Do crop sensor camera's lose sharpness in the same frame?

[Tim Deen]

I understand the basics of a crop sensor vs. a full frame sensor. The crop sensor catches a narrower field of view at a same focal length. The crop factor is the factor between the size of a full frame sensor and a crop sensor. All clear.

What I fail to understand though is when you start comparing images. An often praised feat of crop sensor camera's is the fact that you can enlarge your subject. But what does actually happen? Does the image get enlarged to the same frame as an full frame image (if you compare FF to crop)? And thus resulting in a more zoomed in image?

And if this is the case, do crop sensor images lose sharpness due to being enlarged within a same frame?

 

[robert1955]

An often praised feat of crop sensor camera's is the fact that you can enlarge your subject. But what does actually happen? Does the image get enlarged to the same frame as an full frame image (if you compare FF to crop)? And thus resulting in a more zoomed in image?

I hope I understand you right. If I do you have misunderstood this a bit.

Nothing gets enlarged.

The image gets enlarged when it's viewed. It's maybe 24 mm x 36 mm on the sensor, but you're going to view it much bigger than that. That's enlarged.

An image has no dimension..

The sensor is just a tool to record an image but the result is dimensionless.

You can imagine taking the exact same image, one with FF and the other with APS-C with the same resolution. You would have 2 identical image files. What would it mean to say that the image with the crop sensor needs more enlargment ??

Also, it is important to note that the resolution is present in the image from start. An image has a given resolution (calculated as LW/PH, H is height of the image). So the resolution is understood as resolution per image.

Seems to me you are contradicting your first paragraph. So the image as recorded is actually 'dimensionful' [to coin a word]?

For me there is no enlargment. It is much better to say that an image has been recorded with a sensor of a given size.

 

[Michael Fryd]

An often praised feat of crop sensor camera's is the fact that you can enlarge your subject. But what does actually happen? Does the image get enlarged to the same frame as an full frame image (if you compare FF to crop)? And thus resulting in a more zoomed in image?

I hope I understand you right. If I do you have misunderstood this a bit.

Nothing gets enlarged. Simply put It's just that due to the smaller sensor a lens with a certain focal length makes the subject fill a larger part of the sensor.

Say you want to photograph birds. You have 200mm lens. On a FF you'd need to get very close to small bird to make it fill the sensor. Put the same lens on a MFT camera and it would become a lot more likely that you'd manage to do that, because it corresponds to a 400 mm lens on a FF - and that's because the sensor is smaller, nothing else.

The so called cropping happens at the sensor. Not that it's possible, but imagine you shoot that 200mm lens on a FF camera, but you have cut its sensor down to the size of an MFT sensor. That would give you the same result when it comes to how large a part of the sensor the subject fills..

This is a question of terminology. It doesn't affect the results, just how they are described.

"Enlargement" typically refers to the size of the image as projected on the film/sensor, to the size of the image presented to the viewer.

"Magnification" typically refers to the size of the object as projected onto the sensor/film compared to the size of the object in real life.

Digital files are often described by the pixel dimensions. For instance we might refer to a 4000px by 6000px file. That file might also be described as a 24 megapixel file, as it contains about 24 million pixels.

The metadata of a digital file might contain a "DPI" value. This is a suggested pixel density to use when printing the file. If a 4000x6000px file has a suggested DPI of 400 pixels per inch, then we might say that it is a 10" by 15", 400ppi image. This usage is more common with novices.

 

[meow]

An often praised feat of crop sensor camera's is the fact that you can enlarge your subject. But what does actually happen? Does the image get enlarged to the same frame as an full frame image (if you compare FF to crop)? And thus resulting in a more zoomed in image?

I hope I understand you right. If I do you have misunderstood this a bit.

Nothing gets enlarged. Simply put It's just that due to the smaller sensor a lens with a certain focal length makes the subject fill a larger part of the sensor.

Say you want to photograph birds. You have 200mm lens. On a FF you'd need to get very close to small bird to make it fill the sensor. Put the same lens on a MFT camera and it would become a lot more likely that you'd manage to do that, because it corresponds to a 400 mm lens on a FF - and that's because the sensor is smaller, nothing else.

The so called cropping happens at the sensor. Not that it's possible, but imagine you shoot that 200mm lens on a FF camera, but you have cut its sensor down to the size of an MFT sensor. That would give you the same result when it comes to how large a part of the sensor the subject fills..

I understand that everything, when the photo is taken remains the same size. The smaller sensor just takes a smaller portion of the subject your are making a picture of.
Where it went wrong for me is that I misunderstood that the image will look larger in a same frame, when compared to a FF sensor. To me it feels like the image gets enlarged in that case to match a similar frame of the FF image (taken it's not being cropped).

Thanks for your reply.

Well, in a way that is true. If you view both the FF and the MFT image at the same size the birdie in the MFT image will be larger. I mean if you view the images uncropped and resized to the same size or thereabout. Say you view both images in a §600 pixels wide window that shows 100% of the images.

On the other hand, the FF image will be larger (pixels). So you could crop it and again the birdie will fill more of the frame.

 

[sybersitizen]

I do have a remaining question though. Let's say the pixel density on both a FF sensor and a crop sensor is the same.

I assume that means the individual pixel sizes are the same. (If you instead meant the pixel counts are the same, that would be something different.*)

I take a picture of a subject with both a FF camera and a crop sensor camera.

I assume you're capturing the same field of view in both cases, and also assume there's no difference in the performance of the lens used on each camera.

I then project them within the same frame.

And that means you've viewing both results at the same size.

The crop sensor image would get enlarged to fit the frame.

And that means it's relying on fewer pixels to present an image of the same size.

Would I then lose sharpness due to enlarging the same pixel size compared to the FF sensor?

The cropped version would have lower resolution. If you view both versions in a way that allows you to discern what's going on at or near the pixel level, the lower resolution will indeed result in a less detailed image.

You can simulate this scenario with pretty much any camera. Shoot something (containing detail) using the entire sensor area. Shoot the same something from farther away so that it occupies a much smaller area of the sensor. Then crop and enlarge that second version to match the composition of the first one. Compare both in a way that allows you to discern what's going on at or near the pixel level.

* If the pixel counts are same, there is a possibility that the results from both sensors would be equally sharp. But it's more likely that the full frame sensor result would be at least slightly sharper.

 

[ThrillaMozilla]

Chrisfisheye,

When the OP wrote: "Does the image get enlarged to the same frame as an full frame image (if you compare FF to crop)? And thus resulting in a more zoomed in image?", I believe he was referring to comparing images at the same size. Apparently you have a different interpretation in mind, but I very much doubt that he was thinking of resampling the image with an increased number of pixels.

Some specific replies follow, but I think the following discussion is way off the subject.

An often praised feat of crop sensor camera's is the fact that you can enlarge your subject. But what does actually happen? Does the image get enlarged to the same frame as an full frame image (if you compare FF to crop)? And thus resulting in a more zoomed in image?

I hope I understand you right. If I do you have misunderstood this a bit.

Nothing gets enlarged.

The image gets enlarged when it's viewed. It's maybe 24 mm x 36 mm on the sensor, but you're going to view it much bigger than that. That's enlarged.

An image has no dimension..

Really? The real image is 24 mm x 36 mm in a full frame camera.

A 24 MB digital image is typically 4000 pixels x 6000 pixels.

Those are the dimensions.

Nope. A pixel is not a unit.

When you say 6000 pixels it is a pure quantity..

The sensor is just a tool to record an image but the result is dimensionless.

Really? A two-dimensional array is dimensionless? And the display is dimensionless?

You better look up the meaning of "dimension".

https://en.wikipedia.org/wiki/Pixel...dered in another way, a,a pixel density (ppi).

"Considered in another way, a pixel has no inherent size or unit (a pixel is actually a sample), but when it is printed, displayed, or scanned, then the pixel has both a physical size (dimension) and a pixel density (ppi).[1]"

Sorry, the quote says something about pixels, but nothing about images being dimensionless.

You are correct that a digital image array has no physical dimensions.* It does, however, have array dimensions.

Fun fact: The FORTRAN statement

DIMENSION iPixel (4000, 6000)

describes a 24 MP monochrome image with dimensions 4000x6000. (It's also a 2-dimensional array, obviously.)

You won't see the former use of the word "dimension" very often, because the word has several meanings. However, the former meaning does have well-established usage and precedents.

All of this seems way off the subject. However, after rereading the OP's posts, I am uncertain of his question. So if you can figure it out definitively, more power to you.

----

* Some images have embedded pixel pitch values, and thus have a defined physical size.

 

[Michael Fryd]

...

* If the pixel counts are same, there is a possibility that the results from both sensors would be equally sharp. But it's more likely that the full frame sensor result would be at least slightly sharper.

It's an interesting question.

Lenses tend to have the highest quality towards the center of the frame. Crop bodies use only that "sweet spot" in the center, and don't use the edges of the image circle, which tend to have more distortions and aberrations.

On the other hand, with a crop body you need more enlargement (the ratio of viewing size to the size of the image on the sensor). Higher enlargements magnify any imperfections. Therefore, a crop body needs a higher quality lens in order to maintain the same quality as a full frame. Of course, it's easier to make a higher quality lens, if you can get by with a smaller image circle.

In terms of sharpness, if the pixel counts are the same, there is no inherent advantage to a full frame over a crop body. It depends on the specifics of the lenses involved.

 

[bjn70]

I do have a remaining question though. Let's say the pixel density on both a FF sensor and a crop sensor is the same. I take a picture of a subject with both a FF camera and a crop sensor camera. I then project them within the same frame. The crop sensor image would get enlarged to fit the frame. Would I then lose sharpness due to enlarging the same pixel size compared to the FF sensor?

If by pixel density you mean the number of pixels on the sensor then this becomes a question of the capability of the lens. The lens used with the smaller sensor will need to be able to resolve detail better on the small sensor. It is possible to find lenses than can do this, you can read my earlier post where I did this exact thing comparing images from a 24MP crop sensor camera with a 24MP full frame camera.

If by pixel density you mean the number of pixels in a square mm of sensor area then the full frame sensor should be capable of more enlargement at the same amount of detail.

 

[bjn70]

I have not compared all camera sensor sizes and megapixel counts but I know that some digital cameras come with AA filters and some do not. An image from a camera that does not have the filter will appear sharper when pixel peeping than a camera that does have the filter. In my other post I mentioned a 24MP full frame camera (Nikon D750) that I compared with a 24MP crop sensor camera (Nikon D7200). The D750 has an AA filter, the D7200 does not, consequently the D7200 images had the appearance of being sharper when comparing on the same subject with lots of fine detail. So when comparing between 2 different cameras we have to select models that both have or both do not have the filter.

 

[John Sheehy]

Thanks, good to hear that my way of thought isn't wrong.

I do have a remaining question though. Let's say the pixel density on both a FF sensor and a crop sensor is the same. I take a picture of a subject with both a FF camera and a crop sensor camera.

Focal lengths? Distances? Can't answer your question fully without filling in those blanks.

I then project them within the same frame. The crop sensor image would get enlarged to fit the frame. Would I then lose sharpness due to enlarging the same pixel size compared to the FF sensor?

The idea of losing sharpness due to enlargement is problematic. You don't lose anything, as far as empirical detail is concerned. What you lose is the illusion of acuity that an image had at a lesser enlargement. One image can look much softer than another, as enlarged, but have far more detail. Our perceptual systems are suckers for conflating detail with acuity.

 

[Bob]

Have you ever cropped a photo? That's all it is when using a 'crop' sensor.

 

[Michael Fryd]

Have you ever cropped a photo? That's all it is when using a 'crop' sensor.

Most lenses are sharper in the center than towards the edge of the frame.

Consider a lens that is very sharp in the center, and not at all sharp near the edges of the frame. Cropping an image from such a lens can actually increase the average sharpness of the image.

 

[nick_bianchi]

I understand the basics of a crop sensor vs. a full frame sensor. The crop sensor catches a narrower field of view at a same focal length. The crop factor is the factor between the size of a full frame sensor and a crop sensor. All clear.

What I fail to understand though is when you start comparing images. An often praised feat of crop sensor camera's is the fact that you can enlarge your subject. But what does actually happen? Does the image get enlarged to the same frame as an full frame image (if you compare FF to crop)? And thus resulting in a more zoomed in image?

And if this is the case, do crop sensor images lose sharpness due to being enlarged within a same frame?

The best way to see the difference is to compare.

I use a Sony A7iii to shoot (mostly indoor) corporate events for my employer and a Fuji X-T5 and a X-H2s for my private pleasure.

As I’m less used to the Sony ergonomic and menus, I decided to compare the output of both systems to see if i should use my private gear for those shooting said events.

What does this mean: that I’m aware of the intrinsic difference between the tested FF and APSC sensors, esp. with different MPX counts, and of the “physics”. But what is important to me is to know if a similarly framed shot will be a lot better on the Sony than the X-T5.

The tests I made (same objects, child or pet models shot consecutively with each camera) ended in a clear winner:

My X-T5 shots at f/2.8 (Fuji XF 16-55 mki) and ISO 4000 were sharper and provided more details than the A7iii shots at f/4 - in order to have a similar DoF - (FE 24-70 mm f/2.8 GM II) at ISO 1600, after democaising in Pure Raw 4.

Therefore, there’s really no reason for me to masochistically force myself to use the Sony set up.

I’m fully aware that there are other factors that might prevail in other situations, e.g. Autofocus.

Also, that if I framed the APSC shot in a way that I would end up with 24 MPX instead of 40 in the scene that I’m interested in, the FF would benefit from the bigger pixels (thus increased light exposition). But in practice, this is not relevant.

But stating that FF is always has a clear edge over APSC is simply not true.

EDIT:

For the sake of accuracy, I shot a similar scene with the X-H2S and A7iii (both 26 vs 24 MPX). Same framing, similar DoF, both indoor ISO 5000.
From 200% level onward, the FF starts to shows better results (for example sharper eyelashes). Below this value, both look very similar. Note that this might be less pronounced with better lightning and lower ISO.
But this shows that with the same MPX count, the FF is ahead.
Is it worth going from APSC to FF? Not for me. I'd rather wait for a 40MPX stacked APSC sensor

 

[Dem Bell]

I understand the basics of a crop sensor vs. a full frame sensor. The crop sensor catches a narrower field of view at a same focal length. The crop factor is the factor between the size of a full frame sensor and a crop sensor. All clear.

What I fail to understand though is when you start comparing images. An often praised feat of crop sensor camera's is the fact that you can enlarge your subject. But what does actually happen? Does the image get enlarged to the same frame as an full frame image (if you compare FF to crop)? And thus resulting in a more zoomed in image?

And if this is the case, do crop sensor images lose sharpness due to being enlarged within a same frame?

The best way to see the difference is to compare.

I use a Sony A7iii to shoot (mostly indoor) corporate events for my employer and a Fuji X-T5 and a X-H2s for my private pleasure.

As I’m less used to the Sony ergonomic and menus, I decided to compare the output of both systems to see if i should use my private gear for those shooting said events.

What does this mean: that I’m aware of the intrinsic difference between the tested FF and APSC sensors, esp. with different MPX counts, and of the “physics”. But what is important to me is to know if a similarly framed shot will be a lot better on the Sony than the X-T5.

The tests I made (same objects, child or pet models shot consecutively with each camera) ended in a clear winner:

My X-T5 shots at f/2.8 (Fuji XF 16-55 mki) and ISO 4000 were sharper and provided more details than the A7iii shots at f/4 - in order to have a similar DoF - (FE 24-70 mm f/2.8 GM II) at ISO 1600, after democaising in Pure Raw 4.

Did you get the ISOs the wrong way round?

Were the shutter speeds the same?

Therefore, there’s really no reason for me to masochistically force myself to use the Sony set up.

I’m fully aware that there are other factors that might prevail in other situations, e.g. Autofocus.

Also, that if I framed the APSC shot in a way that I would end up with 24 MPX instead of 40 in the scene that I’m interested in, the FF would benefit from the bigger pixels (thus increased light exposition). But in practice, this is not relevant.

But stating that FF is always has a clear edge over APSC is simply not true.

EDIT:

For the sake of accuracy, I shot a similar scene with the X-H2S and A7iii (both 26 vs 24 MPX). Same framing, similar DoF, both indoor ISO 5000.

Equivalent f-stops, same ISOs, different shutter speeds? Not sure what this is testing.

From 200% level onward, the FF starts to shows better results (for example sharper eyelashes). Below this value, both look very similar. Note that this might be less pronounced with better lightning and lower ISO.
But this shows that with the same MPX count, the FF is ahead.
Is it worth going from APSC to FF? Not for me. I'd rather wait for a 40MPX stacked APSC sensor

 

[nick_bianchi]

No. Auto ISO. SS at 1/80 for all cameras in both tests.

Test 1:

X-T5, APSC 40MPX, same framing, f2.8, SS 1/80, Auto ISO (4000), Auto WB

A7iii, FF 24MPX, same framing, f4, SS 1/80, Auto ISO (1600), Auto WB

Demoicaising and noise reduction: PureRaw 4 (note: XD2S is not working for XxTrans sensors)

More details and better sharpness for X-T5 from 100% onwards.

Test 2:

X-H2S, APSC 26MPX, same framing, f2.8, SS 1/80, Auto ISO (5000), Auto WB

A7iii, FF 24MPX, same framing, f4, SS 1/80, Auto ISO (5000), Auto WB

Demoicaising and noise reduction: PureRaw 4 (note: XD2S is not working for XxTrans sensors)

Notably more details and better sharpness for A7iii from 200% onwards.



Although ISO was 1600 for the A7iii in the first test (vs X-T5), the X-T5 had a better result after PureRaw 4. Seems the X-T5 pushes ISO easier than the X-H2S. But Pure Raw does a great job denoising.

In the second case, Auto ISO put both the A7iii and X-H2S to ISO 5000 (Auto WB) despite the Sony being FF.

Therefore (as same SS), the comparison does make sense.

But the A7iii isn’t the last generation FF, whereas the Fuji is. This is another element to take into consideration. I intend to rent an A7C2 to make some test as well.

This non scientific but real world experience simply shows that the difference between FF and APSC for a given scene, same framing, same SS, similar DoF is negligible unless pixel peeping.

 

[dsjtecserv]

No. Auto ISO. SS at 1/80 for all cameras in both tests.

Test 1:

X-T5, APSC 40MPX, same framing, f2.8, SS 1/80, Auto ISO (4000), Auto WB

A7iii, FF 24MPX, same framing, f4, SS 1/80, Auto ISO (1600), Auto WB

You might have to explain how the full frame image with one stop less exposure and 1 1/3 stop lower ISO would give equivalent brightness for comparison. Were the lighting conditions the same for both; it would seem unlikely. Pushing it in raw would not be equivalent.

Demoicaising and noise reduction: PureRaw 4 (note: XD2S is not working for XxTrans sensors)

More details and better sharpness for X-T5 from 100% onwards.

Assuming that there is an explanation for the exposure discrepancy and you achieved same framing by focal length rather than altering the distance, then it is not at all surprising that the camera with the far greater pixel density delivered more detail. I am not sure a test would be needed to reach that conclusion. But that is not a function of sensors size per se, but just the pixel density of the individual cameras, which is independent of the size of their sensors.

In terms of sharpness, that is a function of a number of factors, not least of which are the lenses involved, but an image with more detail may appear sharper.

Test 2:

X-H2S, APSC 26MPX, same framing, f2.8, SS 1/80, Auto ISO (5000), Auto WB

A7iii, FF 24MPX, same framing, f4, SS 1/80, Auto ISO (5000), Auto WB

Demoicaising and noise reduction: PureRaw 4 (note: XD2S is not working for XxTrans sensors)

Notably more details and better sharpness for A7iii from 200% onwards.

Although ISO was 1600 for the A7iii in the first test (vs X-T5), the X-T5 had a better result after PureRaw 4. Seems the X-T5 pushes ISO easier than the X-H2S. But Pure Raw does a great job denoising.

In the second case, Auto ISO put both the A7iii and X-H2S to ISO 5000 (Auto WB) despite the Sony being FF.

Therefore (as same SS), the comparison does make sense.

But the A7iii isn’t the last generation FF, whereas the Fuji is. This is another element to take into consideration. I intend to rent an A7C2 to make some test as well.

This non scientific but real world experience simply shows that the difference between FF and APSC for a given scene, same framing, same SS, similar DoF is negligible unless pixel peeping.

Dave

--
http://www.pbase.com/dsjtecserv

 

[nick_bianchi]

No. Auto ISO. SS at 1/80 for all cameras in both tests.

Test 1:

X-T5, APSC 40MPX, same framing, f2.8, SS 1/80, Auto ISO (4000), Auto WB

A7iii, FF 24MPX, same framing, f4, SS 1/80, Auto ISO (1600), Auto WB

You might have to explain how the full frame image with one stop less exposure and 1 1/3 stop lower ISO would give equivalent brightness for comparison. Were the lighting conditions the same for both; it would seem unlikely. Pushing it in raw would not be equivalent.

Look, I don't try to understand how Sony and Fuji adjust the Auto Settings (ISO and WB).

When I'm sitting in my armchair, my kids on the Sofa opposite of me and I have both cameras on my lap, and I make all shots within one minute, I expect the conditions to as close to similar as possible.

Demoicaising and noise reduction: PureRaw 4 (note: XD2S is not working for XxTrans sensors)

More details and better sharpness for X-T5 from 100% onwards.

Assuming that there is an explanation for the exposure discrepancy and you achieved same framing by focal length rather than altering the distance, then it is not at all surprising that the camera with the far greater pixel density delivered more detail. I am not sure a test would be needed to reach that conclusion. But that is not a function of sensors size per se, but just the pixel density of the individual cameras, which is independent of the size of their sensors.

In terms of sharpness, that is a function of a number of factors, not least of which are the lenses involved, but an image with more detail may appear sharper.

You're right: I shot at 70mm on The Sony and 50mm (80mm FF) on the APSC. That would be the only "marginal" difference.

My goal was not to make a precise comparison between the two, but to find out if I'd lose a lot in skipping the Sony FF system for my trusted APSC one when I do corporate events.

And to point out that FF will not have the clear edge in any use case.
Esp. as many photographers (be it Wildlife, Landscape or Street, to mention only those) would usually chose the same shooting spot regardless of FF or APSC, and use the focal length to adjust the framing.

The question asked here was:
Do crop sensors lose sharpness (in comp. to FF) in the same frame?
The X-T5 definitely doesn't (but compared to a 4 year older A7iii). The X-H2S does very slightly. But only at pixel peeping level.
If I get a bit of sun, I'll take some time to shoot landscape at lowest ISO this week. This will give another perspective.
But the fact that there is no really perceptible difference indoor after denoising, which is where APSC usually struggles more, is quite positive.

Test 2:

X-H2S, APSC 26MPX, same framing, f2.8, SS 1/80, Auto ISO (5000), Auto WB

A7iii, FF 24MPX, same framing, f4, SS 1/80, Auto ISO (5000), Auto WB

Demoicaising and noise reduction: PureRaw 4 (note: XD2S is not working for XxTrans sensors)

Notably more details and better sharpness for A7iii from 200% onwards.

Although ISO was 1600 for the A7iii in the first test (vs X-T5), the X-T5 had a better result after PureRaw 4. Seems the X-T5 pushes ISO easier than the X-H2S. But Pure Raw does a great job denoising.

In the second case, Auto ISO put both the A7iii and X-H2S to ISO 5000 (Auto WB) despite the Sony being FF.

Therefore (as same SS), the comparison does make sense.

But the A7iii isn’t the last generation FF, whereas the Fuji is. This is another element to take into consideration. I intend to rent an A7C2 to make some test as well.

This non scientific but real world experience simply shows that the difference between FF and APSC for a given scene, same framing, same SS, similar DoF is negligible unless pixel peeping.

Dave

 

[Michael Fryd]

...

Look, I don't try to understand how Sony and Fuji adjust the Auto Settings (ISO and WB).

When I'm sitting in my armchair, my kids on the Sofa opposite of me and I have both cameras on my lap, and I make all shots within one minute, I expect the conditions to as close to similar as possible.

...

For very many circumstances you can get the same result from a crop body as a full frame. The trick is to select the right settings.

Where many people have trouble is that a certain setting value on a crop body will give a different result than that same setting on a full frame.

For instance, at the same angle of view, f/4 will capture less total light, and yield more depth of field than f/4 on a full frame.

Most are aware that a 50mm lens on a crop body yields a narrower field of view than 50mm on a full frame.

An ISO 400 exposure on a crop body will yield a noisier result than ISO 400 on a full frame.

The general rule is that at the same angle of view, same aperture diameter, same shutter speed, and same subject, you get the same result, no matter what the sensor size.

The key is to understand that f/stop is not the aperture diameter. The f/stop is the mathematical formula for the aperture diameter, where "f" is the focal length. Thus "f/2" means the aperture diameter is the focal length divided by 2. Clearly, f/2 will yield different aperture diameters at different focal lengths.

For instance a 25mm lens at f/2 has a 12.5mm aperture diameter. A 50mm lens at f/4 also has a 12.5mm aperture diameter. Thus 25mm at f/2, ISO 100 on a 2X crop body will give us the same results as 50mm at f/4, ISO 400 on a full frame.

.

The problem with just pointing two cameras at the same subject, is you may not have settings that give equivalent results. Depending on your settings, the crop body might yield more, less, or the same depth of field.

If you want to see if you can get the same results from a crop body, choose the equivalent (not the "same") settings as the full frame.

 

[dsjtecserv]

No. Auto ISO. SS at 1/80 for all cameras in both tests.

Test 1:

X-T5, APSC 40MPX, same framing, f2.8, SS 1/80, Auto ISO (4000), Auto WB

A7iii, FF 24MPX, same framing, f4, SS 1/80, Auto ISO (1600), Auto WB

You might have to explain how the full frame image with one stop less exposure and 1 1/3 stop lower ISO would give equivalent brightness for comparison. Were the lighting conditions the same for both; it would seem unlikely. Pushing it in raw would not be equivalent.

Look, I don't try to understand how Sony and Fuji adjust the Auto Settings (ISO and WB).

When I'm sitting in my armchair, my kids on the Sofa opposite of me and I have both cameras on my lap, and I make all shots within one minute, I expect the conditions to as close to similar as possible.

Then something is amiss. If the light and framing did not change, then both cameras would use essentially the same exposure. A 2 1/3 stop difference would not be due to auto algorithms.

I don't know why, but for a useful comparison, equivalent shooting conditions would need to be used.

Demoicaising and noise reduction: PureRaw 4 (note: XD2S is not working for XxTrans sensors)

More details and better sharpness for X-T5 from 100% onwards.

Assuming that there is an explanation for the exposure discrepancy and you achieved same framing by focal length rather than altering the distance, then it is not at all surprising that the camera with the far greater pixel density delivered more detail. I am not sure a test would be needed to reach that conclusion. But that is not a function of sensors size per se, but just the pixel density of the individual cameras, which is independent of the size of their sensors.

In terms of sharpness, that is a function of a number of factors, not least of which are the lenses involved, but an image with more detail may appear sharper.

You're right: I shot at 70mm on The Sony and 50mm (80mm FF) on the APSC. That would be the only "marginal" difference.

My goal was not to make a precise comparison between the two, but to find out if I'd lose a lot in skipping the Sony FF system for my trusted APSC one when I do corporate events.

And to point out that FF will not have the clear edge in any use case.
Esp. as many photographers (be it Wildlife, Landscape or Street, to mention only those) would usually chose the same shooting spot regardless of FF or APSC, and use the focal length to adjust the framing.

The point is that a sensor with a greater pixel density will always have an advantage of one with less density, and have the potential to produce more detail. This isn't a function of sensor size. So you simply demonstrated the advantage of pixel density, which is axiomatic. You didn't demonstrate anything about sensor size itself.

The question asked here was:
Do crop sensors lose sharpness (in comp. to FF) in the same frame?

Your comparison did not address that. To address that the pixel density would need to be normalized, while the sensor size was varied. And ideally the same lens would be used for both.

Your interest is appreciated, but the test didn't quite get at the issue.

The X-T5 definitely doesn't (but compared to a 4 year older A7iii). The X-H2S does very slightly. But only at pixel peeping level.
If I get a bit of sun, I'll take some time to shoot landscape at lowest ISO this week. This will give another perspective.
But the fact that there is no really perceptible difference indoor after denoising, which is where APSC usually struggles more, is quite positive.

Dave

 

[nick_bianchi]

...

Look, I don't try to understand how Sony and Fuji adjust the Auto Settings (ISO and WB).

When I'm sitting in my armchair, my kids on the Sofa opposite of me and I have both cameras on my lap, and I make all shots within one minute, I expect the conditions to as close to similar as possible.

...

For very many circumstances you can get the same result from a crop body as a full frame. The trick is to select the right settings.

Where many people have trouble is that a certain setting value on a crop body will give a different result than that same setting on a full frame.

For instance, at the same angle of view, f/4 will capture less total light, and yield more depth of field than f/4 on a full frame.

Most are aware that a 50mm lens on a crop body yields a narrower field of view than 50mm on a full frame.

An ISO 400 exposure on a crop body will yield a noisier result than ISO 400 on a full frame.

The general rule is that at the same angle of view, same aperture diameter, same shutter speed, and same subject, you get the same result, no matter what the sensor size.

The key is to understand that f/stop is not the aperture diameter. The f/stop is the mathematical formula for the aperture diameter, where "f" is the focal length. Thus "f/2" means the aperture diameter is the focal length divided by 2. Clearly, f/2 will yield different aperture diameters at different focal lengths.

For instance a 25mm lens at f/2 has a 12.5mm aperture diameter. A 50mm lens at f/4 also has a 12.5mm aperture diameter. Thus 25mm at f/2, ISO 100 on a 2X crop body will give us the same results as 50mm at f/4, ISO 400 on a full frame.

.

The problem with just pointing two cameras at the same subject, is you may not have settings that give equivalent results. Depending on your settings, the crop body might yield more, less, or the same depth of field.

If you want to see if you can get the same results from a crop body, choose the equivalent (not the "same") settings as the full frame.

Thanks for the details. I must admit that despite me starting university with Maths, Physics and Chemistry, I didn't stay long enough in those fields to reach the advanced Optics modules

The settings were equivalent, at least as much as possible. And as I said, Auto Iso and WB.
Theoretically, 50mm @ f2.8 on APSC-C = 76.5mm @ f4.28 on FF.At least according to all calculators out there.

Also, I compared the detail and sharpness on the focus point and immediate surroundings only, i.e. eye, eyelashes, skin and skin texture.

 

[nick_bianchi]

No. Auto ISO. SS at 1/80 for all cameras in both tests.

Test 1:

X-T5, APSC 40MPX, same framing, f2.8, SS 1/80, Auto ISO (4000), Auto WB

A7iii, FF 24MPX, same framing, f4, SS 1/80, Auto ISO (1600), Auto WB

You might have to explain how the full frame image with one stop less exposure and 1 1/3 stop lower ISO would give equivalent brightness for comparison. Were the lighting conditions the same for both; it would seem unlikely. Pushing it in raw would not be equivalent.

Look, I don't try to understand how Sony and Fuji adjust the Auto Settings (ISO and WB).

When I'm sitting in my armchair, my kids on the Sofa opposite of me and I have both cameras on my lap, and I make all shots within one minute, I expect the conditions to as close to similar as possible.

Then something is amiss. If the light and framing did not change, then both cameras would use essentially the same exposure. A 2 1/3 stop difference would not be due to auto algorithms.

I don't know why, but for a useful comparison, equivalent shooting conditions would need to be used.

Maybe something was indeed off. But in that case, the FF @ ISO1600 should even have been at a greater advantage vs APSC @ 4000.

Demoicaising and noise reduction: PureRaw 4 (note: XD2S is not working for XxTrans sensors)

More details and better sharpness for X-T5 from 100% onwards.

Assuming that there is an explanation for the exposure discrepancy and you achieved same framing by focal length rather than altering the distance, then it is not at all surprising that the camera with the far greater pixel density delivered more detail. I am not sure a test would be needed to reach that conclusion. But that is not a function of sensors size per se, but just the pixel density of the individual cameras, which is independent of the size of their sensors.

In terms of sharpness, that is a function of a number of factors, not least of which are the lenses involved, but an image with more detail may appear sharper.

You're right: I shot at 70mm on The Sony and 50mm (80mm FF) on the APSC. That would be the only "marginal" difference.

My goal was not to make a precise comparison between the two, but to find out if I'd lose a lot in skipping the Sony FF system for my trusted APSC one when I do corporate events.

And to point out that FF will not have the clear edge in any use case.
Esp. as many photographers (be it Wildlife, Landscape or Street, to mention only those) would usually chose the same shooting spot regardless of FF or APSC, and use the focal length to adjust the framing.

The point is that a sensor with a greater pixel density will always have an advantage of one with less density, and have the potential to produce more detail. This isn't a function of sensor size. So you simply demonstrated the advantage of pixel density, which is axiomatic. You didn't demonstrate anything about sensor size itself.

The question asked here was:
Do crop sensors lose sharpness (in comp. to FF) in the same frame?

Your comparison did not address that. To address that the pixel density would need to be normalized, while the sensor size was varied. And ideally the same lens would be used for both.

Your interest is appreciated, but the test didn't quite get at the issue.

This is where I will disagree, as this thread was never about identical pixel density only.

At least, that's not how I understood it. To me, it's more: "Do I lose sharpness using a crop sensor camera vs a FF one, for a give scene."

What I demonstrate here is that there is no general rule and no YES or NO answer to the question asked by the OP.
Esp. as I used both Sony's and Fuji's red badge lenses and compared the focus point and area around it only - because this is what serves my purpose when I shoot corporate events.

Indeed, if you take the same Pixel density, FF will have a clear advantage. This is obvious.

But the reality is different. Most modern crop sensor cameras have higher pixel density as most FF cameras (26 MPX APSC-C has a FFeq pixel density of 70 MPX!). Therefore, in many cases, a modern crop sensor can give you nearly identical or even sharper pictures and more details than loads of FF cameras, esp. after Post processing (denoising in particular).

In many equivalent shooting situations, identically framed, one would have a hard time telling which shot was made with a FF and which one with a (modern) crop sensor.

Comparing cameras with identical pixel density will be hard: I would have to compare the A7iii FF sensor with (for example) my 10 year older Nikon D300S (I haven't touched it in many years), as FF 24 MPX = APSC-C 10.6 MPX. But there's no point doing such a test.

Cheers
Nick

The X-T5 definitely doesn't (but compared to a 4 year older A7iii). The X-H2S does very slightly. But only at pixel peeping level.
If I get a bit of sun, I'll take some time to shoot landscape at lowest ISO this week. This will give another perspective.
But the fact that there is no really perceptible difference indoor after denoising, which is where APSC usually struggles more, is quite positive.

Dave