Remember the old days of Kodachrome 25? Great color and great detail and no grain. What will we need in a megapixel digital sensor to produce equally detailed grain (noise) free images? Asked another way, is the Current D3s 12 megapixel sensor the equal of the old Kodachrome 25 film? Do we need 20 megapixels, or 30 or more? Asked even another way, what resolution are Nikon lenses capable of? When will increasing the megapixels be of no value because the lenses can no longer resolve that detail on the sensor? So I am asking what are the limits of the digital technology and how close are we to that today?
Kodachrome 25 = how many megapixels in digital camera?(5 posts) (4 voices)
Ahh yes good old Kodachrome. Unbelieveable stuff I'll never forget using it going down the West coast of Canada all the way to San Diego in the States with a F90 for 2 months back in 2000 when I was 20. I have heard that slide film would equal about a 100mp digital body because of the detail and color needed. 25mp is the equivalent to print film. That being said, a lot depends on your photoshop and other post processing skills.
Just like post processing was essential in film its even more important in the age of digital I believe. If you are good, then 12mp can be more than enough especially if 11x14 is your max print size. I have also heard that thanks to Sony we will start seeing multiple +30mp cameras this year although the disaster in Japan might curb that. Eventually we will see more mirrorless designs and medium format digital perhaps from Nikon? MX has been discussed on here before to numerous extents. The skys the limit with modern technology!
The resolution of film seems to be one of those topics that have a lot of people arguing different things. Some people argue that film has a tremendous amount of resolution, and resolves the equivalent of 20-30 MP for 35mm, 100 MP for 6x6 and 300+MP for 4x5, while others will argue that film has long been surpassed by equivalent digital formats.
Having shot and scanned a wide variety of film, and having looked closely at the claims from both sides, I think I can understand why some people argue that digital is still well behind film while others argue that digital is well above it.
Film is by nature an analog medium, which means that it can resolve extremely fine details, but just at low contrast. Thus, theoretically speaking with a perfect lens, you can resolve to any level of detail you want, but you need very high contrast grades. You can see this if you look at the MTF curves of a film- for instance Kodak TMX has a contrast that drops by half at 100 lp/mm, but it keeps going well beyond that, just at really low levels of contrast. Since film doesn't have quantitized levels, you should always be able to pick out fine details by increasing the contrast enough. Actually, there is a real limit on resolution: the size of the silver grains or dye blobs which are quite small but are nonetheless very real. Also, grains of silver or dye aren't located in regular patterns, so you will never have aliasing.
Digital on the other hand has perfect resolution up to the scale of the sensor element size. It doesn't matter if the image size if 3 pixels or 500 pixels on the sensor- it will be recorded with the same level of contrast. However, any details finer than this won't be recorded accurately- since the senor elements are located in a regular pattern, you are essentially sampling the image at a fixed spacial frequency and you will get aliasing and other strange artifacts. Details that are at a high spacial frequency will be aliased down and resemble low frequency data, and will obscure the real low spacial frequency data and ruin your image data. Thus, sensor makers generally put an anti-aliasing filter to reduce the contrast of fine details to prevent this. As sensor resolution gets better, the fineness of the detail needed for aliasing drops. We are starting to see cameras with no anti-aliasing filters, simply because something else acts as the AA filter- whether it be aberrations from the lens itself, the object being out-of-focus (or moving slightly), or even that the object itself doesn't have that much fine detail, the need for a sensor specific AA filter is not as high as it once was. And contrary to what Leica says, there is no mathematical method to remove aliasing once it is done- although you can mask it in the few areas it does occur to make it look like its gone, if you don't start off with very much.
So now we have enough information to figure out both sides of the argument. Taking TMX as the example, Kodak has measured 40% constrast at 150 line-pairs/mm, but a noticeable fall-off starts at 50 lp/mm. To completely outresolve the film entirely, the digital sensor must have more than 300 sensor elements per mm- one for each line. This corresponds to 35 MP for APS-C, 78MP for 35FF, 280MP for 6x6, and 1125MP for 4x5. This is what film advocates use to show that film out resolves digital.
However, nobody really pays attention to those fine details, since they're often masked by other contributors of image softness. Others might consider it to be a more test to have the digital sensor resolve up to the details where the film starts to fall off. Such a case would have the digital sensor produce an image that appears sharper than film, even though the film contains more information. This only requires a third of the linear resolution of the sensor (100 elements per mm), requiring 9 times lower total resolution: 3.8MP for APSC, 8.6 for 35FF, 31 for 6x6, and 125 for 4x5. In this case, it's clear that DSLRs have passed the 35mm mark with the original 1ds, and the 120 mark after the first few generations of MFDBs, which matches what digital proponents have been saying for a long time. And this is only for TMX, which is pretty good for resolution itself. Other films like TMY, Velvia or provia have considerably less resolution- requiring 25-50% total resolution to produce images that appear as sharp as the film can produce.
So there you have it- digital has long been able to produce images that overall appear higher in contrast overall, but film can still resolve the finer details to a much better extent.
MP is only a small variable in the equation of what you are asking. There are many discussions that the Admins maybe able to direct you too for you to find your answers.
Personally I think digital has surpassed 35mm film in everything all but the full gamut of colors film can produce.
On lenses - 50 years ago did your lens resolve an image on Kodachrome 25? Yes. Have lenses gotten better - oh yes. Lenses will resolve anything we throw behind them whether it is 30, 60, 120mp+. I don't think MP are that big of a deal. Color and contrast play a much larger role in image quality than MP.
Digital technology is limitless. It will always improve.
Thanks, very interesting and helpful.
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