Is Full Frame sharper than APS-C? My answer here

[AlanF]

Let us say that you have a APS sensor 24Mp with the same S/N as a  24Mp 24x36 sensor then it is an optical question, it is hard to make a APS  lens 1,5 1,6 times better which is require compared to 24x36mm lens.

This is incorrect.

Because there will be less absolute magnification for a same-sized print with the larger format, even if the sensors have the same pixel dimensions, the larger format will be sharper and have less noise. Again, always assuming all else is comparable, including a longer focal length lens for the larger format.

Cheers,

b&

is it, if the S/N and Mp  is the same from the two sensor areas, then it must be an optical question , and there the APS lenses must be 1,5  1.6 better than the  24x36mm lens.

As I already explained, it is a question of how much enlargement is necessary for a print.

If you're making a 24" x 36" print, the APS-C image will be enlarged 41x from the sensor's original size of 14.8mm x 22.2 mm, but the full-frame will only be enlarged 25x from the sensor's original size of 24mm x 36mm.

Whether you measure S/N in noise per pixel or noise per square mm of sensor, because you've got two and a half times as many square mm of sensor per pixel with the larger format, you're getting that much better of an overall signal to noise ratio.

Imagine you were back in the days of film. You have a 35mm camera loaded with Velveeta on one tripod and an 8x10 view camera loaded with the exact same film on a second tripod. The 35mm camera has a 50mm lens and the view camera has a 400mm lens, both of which give the same normal field of view on the respective cameras.

You'd agree that, since it's the exact same film, the exact same chemistry, that the S/N ratio is exactly the same, right?

Now, let's say we're making an 8" x 10" print from the exposure. The 35mm negative needs to get enlarged 7.5x to make the print, but, for the view camera, it's a contact print.

If you don't agree that the contact print from the view camera will be dramatically sharper and have far less grain than the enlargement from the 35mm camera, then you truly are hopeless.

Now, you might still argue that the pixel dimensions are relevant, but I'll show they're not.

Let's not use traditional printing methods, but rather scan the film. But we want to wind up with the same megapickle files for both, to simulate this contrived example. We're going to scan the 8x10 negate at a lowly 300 ppi, and we're going to scan the 35mm negative at a whopping 2250 ppi. We're still going to make an 8x10 print, and we're going to do it at 300 ppi. And, because of the resolutions I picked, it "just happens" that no interpolation of either file is necessary; both will still print at 300 ppi at 8" x 10".

Once again, if you still don't think that the print from the 300 ppi scan of the view camera's negative will blow away the 2250 ppi scan from the 35mm camera, you're hopeless.

Cheers,

b&

I think S/N based on area (where number of photons captured per unit time is proportional to area) varies fundamentally as the square root of ratio of areas. So increasing area by 2.5x improves S/N only by 1.6x. (I do know other factors do come in, but the basic statistics of S/N is a sqrt relationship).

[klickflip]

Thanks an really interesting test. As you've managed to show that there really isn't much difference comparing 2000px wide Jpgs that show some compression.
If thats all your images are ever going to be finalised as and viewed on screen at 50% then the 650 will be just great.

However... The view selected isn't the best for a proper test I think. Try subjects with smooth tones and darker gradients plus interesting detail and then you'll see the noise & sharpness when especially viewing or working on them in RAW or at least tiffs in photoshop viewed 200%.
Try some nicely lit portraits or some well composed architecture and there will be a big difference.

But its horses for courses really, if you're just going be shooting what we might call messy scenes like this and kids running around and holiday pics then it might not well be distinguishable to FF instantly.

More than anything  it will them more come down to your technique to get the best out of FF, framing, catching beautiful light and the moment together whilst selecting the 'optimum' shutter / aperture, iso and lens plus raw/post processing which can make a huge difference to noise & sharpness plus the grade to push a feel which can be more important than anything.

A good photographer can make APS-C look like FF or MFDB and a bad photographer can make FF look like P&S.

And the previous post that mentioned what about cropping.. well if you are constantly cropping your FF that much then
you shouldn't have FF or a DSLR in my eyes anyway

[TrumpetPower!]

I think S/N based on area (where number of photons captured per unit time is proportional to area) varies fundamentally as the square root of ratio of areas. So increasing area by 2.5x improves S/N only by 1.6x. (I do know other factors do come in, but the basic statistics of S/N is a sqrt relationship).

You're correct about the actual numbers, of course. I didn't mean to imply a specific numerical relationship, which is why I tried to phrase it as loosely as I did.

With each standard increase in format, you gain an effective (roughly) one stop of ISO performance. If you're happy with ISO 400 on 4/3, you'll be happy with ISO 800 on APS-C, and with ISO 1600 on full frame, and ISO 3200 on medium format -- with a big, honkin' caveat that different manufacturers are using different technologies with their sensors in each segment. In the real world, it's more like ISO 100 on APS-C has half the noise as ISO 100 on 4/3, and so on...your MF back might not actually do all that well at ISO 3200, but its ISO 200 will be at least as clean as ISO 100 on full frame.

And, of course, we're also talking about actual prints, not pixel peeping or other meaningless measures.

Cheers,

b&

[TrumpetPower!]

"As I already explained, it is a question of how much enlargement is necessary for a print."

this is about pixels, no film, as long you have 1,6 times better lenses and use f8  and the signal/noise is equal
from the  APS 24 mp  and the  24 mp 24x36 there is no enlargements advantages with 24x36
It is a pure optical question= we need 1,6 better lenses on the APS

Mikael, if what you wrote were true, then a 4000 ppi, 22 megapickle scan of a 35mm negative would produce just as good an 8" x 10" print as a 500 ppi, 20 megapickle scan of an 8" x 10" negative from a view camera. Or, that a 5DIII would make as good a print as a 20 megapickle 8x10 view camera back.

It would also mean that this 18 megapickle toy:

http://www.amazon.com/Cybersnap-1018-Micro-Digital-Camera/dp/B007PVMKPU/ref=sr_1_35?s=photo&ie=UTF8&qid=1358787121&sr=1-35

would beat the pants off of the original 1Ds with its wimpy 11 megapickles.

And that assertion is so laughably idiotic that there's no point in further discussion with you.

Seriously, dude. Get a clue. You're in more need of one than any I've seen here in a looooooooong time.

Cheers,

b&

[AlanF]

I have been using a 7D for 3 years for bird photography and earlier this month I bought a 5D III, with which I am absolutely delighted. But, the old 7D can hold its own at the limits of resolution. This is not scientific as only two photos are compared under slightly different conditions, but they do illustrate the advantages of pixel density at 100% crops for fine detail. Both were in raw, 100% crops and with the 300mm f/2.8 II + 2xTC at f/8. The 7D was at iso 320 and /1250, the 5D III at 800 and 1/500 (so same amount of light but the 7D was given an iso advantage). The 7D shot is less pixillated (1332x1218 vs 809x726) and there is slihgtly better resolution of the feathers on the back. Last night, I took a snow scene lit by lamplight at 1/40 sec and iso 12,800 with the 5D III - I couldn't have done this on on the 7D. It's horses for courses.

[TrumpetPower!]

The 7D shot is less pixillated (1332x1218 vs 809x726) and there is slihgtly better resolution of the feathers on the back.

The 5DIII shot is also a bit underexposed, which isn't doing it any good. Indeed, the loss of IQ because of that underexposure is roughly comparable to the resolution gain of the 7D.

The two are close enough that I wouldn't make the decision of which camera to pick up based on raw resolution. Instead, I'd go with the 5DIII for its superior autofocus performance -- and, presumably, for the not-yet-real 7DII for its autofocus equal to the 5DIII but higher resolution and faster framerate. But I still might pick a 1DX instead of either, despite its lower pixel density, for its superior metering ability plus its even marginally better autofocus performance plus its absolutely insane framerate.

Cheers,

b&

[NormanBates]

Indeed, film is different, it's as if you were comparing a 18 mpix APS-C sensor with a 50 mpix fullframe sensor.
My test is of that which is relevant to me: close to 20 mpix on both

Also, my test is of that which is relevant to me, which means it's basically useles for birding fans

[RLPhoto]

Indeed, film is different, it's as if you were comparing a 18 mpix APS-C sensor with a 50 mpix fullframe sensor.
My test is of that which is relevant to me: close to 20 mpix on both

Also, my test is of that which is relevant to me, which means it's basically useles for birding fans

.

Just saw your tests, Nice job. FF takes a wet dump on APS-C for sharpness, and MF would do the same for FF 35mm.

[AlanF]

The 7D shot is less pixillated (1332x1218 vs 809x726) and there is slihgtly better resolution of the feathers on the back.

The 5DIII shot is also a bit underexposed, which isn't doing it any good. Indeed, the loss of IQ because of that underexposure is roughly comparable to the resolution gain of the 7D.

The two are close enough that I wouldn't make the decision of which camera to pick up based on raw resolution. Instead, I'd go with the 5DIII for its superior autofocus performance -- and, presumably, for the not-yet-real 7DII for its autofocus equal to the 5DIII but higher resolution and faster framerate. But I still might pick a 1DX instead of either, despite its lower pixel density, for its superior metering ability plus its even marginally better autofocus performance plus its absolutely insane framerate.

Cheers,

b&

I had made a decision to buy the 5D III, it is a phenomenal piece of kit and, most importantly with incredible autofocus consistency. The 7D is 3 years older technology. I showed those shots to show that even with outdated technology, pixel density can be important - I am not arguing to buy a 7D. We'll see what a more modern APS-C can do if ever the 7D II arrives.

[Sporgon]

"As I already explained, it is a question of how much enlargement is necessary for a print."

this is about pixels, no film there you are enlarging grain etc , as long you have 1,6 times better lenses and use f8  and the signal/noise is equal from the  APS 24 mp  and the  24 mp 24x36 there is no enlargements advantages with 24x36
It is a pure optical question= we need 1,6 better lenses on the APS

Whoa !! Come on guys, Mikael is right here. I'm amazed how many people still confuse format with digital image size. It must be all us old gits who come from film.

To use 18 MP as example, 18MP of digital info is 18MP - it doesn't matter what format it's in ! A 5D mk1 file has to be "enlarged" more than that from a 7D. Talking of enlarging an APS file "40" times is wrong - who ever said that does not understand what is happening to enable them to view this digital data as a picture. Enlarge an APS Film negative 40 times - yes.

I'm surprised Neuro hasn't jumped in and put that one straight !

[rs]

"As I already explained, it is a question of how much enlargement is necessary for a print."

this is about pixels, no film there you are enlarging grain etc , as long you have 1,6 times better lenses and use f8  and the signal/noise is equal from the  APS 24 mp  and the  24 mp 24x36 there is no enlargements advantages with 24x36
It is a pure optical question= we need 1,6 better lenses on the APS

Whoa !! Come on guys, Mikael is right here. I'm amazed how many people still confuse format with digital image size. It must all us old gits who come from film.

To use 18 MP as example, 18MP of digital info is 18MP - it doesn't matter what format it's in ! A 5D mk1 file has to be "enlarged" more than that from a 7D. Talking of enlarging an APS file "40" times is rubbish - who ever said that does not understand what is happening to enable them to view this digital data as a picture. Enlarge an APS Film negative 40 times - yes.

I'm surprised Neuro hasn't jumped in and put that one straight !

If we're talking about two cameras, both with 18MP of digital perfection, then presuming each has a lens up to the demands of the sensor, there will be no difference. But we are far from perfection, and as lots of this process is analogue, we never will reach digital perfection. Any two sensors of the same tech generation of different sizes will have very different characteristics. The smaller sensor, even if it has the same number of MP (such as a 7D vs a 1D X) will inevitably have smaller individual pixels, each able to gather less light than their FF equivalent and require more amplification to get the same rated sensitivities. This extra amplification of a weaker signal leads to more noise.

Just as adding MP to any one sensor doesn't harm as the final image is the sum total of all the pixels (the entire sensor), the larger sensor will always have an overall advantage - the larger sensor as a whole is able to capture more light. In that way, the analogy of two different size cuts from the same film (read same tech generation) is spot on. The larger one will always win.

Since sensors reached about 10+ MP, magnification of the sensor became much more important than how big each individual pixel is printed. If not, a Nokia Pureview 808 would be better than all but the latest medium format digital backs.

[Sporgon]

"As I already explained, it is a question of how much enlargement is necessary for a print."

this is about pixels, no film there you are enlarging grain etc , as long you have 1,6 times better lenses and use f8  and the signal/noise is equal from the  APS 24 mp  and the  24 mp 24x36 there is no enlargements advantages with 24x36
It is a pure optical question= we need 1,6 better lenses on the APS

Whoa !! Come on guys, Mikael is right here. I'm amazed how many people still confuse format with digital image size. It must all us old gits who come from film.

To use 18 MP as example, 18MP of digital info is 18MP - it doesn't matter what format it's in ! A 5D mk1 file has to be "enlarged" more than that from a 7D. Talking of enlarging an APS file "40" times is rubbish - who ever said that does not understand what is happening to enable them to view this digital data as a picture. Enlarge an APS Film negative 40 times - yes.

I'm surprised Neuro hasn't jumped in and put that one straight !

If we're talking about two cameras, both with 18MP of digital perfection, then presuming each has a lens up to the demands of the sensor, there will be no difference. But we are far from perfection, and as lots of this process is analogue, we never will reach digital perfection. Any two sensors of the same tech generation of different sizes will have very different characteristics. The smaller sensor, even if it has the same number of MP (such as a 7D vs a 1D X) will inevitably have smaller individual pixels, each able to gather less light than their FF equivalent and require more amplification to get the same rated sensitivities. This extra amplification of a weaker signal leads to more noise.

Just as adding MP to any one sensor doesn't harm as the final image is the sum total of all the pixels (the entire sensor), the larger sensor will always have an overall advantage - the larger sensor as a whole is able to capture more light. In that way, the analogy of two different size cuts from the same film (read same tech generation) is spot on. The larger one will always win.

Since sensors reached about 10+ MP, magnification of the sensor became much more important than how big each individual pixel is printed. If not, a Nokia Pureview 808 would be better than all but the latest medium format digital backs.

What you say is correct, but the enlargement required to produce a given picture size from a 7D and a 1DX is the same, irrespective of whether the resulting picture from the 1DX is better or not.

[TrumpetPower!]

If we're talking about two cameras, both with 18MP of digital perfection, then presuming each has a lens up to the demands of the sensor, there will be no difference.

Eh, no.

Not even close.

Camera A has a square sensor, 1" x 1". Camera B has a square sensor, 2" x 2". Both cameras have a 1024-by-1024 pixel array, for a grand total of one megapickle. Both sensors are digital nirvana, counting photons at the very limit of what quantum mechanics allows.

Each of camera B's pixels can gather four times as many photons as camera A's pixels. Camera B has two stops more dynamic range and the gradients it captures are two stops smoother, with two stops less pixelation. Make a 2" x 2" print from both, and the one from camera B will show two stops more detail and appear that much sharper.

Still not convinced?

Imagine that the sensors are so small and so densely packed that a single photon is enough to fill one of camera a's pixel wells. It can only record black and white, but it does so at amazingly high resolution. Camera B's pixels, on the other hand, are twice the linear dimension, so each photosite can record the presence of 0, 1, 2, 3, or 4 photons. The end result for camera A is a 1 megapickle black and white image; the end result for camera B is a 1 megapickle four-bit grayscale image. Obviously, camera B's image contains a great deal more information -- and it looks it, too.

Cheers,

b&

[rs]

"As I already explained, it is a question of how much enlargement is necessary for a print."

this is about pixels, no film there you are enlarging grain etc , as long you have 1,6 times better lenses and use f8  and the signal/noise is equal from the  APS 24 mp  and the  24 mp 24x36 there is no enlargements advantages with 24x36
It is a pure optical question= we need 1,6 better lenses on the APS

Whoa !! Come on guys, Mikael is right here. I'm amazed how many people still confuse format with digital image size. It must all us old gits who come from film.

To use 18 MP as example, 18MP of digital info is 18MP - it doesn't matter what format it's in ! A 5D mk1 file has to be "enlarged" more than that from a 7D. Talking of enlarging an APS file "40" times is rubbish - who ever said that does not understand what is happening to enable them to view this digital data as a picture. Enlarge an APS Film negative 40 times - yes.

I'm surprised Neuro hasn't jumped in and put that one straight !

If we're talking about two cameras, both with 18MP of digital perfection, then presuming each has a lens up to the demands of the sensor, there will be no difference. But we are far from perfection, and as lots of this process is analogue, we never will reach digital perfection. Any two sensors of the same tech generation of different sizes will have very different characteristics. The smaller sensor, even if it has the same number of MP (such as a 7D vs a 1D X) will inevitably have smaller individual pixels, each able to gather less light than their FF equivalent and require more amplification to get the same rated sensitivities. This extra amplification of a weaker signal leads to more noise.

Just as adding MP to any one sensor doesn't harm as the final image is the sum total of all the pixels (the entire sensor), the larger sensor will always have an overall advantage - the larger sensor as a whole is able to capture more light. In that way, the analogy of two different size cuts from the same film (read same tech generation) is spot on. The larger one will always win.

Since sensors reached about 10+ MP, magnification of the sensor became much more important than how big each individual pixel is printed. If not, a Nokia Pureview 808 would be better than all but the latest medium format digital backs.

What you say is correct, but the enlargement required to produce a given picture size from a 7D and a 1DX is the same, irrespective of whether the resulting picture from the 1DX is better or not.

It depends upon whether you're talking about enlargement of each digital pixel in the file, or enlargement of the sensor/film. Enlargement of the sensor (with any moderately large MP sensor) is much more closely linked to image quality than enlargement of the digital file.

[rs]

If we're talking about two cameras, both with 18MP of digital perfection, then presuming each has a lens up to the demands of the sensor, there will be no difference.

Eh, no.

Not even close.

Camera A has a square sensor, 1" x 1". Camera B has a square sensor, 2" x 2". Both cameras have a 1024-by-1024 pixel array, for a grand total of one megapickle. Both sensors are digital nirvana, counting photons at the very limit of what quantum mechanics allows.

Each of camera B's pixels can gather four times as many photons as camera A's pixels. Camera B has two stops more dynamic range and the gradients it captures are two stops smoother, with two stops less pixelation. Make a 2" x 2" print from both, and the one from camera B will show two stops more detail and appear that much sharper.

Still not convinced?

Imagine that the sensors are so small and so densely packed that a single photon is enough to fill one of camera a's pixel wells. It can only record black and white, but it does so at amazingly high resolution. Camera B's pixels, on the other hand, are twice the linear dimension, so each photosite can record the presence of 0, 1, 2, 3, or 4 photons. The end result for camera A is a 1 megapickle black and white image; the end result for camera B is a 1 megapickle four-bit grayscale image. Obviously, camera B's image contains a great deal more information -- and it looks it, too.

Cheers,

b&

I fully agree with you. That's why I followed that first sentence with 'But we are far from perfection, and as lots of this process is analogue, we never will reach digital perfection', and then went on to say 'the larger sensor as a whole is able to capture more light'