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Optics Theory - This forum is aimed towards the TECHNICAL side of photographic OPTICS THEORY. There will be some overlap by camera/manufacturer, but this forum is for the heavy duty tech discussions. This is NOT the place to discuss a specific lens or lens line, do that in the appropriate forum. This is the forum to discuss optics or lenses in general, to learn about the tech behind the lenses and images. IF you have a question about a specific lens, post it in the forum about that type of camera, NOT HERE.

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Old 11-20-2013   #41
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Nice work in the analysis. Of course, you only touched on large format. To me, film has fantastic resolution, as do sensors. If you don't enlarge either, great! But we enlarge both many, many times from where they started. Not with LF contact prints or direct postitives. If I want the sharpest print, say, at 8x10, I use an 8x10 negative and contact print.
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Old 11-20-2013   #42
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Originally Posted by RichC View Post
. . . ● @ Roger Hicks. I feel you are being too dismissive, despite using the phrase "more rigorous". I have been careful to base my initial calculations on sound theory and measurements from reliable sources (tests by Kodak and DPreview using the standard resolution charts). The later calculations do use estimates, but are most certainly not "wishful thinking", and although not precise are reasonable "ball park" values. My working is clear, so if you disagree with these estimates, feel free to substitute your own values. . . .
Sorry. That was the exact opposite of my intention, and I certainly did not wish to accuse you of wishful thinking. I just thought it rather interesting that your carefully stated assumptions and calculations came out at about the middle of others' calculations (many of which are, as you correctly say, much less rigorous than yours) and of empirical tests -- which rather suggests to me that (a) you and they are about right and (b) the advantages of further testing are limited. I am grateful that you confirmed what I had long suspected was the case, but as I say, it's all pretty much converged on the sort of figures you give, give or take a factor of two. EDIT: Well +/-50%, more likely.

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Old 11-20-2013   #43
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Originally Posted by Jason Sprenger View Post
FWIW, here's a link to Norman Koren's thoughts along the same lines from back when the Canon 5D was state of the art.

http://www.normankoren.com/Tutorials/MTF7.html

For myself, while my film scanner captures 4000dpi, I'm under no delusion that 4000 dpi are actually there.

So, we have to be specific here.

You can scan all day at 4000 dpi and in the scanned image you will get the appropriate number of dpi^2 in your image from the scan. There will be the 4000dpi there guaranteed.

Now, would this be an interpolated value because the native resolution of the scanner is lower? That's a different story.

Would there be a one to one correlation of scanned pixels to the grain? That's another story.

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Old 11-20-2013   #44
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What none of these web comparisons addresses is the need to consider bottlenecks in equipment that impact the theoretical resolution of film – i.e. lens resolution and scanner resolution (assuming images will be scanned). Consider a typical scan of 35 mm film at a scanner resolution of 2700 ppi: the resulting file has dimensions of about 3800 × 2400 pixels = 9 MP – but this is not equivalent to a 9 MP image from a digital camera because both are theoretical values based solely on the number of pixels, and fail to account for differences in resolving power between the two mediums. Comparing, say, a 20 MP film scan with a 20 MP digital camera image is thus comparing apples with oranges. What we actually need to compare is the resolving power of frame of film and a digital sensor.

Just comparing two different 20MP digital cameras is a flawed concept in and of itself. You have a lot of factors there...lens, size of photoreceptors, pixel density, method of color interpretation (Bayer, etc) as well as others I am too lazy to look up. Either way, you really need to stick with lines per measurement of the sensor in order to be correct here.

In your case, we are comparing 20MP scanner vs a 20MP camera image. That's complicating matters in that a certain scanner will interpret the scene differently than the camera. You are greatly

In order to do an experiment correctly:

+ Scene must be photographed the exact same way.
+ Sensor must interpret light the same way.
+ Film scanner must interpret that film the same was as the digital camera interprets the light from the scene.
+ Film must be developed to get the most perfect result as close to the theoretical limit of the film as possible
+ Same lens with no post processing by the internals

Food for thought....how can you reduce the variability?
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Old 11-20-2013   #45
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...<SNIP> Also you seem to forget (or be unaware) that the megapixel count of a camera is not a measure of it's resolution, that would be it's pixel density and size.
Further to that a 12mp sensor can't resolve 12mp of detail with a Bayer sensor at best you get 6mp green, 3mp Red and 3mp Blue the output being mathematically calculated from a grid sample.

Film doesn't work like that it has RGB records but has them stacked and randomised, no digital camera has that (foveon is stacked but gridded).

Awesome...and further, how does this compare to how the scanner sees the film and how the film records the scene?

Starting from a digital image is one thing, but starting from an analog image of the scene with a bunch of quantization errors and non-linearity thrown in is another.
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Old 11-20-2013   #46
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I think most of your logic is flawed. Some glaring mistakes you might want to look into is the role of diffraction, and calculating the differences in diffraction over different formats and even different sensors (pixel size) and how they change data.
For instance a 6x7 film with standard lens won't become diffraction limited until after ƒ22 given a 12" wide print.
I disagree... This is only true if aiming to make prints of the same size from all formats. As I've stated, I'm not interested in print size here, just the amount of information recorded on a negative or by a sensor.

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Also you seem to forget (or be unaware) that the megapixel count of a camera is not a measure of it's resolution, that would be it's pixel density and size.
Which is precisely what I said. If you go to, say, Nikon's website, they talk about "a resolution of 36 MP" for the Nikon D800 - so, for better or worse, "resolution" is now used to mean "number of pixels". To reiterate, I am not using it in this sense.

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Further to that a 12mp sensor can't resolve 12mp of detail with a Bayer sensor.
Of course it can't - I state that too! This is precisely why I use measured resolving powers (in lp/mm) from actual real-world tests. These values tell us how exactly how much detail is resolved (assuming the test results are trustworthy).

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I don't know where you get the figure of 80% degradation with drum scans, or the idea that film needs to be scanned.
A scanner is an optical system with a lens, sensor, etc., and as another link in the imaging system it will inevitably lead to loss of data. How did I get 80%? The resolving power of a drum scanner is about 90 lp/mm (measured - Google for confirmation). To work out the loss in resolving power, the resolutions of film and the scanner are combined. The following formula is empirical (i.e. it closely matches experimental results but is not based on theory):

1/R = 1/√[(1/f)² + (1/s)²]

where R is the resolution of the scan (not the scanner), f is that of film (70 lp/mm) and s is that of the scanner (90 lp/mm). Plugging in these values gives

1/R = 1/0.0173
R ~ 55 lp/mm

So, scan resolution = 55/70 = 80% that of film.

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I don't know where you get the idea that film needs to be scanned.
Of course you don't have to scan colour film - if you don't, ignore that step. Most people do scan today, and I certainly do. In fact, I can't imagine where I can get large (> 20 inch) colour darkroom prints today, and dread to think of the price!

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If we output to print what effect does mathematical dithering have on inkjets?
Which is why I barely touched on printing. As the post stated, I primarily wanted to know how much detail film captures compared with digital - ending up with a digital image file, not a print. I'm not dismissing printing - it's important to me, and I always print my photographs, aiming to get prints on gallery walls. But printing is irrelevant to my calculations .

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So many basic errors, mis-calculations and false assumptions in your OP that really I don't know where to start.
By reading my post more carefully...?
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Old 11-20-2013   #47
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I moved this thread into optical theory and placed a sticky on it because I think this issue and discussion is important.

To all the naysaysers which disagree, fine. This is a discussion forum.

However, taking partial potshots of his methods without offering a better overall view is not really all useful or helpful. Neither does it make your own arguments convincing since they are not assembled in a complete form as the OP did.

So, for those of you who think you can do a better job on this subject, let's see you post something better covering all the points which Rich does (and more) that works better !

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Old 11-21-2013   #48
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Originally Posted by RichC View Post
I disagree... This is only true if aiming to make prints of the same size from all formats. As I've stated, I'm not interested in print size here, just the amount of information recorded on a negative or by a sensor.
If you're not interested in printing then fine but that still doesn't change the fact that you can't approximate the diffraction of 4x5 by adding a 3x multiplier because the focal length is 3x.
Diffraction is one of the min causes of degradation of the image in other words the spread function of the light.
It is dependant on the size of your output though so I'm not sure how you are going to duck out of that one.
Simple fact diffraction will act like a blurring filter over your sensor/film and will greatly lower your 'theoretical' lp/mm figure.

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Originally Posted by RichC View Post
Which is precisely what I said. If you go to, say, Nikon's website, they talk about "a resolution of 36 MP" for the Nikon D800 - so, for better or worse, "resolution" is now used to mean "number of pixels". To reiterate, I am not using it in this sense.
If we are talking science then what Nikon say in their literature is not worthy of discussion.

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Originally Posted by RichC View Post
Of course it can't - I state that too! This is precisely why I use measured resolving powers (in lp/mm) from actual real-world tests. These values tell us how exactly how much detail is resolved (assuming the test results are trustworthy).
Sure, I'm more pointing out when you say the D800E has xx resolution it doesn't-just clarification.

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Originally Posted by RichC View Post
A scanner is an optical system with a lens, sensor, etc., and as another link in the imaging system it will inevitably lead to loss of data. How did I get 80%? The resolving power of a drum scanner is about 90 lp/mm (measured - Google for confirmation). To work out the loss in resolving power, the resolutions of film and the scanner are combined. The following formula is empirical (i.e. it closely matches experimental results but is not based on theory):

1/R = 1/√[(1/f)² + (1/s)²]

where R is the resolution of the scan (not the scanner), f is that of film (70 lp/mm) and s is that of the scanner (90 lp/mm). Plugging in these values gives

1/R = 1/0.0173
R ~ 55 lp/mm

So, scan resolution = 55/70 = 80% that of film.
You might like to look at your figures again if you think a drum scanner tops out at 80 lpm I think and I'll have to find out it depends on the aperture of the scan it can resolve grain and further to that I'm not sure of your maths either.

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Originally Posted by RichC View Post
Of course you don't have to scan colour film - if you don't, ignore that step. Most people do scan today, and I certainly do. In fact, I can't imagine where I can get large (> 20 inch) colour darkroom prints today, and dread to think of the price!
When arguing the ultimate difference in resolution of two systems you need to think about those systems as a whole, price shouldn't come into it!
Since we are talking about resolution I presumed (falsely) that that resolution would have a purpose-large display.

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Originally Posted by RichC View Post
Which is why I barely touched on printing. As the post stated, I primarily wanted to know how much detail film captures compared with digital - ending up with a digital image file, not a print. I'm not dismissing printing - it's important to me, and I always print my photographs, aiming to get prints on gallery walls. But printing is irrelevant to my calculations .

By reading my post more carefully...?
I read your post, possibly I didn't understand it certainly I don't understand why you would need resolution if it's not for large display?
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Old 11-21-2013   #49
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If you're not interested in printing then fine but that still doesn't change the fact that you can't approximate the diffraction of 4x5 by adding a 3x multiplier ...

I read your post ... I don't understand why you would need resolution if it's not for large display?
I'll look into diffraction in lenses more carefully.

My original post arose from a recent project. As I've mentioned, I shoot with a Nikon D800E and a Mamiya 645. I regularly make 30-36 inch prints with the Nikon, and that's about the maximum without the print looking slightly soft seen very close up. The Mamiya is new to me - more convenient and cheaper to shoot than my 4x5 camera - and I wanted to compare the resolution of 645 with the 36 MP Nikon, to have some idea how large I can print 645 from scans. So, I sort of had a print size in mind, but it was more useful for me to directly compare cameras - the 645 with my Nikon D800E - in terms of megapixels than find out the maximum "sharp" print size of 645.

I couldn't find an answer on the web - you might find my approach flawed but some of those on the web are beyond hope! Hence my attempt at more rigour.

Film is fairly new to me - I'm used to digital cameras and megapixels; my first "proper" camera was digital, not film. (Hey, at least I'm using film now!) So, to get my head round film, I need to think in terms of digital - for example, I have a very good idea of how large I can print a file from a digital camera if I know its sensor size and "resolution" in megapixels, but am still a bit lost with maximum film print sizes. But not now I've calculated the megapixel equivalents of film formats, assuming my values are about right.

My calculation that 645 colour film and a 36 MP full-frame sensor have similar real-world resolving power has since been born out in practice: my test scans on an Imacon Flextight and Nikon files have similar detail seen on-screen. The Nikon images are a little sharper with a bit more detail, but the Imacon isn't as good as a drum scanner, and film also has grain, which makes the Nikon images look cleaner, but not necessarily better - if I'm printing digital camera images large, I always add a little noise, otherwise I feel the prints look a bit "clinical". Ironically, I use a Photoshop plugin that replicates film grain to add this noise, which is barely visible in the print but still has a tangible effect on its perception (at least to my eye)!
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Old 11-21-2013   #50
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Originally Posted by Bille View Post
Not sure if I understand this post correctly...

There is a theoretical advantage in resolution of ISO100 35mm film over a 21MP full frame digital sensor. This will turn into a real world advantage only if the film camera is perfectly calibrated, shot from a tripod with a good lens stopped down, only with access to a high end drum scanner in post processing.

Wouldn“t it be easier to just chose a D800E or Sony A7R if your photography requires max resolution? (Not even talking about medium format digital...)

By the way, what happens at ISO 200?
I think that's a fair summary of the thread.

However (!)

The thing with film is that you can increase it's size without any great increase in cost, when it comes to cameras. My Leica M3 (sold now), Rolleiflex, and Fotoman 45SPS all cost roughly the same. Cost per shot of course changes, but film is not bound by cost of camera in the way digital is.

So I can shoot 4x5 on a (brand new) camera which costs less than new FF digital, let alone medium format digital.

If you want resolution at any cost, by all means use a Phase One IQ180 (or better it with 8x10 film). But most of us are bound by cost to a point, and for me, medium format film makes a lot more sense than a pricey digital equivalent.
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Old 11-21-2013   #51
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I have most of the books and papers and can publish some info. The studies you mention are the ones by Jones and Zwick where they used microfilm to resolve text down to 2µm high
This is from the paper–


I don't want to publish too much...

If the OP wants know the resolution each system is capable of he'll need to work out the losses from each part of the image chain.
If he does factor in the camera/lens/format/film type/scanner/output/viewing distance etc he'll get different results.

The only way to measure the capabilities of film itself is to count line pairs by microscope, which would be more valid for slide film that could be looked at under a loupe, but then that ignores the viewing medium projector/paper/monitor.

Taking others figures then extrapolating results without verification is fuzzy at best and not going to allow you to arrive at anything more than an VERY rough estimate.

It isn;t possible to get an absolute from a mess of estimated data.
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Old 11-21-2013   #52
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Quote:
Originally Posted by RichC View Post
I'll look into diffraction in lenses more carefully.

My original post arose from a recent project. As I've mentioned, I shoot with a Nikon D800E and a Mamiya 645. I regularly make 30-36 inch prints with the Nikon, and that's about the maximum without the print looking slightly soft seen very close up. The Mamiya is new to me - more convenient and cheaper to shoot than my 4x5 camera - and I wanted to compare the resolution of 645 with the 36 MP Nikon, to have some idea how large I can print 645 from scans. So, I sort of had a print size in mind, but it was more useful for me to directly compare cameras - the 645 with my Nikon D800E - in terms of megapixels than find out the maximum "sharp" print size of 645.

I couldn't find an answer on the web - you might find my approach flawed but some of those on the web are beyond hope! Hence my attempt at more rigour.

Film is fairly new to me - I'm used to digital cameras and megapixels; my first "proper" camera was digital, not film. (Hey, at least I'm using film now!) So, to get my head round film, I need to think in terms of digital - for example, I have a very good idea of how large I can print a file from a digital camera if I know its sensor size and "resolution" in megapixels, but am still a bit lost with maximum film print sizes. But not now I've calculated the megapixel equivalents of film formats, assuming my values are about right.

My calculation that 645 colour film and a 36 MP full-frame sensor have similar real-world resolving power has since been born out in practice: my test scans on an Imacon Flextight and Nikon files have similar detail seen on-screen. The Nikon images are a little sharper with a bit more detail, but the Imacon isn't as good as a drum scanner, and film also has grain, which makes the Nikon images look cleaner, but not necessarily better - if I'm printing digital camera images large, I always add a little noise, otherwise I feel the prints look a bit "clinical". Ironically, I use a Photoshop plugin that replicates film grain to add this noise, which is barely visible in the print but still has a tangible effect on its perception (at least to my eye)!
Ok this would have made a much better OP because it lays out your requirements with real world issues and things you've personally noted.

The resolution of any system is a chain, of which no part can be ignored.

The issue has no real definitive answer, certainly not on the internet, what you have noticed though is the differences in character between film and digital film looks sharper even with more grain, digital smooths and has better edge detail in some cases.
Viewing distance matters too, most people don't have 20/20 vision (text on a eye chart 20 feet away 480 lux lighting) Kodak have their nice PGI with a figure of 25 being no detectable grain.

The resolving power of any given film varies with contrast and colour, you may not be aware that magenta subjects will have less resolution than blue and the red/cyan layer being at the bottom is less able to record fine detail due to light spreading as it travels down.
The magenta layer has the most noise and the red the least acutance so that make our estimate of resolution somewhat subject dependent.
It's similar with digital where it has more green pixels.

I pick a print size, I top out at 20x16 so 6x7 with 100 ISO film like Ektar is fine, but Ektar isn't the sharpest 100 ISO that would probably be Velvia.

If film is new to you try some 100 ISO Fuji E6 and some Ektar scan them and see if you like it at the print size you require, move up a format to 6x7 if you need (I think 645 is too small for 30" prints)

The Imacon is a nice scanner and probably good enough for most but it isn't s drum scanner whatever Hasselblad tell you.

If not use digital and add in noise to your requirements...
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Old 11-21-2013   #53
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Taking others figures then extrapolating results without verification is fuzzy at best and not going to allow you to arrive at anything more than an VERY rough estimate.

It isn;t possible to get an absolute from a mess of estimated data.
No argument from me!

The point was not to get precise values but ballpark figures of the correct order of magnitude. Simply to be able to say that a 645 camera with low-grain colour negative film approximates an 35-45 MP digital camera, for example, or that a 20 MP dSLR gives similar results to a 35 mm camera loaded with the aforementioned film.

My results are a starting point, not an end point. They give me an idea of which film format I need to use if I want to make 40 inch prints, say (645 OK if viewer is at a sensible viewing distance, but 6x7 will be perfect if the prints need to be sharp close up - if "massaged" in Photoshop (adjust contrast, sharpness, etc., to taste).

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The Imacon is a nice scanner and probably good enough for most but it isn't s drum scanner whatever Hasselblad tell you...
No. But it's what the university has, and drum scans aren't cheap or always necessary - there's no point aiming for high resolution if it's not needed.

I prefer the look of film - Portra has subtle colour that I cannot replicate with a digital camera, with more delicate tones, and exposure is more forgiving. But digital is faster, and cheaper (once you've paid for the camera!), and has the appearance of being sharper. I think large film prints look better than large digital prints, but the smaller the print, the more similar. I'll continue to use both formats, depending on the needs of each photography project.
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Last edited by RichC : 11-21-2013 at 03:52. Reason: Our posts crossed!
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Old 11-21-2013   #54
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While we're at it, no one has yet conclusively answered Descartes' equally worthy query:
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How many angels can dance on the head of a pin?
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Old 04-24-2014   #55
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You may wish to consult the recently March 2014 updated film vs digital scientific analysis by an imminent imaging/computer expert at this link:

Last Updated: Mon Mar 3 17:53:33 UTC 2014

Some Observations on Digital vs Wet Film Photography


Dr Carlo Kopp, MIEEE, SMAIAA, PEng
Text, Images © 2010, Carlo Kopp



http://www.csse.monash.edu.au/~carlo...-patterns.html

He lists EKTAR 100 at 154 lp/mm (High contrast).

He also shows normalized MTF curves for various films and discusses the results showing photographic comparisons to illustrate Bayer mosaic/scanner limitations.

His conclusion is that wet film resolution is in fact comparable to the highest digital sensor results—especially when medium format color is selected.

Oil immersion Wet Drum Scanning

A key omission from the extant discussions (Including the above example) is the positive effects of wet drum scanning in reducing scattered light from the negative/transparency original. Often the illuminating scanner's scatter degrades the final file by adding what appears to be veiling, white noise. This scatter is eliminated by fluid immersion strategies.

Though expensive, the wet drum scan process looks perhaps to be the best candidate for those hoping to extract all that their film can offer—especially with EKTAR.

Ideally two camera bodies, one with advanced transparency and the other with advanced color negative film (EKTAR) might be the very best strategy to capture varying dynamic range scenes.

A Photograph Isn't a File...

Finally, a photograph (IMO) isn't a file. It's rightfully an object, optimally with a gelatin media and archival substrate. It's features offer album storage and convenient display that eliminate electricity as a viewing requirement.

A true photograph can properly be with you at all times and its parent negative/transparency. Here, I discount inkjet printers as a poor facsimile to the real thing.
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Old 03-10-2015   #56
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Now this is an interesting post, some really food for thought here, thanks for taking the time to write and share with us. Much appreciated.
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Old 03-10-2015   #57
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Impressive, That was a great essay. One thing that came to my mind was how the final print is made: digital screen, digital printer, analogue printer, or my favorite at this time digital file to laser exposure of photographic paper. A properly or even not so properly done Silver Gelatin print is wonderful, but for me I don't have a darkroom any more so I send my files to Costco and they print on photographic as does Mpix on true B&W paper. These two methods analogue prints and laser printing on photographic paper give the best results in my opinion. I know that digital printers have made great advances but still to me don't look as good as either of the above. So, even though the argument of digital vs film is still alive, my final print is what I look at and how I judge everything that came before it.
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Tim Parkin article
Old 03-12-2015   #58
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Tim Parkin article

Here is a very interesting article on film vs digital resolution written by Tim Parkin for the internet magazine "On Landscape". I find this article quite illuminating, maybe because it includes more images than mathematics/physics...

https://www.onlandscape.co.uk/2014/1...vs-6x7-velvia/
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Old 03-12-2015   #59
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If you want resolution, then subscribe to Hubble.
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Old 03-12-2015   #60
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Wow, that is a ton of homework in the first post. Great work.

I speak from a layman point of view, where I think for "regular joe's", printing from these digital files will not yield much difference at small sizes. We would have to print really large to notice the subtle differences.

I doubt I can tell the difference from a 8R print of a D800 versus a D3.
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Old 03-12-2015   #61
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ah okay i fell for this trap, it's an old thread :P
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What Shutter Type Most Accurate Record of Image
Old 06-01-2015   #62
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What Shutter Type Most Accurate Record of Image

Focal plane shutters move accross the plane and copals open and close somewhat like an iris. some others exist like Minolta Minolina P's. What part of the image is recorded first and last? With shutters moving at 1/8000 of a second compared to 1/60 a lot can change during the exposure in the latter that does not in the former - there is not much discussion about this here.
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Old 06-01-2015   #63
Bill Clark
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Well, this has been my experiences.

In summary, usually the largest enlargement I make with 35mm B&W film is 8 by 10. I have rarely made a few 11 by 14. That's in inches! Same with slides. Medium format I have made pretty good 16 by 20 enlargements.

I have a Canon digital DSLR and have made 40 by 30 inch prints. Try doing that with 35mm film, any type.

Thanks for your information. Appreciate your effort for analysis.
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Old 06-01-2015   #64
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Quote:
Originally Posted by Bill Clark View Post
In summary, usually the largest enlargement I make with 35mm B&W film is 8 by 10. I have rarely made a few 11 by 14. That's in inches! Same with slides. Medium format I have made pretty good 16 by 20 enlargements.

I have a Canon digital DSLR, one which is the monster sized, and have made 40 by 30 inch prints. Try doing that with 35mm film, any type.
I've had good luck doing occasional 13x19 prints from 35mm color. I have one very stunning 13x19 print of the Chicago River that I did using Walgreens rebranded Agfa scanned at max res on the K-M SD 4.

I have another very nice night shot at 13x19 done on Fuji 800, same scan but cleaned up a bit in Neat Image.
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Old 06-04-2015   #65
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I rather expected this when I started researching an upgrade from digital and realized the advantages of film. But now I have to wonder if I still want to make optical paper prints, or go K7 with a good printer. Not sure I am ready to even think about laser-scanning photo paper...

So much for sleeping tonight, dammit!
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Old 06-21-2015   #66
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Quote:
Originally Posted by Bill Clark View Post
I have a Canon digital DSLR and have made 40 by 30 inch prints. Try doing that with 35mm film, any type.
I still recall seeing a poster that Canon sent to its dealers some 25 years ago, hyping the abilities of its 85mm f/1.2L. I was struck by the detail and the very low level of grain. It really looked like a large format image, but it was taken with an EOS 35mm. And this was a 20" x 30" poster, at least.

Another example of 35mm's capabilities. I was at a camera show one day -- this was also about 25 years ago -- and one of the dealers who was a good friend of mine walked up to me and handed me two 8x10 B&W glossies. They were both photos of the same subject -- a small, country church with clapboard sides and a steeple. He asked me if I could tell which was shot with a 4x5 and which was shot with a 35mm. I examined them briefly and then correctly indicated which was which. He asked how I told the difference. "The grain," I said. The 35mm image's grain was more pronounced, otherwise the detail in the two images was equivalent. I asked him about the cameras he used. I don't recall which 4x5 it was anymore, but the 35mm was a Leica IIIg with a 50mm f/3.5 Elmar.

So what I'm getting at is, with a 35mm camera and the right lens and film, it is definitely possible to get image quality bordering on that of a large format camera/lens.

BTW, I found the OP's opening comments very interesting. I had derived the first formula he gave for determining the theoretical resolution capability of a given type of film in megapixels some 15 years ago, but I found his additional discussions to be very informative. They were helpful in explaining to me why it is that I can't get digital like quality from fine grained slides that one would think shouldl compare favorably to even relatively modest megapixel output cameras. In my own tests, however, I've found that often the limiting resolution factor with film is the grain.
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Old 06-22-2015   #67
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I shoot a lot of film formats, from 35mm to 11x14 and most in between. And quite a bit of digital. Resolution is not what I'm trying to get out of Large Format, though it's very readily there. For me with LF it's tones, dynamic range, and the look of the lens aberrations, perspective, depth of field.

35mm is pretty disappointing if you are chasing resolution, compared to a 5x7 or 8x10 contact print. The advantage of 35mm is portability and rapid shooting, same as digital. I find it funny that we try to get ultimate sharpness out of tiny lenses, blowing up a postage stamp sized negative many times in a print or on screen. Whereas some LF shooters take an inherently sharp system, and enjoy the softness and tones.

Here is a 6 1/2 X 8 1/2 negative contact print I made yesterday, from a 1909 Cooke lens.

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Old 06-22-2015   #68
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Nice photograph Garrett!
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Old 06-22-2015   #69
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Very high quality results are possible, but you better be using the best film, an excellent lens, and a tripod with 35 mm. There is no room for error.

In the linked thread I recently posted a Velvia 100f 35mm slide scanned with an em-5 mark ii in 40 mp mode. There are gobs of detail present and I needed all 40 mp. Soon as I get a chance I will re-scan this photo and others at 1:2 (double) resolution to see where that gets me.

http://www.rangefinderforum.com/foru...d.php?t=149510
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Old 06-22-2015   #70
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Thanks.
You should see 4x5 or 5x7 Velvia! It's like a stained glass window in a chapel in France, when held up to the light. Fantastic for scanning. But yes, this is a 35mm forum, so I'll stop.
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Old 01-28-2016   #71
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I enjoyed Rich's theoretical treatment and the discussion about film vs digital!

Every theory needs to be tested for validity against experimental data. So let's do this! I took the same picture of a park in plenty of light with a digital and analogue camera, using the exact same lens and a heavy Gitzo tripod.
  • Nikon D600 (full-frame 24 Mpixel sensor) + Nikon AI-S 50mm f/1.4, stopped down to f/8.
  • Nikon FE2 with Ilford FP4 (ISO 100) + Nikon AI-S 50mm f/1.4, stopped down to f/8.

I then converted the 24 Mpix digital image to monochrome for comparison with the FP4 b/w film. Otherwise, the picture is completely untouched and I made no changes in Photoshop. The FP4 negative was scanned with a Plustek 8100 film scanner at 5,000 dpi. The result from the scan is a 66 Mbytes 16-bit TIF vector file which is equivalent to a 33 Mpixel JPG file (6888x4788 pixels, 8 bit). I'm therefore oversampling any information that is in the negative. Below are low-res versions of the two images (no cropping).

Next, I decreased the resolution of the original full-frame 24 Mpixel digital file to 16 Mpixel, 12 Mpixel, and 8 Mpixel so we can compare them to the scanned full-res FP4 analogue picture. I then picked a region at the column of the statue in the park (marked by a red box) where you can see a street sign in the background. The street sign says: "Capitol St NE 1100." Below are crops from these files so we can compare them. The upper row gives crops of the full-frame 24 Mpix, 16 Mpix, 12 Mpix and 8 Mpix digital images. In the lower row you see the same crop of the full-res scanned FP4 analogue image 4 times for ease of comparison with the digital images above. Let's have a look what we see in the crops:
  • 24 Mpixel digital image: the street sign is super sharp; no pixels are visible even at this high zoom level.
  • 16 Mpixel digital image: the street sign is still sharp; you start to see pixels.
  • 12 Mpixel digital image: the street sign is still legible; pixels become prominent.
  • 8 Mpixel digital image: unable to read the street sign, heavy pixelation.
  • FP4 analogue image: you can barely read the street sign due to the low resolving power of the film. In terms of the amount of information that is stored in the analogue film, it is similar to the 8 Mpix digital file (you can barely read "Capitol 1100", but not "St NE"). However, in terms of overall appearance, the analogue film is somewhere between the 12 Mpix and the 16 Mpix digital image. Now, this is hard to quantify because our eyes and the brain that interprets the information are analog "image processing" organs and favor analogue information (such as film) over digital. I'd argue that you could enlarge a film image to a larger size than a digital image that has stored the same amount of information as the analogue film image because our brain prefers a bit of blurriness over pixelation.

Caveats: you might criticize that I used a film scanner (Plustek 8100) that is not on par with professional drum scanners. However, I have had negatives scanned on a drum scanner by Northcoast in "enhanced scan mode" (3339x5036 pixels) and believe that my scans are of higher quality. But to be fair, if you'd find the perfect film/developer combination to reduce grain as much as you can, and used a high-quality drum scanner, you might be able to push the results a bit further than I did.

My conclusion from this experiment is:

A 35mm ISO 100 analogue film image stores the same amount of information as an 8 Mpix digital image.
In terms of overall appearance and quality, a 35mm ISO 100 analogue film image is equivalent to a 16 Mpix digital image.


Coming back to Rich's analysis, you did a great job and my experiment shows that you overestimated the quality of film by only 25% (20 Mpix vs 16 Mpix).

Looking forward to your comments!





(click on the above image to enlarge)
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Old 01-28-2016   #72
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Quote:
Originally Posted by gnuyork View Post
...
I was able to enlarge scans of 35mm slide film to nearly four feet wide and have a good usable print, albeit not as sharp as smaller prints, but I was surprised how well they held up. ...

There's no way I could do this with the 5DmkII images, or even the D800 for that matter. ...
Perhaps you can't, but I can and do on a daily basis (there's a 29x44" print printing at the moment). I regularly print images this large and larger from both 35mm film scans (typically Velvia and Velvia 50 scanned with an Imacon scanner) and digital images (most from a D800). As a general rule, the D800 images appear a bit sharper* and are always smoother (lower noise, ...).

* sharpness - Sharpness doesn't exist in the real world. It is a figment of the viewer's imagination that is a computer (read: brain) generated impression based on a range of attributes including, but not limited to, resolution, luminance contrast, and color contrast.
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Old 01-28-2016   #73
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Dwig is right: A D800 has 7300 x 4912 pixel. If you blow such an image up to four feet wide, you'd get 10 pixel per millimeter (linear), which would look very sharp, even if the printer doesn't interpolate.
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Old 01-28-2016   #74
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* sharpness - Sharpness doesn't exist in the real world. It is a figment of the viewer's imagination that is a computer (read: brain) generated impression based on a range of attributes including, but not limited to, resolution, luminance contrast, and color contrast.
sharp·ness
/ˈSHärpnəs/
noun
the quality or state of being sharp.
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Old 01-28-2016   #75
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Rich,

Thank-you for posting and starting this discussion. From time to time I've seen other posts around internet about resolving power of film vs digital etc. but never really understood it, & often got further confused, so I appreciate your work on this.

Given my understanding of optical theory is pretty limited, may I ask how the equation R = 4r^2hw/10^6 is derived? (Is there an online source you can point me to, so that I can do some background reading....?) -- thanks
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Old 01-28-2016   #76
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Quote:
Originally Posted by RichC View Post
So, no replies - presumably, then, you all agree with me!

No, it's just that we're all out here trying to remember when was the last time we saw algebraic formulas and level 2 section headings in a forum post.

Nice post, you obviously put some good work into it.

I'll tell you what, though: While you guys are in here pondering this stuff, I'm going to put some hot coffee in a spillproof mug and go make some photos. D810 in one hand, M7 in the other.

Good luck.
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Old 01-28-2016   #77
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D810 in one hand, M7 in the other.
How do you hold your coffee mug?
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Old 01-28-2016   #78
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Just discovered this great exposition by Rich from a couple years ago.

@giganova, thanks for the fabulous entry today. I love real world comparisons.

Quote:
Originally Posted by giganova View Post
I then converted the 24 Mpix digital image to monochrome for comparison with the FP4 b/w film. Otherwise, the picture is completely untouched and I made no changes in Photoshop.
Just a small nit: The camera algorithms and/or/ the RAW conversion have done some manipulation of the image. So it's not completely unprocessed.

A more substantive comment:
- Digital responds to increasing spatial frequency quite flat until it falls apart completely. That is, digital maintains higher contrast until it dies.
- Film gradually loses contrast as spatial frequency increases. Thereby, film can maintain some contrast in very detailed areas, where digital lost it completely.

My own experiments:
- Shooting digital vs. Fuji 200 C-41 film. Scanned Coolscan V, 4000 ppi.
- 6 MPx digital was comparable to film, cleaner image, not quite same resolution
- Today, 24MPx digital is way better than I can get in 35mm film

Here's my comparison, 100% actual pixels:

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Old 01-28-2016   #79
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Good points, Colonel!

Quote:
Originally Posted by ColSebastianMoran View Post
Film gradually loses contrast as spatial frequency increases. Thereby, film can maintain some contrast in very detailed areas, where digital lost it completely.
Is this what you are referring to?

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Old 01-28-2016   #80
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I just have seen this thread today. Thanks for reviving it.

It always interesting to read those comparisons and yours is surely one of the more scientific ones. But the problem with them is that they are merely theoretical, because film and sensors work in different ways. Thus they cannot really be compared objectively. What we can do is to use our equipment and see which one offers us a "better" (= "higher") resolution effectively. And as you have pointed out there is a long chain of influences. Who of us has a drum scanner?

And to be honest, I don't even care if film or sensors show a higher resolution. The only question that everybody has to answer on a very personal level is: Is that good enough for me, my needs and for what I expect?

For me it goes like this:

ISO 200 color neg film 135, exposed in a good cam and decent lens, flatbed neg scan = good enough!

ISO 400 b/w neg film 135, exposed in a good cam and decent lens, flatbed neg scan = good enough!

ISO 800 b/w neg film 135, exposed in a good cam and decent lens, flatbed neg scan = good enough!

ISO 160 colour neg film 120, exposed in a good cam and decent lens, flatbed neg scan = definitely good enough!

ISO 400 b/w neg film 120, exposed in good cam and decent lens, flatbed neg scan = definitely good enough!

Fuji X-T1 "APS" (up to ISO 6400) with a decent lens = definitely good enough!

Nikon Df "fullframe" (up to ISO 6400) with a decent lens = definitely good enough!

Leica M8 "APS-H" (up to ISO 640, b/w higher) with a decent lens = definitely good enough!

Nikon D7000 "APS" (up to ISO 3200) with a decent lens = definitely good enough!

Pentax K100D "APS" (only 6 MPix, up to ISO 800) with a decent lens = good enough!

Panasonic GF3 "µ4/3" (up to ISO 800) with a decent lens = good enough!

Nikon D1 "APS" (only 2,7 MPix, up to ISO 400) with a decent lens = just good enough (in most cases)!


Modern cams with good lenses and good old cams with good lenses and good film will always be "good enough" for me!

My personal photographic abilities and the draw-backs of real-life-shooting will be much more restrictive to the quality of the outcome than any of my gear.
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