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  • Welcome to the new site. Here's a thread about the update where you can post your feedback, ask questions or spot those nasty bugs!

Size matters, but just how?

Doug Kerr

Well-known member
Hi, Jerome,

Nice essay. Much useful information.

-the smaller camera will saturate earlier because the diode is smaller, hence has a smaller capacity (i.e. we will blow highlights)
Well, we can blow highlights with any sensor.

Do you mean for a given photometric exposure (H)?

If so, why would what you say be so? For a given H (flux times time per unit area), a smaller detector (smaller capture area) would receive less "photometric energy" (flux times time), but would also presumably have a lesser "capacity" (photometric energy required for full discharge; that is, at saturation). So it would seem that the Hsat (photometric exposure at saturation) would be about the same.

Best regards,

Doug
 

Jerome Marot

Well-known member
Now that's clear I can move on. No, I wait impatiently for the bokeh explanation. Thanks Jerome.
A thanks from you on a subject about the technicalities of cameras? What happened to your australian spirits? Did you, by some chance, convert to Buddhism and were given only so much time to improve your karma? Is this the NSA impersonating you? You are frightening me!

A little bit.
 

Jerome Marot

Well-known member
Well, we can blow highlights with any sensor.

Do you mean for a given photometric exposure (H)?

If so, why would what you say be so? For a given H (flux times time per unit area), a smaller detector (smaller capture area) would receive less "photometric energy" (flux times time), but would also presumably have a lesser "capacity" (photometric energy required for full discharge; that is, at saturation). So it would seem that the histeric (photometric exposure at saturation) would be about the same.
Quite a good question indeed.

At first sight, it seems that the capacity of the photodiode increases with its surface (the deepness being somewhat constant for a given process) and that the number of photon collected also increases with the surface. The two being proportional, we should not have more saturation.

Except that there is a fixed amount of noise per pixel coming from the readout and amplifier. That fixed amount is easier to see when the signal is small than when it is large, so manufacturers of small sensels like to cheat a bit more, expose a bit more "to the right" and take blown out highlights as a lesser evil. The present hysteria about low noise and high isos only make the problem worse.

I might actually please Tom here: the present hysteria about low noise lead to photographic practices which may look good on an engineering paper but do not produce pleasing pictures. We traded off smooth highlights (to which the human eye is very sensitive) against low noise shadows (to which the human eye is less sensitive). People who remember slide film will know that the choice at the time was to not overexpose, and not care about blocked out shadows. Most people ran their cameras with a continuous -1/3ev correction. Indeed, if you do that on a SLR today, and push back the raw files, you will generally have better pictures at reasonable isos. But if you do that on a P&S, you'll quickly hit a limit: the shadows get noisy and the camera electronics with turn shadow details to mush to hide the noise.

This to show that we cannot study a sensor in insulation: the camera is a complete system and is used as such, including the little tricks that the manufacturers don't want us to know about.

Last but not least, in real life small sensels have proportionally smaller diodes. On figure 1 of the Aptina document, the diode is a nice yellow box. In real components, it is an area that is created by chemical action. For a given process, it is easier to go deeper on larger pixels, so the scaling of the diode is by volume not by area (somewhat, because the manufacturer will make more effort for small sensels and may use more refined processes). That yellow box also needs walls for insulation and these walls don't scale down or we would degrade insulation, so they take a fixed area around the diode (in practice a compromise is chosen and we get a little more crosstalk as well).

This last paragraph shows that things do not scale nicely in real life. There are elements which cannot scale, because the physical values on which they depend does not change (here insulation thickness, since we do not scale voltage).
 

Doug Kerr

Well-known member
Hi, Jerome,

Quite a good question indeed.

At first sight, it seems that the capacity of the photodiode increases with its surface (the deepness being somewhat constant for a given process) and that the number of photon collected also increases with the surface. The two being proportional, we should not have more saturation.

Except that there is a fixed amount of noise per pixel coming from the readout and amplifier. That fixed amount is easier to see when the signal is small than when it is large, so manufacturers of small sensels like to cheat a bit more, expose a bit more "to the right" and take blown out highlights as a lesser evil. The present hysteria about low noise and high isos only make the problem worse.

I might actually please Tom here: the present hysteria about low noise lead to photographic practices which may look good on an engineering paper but do not produce pleasing pictures. We traded off smooth highlights (to which the human eye is very sensitive) against low noise shadows (to which the human eye is less sensitive). People who remember slide film will know that the choice at the time was to not overexpose, and not care about blocked out shadows. Most people ran their cameras with a continuous -1/3ev correction. Indeed, if you do that on a SLR today, and push back the raw files, you will generally have better pictures at reasonable isos. But if you do that on a P&S, you'll quickly hit a limit: the shadows get noisy and the camera electronics with turn shadow details to mush to hide the noise.

This to show that we cannot study a sensor in insulation: the camera is a complete system and is used as such, including the little tricks that the manufacturers don't want us to know about.

Last but not least, in real life small sensels have proportionally smaller diodes. On figure 1 of the Aptina document, the diode is a nice yellow box. In real components, it is an area that is created by chemical action. For a given process, it is easier to go deeper on larger pixels, so the scaling of the diode is by volume not by area (somewhat, because the manufacturer will make more effort for small sensels and may use more refined processes). That yellow box also needs walls for insulation and these walls don't scale down or we would degrade insulation, so they take a fixed area around the diode (in practice a compromise is chosen and we get a little more crosstalk as well).

This last paragraph shows that things do not scale nicely in real life. There are elements which cannot scale, because the physical values on which they depend does not change (here insulation thickness, since we do not scale voltage).
Indeed all well said, and very illuminating.

The matter that I was trying to "provoke out" by my question is this (and you nicely dealt with it): regarding saturation, the disadvantage of the smaller sensel is not that it "saturates more easily" in any absolute terms (value of H, for example), but rather that its saturation photometric exposure is less by comparison to the noise level encountered at lower values of H.

If we reckon the "dynamic range" of a sensor in terms of the ratio of H at saturation (Hsat) to the H at which the signal-to-noise ratio is some arbitrary value (Hsnr), we then find that typically this ratio is less for a smaller sensel sensor.

Now is this because Hsat is less for the smaller-sensel sensor? Perhaps in small part. But mostly it is because Hsnr is greater.

Best regards,

Doug
 

Tom dinning

Registrant*
A thanks from you on a subject about the technicalities of cameras? What happened to your australian spirits? Did you, by some chance, convert to Buddhism and were given only so much time to improve your karma? Is this the NSA impersonating you? You are frightening me!

A little bit.
Don't be frightened, Jerome. I'm harmless. I guess what am doing is talking to myself but out loud. I understand your interest in these areas and also your knowledge. I do read the posts. I do also, surprisingly, understand it if I stay with it long enough.
As I read what you say, I have thoughts that I have the urge to be said. That's what forums are about, are they not? I'm not criticizing you for starting such threads or writing in such a way. I guess I just question the value of it for 99% of the photographers out there. It's a narrow and specialized field and only a few people will understand it let alone utilize it in their decision making. I bet there are more people who consider the color of the camera more important that the contents of this discussion, yet we never discuss color of cameras as deeply. Maybe we should. Why is it that Nikon have produced a whole range of cameras in red recently?

So, as a viable and somewhat cynical member of OPF I stand by my right to offer any comment I feel is relevant, including a reflection of the 'common man'. Why, some may even find what I say favorable to their own thoughts.
Life, and photography isn't all numbers. Sometimes it has a simple explanation beyond the graphs and statistics.
As you will, continue to enlighten us on the details. As I will continue to remind you of a more common place.
 

Doug Kerr

Well-known member
Hi, Tom,

I bet there are more people who consider the color of the camera more important that the contents of this discussion, yet we never discuss color of cameras as deeply.
In fact, at one time a gigantic matter of discussion in various camera forums (this one was not yet founded then) was how dare Canon make the EOS 300D silver when everybody knew that a professional camera should be black.

Best regards,

Doug
 

Tom dinning

Registrant*
I pull out my cute white V2 from time to time and get laughed at by the blokes and adulated by the women. It's like having a furry animal on a lead. I'd much prefer to be a laughing stock and a chick magnet than a pro with penis envy. You can have your black body. (No ethic reference intended).
 

Jerome Marot

Well-known member
Don't be frightened, Jerome. I'm harmless. I guess what am doing is talking to myself but out loud. I understand your interest in these areas and also your knowledge. I do read the posts. I do also, surprisingly, understand it if I stay with it long enough.
As I read what you say, I have thoughts that I have the urge to be said. That's what forums are about, are they not? I'm not criticizing you for starting such threads or writing in such a way. I guess I just question the value of it for 99% of the photographers out there. It's a narrow and specialized field and only a few people will understand it let alone utilize it in their decision making. I bet there are more people who consider the color of the camera more important that the contents of this discussion, yet we never discuss color of cameras as deeply. Maybe we should. Why is it that Nikon have produced a whole range of cameras in red recently?

So, as a viable and somewhat cynical member of OPF I stand by my right to offer any comment I feel is relevant, including a reflection of the 'common man'. Why, some may even find what I say favorable to their own thoughts.
Life, and photography isn't all numbers. Sometimes it has a simple explanation beyond the graphs and statistics.
As you will, continue to enlighten us on the details. As I will continue to remind you of a more common place.

I think that we are in disagreement on the interests of the common man. In my experience, the common man or woman is actually quite interested when told in simple, understandable terms how his or her camera actually works (or other pieces of technology). They enjoy being explained what they can do with it, what choices they have and the consequences of these choices on their pictures.

There is actually a considerable interest for technology amongst "common people". Not all of them, of course, but quite a few. It would seem that you are underestimating the so called "common man".

As to cameras in colors, feel free to start a post on the subject. I will contribute one or two articles, it is a subject which is quite interesting actually. There is a reason why the most popular camera on the planet has just been issued in 5 different candy colors.
 

Jerome Marot

Well-known member
In fact, at one time a gigantic matter of discussion in various camera forums (this one was not yet founded then) was how dare Canon make the EOS 300D silver when everybody knew that a professional camera should be black.
I would seem that the answer is in the question.
 

Tom dinning

Registrant*
I think that we are in disagreement on the interests of the common man. In my experience, the common man or woman is actually quite interested when told in simple, understandable terms how his or her camera actually works (or other pieces of technology). They enjoy being explained what they can do with it, what choices they have and the consequences of these choices on their pictures.

There is actually a considerable interest for technology amongst "common people". Not all of them, of course, but quite a few. It would seem that you are underestimating the so called "common man".

As to cameras in colors, feel free to start a post on the subject. I will contribute one or two articles, it is a subject which is quite interesting actually. There is a reason why the most popular camera on the planet has just been issued in 5 different candy colors.
You're joking, right, Jerome. If you're not I'm pissing myself laughing here for nothing. I don't know who you mix with but if that's what you call 'simple, understandable terms' I'll eat my cameras one at a time and **** fully framed prints ready for the wall. Or is it just me? I'm not about to do a survey to prove a point but somehow I have the feeling if I stood outside the average camera store and asked people to read what you have written here then explain it back to me with a display of interest, I might be home before lunch.
I'm not putting you down on what you say. It's all good stuff, but as I have said before, for whom?
Even from this forum you might get some indication of interest from the number of contributors. There's just 3-4 of us and I'm just here for the heckling.

As for color, it's not interesting at all, Jerome. You're just taking the Micky out of me. Good one! Now I just laughed so much I fell out of bed.

This place is getting better by the day.
Next thing you know, Fahim will be telling me what a nice bloke I am and he's glad to see me back.
 

Doug Kerr

Well-known member
Hi, Tom,

In the U.S., we have a large institution devoted to the debate as to the relative merits of knowledge and ignorance. It has two chambers, and meets in Washington, D.C.

Best regards,

Doug
 

Jerome Marot

Well-known member
I'm not joking as much as you believe I am, Tom. You can't pretend to be a common man, say that you understand what I wrote and state that the common man cannot understand it. Not at the same time.
 

Tom dinning

Registrant*
Hi, Tom,

In the U.S., we have a large institution devoted to the debate as to the relative merits of knowledge and ignorance. It has two chambers, and meets in Washington, D.C.

Best regards,

Doug
It's appropriate that both knowledge and ignorance is discussed at the same institute, Doug, since the acquisition of one doesn't necessarily lead to the extirpation of the other.
 

Tom dinning

Registrant*
I'm not joking as much as you believe I am, Tom. You can't pretend to be a common man, say that you understand what I wrote and state that the common man cannot understand it. Not at the same time.
Pretend! Bloody hell, Jerome. I don't have to. I'm told so each and every day by she who I love and trust dearly, as well as my neighbors, friends and relatives. Even the waiter at the restaurant yesterday gave me a look that would have sent a lesser man running for cover. Why is it that people don't take me seriously here! Asher thinks I'm kidding as well.
Sure, I'm educated, of sorts. I have a couple of degrees, worked in education all my life, read stuff and all that ****. But I am a snob. A working class one. I like it like that. I work hard at it, but it seems to come naturally. Christine loves and hates me for it. I'll sit in the gutter and talk to a drunk in preference to going to a dinner with her colleagues. I have never owned a suit, wore a tie or polished shoes. I swear often, used to drink too much, prefer a good fight and only wash when someone reminds me. I wear un ironed clothes (t shirts, jeans and shorts is all I have) I haven't combed my hair for 30 years and shave only when I absolutely need to. My sisters believe I am a replica of my father. I'm definitely OK with that. I enjoy poking fun at peoples behaviors as well as my own. I lie a lot, Dream a lot more and I've never been more content in my life.

I don't know how to be anything else, Jerome. This is not make believe. I really am who I say I am.

Now, back to the question?

Does all this really make a difference to the 'niceness' of the resulting image? Yes or no?
 

Doug Kerr

Well-known member
Hi, Tom,

It's appropriate that both knowledge and ignorance is discussed at the same institute, Doug, since the acquisition of one doesn't necessarily lead to the extirpation of the other.
An excellent point.

The institution to which I cryptically referred, by the way, is the United States Congress, now a specialized type of sporting league, with only a little over two teams, one dedicated to one aspect of that proposition and the other to the other. Just as chess is modeled on medieval combat, and rodeo on the tasks of working cowboys, the game played there is modeled on the governance of our nation, an activity that formerly was actually practiced in the very same arena. It is not clear what trophy is awarded at the end of the season.

Best regards,

Doug
 

Jerome Marot

Well-known member
Tom, I am not disputing what you are, just that you can't say mutually exclusive things at the same time and have me believe them.



Maybe there is something else I feel I should bring up, even if a photographic forum is not quite the place to discuss it. Your stances on suburbs, commoners and the working class is not understandable by me and I believe by some other members of this forums. I mean: I can understand it intellectually, but I cannot relate to it. First, because you are assuming that I belong to a social class of which I don't relate to (I am actually from a family of peasants, I can relate to that). Second, because your very concept of social class is rooted in a cultural context which is alien to me.

I happen to work in a multicultural environment. I meet people from all over Europe every day. The kind of discourse you are holding, I only hear from people coming from England and former british colonies. Not that other cultures do not have social classes, but they don't relate to them in the same manner.

For example: France. I am French and can therefore relate to that culture. French certainly has social classes, but because of our history (the Revolution, liberté, égalité, fraternité, let's guillotine the nobility, etc...), we like to believe that we don't. France also stayed mainly rural for a longer time than Great Britain, with mines and industry being concentrated in limited areas, so a working class in the classical Karl Marx sense could only emerge in these limited areas. In the rest of France, the "working class" was composed by peasants which at the same time were landowners but on tiny patches of land barely sufficient to feed them (because the Revolution redistributed the land and made it such that inherited land was divided between all children of the family). There are very few large landowners in France. Last but not least, we also had Jules Ferry who created our "school system of the Republique". The very idea of a universal, egalitarian school for all children of the nation permeates the French psyche.
On one hand, this made France a more egalitarian society, at least on the surface. On the other hand, we are a very centralised country and parisians somewhat act as a nobility. We also have had recent immigration, some of which formed a new type of lower class. I am not saying that France is a classless culture, just that the perception of social classes is different.

I live in the south of Germany. I can't really relate to the German notion of social classes, but I can tell that it is different again. Not the same as in France and not the same as in England. I can only give some examples: German nobility is poor (because the land was divided between all children). The new rich families are the ones whose grandfather started a small industry less than 100 years ago, usually with a university diploma in mechanics or chemistry and I believe that this is the reason for Germans' obsession with the Doktor title (the biggest political scandals of past year were about politicians who faked their Doktor title...). In south Germany, there is a real passion about traditional clothing (and not only during Oktoberfest), which is a way to dress yourself as a member of a specific social class and most of them dress as lower class peasants, not as landowners. And there are "Biergarten" (places to drink beer outside) and all my British friends are always baffled how the people of all sorts of background can sit together at the same table at these places.

So: two neighbouring countries and two completely different perception of social classes. I could go on with it, but I suppose that you would have understood by know that the kind of discourse that you are holding leaves me wondering what you are saying and why you insist of saying it. How you dress or who you dine with is not important to me. And to me, your discourse is just as puzzling as the one of Fahim. He does not need to convince me that the muslim world is civilised. I already know that this part of the world invented agriculture and that they had mathematicians and philosophers when Europe essentially perfected how to pray that the barbarian invasions avoided them. Sure, I have learned a bit about his country and its history which I did not know, but his insistence on defending his culture leaves me wondering why he is so eager to defend it. Your stances on the working class leave me the same after taste: I have the strange feeling that you assume that we are enemies of class. Could we please go back to a discussion where we would simply all be photographers?



And to go back to photography: yes, sensor size makes a difference to the "niceness" of the resulting image. More latter, when I'll have time to write the part about the lenses.
 

Doug Kerr

Well-known member
Hi, Jerome,

Thank you for your interesting essay on social classes in different cultures and such. It is very insightful.

And to go back to photography: yes, sensor size makes a difference to the "niceness" of the resulting image. More latter, when I'll have time to write the part about the lenses.
I'm looking forward to it.

In the meantime, now that the bulk of our photographic work is being done with a camera with a 7.7 mm sensor, I am trying to characterize the differences in the results compared to those from our prior workhorse, with a 27 mm sensor.

Here are some anecdotal reports.

I took the "lockdown shot" image of our living room (part of a series at different ISO sensitivity settings) for ISO 400 and printed it, with no explicit postprocessing, at a size of 11" × 14".

Examining the print (paying no attention to viewing distance - just handling it as if it had been handed to me by a colleague in a social situation) I was amazed at how "nice" it was. I did not do the same shot with the larger-sensor camera to do an A-B comparison.

Later, I was involved in processing a large number of shots from the new small camera taken at a charity event, involving both available-light shooting at a banquet and late-afternoon outdoor shooting at a high school stadium.

Independent of the "small camera" shift. I've been playing with our basic technique for downsizing images, based on some suggestions by Bart and others. Basically, I am normally now first applying a bit of Gaussian blur (a pre-downsampling antialiasing filter), then downsampling, then applying some unsharp mask sharpening.

As I tuned this up working with the images from the small camera, I noticed that if I omitted the antialiasing step (as had been my practice for many years, then when I applied the post-downsampling sharpening, for faces that were fairly small on the image I could see what looked like severe skin trouble! I presume that this was the effect, at the end of this chain of abuse to the image, of noise in the original image.

So the interaction of all these matters is indeed a complicated one. No wonder it is not easy to consider an image and say, "what about it makes it 'nicer' than this other one."

Best regards,

Doug
 

Jerome Marot

Well-known member
In the meantime, now that the bulk of our photographic work is being done with a camera with a 7.7 mm sensor, I am trying to characterize the differences in the results compared to those from our prior workhorse, with a 27 mm sensor.
This is very difficult, in particular because the small and big camera default sharpenings and saturations are probably
different. A picture with a bit more sharpening and saturation is more pleasing to the eye, but cannot be processed as easily afterwards.
 

Jerome Marot

Well-known member
Lenses, bokeh, diffraction and optical effects.

We are now coming to the part about lenses, bokeh, diffraction and optical effects.

Earlier in this thread I compared a Leica S2 to an hypothetical Nikon D800+, which is a D800 blown up so that its sensor size matches the one of the S2. That was including the lens, so the D800+ had a 62mm f/1.8 lens (a blown up 50mm f/1.8). The important part is that the f number did not scale at all, because f numbers are dimensionless. And this is very important, because many things are dependent on the f number.

For small sensors, the important part is diffraction. You will find a nice article about diffraction here. What is important from us in this article, is that the size of the sensels dictates the minimum aperture of a lens. For example, for a sensor with 6µm sensels, diffraction first effects will be barely noticeable when stopped down beyond about f/11-f/16. This is not a practical limitation, unless you are interested in macrophotography. For smaller sensors, however, the limitation is more serious. Typically, for the tiny sensors used in P&S or cellphones with pixels under 2µm, f/2.8 may be the slowest aperture that does not degrade the picture. Typically, these cameras do not have a diaphragm at all, but use gray attenuation filters (as is also customary practice for video cameras). Typically as well, they use zoom lenses with sliding apertures and the long end can be as slow as f/5.6 or f/8. Since the lens barely resolve the sensels at f/2.8, you will have divided your linear resolution by 2 and your pixel count by 4 at the long end. And you have no depth of field control, since you don't have a real diaphragm.

For medium and larger sensors, the main difference is in the bokeh. Older photographers may remember the saying that large and medium format cameras allowed better depth of field control. But this is not quite true: due to the availability of very fast lenses (f/1.4 or faster), "Kleinbild" (24x36) cameras are actually the cameras which produce the thinner depth of field. So where did this belief come from?

The belief first comes from the fact that medium and large format cameras were used to produce larger prints. The formulas for calculating depth of field are dependent on the apparent size of the prints and we have seen that large prints seen close have been particularly attractive to the average viewer since the time of classical paintings.

But even if we do not want to produce larger prints, depth of field is, in practice, dependent of the sensor size: smaller sensors need a faster aperture to produce the same apparent depth of field all other things being equal. But aperture does not scale and a faster aperture, with any sensor size, comes with more optical aberrations. Spherical aberration, chromatic aberrations, coma, etc… are all dependent on aperture and increase considerably faster than the scaling power. Moreover, these aberrations also tend to be more difficult to control with smaller focal lengths, so smaller sensors are at a further disadvantage.

What does this mean in practice for different formats?

For tiny electronic sensors with tiny pixels, we would need apertures must faster than f/1.0 if we wanted small depth of field. The optical engineer can't do these at the standard focal length of these sensors and, in practice, the best they can do is f/1.8 (and much less for zooms at the long end). The f/1.8 lens is complex, need aspherical surfaces and special glass, mechanical tolerances are a nightmare since everything is so small (especially at the price the user is ready to pay) and the lens is plagued by aberrations, most noticeably chromatic aberration. Software corrections are often the only solution.

For 24x36 cameras, fast lenses are doable around 50mm, produce a very thin depth of field, but are also difficult to correct. When the photographer wants a depth of field small enough to emphasize the subject with a lens around the standard focal length, apertures around f/2.0-f/2.8 are chosen and we are in a zone where the aberrations are still responsible for bad bokeh: donut shape of out of focus highlights / split highlights (spherical aberration) or colored out of focus highlights (longitudinal chromatic aberration). Sweet spot of the lenses is around f/5.6-f/8, but depth of field is fairly large at these apertures.

For large format digital cameras, very fast lenses are usually not available. The reason is that these cameras use a central shutter and that limits the practical maximum aperture of the lenses. Still, when one wants depth of field control, apertures around f/5.6-f/8 are used and we are in the sweet spot: the lens is almost perfect and bokeh is neutral.

For much larger sensors: large format cameras, we have so much resolution on the sensor than we can afford to waste some and close down beyond the limits of diffraction. f/64 is a value for aperture rendered famous by large format photographers. Even when the photographer wants small depth of field, f/11-f/16 or slower is common (*). Not only aberrations are negligible, but the out of focus highlights take a shape produced by diffraction. This shape, approximately a bell curve, is just what we need for very pleasing bokeh.

(* optimal depth of field is very much an acquired taste, but correspond in practice to fast lenses on 24x36 cameras because this is what we are used to. Very fast lenses on large format have been emulated, check the Brenizer method in google, and the results are strange. The viewer interprets the results as if the subject were a miniature.)
 

Michael Nagel

Active member
Talking about sensor size in relation to DoF, OoF rendering (aka bokeh) and diffraction, it is worthwile to put a focus on the desired ouput and the choices forced upon the photographer depending on the sensor size.

For small sensors you obviously need a short focal length for a FoV which is equivalent to let's say 50mm at 36x24mm sensor size (e.g. approx. 13mm for a 2/3" sensor).
With increasing sensor size you need a larger focal fength for the same FoV.
For MF you end up in the 70-90mm ballpark.

What does this mean for OoF rendering (bokeh)?
Well, I recall only very few WA lenses with a beautiful OoF rendering, regardless of the sensor size (WA equals <14mm here).
The OoF rendering gets usually better with longer focal lengths.

Diffraction is becoming more and more an issue - also with larger sensors as the sensel size is decreasing with the Megapixel race revived. If you stay with the classic CoC definition, nothing changes, but if you want to use full resolution, this is obviously different.

A good compact camera with a fast lens (f1.4 is currently the best) and a not too small sensor (1/1.7" or 2/3") can deliver full sensor resolution at the lower end of the zoom range. This is obviously not the case for even smaller sensors and cheaper compact cameras which usually boast higher resolutions...

Typical questions I ask myself befoore taking a camera with me:
What DoF do I need?
How much light will I have (I usully shoot without flash)?
What FoV will I use (WA, Normal, Long)?
What exposure times do I want to use?
Depending on the answers it can be a different camera.

For me it is a matter of application as I mentioned before.

Best regards,
Michael
 
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