IQ advantage of Aps-c vs cropping FF?

[tbcass]

but you are introducing extra variables [different pixel pitch, not same generation, probably not same lense]. this discussion is far more limited

Yes, of course I included more to the discussion: Our colleague asked if the results would be the same in IQ. And image quality is not only about pixel count. Noise itself is something that vastly influences on the results in question! Otherwise, the discussion won't find much link to the real world, don't you think?

No the OP said this "with the same pixel density and everything else equal". To me, everything else equal means just that, the exact same sensor except for the size.

 

[tbcass]

By equal, what is meant is pixels per duck. (birder term...)

What it means is that if after cropping the FF shot you still have the same amount of pixels you have in the APS one, yes the image will be (more or less) the same.

The problem is that if ,say, your FF has a 42MP sensor, the APS crops gives you 18MP, so in this case the 24MP APS version would be better.

If you start with a FF 24MP sensor, well you end up with 10MP....

He said the same pixel pitch which means the same resolution.

 

[tbcass]

Only talking image quality, is there an advantage of using an Aps-c camera over cropping a FF (with the same pixel density and everything else equal) to get more "reach"? Or will the result be identical?

There might be an advantage in using a particular APS-C camera over a particular FF camera, or the advantage might go the other way round. As a generalisation though, if the pixel size is the same then the APS-C and cropped FF will produce exactly the same result. This is particularly true because if the pixel size and tech (i.e, FSI vs BSI) is the same and the sensor manufacturer is the same, it's highly likely that the pixel design itself will be the same and thus work exactly the same way.

Absolutely correct. I got frustrated with some of the answers which deviated from the original premise.

 

[PHAER]

but you are introducing extra variables [different pixel pitch, not same generation, probably not same lense]. this discussion is far more limited

Yes, of course I included more to the discussion: Our colleague asked if the results would be the same in IQ. And image quality is not only about pixel count. Noise itself is something that vastly influences on the results in question! Otherwise, the discussion won't find much link to the real world, don't you think?

No the OP said this "with the same pixel density and everything else equal". To me, everything else equal means just that, the exact same sensor except for the size.

Cropping the post of our colleague:

"Only talking image quality, is there an advantage of using an Aps-c camera over cropping a FF (with the same pixel density and everything else equal) to get more "reach"? Or will the result be identical?"

I honestly understood choosing an APS-C camera over another one, FF, and cropping to compensate for the crop factor.

 

[PHAER]

By equal, what is meant is pixels per duck. (birder term...)

What it means is that if after cropping the FF shot you still have the same amount of pixels you have in the APS one, yes the image will be (more or less) the same.

The problem is that if ,say, your FF has a 42MP sensor, the APS crops gives you 18MP, so in this case the 24MP APS version would be better.

If you start with a FF 24MP sensor, well you end up with 10MP....

He said the same pixel pitch which means the same resolution.

He said same pixel density, which doesn't mean same resolution, but same ratio between resolution and sensor size.

 

[PHAER]

Only talking image quality, is there an advantage of using an Aps-c camera over cropping a FF (with the same pixel density and everything else equal) to get more "reach"? Or will the result be identical?

There might be an advantage in using a particular APS-C camera over a particular FF camera, or the advantage might go the other way round. As a generalisation though, if the pixel size is the same then the APS-C and cropped FF will produce exactly the same result. This is particularly true because if the pixel size and tech (i.e, FSI vs BSI) is the same and the sensor manufacturer is the same, it's highly likely that the pixel design itself will be the same and thus work exactly the same way.

I honestly understood he was comparing two different hypothetical cameras: choosing an aps-c over another one, FF. Keeping same pixel density, not pixel count.

"Only talking image quality, is there an advantage of using an Aps-c camera over cropping a FF (with the same pixel density and everything else equal) to get more "reach"? Or will the result be identical?"

But question still remains: taking same pixel density, same lens, same situation where, for example, ISO 12800 is necessary for the exposure. The image quality would be exactely the same between the aps-c and the FF file, cropped?

 

[bobn2]

Only talking image quality, is there an advantage of using an Aps-c camera over cropping a FF (with the same pixel density and everything else equal) to get more "reach"? Or will the result be identical?

There might be an advantage in using a particular APS-C camera over a particular FF camera, or the advantage might go the other way round. As a generalisation though, if the pixel size is the same then the APS-C and cropped FF will produce exactly the same result. This is particularly true because if the pixel size and tech (i.e, FSI vs BSI) is the same and the sensor manufacturer is the same, it's highly likely that the pixel design itself will be the same and thus work exactly the same way.

I honestly understood he was comparing two different hypothetical cameras: choosing an aps-c over another one, FF. Keeping same pixel density, not pixel count.

"Only talking image quality, is there an advantage of using an Aps-c camera over cropping a FF (with the same pixel density and everything else equal) to get more "reach"? Or will the result be identical?"

But question still remains: taking same pixel density, same lens, same situation where, for example, ISO 12800 is necessary for the exposure. The image quality would be exactly the same between the aps-c and the FF file, cropped?

Whether or not it would depends on the particular cameras, since not all cameras of the same sensor and pixel size perform the same. That's why I raised the issue of whether it was a generalisation or based on p[articular cameras. If it is a generalisation, we need to build in some base assumptions. The particular one is that the pixels are the same size and to the same design, and the rest of the capture chain remains the same, including the same readout speed. In that case the APS-C and cropped FF file would be identical.

I'm not sure of the idea of 'ISO 12800 being necessary for exposure'. You choose the exposure that you will use when you choose an ISO. Exposure is your choice, not 'necessary'. It may that the exposure that goes with ISO 12800 is necessitated by your requirements for depth of field and shutter speed, given the scene luminance available.

 

[PHAER]

Only talking image quality, is there an advantage of using an Aps-c camera over cropping a FF (with the same pixel density and everything else equal) to get more "reach"? Or will the result be identical?

There might be an advantage in using a particular APS-C camera over a particular FF camera, or the advantage might go the other way round. As a generalisation though, if the pixel size is the same then the APS-C and cropped FF will produce exactly the same result. This is particularly true because if the pixel size and tech (i.e, FSI vs BSI) is the same and the sensor manufacturer is the same, it's highly likely that the pixel design itself will be the same and thus work exactly the same way.

I honestly understood he was comparing two different hypothetical cameras: choosing an aps-c over another one, FF. Keeping same pixel density, not pixel count.

"Only talking image quality, is there an advantage of using an Aps-c camera over cropping a FF (with the same pixel density and everything else equal) to get more "reach"? Or will the result be identical?"

But question still remains: taking same pixel density, same lens, same situation where, for example, ISO 12800 is necessary for the exposure. The image quality would be exactly the same between the aps-c and the FF file, cropped?

Whether or not it would depends on the particular cameras, since not all cameras of the same sensor and pixel size perform the same. That's why I raised the issue of whether it was a generalisation or based on p[articular cameras. If it is a generalisation, we need to build in some base assumptions. The particular one is that the pixels are the same size and to the same design, and the rest of the capture chain remains the same, including the same readout speed. In that case the APS-C and cropped FF file would be identical.

I'm not sure of the idea of 'ISO 12800 being necessary for exposure'. You choose the exposure that you will use when you choose an ISO. Exposure is your choice, not 'necessary'. It may that the exposure that goes with ISO 12800 is necessitated by your requirements for depth of field and shutter speed, given the scene luminance available.

the idea of the high ISO is a development of what I said on my first post, considering that I understood the OP was refering to two different cameras, one aps-c and another FF.

"On good light, I'd say they will be very very similar. On worst light conditions, not really."

I guess I should quote him again to clarify stuff...

 

[PHAER]

Only talking image quality, is there an advantage of using an Aps-c camera over cropping a FF (with the same pixel density and everything else equal) to get more "reach"? Or will the result be identical?

After some development of the discussion here, I guess one point should be clarified (I'm sorry if I misunderstood): Would it be about two different cameras, one with aps-c and another with FF?

 

[BackToNature1]

Only talking image quality, is there an advantage of using an Aps-c camera over cropping a FF (with the same pixel density and everything else equal) to get more "reach"? Or will the result be identical?

It matters not if we are talking same brands and similar tech. There is a given point where having more Lens on the the Subject will far outweigh the advantages of FF over smaller sensor sizes. Aka that cropped Factor.

No matter how many times folks will tell you otherwise. If the FF camera does not have enough reach for the Camera and Lens combo to adequately focus on the subject but the cropped camera does have it, one will see a Crystal Clear Advantage.

 

[FingerPainter]

If all else is equal , then you are using the same lens, so sharpness should be the same. However, if both sensors have the same pixel pitch, then the larger sensor has more pixels. This means the larger sensor will probably exhibit a fraction of a stop more read noise, especially at low exposures (high ISO).

Not true because pixel density is the same which was a qualifier mentioned by the OP. The cropped FF is the same as the APSC.

Pixel density is the same (not pixel count on the two sensors). The larger sensor is larger. Therefore there are ~2.25 times as many pixels on the larger sensor. More pixels means more read operations, which generally means more read noise.

OP Said "cropping a FF" [image]. This implies that the whole FF image was captured and then cropped, so those extra read operations did take place.

You may wish to note that even though the Z7II and the Z50 have similar pixel sizes and similar pixel architecture, the Z50 has about 1/3 stop better ISO performance than the APS-C crop of the Z7II. (See Photons to Photos). It is no coincidence that the Z7II has about 2.25 times as many pixels as the Z50.

 

[bodeswell]

Only talking image quality, is there an advantage of using an Aps-c camera over cropping a FF (with the same pixel density and everything else equal)

That’s the tricky part. If you meant to ask a purely theoretical question you have gotten the answer.

If you are wondering whether you should get say, an R5 or an R7- just because I happen to be a Canon shooter- well, you should get the R7 if “reach” is what you are prioritizing.

to get more "reach"? Or will the result be identical?

 

[sybersitizen]

Only talking image quality, is there an advantage of using an Aps-c camera over cropping a FF (with the same pixel density and everything else equal) to get more "reach"?

No, not if the sensor technology is the same.

Yes, precs9ley because the sensors tech is the same. The amount of read noise depends in part on the number of read operations. More pixel of the same tech then produce a larger total of read noise.

First, you should see if bobn2 agrees with you. At the moment he's agreeing with me:

https://www.dpreview.com/forums/thread/4692352#forum-post-66771402

Second, one of you should explain why reading more pixels would result in more read noise per pixel.

Third, if reading more pixels results in more read noise per pixel, it would be helpful to explain how much less noise the OP should expect with an APS-C camera so the presumed advantage can at least be somewhat quantified.

Or will the result be identical?

As close to identical as two results can be.

 

[sybersitizen]

Only talking image quality, is there an advantage of using an Aps-c camera over cropping a FF (with the same pixel density and everything else equal) to get more "reach"? Or will the result be identical?

The FF lens will be computed to cover the FF sensor, while the APS-C lens is made for the smaller circle. I'd expect more sharpness in APS-C. But that is not necessarily so. Modern FF lenses are sharpest in the center, neglecting the corners when wide open.

Nothing was said about using different lenses. Since everything else is equal, the lens is equal, and presumably it's the same lens.

 

[Dem Bell]

If all else is equal , then you are using the same lens, so sharpness should be the same. However, if both sensors have the same pixel pitch, then the larger sensor has more pixels. This means the larger sensor will probably exhibit a fraction of a stop more read noise, especially at low exposures (high ISO).

Not true because pixel density is the same which was a qualifier mentioned by the OP. The cropped FF is the same as the APSC.

Pixel density is the same (not pixel count on the two sensors). The larger sensor is larger. Therefore there are ~2.25 times as many pixels on the larger sensor. More pixels means more read operations, which generally means more read noise.

per pixel?

OP Said "cropping a FF" [image]. This implies that the whole FF image was captured and then cropped, so those extra read operations did take place.

You may wish to note that even though the Z7II and the Z50 have similar pixel sizes and similar pixel architecture, the Z50 has about 1/3 stop better ISO performance than the APS-C crop of the Z7II. (See Photons to Photos). It is no coincidence that the Z7II has about 2.25 times as many pixels as the Z50.

True, but how do we know what explains this difference?

 

[Photografica]

Only talking image quality, is there an advantage of using an Aps-c camera over cropping a FF (with the same pixel density and everything else equal) to get more "reach"? Or will the result be identical?

The FF lens will be computed to cover the FF sensor, while the APS-C lens is made for the smaller circle. I'd expect more sharpness in APS-C. But that is not necessarily so. Modern FF lenses are sharpest in the center, neglecting the corners when wide open.

Nothing was said about using different lenses. Since everything else is equal, the lens is equal, and presumably it's the same lens.

That is correct! Thanks for all the answers! Much appreciated.

 

[robgendreau]

Only talking image quality, is there an advantage of using an Aps-c camera over cropping a FF (with the same pixel density and everything else equal) to get more "reach"? Or will the result be identical?

The FF lens will be computed to cover the FF sensor, while the APS-C lens is made for the smaller circle. I'd expect more sharpness in APS-C. But that is not necessarily so. Modern FF lenses are sharpest in the center, neglecting the corners when wide open.

Nothing was said about using different lenses. Since everything else is equal, the lens is equal, and presumably it's the same lens.

That is correct! Thanks for all the answers! Much appreciated.

If you meant a different but basically equal sensor, APS-C vs FF, then there isn't much change (a benefit might be faster bursts on the APS-C, although some full frames take advantage of that in crop mode too). It can be a dandy way to realize that you've missed focus or that the lens wasn't as good as you thought it was

 

[tbcass]

If all else is equal , then you are using the same lens, so sharpness should be the same. However, if both sensors have the same pixel pitch, then the larger sensor has more pixels. This means the larger sensor will probably exhibit a fraction of a stop more read noise, especially at low exposures (high ISO).

Not true because pixel density is the same which was a qualifier mentioned by the OP. The cropped FF is the same as the APSC.

Pixel density is the same (not pixel count on the two sensors). The larger sensor is larger. Therefore there are ~2.25 times as many pixels on the larger sensor. More pixels means more read operations, which generally means more read noise.

I don't think so because the read operations are spread evenly across the sensor so the net S/N ratio is the same because the noise per pixel is the same.

OP Said "cropping a FF" [image]. This implies that the whole FF image was captured and then cropped, so those extra read operations did take place.

But spread evenly across the sensor.

You may wish to note that even though the Z7II and the Z50 have similar pixel sizes and similar pixel architecture, the Z50 has about 1/3 stop better ISO performance than the APS-C crop of the Z7II. (See Photons to Photos). It is no coincidence that the Z7II has about 2.25 times as many pixels as the Z50.

--
Tom

 

[tbcass]

By equal, what is meant is pixels per duck. (birder term...)

What it means is that if after cropping the FF shot you still have the same amount of pixels you have in the APS one, yes the image will be (more or less) the same.

The problem is that if ,say, your FF has a 42MP sensor, the APS crops gives you 18MP, so in this case the 24MP APS version would be better.

If you start with a FF 24MP sensor, well you end up with 10MP....

He said the same pixel pitch which means the same resolution.

He said same pixel density, which doesn't mean same resolution, but same ratio between resolution and sensor size.

It means the cropped FF image will have the same resolution as the uncropped APSC sensor.

 

[tbcass]

Only talking image quality, is there an advantage of using an Aps-c camera over cropping a FF (with the same pixel density and everything else equal) to get more "reach"? Or will the result be identical?

There might be an advantage in using a particular APS-C camera over a particular FF camera, or the advantage might go the other way round. As a generalisation though, if the pixel size is the same then the APS-C and cropped FF will produce exactly the same result. This is particularly true because if the pixel size and tech (i.e, FSI vs BSI) is the same and the sensor manufacturer is the same, it's highly likely that the pixel design itself will be the same and thus work exactly the same way.

I honestly understood he was comparing two different hypothetical cameras: choosing an aps-c over another one, FF. Keeping same pixel density, not pixel count.

If the pixel density is the same the FF sensor will have a greater pixel count.

"Only talking image quality, is there an advantage of using an Aps-c camera over cropping a FF (with the same pixel density and everything else equal) to get more "reach"? Or will the result be identical?"

But question still remains: taking same pixel density, same lens, same situation where, for example, ISO 12800 is necessary for the exposure. The image quality would be exactely the same between the aps-c and the FF file, cropped?

Yes IF the sensor technology is the same. In this case, we are talking about cutting from the same type of die which is usually the case. The reason FF sensors cost more is that you get fewer sensors out of the same die.

--
Tom