or so. Shooting the wedge is quite demanding as you need to eliminate all light leaks.

Indeed. it seems so simple, but it requires a lot of preparation and understanding, just like shooting Color profile targets. And even then, I get better (= more accurate) results from shooting multiple uniform area shots (even pairs of shots for elimination of pattern noise).

Cheers,
Bart
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== If you do what you did, you'll get what you got. ==
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