Actually, we need even more resolution.

[ErikKaffehr]

Hi Edmund,

My point is to illustrate a law of nature that sets limits to resolution.

Best regards
Erik

If we had the design files for trees, flowers, mountains etc we wouldn't need to photograph, we could just generate.

Edmund

[Theodoros]

All this know-how on maximising achievable resolution is of course (as with all knowledge) good to know... My concern has much more to do with the O/P... I still don't understand why printing on 300dpi is a necessity, why is it that we need more pixels and how achieving maximum resolution is related with improvements in ones photography...? My impression (and I think most of those that print big and sell their pictures) is that decreasing pixel size may increase resolution to some extend, but OTOH, they affect picture qualities that are much more important than resolution...
What is enough resolution is of course both personal and subjective, but since resolution has been improved a lot in the (say 7 - after 6 micron backs first arrived) later years, even from what 8x10 film can give, but photographs haven't improve at all (Its the opposite that happens actually), I don't see how seeking for more resolution (by inevitably decreasing pixel size which will affect negatively other pixel qualities) will lead into improving photographs....
In fact, the cases I miss more resolution in prints I see published, are extremely rare... it's rather the opposite... there is a good number of todays photographs that one finds that resolution is more than it should be! In fact, in some cases depending on the subject, resolution is so much that distracts ones attention to the subject itself... which of course isn't a good thing to happen.

[ErikKaffehr]

Hi,

I would say I agree on that few images we see are lacking in resolution. But on the other hand there is a feeling of immersion when you walk close up to a great image and check out all details.

Best regards
Erik

All this know-how on maximising achievable resolution is of course (as with all knowledge) good to know... My concern has much more to do with the O/P... I still don't understand why printing on 300dpi is a necessity, why is it that we need more pixels and how achieving maximum resolution is related with improvements in ones photography...? My impression (and I think most of those that print big and sell their pictures) is that decreasing pixel size may increase resolution to some extend, but OTOH, they affect picture qualities that are much more important than resolution...
What is enough resolution is of course both personal and subjective, but since resolution has been improved a lot in the (say 7 - after 6 micron backs first arrived) later years, even from what 8x10 film can give, but photographs haven't improve at all (Its the opposite that happens actually), I don't see how seeking for more resolution (by inevitably decreasing pixel size which will affect negatively other pixel qualities) will lead into improving photographs....
In fact, the cases I miss more resolution in prints I see published, are extremely rare... it's rather the opposite... there is a good number of todays photographs that one finds that resolution is more than it should be! In fact, in some cases depending on the subject, resolution is so much that distracts ones attention to the subject itself... which of course isn't a good thing to happen.

[hjulenissen]

They are not readily available. Which is the whole point of this thread: internet forum analysts argue that resolutions beyond 20 (argued around 2009), 50 (argued around 2011) or 80 mpix (argued today) are not needed, yet printers capable of taking advantages of over 400 mpix are readily available and cost less than the average MF back (the Epson 11880 discussed earlier costs 7000$ at B&H).

I am not sure how you interpret the availability of "400 mpix" printers to say anything about the utility of 400 mpix cameras? There can be many reasons why "400 MP" printers are available, not all of them pointing to 400MP prints looking very different from 200MP prints for the majority of cases.

Focusing on a given spec (e.g. "I only ever print at 300 dpi, no matter what") seems less productive than a more pragmatic "let's see what works".

The same internet forum analysts argue that the properties of human vision are such that large prints can only be seen from far away,

Not sure what you are saying here, but I am pretty sure that no one have ever stated that it is impossible to approach a large print?

If there is a technical difference, chances are fair that it is possible to make a scenario where this technical difference can be percepted. Thus, one could say that any technical improvement can concievably lead to a perceived improvement. But does this also make it worth the effort and cost? In my view, it makes sense to do some sanity-test on the scenario. I don't shoot and print images for people bringing a loupe. If they choose to bring one anyways, I could care less about their experience.

internet forum analysts ...

It seems to me that you pick your words in order to ridicule those that disagree with you. While this may make for an interesting argument, it is less likely that anyone of us will learn anything from the discussion.

-h

[ErikKaffehr]

Hi,

I would say Mr. Hjulenissen has a couple of valid points.

Best regards
Erik

I am not sure how you interpret the availability of "400 mpix" printers to say anything about the utility of 400 mpix cameras? There can be many reasons why "400 MP" printers are available, not all of them pointing to 400MP prints looking very different from 200MP prints for the majority of cases.

Focusing on a given spec (e.g. "I only ever print at 300 dpi, no matter what") seems less productive than a more pragmatic "let's see what works".
Not sure what you are saying here, but I am pretty sure that no one have ever stated that it is impossible to approach a large print?
It seems to me that you pick your words in order to ridicule those that disagree with you. While this may make for an interesting argument, it is less likely that anyone of us will learn anything from the discussion.

-h

[Mr. Rib]

A bit less technical chiming in from me- the aforementioned large prints of Andreas Gursky, in close inspection aren't really sharp / shock you with detail. They are meant to be viewed from a certain distance and one may feel let down if you are looking for super high resolution, at close-up. If you watch some documentaries about his work, you will be told that his shots are amazing in this regard and that you can walk into them and still find fine detail- that's not true. For pixel-peepers / guys with technical approach it will be even more evident.
Maybe his more "artificial" work like the Formula 1 diptych composite has more resolution but that piece was engineered/manufactured rather than shot- haven't seen those in person.
Theodoros is right about that- the ones that sell for fortunes had image resolution quite low on the priority list of the authors
Nevertheless I think that for these tack-sharp, enormous prints, taken with a single shot, some kind of revolution / totally different approach is needed. There are too many bottlenecks in current approach. You want to shoot BIG formats and you run into big aperture/shallow DoF vs small aperture / diffraction dilemma. You go smaller with the format- the lenses don't resolve enough to give that hundreds of Mpix, even if the sensor would do that. And there are optics limits- at certain point better stuff is simply impossible due to physical laws. So maybe to get these enormous prints we need a revolution, a breakthrough?

[Theodoros]

I've seen excellent prints at 72ppi and I've seen bad prints at 360ppi... Printing is a process that requires high skills to be done properly. Some think of it as PPIs, some others think of it as a pre-visualised outcome that makes a photograph... To some the file is the photograph... to some others the print is the photograph... Never the less, photography is by definition a print... So the second group is right by definition of photography.
Further more, resolution is a part of the look of a photograph... This is not a matter of  higher resolution making a better photograph, it is only an intentional part of visualisation. In my photographic career never thought of resolution as an important part of picture quality, I only made sure that I have enough of it (under personal judgement)  for the result (the print) to be well communicated... Therefore, I don't see why one should print at a certain number of pip, nor I see why printing at less should be forbidden... Certainly "we need more..." I feel is a wrong expression, one may say "I want more..." or "I suggest more...", but if one says "WE NEED more..." then, I feel he includes ME as well without ever asking me... and he does so at the time where in many of my pictures, I try to find ways to avoid extensive resolution... at the point where more resolution can be destructive for "the look" I want... How one can say what I need?  ...in six months time I will be selling all my Nikon gear to finance and replace it with a Leica S (007)... I will be using my 7 Contax-Zeiss lenses with it and it will be used along side my C645 cameras and the dedicated back I use on them for what I was using a DSLR up to now, as well as for replacing the purchase of a single shot back (the back I use is MS). I can honestly say, that if the camera was of less than 6μm pixel size I wouldn't buy it... I am very suspicious with ultra small pixels and I never had resolution in more than the 5th place on my criteria when buying... In fact, in most cases I do prefer my Nikon's 16mp prints than my other Nikon's 36mp prints, not to mention my 22 MFDB prints that are superior than both...

[Alan Klein]

Theodoros:  what makes the 16mp prints better than the 36,p and the 22 MFDB better than the opther two?

I am very suspicious with ultra small pixels and I never had resolution in more than the 5th place on my criteria when buying... In fact, in most cases I do prefer my Nikon's 16mp prints than my other Nikon's 36mp prints, not to mention my 22 MFDB prints that are superior than both?

[ErikKaffehr]

Hi Alan,

It is an interesting question and I try to look at it in this article:

http://echophoto.dnsalias.net/ekr/index.php/photoarticles/82-why-i-cannot-see-a-difference-in-a2-size-prints

My impression is that once image quality reaches a certain level it is good enough and little or no improvement will be observed. But this is based on my own vision and just a few observers.

Michael Reichmann had an interesting discussion with Ctein, and Ctein was perfectly satisfied with shooting 16 MP Olympus 4/3 for A2-size prints. It was "good enough". But he also posted this article: http://theonlinephotographer.typepad.com/the_online_photographer/2009/02/why-80-megapixels-just-wont-be-enough.html

My take may be that more pixels are good for correct rendition. Ideally, the lens should be the limiting factor and not the sensor.

Best regards
Erik

Theodoros:  what makes the 16mp prints better than the 36,p and the 22 MFDB better than the opther two?

[ErikKaffehr]

Hi,

Personally, I feel the largest need for resolution is the suppression of artefacts.

This image was shot at 3.8 m distance using a 150/4 Sonnar on a 6.8 micron pitch sensor at f/8:



The next was shot with a Sony SAL 70-400/4-5.8 at 150mm still at 3.8 m distance on a 3.8 micron pitch sensor, still at f/8.



The lenses are pretty close regarding MTF, but the smaller pitch sensor makes a larger image, with more detail.

The next pair of images shows the original 6.8 micron pitch image to the left and the 3.8 micron pixel image downscaled using Lanzcos interpolation on the right:


Note that the left image has a criss-cross pattern and the strains seem to be stippled, while the right one is more credible. Seen at distance the left image may look sharper.

Both images have now  approximately the same resolution, but the downscaled 3.8 micron image shows a good approximation of real detail while the 6.8 micron image has invented a lot of artificial detail. On full frame 135 this images would correspond to 30 resp. 54 MP. On full frame 645 this would be 50 MP resp. 160 MP.

So it would take something like 50 MP to render an f/8 image correctly on 135 or something like 160 MP on full frame 645.  With better lenses we would need even more pixels.

What I have seen is that I still have significant aliasing on my P45+ back at f/11, but it goes away almost completely at f/16. As Airy disk diameter is proportional to aperture, we would need half the pixel size at f/8 for non aliased rendition. That figure would also correspond to 39x4 something like 156 MP. Now, put a really sharp lens like an Otus on that sensor and shoot at f4, something like 620 MP would be needed for unaliased rendition!

Best regards
Erik

[jerome_m]

(useful reminder: all my posts in this thread are to be taken with a pinch of salt...    )

Yesterday, I visited the new gallery from Lumas which opened near my house. They are specialised in selling large sheet of acrylic glass with pictures glued on the back side. They had massive prints for display, of the size we discuss in this thread.

I was really disappointed by the resolution used for the prints. First example, that picture of an elephant in a forest:
http://img.lumas.de/showimg_jmc04_1600_1600.jpg
The structure of the trees and the shape of the leaves breaks in digital artefacts at the size presented (120 x 180 cm, €1800).

Second example: that seascape, reminiscent of works by Shugimoto:
http://img.lumas.de/showimg_wuh21_1600_1600.jpg
The waves do not look real. The lens is not sharp on a circular zone extending 2/3 of the center. (123 cm x 178 cm, €1800, one of their best sellers).

Third example: that cityscape from Hong Kong:
http://img.lumas.de/showimg_bbk13_1600_1600.jpg
Wouldn't that be the perfect subject for stitching? It would, but the picture presented here is full of digital artefacts and the devastating effects of high iso noise reduction. (150 cm x 187 cm, €2300, the print had one of the most prominent spots in the gallery).

Isn't it time that we, as recognised Internet experts, teach Lumas how to print right? The prints are too large for the poor technique used. Unfortunately Lumas is not accepting application portfolios from independent photographers, but maybe an online petition could be an option?

[Theodoros]

Theodoros:  what makes the 16mp prints better than the 36,p and the 22 MFDB better than the opther two?

Better DR, more contrasty mids, better balance between LLs and HLs, more accurate colour.... I find that with small pixels, if one is after keeping the captured DR, he ends up with a dull look and thus he is forced to process in a way that affects DR negatively.

[ErikKaffehr]

Hi,

I would say it may be the other way around. The small pixel cameras have high DR, due to low read noise. Making use of that DR make the image flat, as neither screen or print has similar brightness range.

Best regards
Erik

Better DR, more contrasty mids, better balance between LLs and HLs, more accurate colour.... I find that with small pixels, if one is after keeping the captured DR, he ends up with a dull look and thus he is forced to process in a way that affects DR negatively.

[Theodoros]

Hi,

I would say it may be the other way around. The small pixel cameras have high DR, due to low read noise. Making use of that DR make the image flat, as neither screen or print has similar brightness range.

Best regards
Erik

Its noise per sensor area that is lower with larger sensors Erik... at least that's what Physics suggest. Back to the artefacts matter though... I see that you only mean moire when you refer to artefacts, isn't it?  We all have to understand that if Bayer pattern was absent, there would have been no moire problem... Detail would also improve considerably since what the human eye understands as resolution is the colour difference between pixels and thus interpolated colour mistakes affects resolution too and DR would improve considerably...

IMO, the problem is more with the technology used than with pixel density. I believe that soon there will be a technological revolution and what we now use, in a few years will be considered as ancient equipment... From that POV, one has to see on how he may improve with the short period he'll be using the current technology, to do that he has to judge what is more important to him as far as the benefits and the handicaps of using smaller pixels is concerned, which of course is highly subjective and personal...

Only thing I'm saying, is that there is a high number of photographers that consider resolution low in their list of priorities and that what is higher in the list for them is better served with larger pixels. Take a view camera user for instance....

[ErikKaffehr]

Hi,

I would suggest that you need to read up a little bit on basic signal processing as your understanding of the issues involved seems to be incomplete. But I agree on the resolution not being a major issue.

Two direct problems with your interpretations I would like to point out.

One is that moiré has no relation to bayer pattern, even monochrome implementations have moiré, but not colour aliasing. You can just check the wikipedia page: http://en.wikipedia.org/wiki/Moiré_pattern

Noise levels are not really related to pixel size. Basically there is shot noise that depends on statistical properties of light and more dependent on sensor size than pixel size and readout noise which depends on readout circuitry.

At the present stage all full frame small pixel sensors are coming from Sony and use on chip converters. These how low readout noise, thereby delivering cleaner and deeper shadows than older designs with external ADCs. The reasons that the on chip converters work so well is probably in part that are many of them working in parallell, so each converters only processess say 5000 pixels/frame while a traditional external ADC may need to process 4 million pixels/frame (assuming four readout channels).

It seems that the on chip converters have something like 1/3 - 1/4 of the readout noise levels of external converters.

Now, readout noise is not dependent on pixel size, so larger pixels would have somewhat better dynamic range, but as said the small pixel cameras all have superior readout circuitry that more than compensates for the pixel size.

This sample is from a P45+:

And this one is from a Sony Alpha 99 SLT


The second image is brighter than the first one. I guess that it has to do with the zoom lens on the Sony having more lens flare. Exposure had been very similar.


Best regards
Erik

Its noise per sensor area that is lower with larger sensors Erik... at least that's what Physics suggest. Back to the artefacts matter though... I see that you only mean moire when you refer to artefacts, isn't it?  We all have to understand that if Bayer pattern was absent, there would have been no moire problem... Detail would also improve considerably since what the human eye understands as resolution is the colour difference between pixels and thus interpolated colour mistakes affects resolution too and DR would improve considerably...

IMO, the problem is more with the technology used than with pixel density. I believe that soon there will be a technological revolution and what we now use, in a few years will be considered as ancient equipment... From that POV, one has to see on how he may improve with the short period he'll be using the current technology, to do that he has to judge what is more important to him as far as the benefits and the handicaps of using smaller pixels is concerned, which of course is highly subjective and personal...

Only thing I'm saying, is that there is a high number of photographers that consider resolution low in their list of priorities and that what is higher in the list for them is better served with larger pixels. Take a view camera user for instance....

[Theodoros]

Hi,

I would suggest that you need to read up a little bit on basic signal processing as your understanding of the issues involved seems to be incomplete. But I agree on the resolution not being a major issue.

Two direct problems with your interpretations I would like to point out.

One is that moiré has no relation to bayer pattern, even monochrome implementations have moiré, but not colour aliasing. You can just check the wikipedia page: http://en.wikipedia.org/wiki/Moiré_pattern

Noise levels are not really related to pixel size. Basically there is shot noise that depends on statistical properties of light and more dependent on sensor size than pixel size and readout noise which depends on readout circuitry.

At the present stage all full frame small pixel sensors are coming from Sony and use on chip converters. These how low readout noise, thereby delivering cleaner and deeper shadows than older designs with external ADCs. The reasons that the on chip converters work so well is probably in part that are many of them working in parallell, so each converters only processess say 5000 pixels/frame while a traditional external ADC may need to process 4 million pixels/frame (assuming four readout channels).

It seems that the on chip converters have something like 1/3 - 1/4 of the readout noise levels of external converters.

Now, readout noise is not dependent on pixel size, so larger pixels would have somewhat better dynamic range, but as said the small pixel cameras all have superior readout circuitry that more than compensates for the pixel size.

This sample is from a P45+:

And this one is from a Sony Alpha 99 SLT


The second image is brighter than the first one. I guess that it has to do with the zoom lens on the Sony having more lens flare. Exposure had been very similar.


Best regards
Erik

I hate to argue on theory... Larger pixels DO HAVE less read noise per area they cover and this is theory... (that's why the "LL champion cameras" have larger pixels). On the images that you posted, the second one isn't "brighter", its considerably duller (luck of contrast) and the HLs have been "blown" (which can't be an effect of flare - flare does decrease contrast but it doesn't blow HLs) while in the first one whites do hold some surface information... I also suspect, that the first image is not processed using C1 (which would have increased DR considerably), but rather an inadequate processing method that has been designed for general processing that has the masses of "photographers" in mind... Finally... moire on a B&W sensor is as rare as rain in the moon and in a true colour multishot is simply non existent... Also... the cases that moire is not the result of colour alising (which you correctly say is absent if BP is absent) are rare to the extent that they may be considered negligible.
 One more thing that is questionable is the phrase "the small pixel cameras all have superior readout circuitry that more than compensates for the pixel size." that you used... is that theory? ...Is comparing (years back of) different processing technology a criterion that one may use to prove his case? ...its not to me (and the most sensible thinking).

[ErikKaffehr]

Hi,

Just for your information, both images were pushed 4 stops in development.

Here is the actual page from the article: http://echophoto.dnsalias.net/ekr/index.php/photoarticles/80-my-mfd-journey-summing-up?start=1

Best regards
Erik

I hate to argue on theory... Larger pixels DO HAVE less read noise per area they cover and this is theory... (that's why the "LL champion cameras" have larger pixels). On the images that you posted, the second one isn't "brighter", its considerably duller (luck of contrast) and the HLs have been "blown" (which can't be an effect of flare - flare does decrease contrast but it doesn't blow HLs) while in the first one whites do hold some surface information... I also suspect, that the first image is not processed using C1 (which would have increased DR considerably), but rather an inadequate processing method that has been designed for general processing that has the masses of "photographers" in mind... Finally... moire on a B&W sensor is as rare as rain in the moon and in a true colour multishot is simply non existent... Also... the cases that moire is not the result of colour alising (which you correctly say is absent if BP is absent) are rare to the extent that they may be considered negligible.
 One more thing that is questionable is the phrase "the small pixel cameras all have superior readout circuitry that more than compensates for the pixel size." that you used... is that theory? ...Is comparing (years back of) different processing technology a criterion that one may use to prove his case? ...its not to me (and the most sensible thinking).

[Theodoros]

I still don't see why we need higher resolution sensors.... Is the proposal that the makers should increase per area read noise so that one may be able to print at 300ppi but with considerably more noise on the print?  Wouldn't a (same technology) sensor with considerably smaller pixels have much worst charasterics as far as read noise is concerned? Isn't "per pixel noise" more difficult to control the more the size of the pixel is compressed? Shouldn't we prefer that the makers solve the issues of artefacts that are present on todays pixel size before they proceed into making smaller pixels? 

[ErikKaffehr]

Hi,

Noise (shot noise) is not really affected by pixel size in print. Is the image is upsized the upsizing algorithm will distribute each image pixel over more printed pixels, if the image is downsized the downsizing algorithm will merge more pixels into a printed pixel. Upsizing  and downsizing algorithm have of course their own issues.

Aliasing artifacts like moiré and staircase effects are caused by large pixels. You get them any time the lens out-resolves the sensor. There are essentially three ways around this:

- Making the pixels smaller
- Stopping down so lens resolution is reduced
- Adding an OLP filter that reduces lens resolution

In practice, OLP filters are not strong enough to eliminate aliasing, it seems that their purpose is to reduce colour artefacts.

The screenshot below illustrates this pretty well:

- The A7 at 24 MP has most artefacts, although it has an OLP-filter
- The A7r has less artefacts than the A7 although it lacks OLP filter, but higher resolution reduces artefacts. Note that you can see fewer lines at the right side than in the image above
- The IQ 180 has even less artefacts, it probably outresolves the target.

This is also a well known aspect of signal processing, it is explained decently well in this video from Panavsion: https://www.youtube.com/watch?v=ht4Mv2wIRyQ

Best regards
Erik

I still don't see why we need higher resolution sensors.... Is the proposal that the makers should increase per area read noise so that one may be able to print at 300ppi but with considerably more noise on the print?  Wouldn't a (same technology) sensor with considerably smaller pixels have much worst charasterics as far as read noise is concerned? Isn't "per pixel noise" more difficult to control the more the size of the pixel is compressed? Shouldn't we prefer that the makers solve the issues of artefacts that are present on todays pixel size before they proceed into making smaller pixels?  

[Theodoros]

Hi,

Noise (shot noise) is not really affected by pixel size in print. Is the image is upsized the upsizing algorithm will distribute each image pixel over more printed pixels, if the image is downsized the downsizing algorithm will merge more pixels into a printed pixel. Upsizing  and downsizing algorithm have of course their own issues.

This is irrelevant to my post... No one says that noise is affected by pixel size in print... Printing (as well as sampling up or down in order to print at a certain size) is a method that also requires extensive skills which have to be adopted differently to the equipment used (an Epson requires different sampling than a Canon for instance). My post has to do with smaller pixels and the increased per image area noise that they inevitably have if compared with (same technology) larger sensors.

Aliasing artifacts like moiré and staircase effects are caused by large pixels. You get them any time the lens out-resolves the sensor. There are essentially three ways around this:

- Making the pixels smaller
- Stopping down so lens resolution is reduced
- Adding an OLP filter that reduces lens resolution

In practice, OLP filters are not strong enough to eliminate aliasing, it seems that their purpose is to reduce colour artefacts.

You don't get aliasing "every time the lens out resolves the sensor" as you say..., you need a repeated pattern at the right frequency for moire to exist, or cross talking between neighbouring pixels with different BP colour filtering for colour aliasing..
If the Bayer pattern was absent, you wouldn't get colour aliasing or moire at all... True colour sensors (either MS or Scanning backs) never present any colour aliasing or moire although the pixels are huge and the lens out resolves the sensor. In B&W sensors, there can be some moire (it is extremely rare though to the extend that it cannot be considered as an issue) with extremely high contrast patterns of specific frequency.

 The aliasing we get is not a consequence of Nyquist's theory of sampling rate, but because there is cross talk (due to the existence of Bayer pattern and the consecutive interpolation circuit) between pixels. Moire is dependent on a pattern's frequency but its the existence of Bayer pattern (again) that keeps the sensor's frequency low (more than the number of pixels).

EDIT: Moire is reduced with smaller pixels, but the size of pixels by itself cannot make moire disappear... All sensors that have Bayer pattern and colour is a result of interpolation will present moire at some times... Colour aliasing won't benefit though with smaller pixels... it's to the opposite actually.