How many megapixels was/is the benchmark to "Equal" 35mm film?

[Waterdonkey]

A long time ago I thought I remembered, reading or hearing, that 8MP was the goal or benchmark. That at 8MP this was the number that would be most analogous to film.

What IS the MP count- or is the question more complicated then this?

 

[mb66energy]

I remember something like 50 lines per mm resolution for very good lenses under optimum conditions with high quality color slide film (not technical pan or something similar). Perhaps this was limited mainly by the resolution of the film.

In pixels it is roughly equivalent to 100 pixels per mm or in terms of standard 35 mm film 3600 x 2400 pixels resulting in ca. 8.6 million pixels - on the small sensor.
That was the reason to buy an EOS 20D in 2005 with the EF-S 60mm - showing a better quality (in terms of resolution) I ever had with my Canon EF with the FD 3.5 Macro lens and others.

I think, that modern zoom lenses and older primes - to mention the EF 2.0/100 - have higher resolving power and something like 1.6 x 1.6 x 8.6 MP are the optimum for full frame sensors resulting in 22.1 (Oops - is that the magic number now?) million pixels.

So IMHO full frame cameras play in the league of the former medium format cameras with 55 x 38mm image area - if you use good lenses.

Best - Michael

 

[Canon-F1]

A long time ago I thought I remembered, reading or hearing, that 8MP was the goal or benchmark. That at 8MP this was the number that would be most analogous to film.

What IS the MP count- or is the question more complicated then this?

well i don´t know what is the truth.... but i read everything from 8 - 45 million pixel.

edit: well there is one guy (but i don´t give him more credit then my dog on photographic things) that wrote the following:

Since the lie factor factor from digital cameras is about two, you'd need a digital camera of about 87 x 2 = 175 MP to see every last detail that makes onto film.

i don´t want to support the guy so i don´t give the source.. i think some here can guess.

 

[Waterdonkey]

So its not like I dreamed this number up. But it does seem to be a bit more complicated of a question.

I find my MP thirst is quenched a bit with at least one person, thanks mb66energy, having the breakdown of how to go about thinking about it. And Canon-F1, having read 8-45mp, as least the 8 mp floor is somewhat established given what I think I remembered of 8Mp being the "standard or goal".

Interested to read others recollections or thoughts. Or facts

 

[7enderbender]

There are people here and elsewhere that are far more knowledgeable than me and can give you all sorts of physics and factoids. Problem is: I still don't have an answer to that question and related question. It appears that it's really comparing apples and oranges to some degree. Folks will come to all sorts of answers and they sound reasonable until you start to poke holes into the explanations.

The other thing is probably the question why you and I would even ask the question. To me it was always: what has to happen that I'm willing to switch from 35mm film to digital? Again, a complex question since equivalent file/negative/slide quality is only one factor next to cost of the gear, cost of processing - and print quality. Yep, here I go again. My biggest beef with this question still is that I simply don't know if my 5DII (for all practical purposes) beats my old Canon FD gear. Why? Because I have yet to make the effort of a fair comparison by making a test by shooting the same subject under the same conditions and then picking the best possible print process.

It has become close to impossible to get color prints from film the traditional way. There are a few places left that do black and white. And then you'd have to compare that to a similar process that uses my 5DII files. Difficult project. The issue is not the file size coming from the camera but what is left of it in print. Usually not much given the limits of 300 dpi today (or even less). So you'd have to compare relatively large prints up to a point where film may start to lose out just because of size - but I'm not even sure about that.

All I can say is that my prints from the 90s and prior coming from 35mm look better than what I get from my 5DII. I don't think it's the camera's fault but the fact that a lot of data is lost at print sizes in the 8x10 neighborhood (my preference for the most part). But again, the game changes once you are in the over 20" print size.

So in short (and this is my personal observation):

Full frame 5DII vs 35 film = very similar with strengths and weaknesses on both sides
Medium format film prints = still hard to beat
35mm (b/w) film = still better up to a certain size given a traditional process, certainly more dynamic range

But again, for all practical purposes I consider them equivalent. In prints I miss the certain depth and richness but I think that is not a camera issue but rather a result of the "modern" digital print process. It's possible that alternative (and expensive) methods such as LightJet type prints or high quality (and costly) metal prints make up for that but I haven't tried that yet.

 

[Meh]

@Canon-F1 +1 for not naming that guy

 

[Wrathwilde]

From Wikipedia...

Estimates of a photograph's resolution taken with a 35 mm film camera vary. More information may be recorded if a fine-grain film, combined with a specially formulated developer, are used. Conversely, use of poor quality optics or coarse-grained film yield lower image resolution . A 36 mm x 24 mm frame of ISO 100-speed film was initially estimated to contain the equivalent of 20 million pixels,[6], although this estimation was later revised to between 4 and 16 million pixel depending on the type of film used. [7]

 

[Kernuak]

I'm not entirely sure it answers the question (or even if there is a definitive answer), but if you scan 35mm film at the usual professional resolution of 4000 ppi, it works out to around 20.9 MP. However, on my Coolscan V, the resulting images look much softer (and noisier), but I have heard that the higher end Nikon scanners have better quality lenses and electronics (which makes sense), so I would imagine that the image quality is better from those.

 

[dtaylor]

A long time ago I thought I remembered, reading or hearing, that 8MP was the goal or benchmark. That at 8MP this was the number that would be most analogous to film.

What IS the MP count- or is the question more complicated then this?

Two huge variables are film and scanner. When I first got my 7D I did some pretty extensive testing against 35mm film. I found that 7D RAW files processed in ACR could out resolve Velvia 50 and Tech Pan scanned on Nikon CoolScans (4000 dpi) and the Minolta 5400 dpi scanner.

Velvia 50 on an Imacon matched, but could not beat, the 7D on high contrast detail, but the 7D still out resolved it on low contrast and color detail, and was cleaner. Velvia 50 is the highest resolving color film, and an Imacon is about as good as it gets. Other 35mm films have considerably lower resolution, especially with low contrast detail.

There used to be a site with multiple film scans and DSLR shots of the same target. It's gone now, but I recall that the 12 MP D2x was a pretty good match for Velvia 50 on a CoolScan. Velvia 50 out resolved it on high contrast detail, but the D2x won on low contrast and color detail. Other films were matched or beat by cameras in the 8-10 MP range.

Traditional film prints do not change this. Pros like Galen Rowell were leaving traditional printing behind for digital years before scanners and photo printers came down in price for the masses. I enjoy B&W darkroom work, but I can generally match a B&W optical print even with a 2700 dpi 35mm film scan.

Speaking of prints, today's 16 MP and higher DSLRs produce 24" prints that are a pretty good match for MF film. With larger sizes MF certainly pulls away. But you would be hard pressed to tell 24" prints apart based on detail.

Dynamic range? Pro portrait films and some B&W films have more than even the best DSLRs. The right B&W emulsion and developer can achieve pretty extreme DR (18 stops?). But most other print films do not, and no slide films do. The trade off with color portrait film is that it can't touch a DSLR for resolution and detail, at least not at 35mm size.

 

[Waterdonkey]

Wow. Much bigger question then I thought

 

[traveller]

I'm not entirely sure it answers the question (or even if there is a definitive answer), but if you scan 35mm film at the usual professional resolution of 4000 ppi, it works out to around 20.9 MP. However, on my Coolscan V, the resulting images look much softer (and noisier), but I have heard that the higher end Nikon scanners have better quality lenses and electronics (which makes sense), so I would imagine that the image quality is better from those.

The file size might work out at 20.9MP, but that doesn't mean that you're resolving anything other than grain patterns. That's not to say that your colour film can't resolve this amount of detail, just that this is a poor metric to use as a comparison.

Here are a number of opinions:

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

http://www.clarkvision.com/articles/film.vs.digital.summary1.html

Some more real world test:

http://www.luminous-landscape.com/reviews/shootout.shtml

http://static.timparkin.co.uk/static/tmp/cameratest-2/800px.html

Never an easy question!!!

 

[archangelrichard]

1) this IS much more complicated than you thought

2) You are probably asking the wrong question

Here goes: Black & White 35mm Film's resolution has been estimated (high grade) at 7,200,000,000,000 Pixels equivalent BUT then you have to develop it and print it and each step costs resolution (and even paper is graded fine, very fine, extra fine, etc.) (color a bit less at 800,000,000,000 Pixels) (we are not talking about lenses, etc. just the film itself)

NOTE - viewing on screen is even worse - video displays are from 72 DPI (normal) to 96 DPI (very expensive) - nowhere near the 300 dpi of cheap printers

To test this take your old filmstrips and enlarge them onto a ten foot wall. Now try doing the same with digital (ooooops!)

Which is not the point; what people are referring to when they give a figure of 8MP is that to your eye when you make an 8MP print on a 300 dot per inch printer on an 8 x 10 paper you can't tell the difference (some people claim they can tell the quality to 1200 DPI, canon makes printers that print 9600 DPI (at which point your 8 MP image is less than 1/2 inch wide!)

Digital was always meant to be a CONVENIENCE medium - it is so much easier to deal with than film, and that is the selling point; easier to make cameras for, easier to "develop", easier to edit, etc. It was never meant to be the quality medium that film is (look at movies)

So Don't worry about the resolution of film, you will never get there anyways (and neither did prints, remember those paper grades?). 8MP gets you more than a 300 DPI printer will print at 8 x 10, the rest gets wasted and that is all that should be important to you

It's all about the Viewing medium, you are throwing away pixels anyways

 

[markd61]

Many years ago I read (early 80's IIR) Kodak estimated that a file of 50MB was necessary to match the resolution of 35mm Kodachrome. As 5 inch floppies were in use at that time we really felt that digital imaging was still a long way off.

In 1995 our photo lab entered the digital age with a Kodak 3570 scanner and an Agfa Arcus II flatbed scanner. We were printing on Kodak dye sub material. Right away we saw that scanned 35 mm negs were the equal of optical printing at 8x10. Large prints not so good. Slides were also very good and actually exceeded the sharpness of internegs and type R prints. The DR of both negs and slides were better than optical prints. So at that point for small prints we were already at 35 mm film quality.

The 3570 scanner made 18MB files from 35 mm negs. This was three separate exposures at 6MP each.

Our first digital camera was a Canon 10D that was a 6MP sensor yielding 18MB files. The very first portrait test I shot with it was a head and shoulders image with the 28-105 3.5-4.5 lens. It was astoundingly sharp.

I printed it at 40x60 inches on our HP printer and was blown away by the quality. A number of pros were certain I had shot it on MF if not 4x5. It was truly excellent. We scanned carefully exposed and focused 35 mm Vericolor negs on our Scitex scanner producing 28MB files and had decent prints but nowhere near the quality of the digital file.

But that was a portrait. I had a very detailed landscape taken on Kodacolor that made a gorgeous 30x40 optical print. With the 10D the detail of the same scene fell far short of the neg.

Today my 5Dmk2 greatly exceeds the quality of film. It partly explains our obsession with pixel peeping today in that in the old days we looked at prints and liked them for content and print quality with only limited ability to discern optical shortcomings. Now that we can zoom to 1600% we will.

 

[jbwise01]

The simple answer is that there is no digital equivalent because film can be scanned at many different resolutions. The next variable is the lack of noise in film, unless intended, compared to digital MP, there are many many forums discussing noise in relation to sensor size. I an assuming you are wondering what s We make camera would equal film. Like many have mentioned, it's difficult to compare the two.

 

[TexPhoto]

I've seen this question asked and answered a bunch of times. There are so many variables, and so much judgment involved that there is no real answer. I also recall that every time we made a jump from 3 to 4MP or 8 to 10MP, someone was always claiming this was finally the 35mm equivalent. While others talked of the subtle qualities of film being impossible to replicate. (Grain was better than noise, digital bokeh was terrible etc)

 

[traveller]

The simple answer is that there is no digital equivalent because film can be scanned at many different resolutions. The next variable is the lack of noise in film, unless intended, compared to digital MP, there are many many forums discussing noise in relation to sensor size. I an assuming you are wondering what s We make camera would equal film. Like many have mentioned, it's difficult to compare the two.

As I've stated previously, scanning at a higher resolution does not necessarily mean that you are getting more detail from your scan. In most cases, when compared to film, digital noise is far less troublesome than film grain (at equivalent ISO ratings).

Here's another interesting comparison for anyone that's interested:

http://static.timparkin.co.uk/static/tmp/cameratest-2/800px.html

BTW, I don't know where this page has come from because Tim Parkin hasn't updated his site for ages, but this comparison seems to have been done quite recently, i.e. post-IQ180 release?

 

[Policar]

There's actually a pretty easy answer to this question. But it takes a while to get there.

First, take into account that bayer sensors don't resolve the full resolution of the image you end up with. They resolve about 70% in each axis to nearly 100% mtf, then alias a bit, then mtf drops to zero. But with sharpening (since digital is so low noise) you can boost this up so it seems higher. Remember, perceptual sharpness is most accurately represented by the measure of the area under the mtf curve--NOT where that curve hits extinction--and sharpening can bring areas of that curve over 100%. This means 25 megapixels is really closer to 12 "perfect" megapixels, but in practice seems significantly sharper than that.

Take fuji velvia 50, the sharpest color film; it has 100% mtf up until the equivalent of 4-6 megapixels, I think, (not going to bother to look up numbers, could be more or less), then hits extinction at about 25 megapixels. And my scans back this up.

Depending on how you measure (mtf going under 100; mtf reaching extinction; area under mtf curve), you'd get something like 4, 12, or 25 megapixels from 35mm slides is my guess. I'd put APS-C digital on par with 35mm film but much faster and full frame digital on par with 645 or 6x7 but faster, just personally. I prefer 6x7 chromes to full frame digital, but once printed they look pretty similar to me!

But film also has a LOT more grain. Taking SNR into account, film takes a huge hit...

Fwiw, black and white is even sharper and c41 is generally less sharp but not bad at all!

But film, shot properly, still looks better! Love the colors and highlight roll off.