solentbirder
Well-known member
Anyone know how many megapixels are required to equal the resolution and quality of a good 35mm negative/transparency ? I suspect the answer is not straightforward due to the noise factor vs emulsion grain.
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How many Megapixels = a 35mm negative ? (2 Viewers)
- Thread starter solentbirder
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robski
Well-known member
Well to get the ball rolling on this one.
It's easier to think of the resolving power of the lens over that area. Typically a very good lens can resolve say 90 lines per mm. So you need 180 pixels to capture that information. (each line is an area of white and black).
Therefore
36mm x 180 x 24mm x 180 is 27993600 pixels
So it is considered that 25 - 30 M pixels for a full frame camera will match film.
If you consider that if a Canon 20D was full frame it would be a 20M pixel camera. So pretty close to that target.
It is also consider that 8M pixel sensors often have a higher resolution than many consumer lens.
Robert
A snippet taken from Bob Atkin site on lens testing with a 10D
"The 10D has the smallest pixel pitch (7.7 microns) and so the highest native resolution of any current DSLR. It can resolve around 65 lp/mm at the sensor. Film can resolve more, typically up to around 80-90 lp/mm with slow speed, high resolution films and the best lenses
http://www.bobatkins.com/photography/reviews/28zooms.html
The 20D pixel pitch is 6.4 micron so above is a bit dated now.
It's easier to think of the resolving power of the lens over that area. Typically a very good lens can resolve say 90 lines per mm. So you need 180 pixels to capture that information. (each line is an area of white and black).
Therefore
36mm x 180 x 24mm x 180 is 27993600 pixels
So it is considered that 25 - 30 M pixels for a full frame camera will match film.
If you consider that if a Canon 20D was full frame it would be a 20M pixel camera. So pretty close to that target.
It is also consider that 8M pixel sensors often have a higher resolution than many consumer lens.
Robert
A snippet taken from Bob Atkin site on lens testing with a 10D
"The 10D has the smallest pixel pitch (7.7 microns) and so the highest native resolution of any current DSLR. It can resolve around 65 lp/mm at the sensor. Film can resolve more, typically up to around 80-90 lp/mm with slow speed, high resolution films and the best lenses
http://www.bobatkins.com/photography/reviews/28zooms.html
The 20D pixel pitch is 6.4 micron so above is a bit dated now.
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The resulution of a typical ISO 100 film from the supermarket is about 100 lines/mm, a high quality ISO 25 film can go up to 200.
100 lines/mm give you 2x3600x2400 pixel (sligtly more than 17 megapixel)
200 lines/mm give you 2x7200x4800 pixel (sligtly more than 70 megapixel)
However, due to a bad signal to noise ratio this theoretical resolution has to be devided by 2 to get a realistic value for the praxis (ca. 10 megapixel is realistic for a 100 ISO film).
At higher ISO ratings the Grain of the film will increase more than the noise of the sensor, wich means the resolution for digital will actually be better than for film. This means in most real life situations the resolution of a good DSLR will be better than that of the film you'd choose for that same occasion.
Anyway keep in mind that the resolution of state of the art media (both film and digital sensors) is likely to be far better than the optical resolution of the lenses you're using. |8(|
100 lines/mm give you 2x3600x2400 pixel (sligtly more than 17 megapixel)
200 lines/mm give you 2x7200x4800 pixel (sligtly more than 70 megapixel)
However, due to a bad signal to noise ratio this theoretical resolution has to be devided by 2 to get a realistic value for the praxis (ca. 10 megapixel is realistic for a 100 ISO film).
At higher ISO ratings the Grain of the film will increase more than the noise of the sensor, wich means the resolution for digital will actually be better than for film. This means in most real life situations the resolution of a good DSLR will be better than that of the film you'd choose for that same occasion.
Anyway keep in mind that the resolution of state of the art media (both film and digital sensors) is likely to be far better than the optical resolution of the lenses you're using. |8(|
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Tannin
Common; sedentary.
Excellent post from the Barn Owl above. Robski's advice is good too. Now that they have competently dealt with the main issues I'm going to say a couple of things about related matters:
First, your pictures are only as good as the shots you actually take. With digital, you take a lot more shots (why not? it costs nothing) and even though you take masses of dud shots - many more than you would take with a film camera - sooner or later the law of averages comes to your aid. Sooner or later you shrug and say "why not bang off another dozen frames at this unpromising subject", as you do a dozen times a day, "knowing" that you are only going to throw them away later on, and - hey presto! - something unexpected happens and you get a genuine keeper.
Below is an example. It wasn't really worth taking that first shot of a Black-faced Cuckoo-shrike (or any of the other 15-odd others I threw away that were even less worthwhile), but because frames are free and there weren't any more promising subjects around at that particular minute, I fired a few off. And .... look at that second shot! Pure luck. ..... Or is it luck? Nope, I think of it as return on investment: you keep on plugging away, even when the chances are 10000 to 1 against getting a usable shot, because if you spend the $0.00 it takes to get those ten thousand shots, every once in a while you will get a nice surprise. You simply can't afford to do that with film.
Second point: modern digital cameras have phenomenal ability to return usable results in very low light. You can shoot on into the evening where you wouldn't have a hope with film.
In other words, the point I am making in my roundabout way is that the resolving power of digital these days is infinately better than film, because it retuurns pretty fair images of scenes you otherwise wouldn't have got at all
First, your pictures are only as good as the shots you actually take. With digital, you take a lot more shots (why not? it costs nothing) and even though you take masses of dud shots - many more than you would take with a film camera - sooner or later the law of averages comes to your aid. Sooner or later you shrug and say "why not bang off another dozen frames at this unpromising subject", as you do a dozen times a day, "knowing" that you are only going to throw them away later on, and - hey presto! - something unexpected happens and you get a genuine keeper.
Below is an example. It wasn't really worth taking that first shot of a Black-faced Cuckoo-shrike (or any of the other 15-odd others I threw away that were even less worthwhile), but because frames are free and there weren't any more promising subjects around at that particular minute, I fired a few off. And .... look at that second shot! Pure luck. ..... Or is it luck? Nope, I think of it as return on investment: you keep on plugging away, even when the chances are 10000 to 1 against getting a usable shot, because if you spend the $0.00 it takes to get those ten thousand shots, every once in a while you will get a nice surprise. You simply can't afford to do that with film.
Second point: modern digital cameras have phenomenal ability to return usable results in very low light. You can shoot on into the evening where you wouldn't have a hope with film.
In other words, the point I am making in my roundabout way is that the resolving power of digital these days is infinately better than film, because it retuurns pretty fair images of scenes you otherwise wouldn't have got at all
Attachments
Yelvertoft
Rabbit Fan
Tannin said:
Very, very good points from Tannin. Putting the effort into taking pictures rather than worrying about the technicalities will get you the best results.
Regards,
Duncan.
robski
Well-known member
tyto alba said:
tyto alba
A slight flaw in your math it should be
100 lines/mm give you 4x3600x2400 pixel (sligtly more than 34 megapixel)
200 lines/mm give you 4x7200x4800 pixel (sligtly more than 140 megapixel)
The main thing is the argument that digital camera are as good as film for resolving power is now pretty well true for the top end Digitals. As the main limiting factor is the Lens. Many diehard film users are begining to concede that digital is now on par.
I've had just as many naff blurry shots on film as I have on digital
3
"if you spend the $0.00 it takes to get those ten thousand shots"
This statement is not completely true - You have forgotten the cost of ware and tear on your camera. The machanical components have a limit life of operations.
i.e a 20D shutter life is rated at approx 100,000 operations
Robert
Sorry about the nit picking but that is the engineer in me :scribe:
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Keith Reeder
Watch the birdie...
Tannin!
That second shot is staggering!
You make a very good point, very well.
That second shot is staggering!
You make a very good point, very well.
Tannin
Common; sedentary.
It's one of my favourites, Keith. The funny thing is, I nearly didn't recognise it. I was flicking more-or-less randomly through the 1000-odd shots I took that day (yes, it was a long and rewarding day on my way back from New South Wales for the Cup Day long weekend and I was very tired) and saw a random-looking jumble of feathers and almost deleted it in a split second as a dud shot of the back of a bird before I twigged to what it was. And from that angle, I'd have been flat out picking it for a Black-faced Cuckoo-shrike if I hadn't had the other (boring) shots of the same bird on the same branch to compare it to.
But that brings me to another point. I claimed that these one-in-a-thousand shots are "free". Well, that wasn't really true. My $2500 camera has a shutter rated for 100,000 shots. Assuming that it fails as per spec on shot number 100,001, it will be worn out after about two years of use. I don't know what it costs to have a shutter replaced, but I bet you it ain't cheap. AU$600 maybe? If so, that works out to $0.00.06 per shot - six one-hundredths of a cent each time you press the shutter, as opposed to maybe a dollar a shot for film by the time you have it processed and printed or mounted. Come to that, how much will I have spent on petrol in that time? In the overall scheme off things, so far as the money side of it goes, I reckon "free" is a near-enough approximation.
Besides, in reality, I hope and expect that the 20D shutter will last for a good many more than 100,000 shots. Hard disc drives, for example, typically have a design life of 5 years, but although a small number fail early, the majority keep on operating without trouble for 10 to 15 years.
But there is a second and more significant factor that makes the extra shots "expensive" rather than "free". This is time. I don't count the time it takes to actually get the pictures, of course: time spent outdoors looking at birds is never wasted. (And I don't think the good lord counts time spent birdwatching against our allotted span of years.)
But the more shots you take, the longer you have to spend in front of a computer sorting them out each night. If it takes me 6 or 8 hours (not counting travel) to take 500 or 1000 shots each day - which sounds about right - I find that it takes me almost the same amount of time sitting in front of the computer to sort the darn things out! Getting rid of the worst 50% is easy. Geting rid of the second-worst 20% is harder. Geting rid of the third-worst 10% is harder still, and so on. You have to be utterly ruthless, and yet keep your mind open to see the possibilities in shots that you might at first have thought were nothing special. It helps a lot to do it in sessions: do the first (50%) pass on today's shots, then take a break by doing the fourth (5%) pass on the shots you took a week ago, then something from last month (reduce the remaining 107 out of 865 to just the best 82), then return to do the second pass on today's shots, and so on.
On a trip, I barely have time to eat and sleep, and never cook, just grab a burger if I'm near a town, or make do with nuts and museli if I'm outback. Who was the fool who invented the day, and why did he only put 24 hours in it?
Err ... I seem to be a long way off-topic. Or perhaps not.
But that brings me to another point. I claimed that these one-in-a-thousand shots are "free". Well, that wasn't really true. My $2500 camera has a shutter rated for 100,000 shots. Assuming that it fails as per spec on shot number 100,001, it will be worn out after about two years of use. I don't know what it costs to have a shutter replaced, but I bet you it ain't cheap. AU$600 maybe? If so, that works out to $0.00.06 per shot - six one-hundredths of a cent each time you press the shutter, as opposed to maybe a dollar a shot for film by the time you have it processed and printed or mounted. Come to that, how much will I have spent on petrol in that time? In the overall scheme off things, so far as the money side of it goes, I reckon "free" is a near-enough approximation.
Besides, in reality, I hope and expect that the 20D shutter will last for a good many more than 100,000 shots. Hard disc drives, for example, typically have a design life of 5 years, but although a small number fail early, the majority keep on operating without trouble for 10 to 15 years.
But there is a second and more significant factor that makes the extra shots "expensive" rather than "free". This is time. I don't count the time it takes to actually get the pictures, of course: time spent outdoors looking at birds is never wasted. (And I don't think the good lord counts time spent birdwatching against our allotted span of years.)
But the more shots you take, the longer you have to spend in front of a computer sorting them out each night. If it takes me 6 or 8 hours (not counting travel) to take 500 or 1000 shots each day - which sounds about right - I find that it takes me almost the same amount of time sitting in front of the computer to sort the darn things out! Getting rid of the worst 50% is easy. Geting rid of the second-worst 20% is harder. Geting rid of the third-worst 10% is harder still, and so on. You have to be utterly ruthless, and yet keep your mind open to see the possibilities in shots that you might at first have thought were nothing special. It helps a lot to do it in sessions: do the first (50%) pass on today's shots, then take a break by doing the fourth (5%) pass on the shots you took a week ago, then something from last month (reduce the remaining 107 out of 865 to just the best 82), then return to do the second pass on today's shots, and so on.
On a trip, I barely have time to eat and sleep, and never cook, just grab a burger if I'm near a town, or make do with nuts and museli if I'm outback. Who was the fool who invented the day, and why did he only put 24 hours in it?
Err ... I seem to be a long way off-topic. Or perhaps not.
solentbirder
Well-known member
Thanks to everyone for the great feedback. I've been using 35mm SLR's and medium format for many years and haven't quite convinced myself to invest in a digital SLR yet. Perhaps I'll wait a bit until the price of the 10+ megapixel models fall. I use a digital compact for snapshots but I still seem to prefer the images I get from film (perhaps I'm an old dog reluctant to learn new tricks !).
Yelvertoft
Rabbit Fan
solentbirder said:
It's not an exclusively "either/or" situation. You don't have to stop using film if you have an dSLR. I still put a reel of film through my K1000 if I'm feeling nostalgic or feel I need to keep my hand in. I even put a reel of 120 through the Rolleiflex now and again when I need a bit of enforced relaxation, a very different kind of photography. Film can co-exist with digital.
I can honestly say that a dSLR revitalised my photography for exactly the kind of reasons Tannin stated in post #4. It's not the number of megapixels that makes the difference, there's a lot more variables than that. If you're a die-hard film man, using a dSLR and shooting "raw" will get you a lot closer to film than a compact ever will.
I certainly don't regret my purchase, it's been a whole lotta fun!
Duncan.
solentbirder said:
In my experience the theoretical figures given above are way out.
In practice a decent 6MP sensor can roughly match Fuji Provia 100F in terms of resolution. In practice the digital image looks much much better. A decent 12MP sensor starts to approach scanned MF in terms of subjective image quality if not actual resolution. And of course you have other benefits form digital: no reciprocity failure, no grain, no need to use colour correcting filters, white balance that can be adjusted on a PC, ISO that can be changed at any time, and so on.
Resolution in itself is not a good measure of image quality. When I view a slide with a loupe, I can see lots of detail, but much of it is submerged in coarse grain, and the tones are awful. A4 prints from a Nikon D70 are far better than prints from slides, and are medium format like due to the smoothness of tones. Obviously resolution is nowhere near that of MF.
There are numerous real world tests on the net:
http://www.borutfurlan.com/test_nikon_fuji_en.html
http://www.photographical.net/canon_1ds_35mm.html
My own experiences with a Nikon D70 are consistent with the above.
Leif
madmike
Well-known member
Digital V's 35mm
I think Leif is dead right and of course it's a very subjective subject.
I've used medium format for years, but my 20D is almost as good. I gave the new Canon 5D a brief test the other day and I feel that it could be a cracking camera especially with the right lens.
A professional photographic friend recently had a 6 ft X 4 ft print done from his top end Nikon and said the quality is superb - what more do you want?
However, no amount of grunt in a camera is any good without good technique PARTICULARY in understanding the quality of the light.
I'm sure this thread will run and run!
madmike
I think Leif is dead right and of course it's a very subjective subject.
I've used medium format for years, but my 20D is almost as good. I gave the new Canon 5D a brief test the other day and I feel that it could be a cracking camera especially with the right lens.
A professional photographic friend recently had a 6 ft X 4 ft print done from his top end Nikon and said the quality is superb - what more do you want?
However, no amount of grunt in a camera is any good without good technique PARTICULARY in understanding the quality of the light.
I'm sure this thread will run and run!
madmike
solentbirder
Well-known member
I think I'm partly held back because of my investment in manual Nikkor lenses (especially some nice wide-angles such as 24mm f2, 35mm f2). If Nikon would bring out a body with a full-frame sensor (compatible with the manual Nikkors) I'd be a lot more tempted.
solentbirder said:
Solent: Well let's see. The forthcoming D200 will meter - including matrix metering - with manual lenses. Your 24mm will thus behave like a ~35mm lens (in terms of FOV) so your 24mm is very useable (if you considered your 35mm useable). I bought a manual 75-150mm zoom for my D70 (for the massive sum of £75) and I have a manual 200mm micro which works even better on the smaller sensor as I get even more working distance. I guess the question is do you want to spend money on a DX format lens to get proper wide angle again. Well, the ~12-24mm Tokina, Sigma and Tamron wide angle zooms are almost as good as Nikon/Canon equivalents for about £300 a pop. I am a little annoyed that my manual 28mm AIS lens does not go so well on DX format.
I suspect you will have a long wait for a full frame Nikon DSLR. I might be wrong.
Leif
robski
Well-known member
Another factor in the film resolution debate, Solent were you refering to colour or monochrome negs ? Of course colour negs are inherently lower resolution because of the number of layers of emulsion ( in total giving an increased emulsion thickness compared to the single layer of monochrome) which introduces factors of flare and light bleeding into the emulsion.
For colour I suspect we are pretty well there with 16M pixel. For Monochrome the file grain can vary from 0.2 - 2 microns so when we have sensors with 2 micron or smaller pixels we should be there. But all this is academic because we are using glass lens that have a resolution in the range of 30 - 90 lines per mm dependent of f stop setting and quality of glass. For glass-less photographic systems such as x-ray machines I am sure higher resolution is an important factor.
Something perhaps you can relate to in everyday life is printed matter for image quality and resolution. These days the printing plates are produced by scanning photographic material with lasers. For newspapers the plates are typically scanned at resolution of 1016 to 1270 dots per inch and glossy magazines are scanned at 2400 - 3048 dots per inch.
For wide angle work landscape work ( especailly leaves on trees ) I feel the 8 M pixel image is poor compared to what I used to see when I processed mono fine grain 25 ISO film. With the digital image the small leafs being just 1 or 2 pixels giving poor graduation of tone.
I was a lasped photographer who got rid of his photographic gear 20 years ago so when I restarted 2 years ago with a 300D I had to start again from scratch.
Robert
For colour I suspect we are pretty well there with 16M pixel. For Monochrome the file grain can vary from 0.2 - 2 microns so when we have sensors with 2 micron or smaller pixels we should be there. But all this is academic because we are using glass lens that have a resolution in the range of 30 - 90 lines per mm dependent of f stop setting and quality of glass. For glass-less photographic systems such as x-ray machines I am sure higher resolution is an important factor.
Something perhaps you can relate to in everyday life is printed matter for image quality and resolution. These days the printing plates are produced by scanning photographic material with lasers. For newspapers the plates are typically scanned at resolution of 1016 to 1270 dots per inch and glossy magazines are scanned at 2400 - 3048 dots per inch.
For wide angle work landscape work ( especailly leaves on trees ) I feel the 8 M pixel image is poor compared to what I used to see when I processed mono fine grain 25 ISO film. With the digital image the small leafs being just 1 or 2 pixels giving poor graduation of tone.
I was a lasped photographer who got rid of his photographic gear 20 years ago so when I restarted 2 years ago with a 300D I had to start again from scratch.
Robert
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solentbirder
Well-known member
Thanks Robert, that's very interesting. I think I'm going to wait a while before getting a digital SLR as the models I'd be interested in are too expensive at the moment (and I still hope Nikon might make a full-frame model...I can dream !). Given the way technology improves I'm guessing/hoping that within 18 months most SLR's will be at least 12 megapixels and a lot cheaper. Thanks to everyone for all the valuable comments and perspectives.
John
John
Keith Reeder
Watch the birdie...
Cool!Solentbirder said:
Does that mean if I just wait a year and a half, my D70 will grow another 6 megapixels?
I'd say you're right though, John - 12mp as a "benchmark figure" is getting closer.
robski
Well-known member
Klant said:
I bumped into this on dcviews.com
"The eye’s high-resolution color vision system however has a much narrower angle of coverage and is concentrated around the eye’s fovea, which could be compared to the central focal point of a camera lens. It manages to distinguish 7 line pairs per millimeter, which is equivalent to 355.6 dpi. This is almost exactly the baseline resolution of most high quality printers of 360 dpi."
Robert
