Performance Difference between APS-C and Full frame digital cameras - Resolution
Jul 9, 2018 10:22:17 #
The explanation for the difference in resolution and sharpness between APS-C and Full Frame is not trivial.
You mght think that a 24 MP image from either format, since it still contains about 4000x6000 pixels, should produce about the same image. The reason this cannot happen is the lens. To get a true measure of resoution for an image you need to consider the system resolution - combining the resolution of the lens with the sensor.
For several decades, the 50mm Leica Summicron was considered the gold standard for resolution and quality and for good reason. Few lenses have surpassed its sharpness. Older copies have been reported to produce a resolution of about 50 line pairs per millimeter (lp/mm) and that was perfectly fine for film which can record resolutions between 125 and 800 lp/mm.
An FX sensor has 4000 pixels over a span of 24mm - about 166.7 lines per millimeter or 83.33 lp/mm. A DX sensor is only 16mm high so the number is (4000/16)/2=125 lp/mm.
The combined resolution of the lens and sensor can be calculated from:
1/Rs^2 = 1/Rl^2 + 1/Rc^2
where Rl is the lens resolution, Rc is the camera's sensor resolution and Rs is the combined system resolution.
Rs can never exceed the value of the lesser of Rl or Rc, even if the other value is very large.
If you plug in the numbers for the Summicron and the two 24 MP sensors you get 46.42 lp/mm for DX and 42.87 lp/mm for FX. They seem to be close and both are less than the lens's Rl of 50.
But you can't look at an image at 1x1-1/2 inches. So what happens when you make an 8x10 inch print from each image? The FX image will need to be magnified about 8x and the DX image about 12x. That stretches the resolutions to 47.42/12=3.87 lp/mm for DX and 5.36 lp/mm for FX. The FX version will appear to be 5.36/3.87=1.39 nearly 40% sharper! You can see the difference if you look closely and here is why.
The critical viewing distance for an 8x10 image is about 10 inches. At that distance you would want an image with about 300 pixels per inch. In millimeters that would be about 300/25=12 pixels per millimeter, about 12 lines per millimeter or 6 lp/mm.
If you can achieve a combined system resolution of about 48 lp/mm, the FX image will produce a print of 48/8=6 lp/mm but the DX print would be only 48/12=4 lp/mm. You can see the difference. It will become even more apparent if you make a larger print.
You mght think that a 24 MP image from either format, since it still contains about 4000x6000 pixels, should produce about the same image. The reason this cannot happen is the lens. To get a true measure of resoution for an image you need to consider the system resolution - combining the resolution of the lens with the sensor.
For several decades, the 50mm Leica Summicron was considered the gold standard for resolution and quality and for good reason. Few lenses have surpassed its sharpness. Older copies have been reported to produce a resolution of about 50 line pairs per millimeter (lp/mm) and that was perfectly fine for film which can record resolutions between 125 and 800 lp/mm.
An FX sensor has 4000 pixels over a span of 24mm - about 166.7 lines per millimeter or 83.33 lp/mm. A DX sensor is only 16mm high so the number is (4000/16)/2=125 lp/mm.
The combined resolution of the lens and sensor can be calculated from:
1/Rs^2 = 1/Rl^2 + 1/Rc^2
where Rl is the lens resolution, Rc is the camera's sensor resolution and Rs is the combined system resolution.
Rs can never exceed the value of the lesser of Rl or Rc, even if the other value is very large.
If you plug in the numbers for the Summicron and the two 24 MP sensors you get 46.42 lp/mm for DX and 42.87 lp/mm for FX. They seem to be close and both are less than the lens's Rl of 50.
But you can't look at an image at 1x1-1/2 inches. So what happens when you make an 8x10 inch print from each image? The FX image will need to be magnified about 8x and the DX image about 12x. That stretches the resolutions to 47.42/12=3.87 lp/mm for DX and 5.36 lp/mm for FX. The FX version will appear to be 5.36/3.87=1.39 nearly 40% sharper! You can see the difference if you look closely and here is why.
The critical viewing distance for an 8x10 image is about 10 inches. At that distance you would want an image with about 300 pixels per inch. In millimeters that would be about 300/25=12 pixels per millimeter, about 12 lines per millimeter or 6 lp/mm.
If you can achieve a combined system resolution of about 48 lp/mm, the FX image will produce a print of 48/8=6 lp/mm but the DX print would be only 48/12=4 lp/mm. You can see the difference. It will become even more apparent if you make a larger print.
Jul 9, 2018 10:37:39 #
Jul 9, 2018 10:45:52 #
"If you can achieve a combined system resolution of about 48 lp/mm, the FX image will produce a print of 48/8=6 lp/mm but the DX print would be only 48/12=4 lp/mm. You can see the difference."
any chance you have the photo of this?
any chance you have the photo of this?
Jul 9, 2018 11:05:38 #
nikonmikey wrote:
... any chance you have the photo of this?
Sorry, I haven't used a DX camera since I traded my D7000 for a D610 four years ago.
I could put my D7000 images next to my Df images but it wouldn't be a fair fight. The Df is superior in too many ways.
But I do use 120 and 4x5 film. If you want resolution and can put up with the bulk and weight, there is no substitute for a larger format.
There is another whole order of magnitude difference with each step up.
Jul 9, 2018 12:36:59 #
Excellent !!
THANK YOU
You apparently stayed awake & fully alert while attending all your Math & Science classes while I stayed asleep
My far less technical take on why FORMAT that is LARGE FORMAT matters are all those wonderful Civil War photos --- When you realize these folks had nothing but a LARGE FORMAT in their favor ---- No Film (glass plates)
; ISO/ASA of around 8 to 12; lens cap working as a shutter timed with a pocket watch; no adjustable aperture --- They did have a form of live view even though it displayed an upside-down image --- then there was, of course, those crappy lenses they used long-long before Zeiss/Leica existed
THANK YOU
You apparently stayed awake & fully alert while attending all your Math & Science classes while I stayed asleep
My far less technical take on why FORMAT that is LARGE FORMAT matters are all those wonderful Civil War photos --- When you realize these folks had nothing but a LARGE FORMAT in their favor ---- No Film (glass plates)
; ISO/ASA of around 8 to 12; lens cap working as a shutter timed with a pocket watch; no adjustable aperture --- They did have a form of live view even though it displayed an upside-down image --- then there was, of course, those crappy lenses they used long-long before Zeiss/Leica existed
Jul 9, 2018 13:15:11 #
selmslie wrote:
Sorry, I haven't used a DX camera since I traded my D7000 for a D610 four years ago.
I could put my D7000 images next to my Df images but it wouldn't be a fair fight. The Df is superior in too many ways.
But I do use 120 and 4x5 film. If you want resolution and can put up with the bulk and weight, there is no substitute for a larger format.
There is another whole order of magnitude difference with each step up.
I could put my D7000 images next to my Df images but it wouldn't be a fair fight. The Df is superior in too many ways.
But I do use 120 and 4x5 film. If you want resolution and can put up with the bulk and weight, there is no substitute for a larger format.
There is another whole order of magnitude difference with each step up.
yessir, like they say, "there is no substitute for cubic(or square) inches
Jul 9, 2018 13:40:02 #
Jul 9, 2018 14:46:17 #
nikonmikey wrote:
yessir, like they say, "there is no substitute for cubic(or square) inches
I know that term as: "There Is NO replacement for DISPLACEMENT" --
A concept I became quite familiar with when I drove an Integra Type R for 17 yrs. --- Stay away from Mustang's with Two or more Tailpipes ----
I also love & enjoy all those Pixels that came with my 5Ds ---
BUT be assured --
It will never approach the quality of a well-taken image from a Medium Format or higher
Jul 9, 2018 15:06:33 #
nikonmikey wrote:
yessir, like they say, "there is no substitute for cubic(or square) inches
Unless you can afford to spend a lot of money on a Formula 1 hybrid, "Energy recovery system can deliver up to 163 HP, meaning that for a total of 1 000 HP the 1,6-liter V6 the engine needs to have at least 837 HP."
That's a lot of HP for a very small engine and you will probably have to replace it after about four 200 mile races.
Jul 9, 2018 15:18:46 #
My old Type R -4cyl- 1.8 liter - generated 195 HP --- My current WRX 2.0 Liter -4cyl- generates 268 HP -- With either car, I leave the two tailpipes+ Mustangs all to themselves
But I do feel like a "real' winner since my "stuff" is far more efficient
But I do feel like a "real' winner since my "stuff" is far more efficient
Jul 9, 2018 15:36:06 #
ken_stern wrote:
My old Type R -4cyl- 1.8 liter - generated 195 HP --- My current WRX 2.0 Liter -4cyl- generates 268 HP -- With either car, I leave the two tailpipes+ Mustangs all to themselves
But I do feel like a "real' winner since my "stuff" is far more efficient
But I do feel like a "real' winner since my "stuff" is far more efficient
My TTS was the same. But I traded it for a Wrangler which was more suited to the beach.
Jul 9, 2018 15:59:56 #
Whatever meets your needs ---
As for me ---
I have always have felt that super FAST is overrated
I'm all for incredibly QUICK
As for me ---
I have always have felt that super FAST is overrated
I'm all for incredibly QUICK
Jul 9, 2018 22:50:06 #
nikonmikey wrote:
yessir, like they say, "there is no substitute for cubic(or square) inches
Except cubic feet (as old engine builders used to say). Of course that neglects turbos and superchargers and anything else that boosts volumetric efficiency (ie: how much fuel-air mixture can you fill that displacement with).
Jul 10, 2018 01:47:00 #
ken_stern wrote:
Whatever meets your needs ---
As for me ---
I have always have felt that super FAST is overrated
I'm all for incredibly QUICK
As for me ---
I have always have felt that super FAST is overrated
I'm all for incredibly QUICK
You may want to trade your ricer in for a Tesla if you want incredibly QUICK.
Btw, the New Tesla Roadster that is coming out will go 0-60 in 1.9 seconds, top speed is over 264mph if I remember correctly and you will be able to drive from SF to LA and back on a single charge. At a bargain price of 200k. And you get 4 seats, well 2+2
Jul 10, 2018 05:47:08 #
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