Luminous Landscape Forum
Equipment & Techniques => Medium Format / Film / Digital Backs – and Large Sensor Photography => Topic started by: johnvr on June 19, 2014, 09:41:41 pm
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And wrote a quick impressions post on my blog: http://photographicwanderings.com/2014/06/19/hands-on-with-the-pentax-645z-medium-format-dslr/
Short version: I wish I had some extra cash lying around. Never before have I considered digital MF, but now it seems within reach.
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Tease!
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Appreciate the preview, and understand that you can't publish full pictures or crops, but that pretty much removes the reason for writing about it, no? It's big. It works. It's got a lot of pixels. It doesn't do great above ISO bliddity-blat.
What did you notice that you did not expect? Did you see any prints made from 645Z files?
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What did you notice that you did not expect? Did you see any prints made from 645Z files?
I saw one in Paris. It's a huge kludgy camera, no fun to use IMHO, but probably perfectly good pictures as there wasn't anything wrong with the 645D. Focus was fast, but the focus points are all located in an APS size area in the center so you're not going to move focus to model's eyes in a portrait shot. I think Hasselbad's True Focus is probably the only way to get decent full-field focus ability in MF at the moment, and that is focus and recompose.
Edmund
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If the model doesn't move, then I would think that manual focus is also a pretty decent solution?
I am getting a reasonnably high rate of reasonnably well focused images at f1.4 when using the Otus on my D800 (images looking very sharp on the eyes on an A4 print), I would think that getting a similar level of success with the f2.8 lenses of the 645Z should be pretty feasable thanks to its larger viewfinder?
Cheers,
Bernard
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If the model doesn't move, then I would think that manual focus is also a pretty decent solution?
I am getting a reasonnably high rate of reasonnably well focused images at f1.4 when using the Otus on my D800 (images looking very sharp on the eyes on an A4 print), I would think that getting a similar level of success with the f2.8 lenses of the 645Z should be pretty feasable thanks to its larger viewfinder?
Cheers,
Bernard
Bernard,
You are doubtless right concerning manual focus using a 50mm. We should all use manual focus, since it implicates the photographer so much more in the photographic process. Personally, I prefer the Leica manual focus system, and see no reason for viewing through the lens when using a 50. In fact a good rationale for using a 50 is that there is little rationale for viewing through the lens :)
But the question is whether the AF on the 645Z is adequate for the uses people expect; my impression is that it is fast and accurate, even in low light, however not perfect for portrait use, because focus and recompose doesn't work that well in MF.
Of course the argument can be made that Phase has now trained photographers to expect rudimentary focus from their MF systems and therefore expectations will certainly be met.
Edmund
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Appreciate the preview, and understand that you can't publish full pictures or crops, but that pretty much removes the reason for writing about it, no? It's big. It works. It's got a lot of pixels. It doesn't do great above ISO bliddity-blat.
What did you notice that you did not expect? Did you see any prints made from 645Z files?
They had three life-size posters made with the camera. They were tack sharp and detailed. I think the real story will come from the lenses and a quick hands-on doesn't give the ability to test those.
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Is it possible to get my paws on a raw file? I like to add support to the open-source raw converter RawTherapee. I have a .DNG file already (that works of course), but I think that was some sort of conversion, as far as I understand the camera itself produces .PEF raw files. If you have one I can look at please let me know. I will only use it for format testing, ie not publish it somewhere.
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Hi john,
I tested the camera yesterday as well, I was surprised that there were not more people attending. Perhaps most attended later in the day?
My camera was also set to shoot DNG files and it makes me wonder if the color reproduction would not differ from the native PEF file format that Pentax uses?
Regardless, I think Ricoh has a big hit on their hands with the 645Z!
Working with the 645z files was very informative, I liked what I saw...
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I've added a link to some original files to my article.
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Hi john,
I tested the camera yesterday as well, I was surprised that there were not more people attending. Perhaps most attended later in the day?
My camera was also set to shoot DNG files and it makes me wonder if the color reproduction would not differ from the native PEF file format that Pentax uses?
Regardless, I think Ricoh has a big hit on their hands with the 645Z!
Working with the 645z files was very informative, I liked what I saw...
I think they were all set at DNG, a safe bet since it's ready for Adobe, which is why I didn't look any further. If I had known that Adobe was launching an update including support for the 645Z that same day, I might have acted differently.
I think their media invite list was pretty short for the event. They seemed to be ready for an onslaught of pro photographers after our session.
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Is it possible to get my paws on a raw file? I like to add support to the open-source raw converter RawTherapee. I have a .DNG file already (that works of course), but I think that was some sort of conversion, as far as I understand the camera itself produces .PEF raw files. If you have one I can look at please let me know. I will only use it for format testing, ie not publish it somewhere.
I only have DNG files. Sorry.
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I only have DNG files. Sorry.
Ok no problem.... we'll wait and see.
I've looked at the Pentax DNG file and it does not have any color profile embedded (just a color matrix), so it's likely that the color rendering will change a bit when color profile becomes available.
I've compared the color matrix from the Pentax with the one coming from a H5D-50c and it seems like Pentax has opted for a more saturated look, at least per default. The sensors are probably exactly the same, but properties of IR filter might differ a bit slightly affecting color rendition.
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who cares - just use the IQ250 or H matrix - lenses probably account for at least as much divergence of colors from the naked sensor spectral response as a filter difference. Let's just hope that UV and IR filtration are adequate.
Edmund
Ok no problem.... we'll wait and see.
I've looked at the Pentax DNG file and it does not have any color profile embedded (just a color matrix), so it's likely that the color rendering will change a bit when color profile becomes available.
I've compared the color matrix from the Pentax with the one coming from a H5D-50c and it seems like Pentax has opted for a more saturated look, at least per default. The sensors are probably exactly the same, but properties of IR filter might differ a bit slightly affecting color rendition.
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Bernard,
You are doubtless right concerning manual focus using a 50mm. We should all use manual focus, since it implicates the photographer so much more in the photographic process. Personally, I prefer the Leica manual focus system, and see no reason for viewing through the lens when using a 50. In fact a good rationale for using a 50 is that there is little rationale for viewing through the lens :)
But the question is whether the AF on the 645Z is adequate for the uses people expect; my impression is that it is fast and accurate, even in low light, however not perfect for portrait use, because focus and recompose doesn't work that well in MF.
Of course the argument can be made that Phase has now trained photographers to expect rudimentary focus from their MF systems and therefore expectations will certainly be met.
Edmund
I will like to add , that at the same focal length, composition, aperture and same pixel density, MF should be harder to MF on therms of precision (the photographer is closer to the subject).
In the other Hand the view finder is bigger and more luminous. Edmund I believe that you commented elsewhere that the 645Z viewfinder was dark.
Was it compared to Canon (Nikon is dimmer) or the Hasselblad /Phase One?
Best regards,
J. Duncan
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I will like to add , that at the same focal length, composition, aperture and same pixel density, MF should be harder to MF on therms of precision (the photographer is closer to the subject).
In the other Hand the view finder is bigger and more luminous. Edmund I believe that you commented elsewhere that the 645Z viewfinder was dark.
Was it compared to Canon (Nikon is dimmer) or the Hasselblad /Phase One?
Best regards,
J. Duncan
I cannot remember exactly about brightness, but I was not wowed by the viewfinder. My 1Ds3 with 85/1.2 has a wonderful big and acceptably bright finder for a 35mm camera, the Mamiya AFDII was nothing special as I remember mine, but it was a biggish image as I had dash masks for the back's zone.The Pentax finder experience struck me as a bit *small* in a way, no fun.
The whole 645Z camera experience is probably very similar to the 645D, and neither good nor bad - it kind of feels generic, a big box with buttons, a viewfinder to compose with, AF that actually works,a reasonably short shutter delay with no over-hard slap etc. But the whole feeling is a bit distancing. Basically the 645Z screams "I'm a PC, I get the job done" !
In contrast, I have always felt that with the pro SLRs the shooting experience is addictive, the more you look at the world through the finder the more you like doing it.
Edmund
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Here, you can compare 645D to a few other cameras...
http://photographycompared.tumblr.com/
The Z should beat the D, at least with res. It may not produce as pleasing of an image with the 'look,' but I don't know.
The D has a way of producing beautiful, painterly images. The only think I don't like about the D is the low ISO. Although, the low ISO is only a problem with street and doc work.
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I saw one in Paris. It's a huge kludgy camera, no fun to use IMHO, but probably perfectly good pictures as there wasn't anything wrong with the 645D. Focus was fast, but the focus points are all located in an APS size area in the center so you're not going to move focus to model's eyes in a portrait shot. I think Hasselbad's True Focus is probably the only way to get decent full-field focus ability in MF at the moment, and that is focus and recompose.
Edmund
Well, they had to improve on the mp and ISO. You know how the pixel peepers are, always demanding more.
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The D has a way of producing beautiful, painterly images. The only think I don't like about the D is the low ISO. Although, the low ISO is only a problem with street and doc work.
Mine lives on a tripod. The ISO could be fixed at 12 (like the first version of Kodachrome my dad used in the 1950s) and it wouldn't make much difference in how I use it. :D
-Dave-
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Mine lives on a tripod. The ISO could be fixed at 12 (like the first version of Kodachrome my dad used in the 1950s) and it wouldn't make much difference in how I use it. :D
-Dave-
All my cameras seem to be permanently set to 200 Iso in the summer and 1600 the rest of the year.
Maybe because I don't own a tripod :)
Edmund
PS. The 645D was marketed from the start as a landscape camera. I don't think landscape cameras need to be light, fast or sexy. But then I wouldn't know, I don't do landscape. Michael, on the other hand does, and it will be interesting to read his review of the Z.
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Mine lives on a tripod. The ISO could be fixed at 12 (like the first version of Kodachrome my dad used in the 1950s) and it wouldn't make much difference in how I use it. :D
-Dave-
If you want a camera with Iso12 you perhaps need to buy an old Kodak DCS/n or /c. I can remember, that you could use there this Iso for long exposures. :)
Ok. It's 35mm and not MF... ::)
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If you want a camera with Iso12 you perhaps need to buy an old Kodak DCS/n or /c. I can remember, that you could use there this Iso for long exposures. :)
The Contax N Digital also had a low-ISO mode, something like 25 if I remember right. I think noise reduction was the primary intent.
With the 645D I've had no need for anything slower than ISO 100 but I do own some ND filters... ;)
-Dave-
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who cares - just use the IQ250 or H matrix - lenses probably account for at least as much divergence of colors from the naked sensor spectral response as a filter difference. Let's just hope that UV and IR filtration are adequate.
Yep you're probably right. As an experiment I have converted the Pentax 645Z DNG file to a Phase One IIQ IQ250 file and opened it in Capture One just to see how it renders (as Capture One thinks it's an IQ250 file it renders the raw data exactly as if the image was shot with an IQ250 rather than a 645Z), and to my untrained eye color looks good, a bit saturated but nice skin tones. So if there is any divergence is certainly not huge.
I've done the same experiment with a Hasselblad H5D-50c file, and that too turned out well, so probably the differences in color response between those three cameras is very very small, and as you say lenses could be the largest part in any differences. The difference in color is certainly smaller than the difference in price ;D
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Yep you're probably right. As an experiment I have converted the Pentax 645Z DNG file to a Phase One IIQ IQ250 file and opened it in Capture One just to see how it renders (as Capture One thinks it's an IQ250 file it renders the raw data exactly as if the image was shot with an IQ250 rather than a 645Z), and to my untrained eye color looks good, a bit saturated but nice skin tones. So if there is any divergence is certainly not huge.
I've done the same experiment with a Hasselblad H5D-50c file, and that too turned out well, so probably the differences in color response between those three cameras is very very small, and as you say lenses could be the largest part in any differences. The difference in color is certainly smaller than the difference in price ;D
Color is a lot more complicated than is indicated by the level of experimentation you made before making such strong conclusions. Have you done this under multiple illuminates? Have you done this with dozens of people with different variations of skin? Have you done this with under and over exposed images with appropriate recovery? Have you examined product color for linearity of color throughout the tonal range?
My *initial* examination of the IQ250 color took several weeks and I won't feel I know it's color response as well as I do for backs like the IQ160 (which I've simply had more total shoots with) for many more months.
Cameras with excellent color are robust in color response; they look great even under duress.
It's odd because I'd never imagine you making such strong conclusions about noise, or sharpness with such minimal testing.
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It's odd because I'd never imagine you making such strong conclusions about noise, or sharpness with such minimal testing.
I dare to do that based on that I know it's the same sensor, and that a CMOS which has digital output rather than analog like CCD is much less affected by surrounding electronics.
But it's just a fun experiment with a test software only I have. The general photographer can't and wouldn't convert Hasselblad and Pentax files into IQ250 files, and of these three cameras only the IQ250 can be used with Capture One. I think Capture One is a very important link in the great color rendition reputation Phase One has.
Even if these three cameras have the exact same color response, the raw converter softwares are different and color profiles are different so results will be different. So Phase One don't need to worry just yet :).
This experiment is a "what if" experiment showing what would happen if all these cameras had the same raw converter and color profiles. And the indication I have is that it will then render very similar results (which is the expectation when knowing about the hardware), but you're right that it's early to come to the safe conclusion, shooting all three cameras on a large color checker under the same light and do measurements on that would be required to draw safe conclusions.
To be perfectly honest what I see is good color, as I don't have a reference file from an IQ250 shot at the same place I cannot know for sure if the IQ250 would render the same scene with good color in a radically different way, I just find that unlikely.
At some point I hope someone will actually make side-by-side shooting and provide raw files so I can convert them all to IIQ (open them in RawTherapee and use same profiles will also work) so one can directly compare how the hardware performs. There's a bunch of mythology around the superiority of Phase One hardware some true some less so, and this type of test would be revealing in that aspect. However for real use it makes little difference and you need to take the whole pipeline into account. It will be Pentax + Lightroom(?) vs IQ250 + Capture One vs Hasselblad + Phocus/Lightroom. And I think for portrait style of work that Capture One will have an edge. And of course we have the lens parameter too, which I'm uncertain about how much effect it has.
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Even though the Sony A7R and the D800E have a basically identical sensor the image quality and performance is not identical. So that is just one example of two cameras with the same sensor performing differently. Ok, the differences are not major but are there.
And again, I see the undertone, that the IQ250 is not a good value. Of course it isn't (once the 645Z is out, available and tested) in sensor image quality per dollar terms but it offers something different. It is a back that can be used in a LOT of different camera systems with lot's of different lenses. Yes, that has a price, but is something the 645z just can't do and the H5D-50c can do in limited capacity (no untethered live view, crappy lcd screen etc).
That out of the way it would be cool to see tests and comparisons between all three 50mp CMOS cameras (H5D-50c. 645Z and the IQ250)
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The A7r and D800E has documented CFA differences (you can see scientific measurements on DxOmark).
I don't rule out that there are CFA differences here too, need side-by-side controlled testing to make sure. Sometimes CFA can be quite different and color still look good if you switch profiles.
Anyway this is the first time(?) we see three cameras with these type of price differences using the same sensor. I find it very interesting to know exactly how much that is the same.
It could be the case that the Pentax 645Z still would use some high ISO optimized CFA (like most DSLRs is said to do) and render skin tones worse due to the hardware. It could also be the case that the CFAs are exactly the same and the exact same result with minor differences caused by lenses can be had if applying the same profiles.
I imagine that Phase One owners are not so interested in such an investigation, but people that look into buying the 645Z to get into MF in an affordable way probably are. At least I would then like to know if I get a "true" MF camera with MF optimizations concerning color, or if I just get an enlarged DSLR, and ugly too.
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Doug,
Yes, it would be possible that P1 and H and Pentax are using the chip differently, and in particular when it come to data in the highlight shoulders or extreme shadows one might see real differences. But Torger does have a point when he considers that the essential ability of the camera to discriminate color is intrinsically defined and delimited by the CFAs and the IR and UV filtration. This is an inherent weakness of the Bayer CFA model, and you cannot magically make it go away: The CFAs never match the human eye's response (cone or observer functions) and thus cameras do not see like the human eye. The camera's ability to discriminate *texture* ie. skin texture is a different story as it will depend on the signal processing.
Edmund
PS: It is an INCONVENIENT TRUTH that cameras using the same CMOS chip with the same CFA and the same on-sensor A/D conversion are quite possibly going to have very similar imaging behavior. Unfortuntately, Phase 1 were never a camera company, they have been a back company, and if they buy in a complete-solution chip they lose differentiation. Please don't blame the geeks for stating and experimentally confirming the obvious.
Color is a lot more complicated than is indicated by the level of experimentation you made before making such strong conclusions. Have you done this under multiple illuminates? Have you done this with dozens of people with different variations of skin? Have you done this with under and over exposed images with appropriate recovery? Have you examined product color for linearity of color throughout the tonal range?
My *initial* examination of the IQ250 color took several weeks and I won't feel I know it's color response as well as I do for backs like the IQ160 (which I've simply had more total shoots with) for many more months.
Cameras with excellent color are robust in color response; they look great even under duress.
It's odd because I'd never imagine you making such strong conclusions about noise, or sharpness with such minimal testing.
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I got permission to show the file by the anonymous photographer that I got the test file from. That photographer was at the same testing event as johnvr as obvious from the model but it's not him I got the file from. It's a test file useful for testing format support with a color checker in focus so it's not exactly a good example of imaging performance, but it does show skin color and gives a general idea of saturation etc.
Note that the white balance is crazy, it's that also in the original Pentax DNG, so it probably just was some camera setting that was off. Just use the wb pipette on the color checker to restore a sane white balance.
So here's how a Pentax 645Z file raw data looks if it's rendered the same way as an IQ250:
edit, link removed too many downloads :), but anyone really interested just send me a PM
If someone wants me to convert another file for testing just send me one. One with the model actually in focus would be cool I guess :)
(The reason I've made IIQ writer is not for these type of conversions, but for Phase One owners to be able to use our Lumariver HDR software in a raw in to raw out workflow, Capture One's DNG support is not exactly great. The version with IIQ support is still in the making.)
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Mine lives on a tripod. The ISO could be fixed at 12 (like the first version of Kodachrome my dad used in the 1950s) and it wouldn't make much difference in how I use it. :D
-Dave-
I agree. For the work that is mine (studio), a very low sensitivity is an asset. This allows to work in the best conditions (choice of f-stop) with flash. In the studio today, it is often necessary to have to work with a too small aperture.
PdF
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I agree. For the work that is mine (studio), a very low sensitivity is an asset. This allows to work in the best conditions (choice of f-stop) with flash. In the studio today, it is often necessary to have to work with a too small aperture.
Uhm, couldn't you just use an ND filter?
Low sensitivity in digital photography is unfortunately generally not implemented the way one would like, ie that you have a huuuuuge collector of photons that just takes a very long time to fill up. Rather, in digital low sensitivity generally means that the sensor only registers a part of the light and throws away the rest, due to low fill factor (fill factor = how much of the sensor area that actually registers light) and/or inefficient micro lenses (micro lenses are used to direct light into the light-sensitive photo diodes).
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Hi,
I don't know about the data DxOmark publishes, they publish the color conversion matrixes, RGB channel sensivities and SMI for two illuminants. Regarding SMI I have seen that Tim Parkin feels it correlates well with color rendition, while Iliah Borg seems to say it is irrelevant.
For my part, I am not sure DSLR CFAs are optimized for high ISO. The best optimisation for high ISO is low readout noise and fat pixels. The P45+ I happen to have is one of the worst sensors regarding SMI.
I am a bit reserved about basing colour accuracy on just the color checker fields. I have made some additional tests on an IT80 card and found that the P45+ was pretty accurate, specially with Capture One and linear profile. But my Sony Alpha 99 was still a bit more accurate.
To me it seems that there may be a lot of myths about the accuracy of MFD colours. It may also be that there is no real good definition of good skin colour, many MFD images shown have highly artificial skin tones. I would think it could be that MFD color profiles are a bit tweaked for what is regarded good skin tones,especially under studio conditions.
My experience is limited to Sony cameras and a single P45+.
Best regards
Erik
The A7r and D800E has documented CFA differences (you can see scientific measurements on DxOmark).
I don't rule out that there are CFA differences here too, need side-by-side controlled testing to make sure. Sometimes CFA can be quite different and color still look good if you switch profiles.
Anyway this is the first time(?) we see three cameras with these type of price differences using the same sensor. I find it very interesting to know exactly how much that is the same.
It could be the case that the Pentax 645Z still would use some high ISO optimized CFA (like most DSLRs is said to do) and render skin tones worse due to the hardware. It could also be the case that the CFAs are exactly the same and the exact same result with minor differences caused by lenses can be had if applying the same profiles.
I imagine that Phase One owners are not so interested in such an investigation, but people that look into buying the 645Z to get into MF in an affordable way probably are. At least I would then like to know if I get a "true" MF camera with MF optimizations concerning color, or if I just get an enlarged DSLR, and ugly too.
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I think few talk in terms about "accuracy", but rather pleasing or film-like or some other hazy concept. I'm too a bit skeptical about it, therefore I think it's an interesting experiment to cross-convert H5D-50c, Pentax 645Z so they all can be compared with an IQ250 type of rendering. If equivalent or at least pleasing results can be had we at least know that differences can be equalized with profiling.
I'm a bit surprised that there are not more third-party profiles, it seems like many photographers are willing to spend say $20k extra for a camera because they don't really know how to get good results of lower cost competing systems.
I will expect that 1) Pentax 645Z will not be supported by Capture One (I would not do it if I were Phase One), 2) color profiles in Lightroom or Pentax own software will not produce as pleasing results as MF portrait photographers want, and IQ250 results will be considered superior, and 3) many will claim it's due to the hardware, and that $15-20k extra you get to spend for it is what's required to get the best color, 4) few will investigate if it's possible to tune profiles for the Pentax to get as good results.
I think MF needs competition, their business model which is what makes the products so insanely expensive is ancient and need to change, and Pentax 645Z is a dynamic contribution to the market and I very much would like to see it become a success. I don't wish any bad luck onto Phase One or Hasselblad, but I don't think they will ever change their business model unless there's some pressure put on them, and someone else (ie Pentax) shows that you can make money by selling lower cost to a broader market.
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well, as Hassy's main client base is fashion, I don't think they will allow their skin tones to get too bad :)
skin tone are a mix of color and texture. color depends on the CFAs except in extreme shadows and highlights where camera firmware affects antiblooming settings (top shoulder) and channel noise removal (bottom clipping). Texture depends on firmware filtering and the raw converter.
anyway, I would expect the CMOS MF sensors from Sony to track the 35mm cameras from Sony pretty exactly when it comes to color.
Edmund
PS. Note that there is nothing to prevent a camera from loading new firmware with different characteristics to switch from architecture to portrait, eg. shadow noise filtering vs more noisy and harder hilite clipping, but manufacturers have not done this so far.
I think few talk in terms about "accuracy", but rather pleasing or film-like or some other hazy concept. I'm too a bit skeptical about it, therefore I think it's an interesting experiment to cross-convert H5D-50c, Pentax 645Z so they all can be compared with an IQ250 type of rendering. If equivalent or at least pleasing results can be had we at least know that differences can be equalized with profiling.
I'm a bit surprised that there are not more third-party profiles, it seems like many photographers are willing to spend say $20k extra for a camera because they don't really know how to get good results of lower cost competing systems.
I will expect that 1) Pentax 645Z will not be supported by Capture One (I would not do it if I were Phase One), 2) color profiles in Lightroom or Pentax own software will not produce as pleasing results as MF portrait photographers want, and IQ250 results will be considered superior, and 3) many will claim it's due to the hardware, and that $15-20k extra you get to spend for it is what's required to get the best color, 4) few will investigate if it's possible to tune profiles for the Pentax to get as good results.
I think MF needs competition, their business model which is what makes the products so insanely expensive is ancient and need to change, and Pentax 645Z is a dynamic contribution to the market and I very much would like to see it become a success. I don't wish any bad luck onto Phase One or Hasselblad, but I don't think they will ever change their business model unless there's some pressure put on them, and someone else (ie Pentax) shows that you can make money by selling lower cost to a broader market.
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I just saw these high ISO samples from Ming Thein. To my eyes I can easily use ISO 12800, it opens a lot of posibilities.
https://www.flickr.com/photos/mingthein/14495613532/in/photostream/ (https://www.flickr.com/photos/mingthein/14495613532/in/photostream/)
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Uhm, couldn't you just use an ND filter?
When I try to have the best available definition, this is not interposing any filter that will rot my image. And the live video can be found useless ...
PdF
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?
A good filter will not affect the image significantly, and live view works very well with ND filters.
Best regards
Erik
When I try to have the best available definition, this is not interposing any filter that will rot my image. And the live video can be found useless ...
PdF
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?
A good filter will not affect the image significantly, and live view works very well with ND filters.
Best regards
Erik
Just try it. A good 2ND or 3ND. Look at the quality of your live image in a low lighting with such an equipment.
PdF
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Hi,
I use either 8X or a Kenko variable NDX, never had problem with live view on the Sony, but I don't use ND filters in really low light as they are not needed for the exposures I want to achieve.
The Pentax 645Z sensor is a Sony Exmoor, so it would behave as mine.
Anyway, as Anders Torger pointed out, low ISO is not very feasible on digital sensors. The lowest ISO is on the IQ280 and around 35 (measured), I believe, going below that you need ND anyway.
Best regards
Erik
Just try it. A good 2ND or 3ND. Look at the quality of your live image in a low lighting with such an equipment.
PdF
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Hi,
I see your reasoning.
Just adding a few points:
- I am not sure lenses affect color rendition that much because I would guess lens colour shift will be mostly well taken care of by choosing white balance.
- Regarding tuned profiles, I would presume that it takes a lot of experience to fix a pleasant profile and I guess the 'image professor' at Phase One is very good at it.
I compared the normal studio flash profile for my P45+ with the portrait profile, and they are very, very close. As far as I can recall the DeltaE just differed about 1.0 on an IT8 test target. So those profiles are very subtle work.
Best regards
Erik
I dare to do that based on that I know it's the same sensor, and that a CMOS which has digital output rather than analog like CCD is much less affected by surrounding electronics.
But it's just a fun experiment with a test software only I have. The general photographer can't and wouldn't convert Hasselblad and Pentax files into IQ250 files, and of these three cameras only the IQ250 can be used with Capture One. I think Capture One is a very important link in the great color rendition reputation Phase One has.
Even if these three cameras have the exact same color response, the raw converter softwares are different and color profiles are different so results will be different. So Phase One don't need to worry just yet :).
This experiment is a "what if" experiment showing what would happen if all these cameras had the same raw converter and color profiles. And the indication I have is that it will then render very similar results (which is the expectation when knowing about the hardware), but you're right that it's early to come to the safe conclusion, shooting all three cameras on a large color checker under the same light and do measurements on that would be required to draw safe conclusions.
To be perfectly honest what I see is good color, as I don't have a reference file from an IQ250 shot at the same place I cannot know for sure if the IQ250 would render the same scene with good color in a radically different way, I just find that unlikely.
At some point I hope someone will actually make side-by-side shooting and provide raw files so I can convert them all to IIQ (open them in RawTherapee and use same profiles will also work) so one can directly compare how the hardware performs. There's a bunch of mythology around the superiority of Phase One hardware some true some less so, and this type of test would be revealing in that aspect. However for real use it makes little difference and you need to take the whole pipeline into account. It will be Pentax + Lightroom(?) vs IQ250 + Capture One vs Hasselblad + Phocus/Lightroom. And I think for portrait style of work that Capture One will have an edge. And of course we have the lens parameter too, which I'm uncertain about how much effect it has.
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For my part, I am not sure DSLR CFAs are optimized for high ISO. The best optimisation for high ISO is low readout noise and fat pixels.
that was just an unfortunate wording - CFA are "optimized" not for "high ISO", but to let more light in through (naturally "blue"/"red" filters are primary targets to be less selective) - as those cameras had to be marketing-competetive in available light situations (or really competetive for actions shooters who do not care that much about proper color separation)... using higher gains just follows the available light situation (specifically for JPG shooters with raw conversion done in camera).
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Hi,
I am aware of that, but I have not seen any real evidence pointing in that direction for DSLRs.
DxO mark had an article discussing comparing two cameras, a Canon and a Nikon where they published spectral data for the CFA. DxO also shows something called SMI (Sensivity Metamerism Index) which is said to measure how far a sensor is from Luther-Ives condition for a given illuminant. The SMI values that DxO has measured for DSLRs is mostly higher than for for MFDBs. Some examples (taken from Tim Parkins article: https://www.onlandscape.co.uk/2012/02/the-myth-of-universal-colour/ )
Sony Alpha 87
Canon 5D 84
Canon 5DII 80
Phase One P40 80
Phase One IQ180 80
Nikon D3X 79
Leica M9 76
Phase One P45 72
These data were taken from Tim's list who argues that the SMI values measured by DxO coincide with his perception of good/accurate colour.
Best regards
Erik
that was just an unfortunate wording - CFA are "optimized" not for "high ISO", but to let more light in through (naturally "blue"/"red" filters are primary targets to be less selective)
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Erik,
Spectrally speaking, a lens is like a set of stacked filters. Indeed it may even contain a filter as frontal or back element, by design. So you can "assume" only if you "assume" that any filter can be taken care of white balance.
As for the "fixes" you assume the same person did everything, and is still working there. Do you also assume every photographer who worked for a magazine has the same taste and abilities?
Edmund
Hi,
I see your reasoning.
Just adding a few points:
- I am not sure lenses affect color rendition that much because I would guess lens colour shift will be mostly well taken care of by choosing white balance.
- Regarding tuned profiles, I would presume that it takes a lot of experience to fix a pleasant profile and I guess the 'image professor' at Phase One is very good at it.
I compared the normal studio flash profile for my P45+ with the portrait profile, and they are very, very close. As far as I can recall the DeltaE just differed about 1.0 on an IT8 test target. So those profiles are very subtle work.
Best regards
Erik
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I think you're talking about different live views. MF CCD live views will not work well with NDs, so one would have to remove it while using live view and then put it on when exposing, which makes the workflow a bit more cumbersome. On a modern CMOS sensor like the live view is thanks to the great ISO performance almost like night vision, you see better with live view than with the naked eye.
I use either 8X or a Kenko variable NDX, never had problem with live view on the Sony, but I don't use ND filters in really low light as they are not needed for the exposures I want to achieve.
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skin tone are a mix of color and texture. color depends on the CFAs except in extreme shadows and highlights where camera firmware affects antiblooming settings (top shoulder) and channel noise removal (bottom clipping). Texture depends on firmware filtering and the raw converter.
That "texture" thing I find very interesting, haven't really seen an example of it so I don't know what to look for. I assume it's something you see when you zoom in to 100% rather than looking at the picture from a distance?
One thing I have noticed though is that when I zoom in my Leaf Aptus landscape images the texture I get in Capture One is more artificial and pastel-like compared to the more photographic look I get in RawTherapee. On the other hand Capture One is better at suppressing aliasing artifacts.
Attached an example, RawTherapee to the left, Capture One to the right. As always(?) when doing side-by-side testing the difference is smaller than what I had from memory, but I still think it's there, and as some would say here "it's a galaxy apart" ;). The rock with the lichens, the narrow branches behind it and all the tiny leaves, especially the red ones on the ground (be sure to zoom in to 100%). I think the texture is flatter and more pastel-like with Capture One, while it looks more real and photographic with RawTherapee. I haven't really compared if it's visible in a real print though.
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That "texture" thing I find very interesting, haven't really seen an example of it so I don't know what to look for. I assume it's something you see when you zoom in to 100% rather than looking at the picture from a distance?
One thing I have noticed though is that when I zoom in my Leaf Aptus landscape images the texture I get in Capture One is more artificial and pastel-like compared to the more photographic look I get in RawTherapee. On the other hand Capture One is better at suppressing aliasing artifacts.
Attached an example, RawTherapee to the left, Capture One to the right. As always(?) when doing side-by-side testing the difference is smaller than what I had from memory, but I still think it's there, and as some would say here "it's a galaxy apart" ;). The rock with the lichens, the narrow branches behind it and all the tiny leaves, especially the red ones on the ground (be sure to zoom in to 100%). I think the texture is flatter and more pastel-like with Capture One, while it looks more real and photographic with RawTherapee. I haven't really compared if it's visible in a real print though.
CMOS is more intensively filtered by firmware than CCD, it appears, and so texture loss is going to hit people in MF around now, I think.
Edmund
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Hi,
Default noise reduction in C1 is pretty harsh. Try setting noise reduction to zero.
With LR I sometimes use median filter on a and b channels on the image converted to Lab in Photoshop to get rid of colour artifacts. Raw therapy has an option for that, too.
Best regards
Erik
That "texture" thing I find very interesting, haven't really seen an example of it so I don't know what to look for. I assume it's something you see when you zoom in to 100% rather than looking at the picture from a distance?
One thing I have noticed though is that when I zoom in my Leaf Aptus landscape images the texture I get in Capture One is more artificial and pastel-like compared to the more photographic look I get in RawTherapee. On the other hand Capture One is better at suppressing aliasing artifacts.
Attached an example, RawTherapee to the left, Capture One to the right. As always(?) when doing side-by-side testing the difference is smaller than what I had from memory, but I still think it's there, and as some would say here "it's a galaxy apart" ;). The rock with the lichens, the narrow branches behind it and all the tiny leaves, especially the red ones on the ground (be sure to zoom in to 100%). I think the texture is flatter and more pastel-like with Capture One, while it looks more real and photographic with RawTherapee. I haven't really compared if it's visible in a real print though.
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Hi,
Default noise reduction in C1 is pretty harsh. Try setting noise reduction to zero.
With LR I sometimes use median filter on a and b channels on the image converted to Lab to get rid of colour artifacts. Raw therapy has an option for that, too.
Erik,
Is that a typo? I was not aware one could do that in Lighttroom.
Regards,
Bill
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Bill,
Not a typo, bad writing. I open the image in Photoshop, convert to Lab, do the median filter and save the image.
There is less need to do it in C1.
Best regards
Erik
Erik,
Is that a typo? I was not aware one could do that in Lighttroom.
Regards,
Bill
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Default noise reduction in C1 is pretty harsh. Try setting noise reduction to zero.
I tested that and for that particular crop the difference is practically zero. Instead I think the in comparison lack of texture and pastel-like look in C1 is a result of the demosaicer, with RawTherapee one can cycle through a number of demosaicers and the result is very different for this type of subject. For example the classic VNG4 does not succeed as good to keep the photographic look at 100%, unlike the default Amaze algorithm (written by Emil Martinec), which I think also does a bit better job than C1 as seen in my example. However C1's demosaicer is more robust against phenomena like crosstalk (relevant for certain tech wide + sensor combinations), while the Amaze demosaicer can start producing artifacts in those situations.
I would imagine that the demosaicer algorithm would have a considerably larger effect on the micro textures than any CMOS hardware filtering... but I don't know.
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Hi,
Thanks for sharing. I see your point. I have seen that kind of softness in C1 before but always attributed it to noise reduction, it seems that may not be the case.
Best regards
Erik
I tested that and for that particular crop the difference is practically zero. Instead I think the in comparison lack of texture and pastel-like look in C1 is a result of the demosaicer, with RawTherapee one can cycle through a number of demosaicers and the result is very different for this type of subject. For example the classic VNG4 does not succeed as good to keep the photographic look at 100%, unlike the default Amaze algorithm (written by Emil Martinec), which I think also does a bit better job than C1 as seen in my example. However C1's demosaicer is more robust against phenomena like crosstalk (relevant for certain tech wide + sensor combinations), while the Amaze demosaicer can start producing artifacts in those situations.
I would imagine that the demosaicer algorithm would have a considerably larger effect on the micro textures than any CMOS hardware filtering... but I don't know.
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I would imagine that the demosaicer algorithm would have a considerably larger effect on the micro textures than any CMOS hardware filtering... but I don't know.
Nah.
Edmund
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Nah.
Edmund
Try a few different demosaicers and watch the difference. It's easily seen. I have yet to see a demonstration of the hardware filtering effects, and undemonstrated effects makes me remain skeptical. MFD is full of often claimed and never demonstrated advantages, I'm probably guilty of repeating some of them myself... :-)
I'm not saying there can be a difference, but I find it just as likely that there is no visible impact. If you believe in a difference you will see it even if it's not there, until side by side testing shows that there is none (if that's the case). Sensors produce a pretty linear signal up to clipping, and for well exposed areas noise is low from any modern sensor.
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Sensors produce a pretty linear signal up to clipping
afaik CMOS sensors have (firmware) adjustable shoulders thx to the antiblooming transistors. Aptina confirmed this to me at last PK.
Edmund
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Hi,
From some of my reading I got the impression that digital sensors essentially have a shoulder but the ADCs just use the linear part of the signal. I don't know if this is correct.
Best regards
Erik
Try a few different demosaicers and watch the difference. It's easily seen. I have yet to see a demonstration of the hardware filtering effects, and undemonstrated effects makes me remain skeptical. MFD is full of often claimed and never demonstrated advantages, I'm probably guilty of repeating some of them myself... :-)
I'm not saying there can be a difference, but I find it just as likely that there is no visible impact. If you believe in a difference you will see it even if it's not there, until side by side testing shows that there is none (if that's the case). Sensors produce a pretty linear signal up to clipping, and for well exposed areas noise is low from any modern sensor.
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afaik CMOS sensors have (firmware) adjustable shoulders thx to the antiblooming transistors. Aptina confirmed this to me at last PK
Hi Edmund,
I would not generalize that to all CMOS sensors having such circuits and settings. Most photographic sensor related ADCs output very linear quantized values. It's measurable with very simple means, and I've done it for a number of cameras, all had a linear response curve for most of the tonal range (if we eliminate noise).
Cheers,
Bart
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Hi Edmund,
I would not generalize that to all CMOS sensors having such circuits and settings. Most photographic sensor related ADCs output very linear quantized values. It's measurable with very simple means, and I've done it for a number of cameras, all had a linear response curve for most of the tonal range (if we eliminate noise).
Cheers,
Bart
Bart,
Maybe we should separate circuits and settings ... the fact that the circuitry is there does not mean that the firmware allows the top counts to go all the way through the shoulder into the raw files.
My take on digital SLR cameras, after issues with highlights on my D4, is that the top stop of a saturating channel is problematic due to non linearity, the bottom 2 stops also due to noise and amp mismatch, 1 stop is often lost to channel mismatch eg. incandescent or crepuscular illuminant, so a 14 stop camera is a 10 stop camera under less than ideal conditions, even at low ISO. Exposure lattitude is thus 1 stop each way from the center, move more and you will see damage effects at one end of the histogram. I'm sure my reasoning is wrong somewhere, but this corresponds to what I see in practice :)
I may be wrong, but my impression is that better calibration (or circuitry) and harder clipping add a stop or so to CCD digital backs.
Interestingly, I (most people?) seem to be very sensitive to near-white highlight hues, so non-linearity of a channel at the top means bad color discrimination in the clouds and highlights and me unhappy; on the other hand, a shoulder does mean no hard burnout. I don't think ETTR really makes sense because of this, as eg. sky and cloud nuances will look very different from reality if a channel goes non-linear at the top.
Edmund
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Hi,
I don't see those effects on my Sonys. Actually, I think they would show up in my testing as I always test ETTR. Nikon uses sensors from Sony or Aptina mostly, but the cameras like D4 and DF use Nikon designed sensors.
Best regards
Erik
Bart,
Maybe we should separate circuits and settings ... the fact that the circuitry is there does not mean that the firmware allows the top counts to go all the way through the shoulder into the raw files.
My take on digital SLR cameras, after issues with highlights on my D4, is that the top stop of a saturating channel is problematic due to non linearity, the bottom 2 stops also due to noise and amp mismatch, 1 stop is often lost to channel mismatch eg. incandescent or crepuscular illuminant, so a 14 stop camera is a 10 stop camera under less than ideal conditions, even at low ISO. Exposure lattitude is thus 1 stop each way from the center, move more and you will see damage effects at one end of the histogram. I'm sure my reasoning is wrong somewhere, but this corresponds to what I see in practice :)
I may be wrong, but my impression is that better calibration (or circuitry) and harder clipping add a stop or so to CCD digital backs.
Interestingly, I (most people?) seem to be very sensitive to near-white highlight hues, so non-linearity of a channel at the top means bad color discrimination in the clouds and highlights and me unhappy; on the other hand, a shoulder does mean no hard burnout. I don't think ETTR really makes sense because of this, as eg. sky and cloud nuances will look very different from reality if a channel goes non-linear at the top.
Edmund
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Maybe we should separate circuits and settings ... the fact that the circuitry is there does not mean that the firmware allows the top counts to go all the way through the shoulder into the raw files.
Hi Edmund,
Indeed, circuitry (some of which is not present in all designs) is different from firmware settings. The settings used in the ADC process will determine how much of the total captured signal is transferred to discrete values. Noise is added to the already shotnoise riddled signal during that process. Some conversions are therefore cleaner than others.
In addition, e.g. Sony have started using a non-linear encoding of the in essence linear ADC output in their Raw format. So now it seems like the camera's response curve is vastly non-linear if one were to look at the Raw data in isolation. However, during Raw conversion this added non-linearity is removed again, because demosaicing requires a linear gamma data space.
My take on digital SLR cameras, after issues with highlights on my D4, is that the top stop of a saturating channel is problematic due to non linearity, the bottom 2 stops also due to noise and amp mismatch, 1 stop is often lost to channel mismatch eg. incandescent or crepuscular illuminant, so a 14 stop camera is a 10 stop camera under less than ideal conditions, even at low ISO. Exposure lattitude is thus 1 stop each way from the center, move more and you will see damage effects at one end of the histogram. I'm sure my reasoning is wrong somewhere, but this corresponds to what I see in practice :)
There is probably also a Raw conversion effect in play here, which is not a sensor characteristic. I rarely look at the Raw data, unless I need to analyze it before the demosaicing and conversion process turns the data into an image. During that process a lot can happen to the tonecurve, especially in the LR and ACR Process 2012 (which significantly compresses highlights), or in Capture One when a filmcurve is used instead of a linear tonecurve. But that is all postprocessing, and is not a sensor characteristic.
Interestingly, I (most people?) seem to be very sensitive to near-white highlight hues, so non-linearity of a channel at the top means bad color discrimination in the clouds and highlights and me unhappy; on the other hand, a shoulder does mean no hard burnout. I don't think ETTR really makes sense because of this, as eg. sky and cloud nuances will look very different from reality if a channel goes non-linear at the top
I'm also sensitive to highlight rendering. Using a linear tone curve instead of compressing highlights helps a lot, no, it's essential. It's easier to add a shoulder roll-off, only if and when/where it is needed, than to create linearity where the detail has already been lost. A fantastic tool like Topaz Labs Clarity helps a lot to regain some sparkle in the image by altering local contrast in a very intelligent (and halo free) way, if necessary to be applied locally by clever built-in masking tools, but it won't invent detail where there was none to begin with.
Cheers,
Bart
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Torger
Back to your C1 & Raw Terapee side by sides. By default C1 consistently applies too much noise reduction even on base ISO files. You may try removing as much as 50 percent of the noise reduction. Also adding structure will help get the pastel look removed.
I often see this look on my Phase One conversions especially on distant details. C1 allow for a local adjustment layer where you can add more structure to just those types of areas. It will make a big difference. I don't add any clarity just structure.
Then a final pass with Focus Magic and results look very good.
Paul
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Back to your C1 & Raw Terapee side by sides. By default C1 consistently applies too much noise reduction even on base ISO files. You may try removing as much as 50 percent of the noise reduction. Also adding structure will help get the pastel look removed.
Indeed, on my D800 files at ISO100 I always set all noise reduction to zero in C1 Pro.
Cheers,
Bernard
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Torger
Back to your C1 & Raw Terapee side by sides. By default C1 consistently applies too much noise reduction even on base ISO files. You may try removing as much as 50 percent of the noise reduction. Also adding structure will help get the pastel look removed.
I often see this look on my Phase One conversions especially on distant details. C1 allow for a local adjustment layer where you can add more structure to just those types of areas. It will make a big difference. I don't add any clarity just structure.
Then a final pass with Focus Magic and results look very good.
Paul
Yes, and everyone should also keep in mind you can set the NR defaults in C1 to off with your camera. I have mine set that way as I prefer to always start with no luminance noise reduction at all, regardless of the ISO used. Specifically, I set Luminance NR to Zero, and leave the Color and Single Pixel settings at their standard default, as I rarely find their starting points to be a problem.
Steve Hendrix
Capture Integration
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Yes, and everyone should also keep in mind you can set the NR defaults in C1 to off with your camera.
Steve is correct. The camera defaults can be changed, and I have mine set to zero noise reduction. Capture One also allows to adjust the level of Detail it attempts to pull out of the noise, another trade-off.
Cheers,
Bart
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I re-ran my RT vs C1 test and turned off noise reduction -- virtually no difference in result, but then I looked at the default sharpening, and that's were the major difference is. The default USM of C1 has a 1.0 diameter compared to RT's 0.5. The larger diameter flattens the result making that look I find pastel-like at pixel peep. I guess C1's default is made for less sharp lenses or something.
Anyway, with the same type of sharpening the RT vs C1 result is very similar, I'd say that RT's Amaze is still a little bit ahead in terms of micro detail, but the difference is small so I'd say it's not relevant.
In other words, the difference in demosaicer result was not as large as I first thought.
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Hi Edmund,
I would not generalize that to all CMOS sensors having such circuits and settings. Most photographic sensor related ADCs output very linear quantized values. It's measurable with very simple means, and I've done it for a number of cameras, all had a linear response curve for most of the tonal range (if we eliminate noise).
Cheers,
Bart
That has been my experience with the Nikon D800e, which uses a Sony chip. Here are the results for the green channels which clip at the raw value of 15785. In the first graph shown below, the exposure increments are 0.3 EV and the upper three shots are clipped. A plot of the non-clipped channels shows nearly perfect linearity.
Bill
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I re-ran my RT vs C1 test and turned off noise reduction -- virtually no difference in result, but then I looked at the default sharpening, and that's were the major difference is. The default USM of C1 has a 1.0 diameter compared to RT's 0.5. The larger diameter flattens the result making that look I find pastel-like at pixel peep. I guess C1's default is made for less sharp lenses or something.
Anyway, with the same type of sharpening the RT vs C1 result is very similar, I'd say that RT's Amaze is still a little bit ahead in terms of micro detail, but the difference is small so I'd say it's not relevant.
In other words, the difference in demosaicer result was not as large as I first thought.
Did you crank the details slider (Which modifies parameters of the demosaicer toward more aggressive detail extraction) to max? I think you'll find the comparison moot if/when you do that (and match the noise reduction and sharpening).
The default sharpening radius in C1 is intended for the average commercial photographer, not a pixel-peeping technically oriented one (no slight intended, just identifying two markets). A radius of 0.5 is only appropriate for a narrow range of lens/aperture/sensor/ISO/subject-matter/aesthetics. You can easily increase or decrease the radius and then save that as the default moving forward.
For use with a modern digital back at low ISO you may find you wish to modestly lower the default threshold of sharpening as well, which is kept at 1 by default to avoid sharpening noise (which is nearly absent in a well exposed IQ250 file at low ISO).
If detail is your absolute priority, you have an incredibly sharp lens with a sensor free of an AA filter, and you don't mind a bit of grain then:
- luminance and single-pixel noise reduction to zero
- detail slider to max
- sharpening threshold to 0
- sharpening radius to 0.5
- sharpening amount to taste
- add structure to taste
Many commercial photographers would find the result overly gritty and abrasive, but those who thrive off pixel detail should enjoy it quite a bit.
[written of course for more than just Torger, as he knows all this already]
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That has been my experience with the Nikon D800e, which uses a Sony chip. Here are the results for the green channels which clip at the raw value of 15785. In the first graph shown below, the exposure increments are 0.3 EV and the upper three shots are clipped. A plot of the non-clipped channels shows nearly perfect linearity.
Indeed, also almost perfectly linear. The slight onset of the slope in the most upper 1/3rd stop is usually due to the upper tail of the shot-noise starting to get clipped by saturation. Other noise sources, such as PRNU can be eliminated by plotting subtracted exposure pairs, but these shots already look amazingly (with an R^2 of 0.9999) linear to exposure.
Cheers,
Bart
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Indeed, also almost perfectly linear. The slight onset of the slope in the most upper 1/3rd stop is usually due to the upper tail of the shot-noise starting to get clipped by saturation. Other noise sources, such as PRNU can be eliminated by plotting subtracted exposure pairs, but these shots already look amazingly (with an R^2 of 0.9999) linear to exposure.
Cheers,
Bart
Yes, that upper 1/3 shot does show clipping of the shot noise, as shown by the standard deviation dropping from around 300 to around 30 and then to zero as the channel is totally clipped. I did subtract frames to eliminate PRNU and obtain an electron count, but I did not pursue the matter further as the results were already linear to a large degree. I only extracted the standard deviation of the subtracted images and not the mean. Would that mean add anything significant?
Bill
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[written of course for more than just Torger, as he knows all this already]
I don't use C1 much, just now and then, so these tips are useful to me too, thanks! Details slider did not make much of a difference, but yes I'd say with all things put together the difference in demosaicing performance is negligible. C1 does a great job just as RT.
As a landscape photographer using a 33 megapixel back I would guess that I have different needs of detail extraction than a portrait photographer using an 80 megapixel back, so the defaults are understandable.
What I try to achieve as a starting point is an image that looks as natural as possible at 100%, sharp but not over-sharpened or pastel-like or otherwise "digital"-looking, so the "structure" slider is not for me. Then depending on printer I do additional sharpening to match that.
Handled right, I think those 33 megapixels actually is enough in terms of detail for high end landscape photography, as reasonable depth of fields impose a certain limit on resolving power. The strongest reason for me to have more pixels is to battle aliasing rather than to get more resolving power.
(This thread must have set some sort of record in off-topicness ;) )
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Hi,
Although I also feel that we deviate to much from the OP, I think that this is interesting and a worthwhile issue to discuss. So I add a few observations of my own.
1) I have seen the phenomena you mention in C1 on my P45. It may be a combination of several effects, excessive NR and sharpening philosophy.
2) I have looked quite a lot into sharpness with different print sizes I have some objections about sharpening for actual pixels.
The reason is that we never see an image like pixel peeping on screen. What actually shows details best in real life is a print. But, sharpness in prints is dominated by lower frequencies like 10-20 lp/mm. So sharpening optimally at the pixel level may sharpen detail that has very little effect on perception of an actual print, unless the print is very large and viewed very close. So, C1 sharpening may be pretty good even if it may be excessive in actual pixel view.
For real good sharpness, I think the methods that Bart uses are probably best. No sharpening in the raw developer followed by very good sharpening with FocusMagic and some Topaz tools. The great benefit of FocusMagic is that it sharpens with very little halo.
I also found that sharpening optimally at actual pixels and applying some additional sharpening with USM, like radius 2 and amount 15% pushes low frequency detail close to 100%.
I would suggest that optimal sharpening is worth a separate thread.
Best regards
Erik
I don't use C1 much, just now and then, so these tips are useful to me too, thanks! Details slider did not make much of a difference, but yes I'd say with all things put together the difference in demosaicing performance is negligible. C1 does a great job just as RT.
As a landscape photographer using a 33 megapixel back I would guess that I have different needs of detail extraction than a portrait photographer using an 80 megapixel back, so the defaults are understandable.
What I try to achieve as a starting point is an image that looks as natural as possible at 100%, sharp but not over-sharpened or pastel-like or otherwise "digital"-looking, so the "structure" slider is not for me. Then depending on printer I do additional sharpening to match that.
Handled right, I think those 33 megapixels actually is enough in terms of detail for high end landscape photography, as reasonable depth of fields impose a certain limit on resolving power. The strongest reason for me to have more pixels is to battle aliasing rather than to get more resolving power.
(This thread must have set some sort of record in off-topicness ;) )
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The reason is that we never see an image like pixel peeping on screen.
I know this, that's why it's only a starting point. I believe that an image that looks natural at 100% on screen has a better enlargement potential than one that do not.
So far I make C-prints and for that process I find that print sharpening with some slight halo is best, as the printer kills the halo. But I find using 1.0 diameter is too large also for that, it does not make most out of the back's resolution. I do peep the prints too.
I haven't really worked with low frequency sharpening (other than the typical local contrast increases you can do also on screen), seems like an interesting subject. My guiding principle is natural look though, rather than something that appears as sharp as possible. Many guides I've read seems to be a bit "the more processing the better" rather than stopping when the image looks good and natural.
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Yes, that upper 1/3 shot does show clipping of the shot noise, as shown by the standard deviation dropping from around 300 to around 30 and then to zero as the channel is totally clipped. I did subtract frames to eliminate PRNU and obtain an electron count, but I did not pursue the matter further as the results were already linear to a large degree. I only extracted the standard deviation of the subtracted images and not the mean. Would that mean add anything significant?
Hi Bill,
Assuming that the exposure pairs were exposed to approx. the same level, after subtraction the mean would be close to zero and thus have little informational value. It's the random noise we're after. The means before subtraction would allow to verify shutter repeatability, and raw tonecurve linearity, and gain (by comparing the number of input Photons with the resulting ADUs).
The subtraction is indeed essential if one wants to eliminate systematic noise (pattern noise, PRNU, hot/dead pixels, dust, etc.). After subtraction (and division by Sqrt(2) like you did) one is left with random dark-current+read-noise+shot noise, the latter of which dominates at high exposure levels. Assuming a Poisson noise distribution (if we wanted we could verify that by subtracting a Poisson noise distribution model, which should leave white noise as a residue), we can then reconstruct the average number of photons required to produce that level of noise, by squaring the noise Standard deviation.
Cheers,
Bart
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I know this, that's why it's only a starting point. I believe that an image that looks natural at 100% on screen has a better enlargement potential than one that do not.
Hi,
Given the current small number of actual 645Z users that can contribute, the thread is obviously drifting a bit OT, but such is life.
I'm known to be a huge supporter of proper Capture sharpening. Unfortunately most Raw converters offer little assistance to achieve that essential task accurately. Proper Capture sharpening attempts to only removes the optical/mechanical blur that is inherent to the the capture process. No halos should be created in that restoration process, only restoration of original signal sharpness. The blur is predominantly characterized by hardware (lens+IR/OLPF filter stack+sensel aperture) at this stage, with a small amount (only some 6.4%) of demosaicing compromises/trade-off added.
That Capture sharpened image data is the basis for further image contrast/acutance manipulation, global and local contrast. That part is known as Creative 'sharpening' and is largely influenced by the final viewing conditions/distance, and thus takes a bit of imagination and experience. Output sharpening then attempt to pre-compensate for later losses due to the output media.
I haven't really worked with low frequency sharpening (other than the typical local contrast increases you can do also on screen), seems like an interesting subject. My guiding principle is natural look though, rather than something that appears as sharp as possible. Many guides I've read seems to be a bit "the more processing the better" rather than stopping when the image looks good and natural.
I'd suggest to give the Topaz Labs Detail plugin a serious look. It allows to attenuate or boost several levels of detail, based on size relative to the total image dimensions, and offers options to modify luminance contrast based on complementary color. Maybe the best thing is that it allows to do so without creating halos, and while keeping colors looking natural (Intellicolor technology). This tool allows to stay in control and it offers lots of creative influence. It's one of the essential plugins in my toolchest (along side with FocusMagic for capture sharpening and Topaz Clarity for tonal contrast adjustment).
Cheers,
Bart
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Yes, that upper 1/3 shot does show clipping of the shot noise, as shown by the standard deviation dropping from around 300 to around 30 and then to zero as the channel is totally clipped. I did subtract frames to eliminate PRNU and obtain an electron count, but I did not pursue the matter further as the results were already linear to a large degree. I only extracted the standard deviation of the subtracted images and not the mean. Would that mean add anything significant?
Bill
The IQ-250, using the same sensor, does an automatic and mandatory dark frame subtraction on every exposure, no exceptions. I'm wondering whether the Pentax (and the Hasselblad) also do the same thing? I suspect that with a chip that has this much active circuitry and generates this much thermal noise, a dark frame subtraction just might be strongly recommended in the implementation notes. Does your output suggest that this is occurring?
I've often thought that my D800 ought to have an option to do a dark frame subtraction full-time, certainly at high gain settings.
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The IQ-250, using the same sensor, does an automatic and mandatory dark frame subtraction on every exposure, no exceptions. I'm wondering whether the Pentax (and the Hasselblad) also do the same thing? I suspect that with a chip that has this much active circuitry and generates this much thermal noise, a dark frame subtraction just might be strongly recommended in the implementation notes. Does your output suggest that this is occurring?
This is not correct.
The IQ2 series does not have a user-option to modify the behavior of the dark frame. But it is not taken on every exposure; only when needed. In fact in many temperature/shutter-speed environments it is skipped for many frames at a time, including on multi-second exposures. e.g. If you do several 3 second exposures in a row in a temperature environment it's often only the first exposure which will get a dark frame after it.
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The IQ-250, using the same sensor, does an automatic and mandatory dark frame subtraction on every exposure, no exceptions. I'm wondering whether the Pentax (and the Hasselblad) also do the same thing? I suspect that with a chip that has this much active circuitry and generates this much thermal noise, a dark frame subtraction just might be strongly recommended in the implementation notes. Does your output suggest that this is occurring?
I've often thought that my D800 ought to have an option to do a dark frame subtraction full-time, certainly at high gain settings.
My tests were all at ISO100 with dark frame subtraction turned off. My longest exposure was for 5 minutes. Dark current was minimal and confined largely to a few hot pixels. Rawdigger stats for most of the image (excluding the masked pixels at the right of the frame) and the histogram are shown.
Bill
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This is not correct.
The IQ2 series does not have a user-option to modify the behavior of the dark frame. But it is not taken on every exposure; only when needed. In fact in many temperature/shutter-speed environments it is skipped for many frames at a time, including on multi-second exposures. e.g. If you do several 3 second exposures in a row in a temperature environment it's often only the first exposure which will get a dark frame after it.
Wait Doug, I did not say that the camera took a new dark frame on every exposure. I said that it performed a dark frame subtraction on every exposure. And I said that this was mandatory and cannot (and probably should not) be defeated. My source, by the way, was you. And as you confirmed here, I had my facts straight.
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Wait Doug, I did not say that the camera took a new dark frame on every exposure. I said that it performed a dark frame subtraction on every exposure. And I said that this was mandatory and cannot (and probably should not) be defeated. My source, by the way, was you. And as you confirmed here, I had my facts straight.
Ha. You're completely right. I misread your post and skipped right over the word "subtraction". My appologies. After all, if you're sourcing from me who am I to disagree! ;D