Actually, we need even more resolution.

[eronald]

So these are not really photographs, they are waitographs

Edmund

Bernard, it's a little complicated, and all is not what it seems to be. I can explain.

The idea behind this series, which I call Timescapes, is one dimension of the image is distance, like a normal photograph, but the other dimension is time, quite unlike a normal photograph, but like the images from finish-line cameras at racetracks. I use a Betterlight Super 6K back on a Linhof Master Technica, and occasionally an Ebony field camera, which provides a delicious combination of old=tech and high-tech.

There is a rotating platform available for the Betterlight back that allows it to be used to make panoramas. When the camera software is in panorama mode, the sensor goes to the center of its travel and stays there, expecting the rotating platform to provide the scanning. In this mode, the back can make images of up to 6000x64000 pixels with no interpolation.

So how do I get the camera to make the Timescapes pictures? I lie to the software. I tell it that the camera is on a rotating platform, but it's firmly attached to the head of a normal tripod. Therefore, any changes visible in the picture that results are the result of subject motion. To get multiple exposures for stiching, I use the camera software's built-in intervalometer.

Now, about this image.

I have some succulents that my wife propagated from a cutting Don Worth (yes, that Don Worth; AA's assistant and, with Jack Welpott, creator of one of the great photography education programs) gave to me. The succulent was created by Don — it’s a hybrid of Echeveria Shaviana and Echeveria Subrigida, and it’s called Echeveria Afterglow.

Slit scans need some motion to rise above banality, and succulents are not known for their athleticism. I figured, if I can’t get the plant to move, I can at least get the light to change. In fact, since I’m taking the photographs in direct sunlight, I can’t get the light not to change. So I made a series of images with long exposures. When the slit was vertical, I had time run from right to left, and with the slit horizontal, time goes from top to bottom.

You can see more of the series here.

Jim

[Jim Kasson]

So these are not really photographs, they are waitographs

Edmund, like boiling a pot of water, if you hang around and wait, it takes a lot longer to make a succulent image this way. Same with the clouds and the sunsets. However, the wave exposures are five or ten minutes,  which is too short a time to go do something else, so they are truly wait-o-graphs.

Jim

[Theodoros]

So these are not really photographs, they are waitographs

Edmund

Many PHOTOgraphs are WAITographs... they are still PHOTOgraphs (among other photo-graphs).

[Paul Ozzello]

Hi,

The question posted is not my idea…, the OP wants one pixel resolution for each resolved pixel in the print.

On the other hand the numbers I posted take Bayer interpolation into account. I would also say they are a bit conservative. In experiments I have done there is a clear degradation of image quality once Airy disc diameter gets larger than pixel size, but the figures I give are for twice the pixel size.

The samples below were shot on a 4.77 micron sensor with an 100/2.8 Minolta Macro at f/5.6 resp f/8. The second row was sharpened in FocusMagic, letting FM choosing the sharpening radius.

5.6 micron Airy diameter	8.2 micron Airy diameter
5.6 micron Airy diameter + FocusMagic	8.2 micron Airy diameter + Focus Magic

I would add that I don't think there is anything wrong with the Bayer matrix. It requires an OLP filter to render colour detail correctly, but any point sampled system does require OLP filtering for proper rendition of luminousity.

Best regards
Erik

I keep hoping one day you'll mix it up and surprise us with a $2 bill

[Paul Ozzello]

6.8 microns	3.8 microns

Two images, same camera position and focal length. Which one do you prefer?

Or some road kill from the side of the autobahn...

[BernardLanguillier]

Bernard, it's a little complicated, and all is not what it seems to be. I can explain.

Thanks Jim, fascinating usage of the Betterlight!

Cheers,
Bernard

[Jim Kasson]

Thanks Jim, fascinating usage of the Betterlight!

Mike Collette calls this "intentional misuse".

Jim

[BernardLanguillier]

Mike Collette calls this "intentional misuse".

Yeah, I have seen that on their site.

I guess I need to use mine more. I like the color purity a lot, but looking at the files at 100% depresses me a little compared to those of the D810. I am just getting a much higher image quality much faster doing spherical stitching with the Nikon with top lenses. But then you have the fun of using movements,...

Cheers,
Bernard

[synn]

..."Gursky is overrated because he doesn't use enough ppis"...

No, Gursky is overrated because a ginormous print of an unexceptional frame is still unexceptional.

[ErikKaffehr]

Hi,

There are a few reasons for using a one Dollar bill.

One such reason is that it is widely available so any can take one up, shoot it adequately and reproduce my results. That is also the reason not to use a two Dollar bill, they are quite rare.

The other reason for using a bank note is that they have a lot of fine and hard to reproduce detail, in order to hinder counterfeiting. So they are a good test for proper reproduction.

The reason for using the feather is that I wanted to see if aliasing occurs on natural objects and if that aliasing can be mistaken for real detail.

The discussion here is about high resolution needed for large prints. So I feel the issues demonstrated here are relevant. The Dollar bill is used to demonstrate the effect of diffraction. The feather shows that smaller pixels reproduce fine regular structures better than large pixels.

None of this may be of interest to you if you are still shooting film, but may be of more interest if you shoot digital. Film doesn't have a regular structure like a digital sensor, so it does not alias for instance. Film is affected by diffraction, but large enlargement is needed to make it obvious, except in macro photography. But I have been very familiar with diffraction effects since the late seventies. So it is not a "digital era invention".

If you scan film, aliasing may still be of some interest to you. There is something called grain aliasing, scanning at low resolution can create large amounts of extra grain. So that is a reason to scan at high PPI.

Best regards
Erik

I keep hoping one day you'll mix it up and surprise us with a $2 bill

[orc73]

http://www.macrumors.com/2014/09/29/retina-imac-27-amd/

I did look at my files on a 27" 4k screen few weeks ago and 40mp became like an "ok" resolution


I don't know if this could be of relevance in this discussion.

[Torbjörn Tapani]

I think it is relevant. 8K broadcast is coming before long (Tokyo Olympics 2020) testing starting in 2016. You would need to upres a D800 file to fit the long side.

[Bart_van_der_Wolf]

I don't know if this could be of relevance in this discussion.

Hi,

It still depends on the viewing distance.

Human visual acuity limits visible resolution to approx. 1 arc minute, which translates to 286.48 PPI at a 1 foot viewing distance. The required output PPI is then determined by dividing the 286.48 PPI by the distance in feet. So viewing your 27'' Retina display from a distance of something like 16-18 inches should approximately match average visual resolution.

Of course, if you use Jerome's loupe, you'll just see larger LED pixels, not more resolution.

Cheers,
Bart

[Paul Ozzello]

Hi,

There are a few reasons for using a one Dollar bill.

One such reason is that it is widely available so any can take one up, shoot it adequately and reproduce my results. That is also the reason not to use a two Dollar bill, they are quite rare.

The other reason for using a bank note is that they have a lot of fine and hard to reproduce detail, in order to hinder counterfeiting. So they are a good test for proper reproduction.

The reason for using the feather is that I wanted to see if aliasing occurs on natural objects and if that aliasing can be mistaken for real detail.

The discussion here is about high resolution needed for large prints. So I feel the issues demonstrated here are relevant. The Dollar bill is used to demonstrate the effect of diffraction. The feather shows that smaller pixels reproduce fine regular structures better than large pixels.

None of this may be of interest to you if you are still shooting film, but may be of more interest if you shoot digital. Film doesn't have a regular structure like a digital sensor, so it does not alias for instance. Film is affected by diffraction, but large enlargement is needed to make it obvious, except in macro photography. But I have been very familiar with diffraction effects since the late seventies. So it is not a "digital era invention".

If you scan film, aliasing may still be of some interest to you. There is something called grain aliasing, scanning at low resolution can create large amounts of extra grain. So that is a reason to scan at high PPI.

Best regards
Erik

I was teasing you Erik...

[ErikKaffehr]

Hi,

I am quite clear about that.

But my strategy is to try to give an honest and decently relevant response to postings and also being trying to be a bit polite.

Best regards
Erik

I was teasing you Erik...

[ErikKaffehr]

Hi Bart,

Correct me if I am wrong, but the one minute of arc figure applies to high contrast detail. Maximum contrast sensivity is at much lower frequencies. So I feel that for normal subjects high contrast (MTF) at say 4 arcs of minute would dominate over low contrast at 1 arc of minute.

What I see is that images with low resolution but good sharpening can look pretty good. Another observation may be that it is easier to see the benefits of a high resolution in an image if it contains high frequency high contrast details, like a test chart.

Another way to see it may be that 180 PPI, properly upsized to printer native resolution and properly sharpened would be pretty impressive even if viewed at close by the unaided eye (which normally has maximum resolution at 25 cm viewing distance). Viewing with a loupe changes the game, but I would say that pixel peeping on screen is much more comfortable than studying a large print with a loupe.

Best regards
Erik

Hi,

It still depends on the viewing distance.

Human visual acuity limits visible resolution to approx. 1 arc minute, which translates to 286.48 PPI at a 1 foot viewing distance. The required output PPI is then determined by dividing the 286.48 PPI by the distance in feet. So viewing your 27'' Retina display from a distance of something like 16-18 inches should approximately match average visual resolution.

Of course, if you use Jerome's loupe, you'll just see larger LED pixels, not more resolution.

Cheers,
Bart

[EricWHiss]

>Within reason, that all sorts itself out: http://www.josephjamesphotography.com/equivalence/

Looks interesting, thanks for the link. 

>But your original question was about sensor getting bigger than they are, and they're already a bit under 56mm in the long dimension. I think they could get >a little bigger -- I'd sure like to see a 56mmx56mm sensor, but I don't expect to see 4x5 inch and 8x10inch sensors as standard photographic tools in my admittedly >limited prospective lifetime.

Yes I was thinking 6x6 square myself but also 4x5 though admittedly not much of a chance      to bad I can't just program it into the "matter compiler".   

I'm still of the opinion that the images from smaller cameras look flatter - as in lacking the perception of depth. Even the DSLR's, but then I haven't shot with an Otus or a costal optics lens.    I'm going to have a hard time believing that it all sorts out until I see it at myself.  There's a test waiting… same subject, same framing and DOF, but shot with every size format we can through at it.     

What happens when the pixel pitch goes like 10x finer - say fine enough to resolve diffraction effects and lens effects? Can any special math be applied in that case to improve IQ?

>Good luck with Rollei!

Thanks!

>Jim

[Bart_van_der_Wolf]

Hi Bart,

Correct me if I am wrong, but the one minute of arc figure applies to high contrast detail.

Hi Erik,

That's correct, it's a resolution limiting viewing distance, for average visual acuity. My visual acuity is a bit higher, and young people usually also have a higher visual acuity.

Maximum contrast sensivity is at much lower frequencies. So I feel that for normal subjects high contrast (MTF) at say 4 arcs of minute would dominate over low contrast at 1 arc of minute.

It's a bit more complex. It's true that the human Contrast Sensitivity Function (CSF) peaks at roughly 6-8 cycles/degree for luminosity, but it doesn't stop there, and it's also much flatter for chromaticity. It also varies with the average level of illuminance of our subject.

(see also here)

In addition, the Vernier resolution of our eyes is much higher than that for parallel features.

A properly output sharpened image can somewhat take advantage of all that, by by adding a boost of the contrast for higher spatial frequencies. A PS plugin such as Topaz Labs Detail can do that very effectively. That of course does assume normal viewing conditions, not people with magnifying glasses walking up to the output to do close inspection.

Cheers,
Bart

[ErikKaffehr]

Hi Bart,

More reading, thanks a lot!

I thought about mentioning vernier acuity, but decided to skip over it. My take is really that high resolution is beneficial, but may only visible in some cases.

The resolution trumpet in the test charts will show aliasing quite obviously, but it is nothing we would object to on normal images. For instance, I often see detail (strains) in animal fur that I don't think should be resolved. Another area may be areas in facial skin showing texture while surrounding areas in the same focus not showing texture. I would think that some of that texture are aliases of existing textures, but that is hard to say.

Best regards
Eri

(see also here)[/center]


In addition, the Vernier resolution of our eyes is much higher than that for parallel features.

A properly output sharpened image can somewhat take advantage of all that, by by adding a boost of the contrast for higher spatial frequencies. A PS plugin such as Topaz Labs Detail can do that very effectively. That of course does assume normal viewing conditions, not people with magnifying glasses walking up to the output to do close inspection.

Cheers,
Bart