How can smartphone cameras work thru scratched lenses?

In article , Eric Stevens
wrote:


What about a greasy smudge from a finger print? Wouldn't that make the
clarity of the photo a great deal worse?

not really, unless it's coated with dirt and grime, which would be
noticeable when you tried to take a photo, at which point, you'd wipe
it clean.

And yet a smartphone seems to always make a half decent photo that I
rarely
bother wiping the lens window.

modern technology is amazing.

It's not the modern technology that should get the credit.

yes it most certainly is.

It's the
ancient laws of optics. Several people have already given the correct
explanation.

they might think they have, but they have not, and the 'ancient laws of
optics' actually say the *opposite* of what you think they do.

I expect you to say "no". If you really believe that it is modern
technology please explain what the technology is and how it works.

i already did.

Add one more to add to your famous list of non-existent explanations.

add one more to add to your list of intentionally ignoring what has
been said and then playing dumb. or maybe it's not playing.

On 2018-05-31 05:52:27 +0000, nospam said:

add one more to add to your list of intentionally ignoring what has
been said and then playing dumb. or maybe it's not playing.

Oki... You're on it...
--
teleportation kills

In article ,
RichA wrote:

My smartphone takes reasonably good pictures despite a smeary slightly
scratched protective lens window. (It's not actually the optical
surface of the lens).

I used to caregully clean my 35mm Nikon SLR lenses every time I took the
camera out.

What is it about the optics on a smartphone which allows it to get away
despite such neglect?

Perhaps it's to do with something like the focal length or depth of
focus?

Simple, the image focal point is nowhere near the scratched area so it
behaves more or less like a very mild diffusion filter at worst.

no.

Yes. I see this question all the time dealing with camera lenses.

i'm sure you do, but that doesn't mean you understand it.

there's a very big difference between a scratch on a cellphone lens
versus a scratch on an slr lens, for reasons that should be immediately
obvious.

there are also other factors involved as to why smartphone cameras do
as well as they do (and have been mentioned, eric).

On Thu, 31 May 2018 08:24:22 -0700 (PDT), RichA
wrote:

On Tuesday, 29 May 2018 21:00:35 UTC-4, nospam wrote:
In article ,
RichA wrote:

My smartphone takes reasonably good pictures despite a smeary slightly
scratched protective lens window. (It's not actually the optical surface
of the lens).

I used to caregully clean my 35mm Nikon SLR lenses every time I took the
camera out.

What is it about the optics on a smartphone which allows it to get away
despite such neglect?

Perhaps it's to do with something like the focal length or depth of focus?

Simple, the image focal point is nowhere near the scratched area so it
behaves more or less like a very mild diffusion filter at worst.

no.

Yes. I see this question all the time dealing with camera lenses.

If 99% (or more) of the lense is producing a sharp image the 1% (or
less) which is the scratch is producing no image but only a relatively
faint diffuse illumination of the film plane which may never be
noticed.

https://www.lensrentals.com/blog/200...ent-scratches/

".... its amazing how much dust or how many scratches a front
element can take without significantly impacting image quality."

Read the whole article.
--

Regards,

Eric Stevens

In article , Eric Stevens
wrote:


If 99% (or more) of the lense is producing a sharp image the 1% (or
less) which is the scratch is producing no image but only a relatively
faint diffuse illumination of the film plane which may never be
noticed.

exactly the point,

now compare the size of a scratch to the size of a cellphone lens.

keep in mind that cellphones are designed for abuse and usually have a
sapphire crystal which is *significantly* harder to scratch than an slr
lens, which has no protection unless the user adds a uv filter on their
own.

On Thu, 31 May 2018 11:57:52 -0400, nospam
wrote:

In article ,
RichA wrote:

My smartphone takes reasonably good pictures despite a smeary slightly
scratched protective lens window. (It's not actually the optical
surface of the lens).

I used to caregully clean my 35mm Nikon SLR lenses every time I took the
camera out.

What is it about the optics on a smartphone which allows it to get away
despite such neglect?

Perhaps it's to do with something like the focal length or depth of
focus?

Simple, the image focal point is nowhere near the scratched area so it
behaves more or less like a very mild diffusion filter at worst.

no.

Yes. I see this question all the time dealing with camera lenses.

i'm sure you do, but that doesn't mean you understand it.

there's a very big difference between a scratch on a cellphone lens
versus a scratch on an slr lens, for reasons that should be immediately
obvious.

there are also other factors involved as to why smartphone cameras do
as well as they do (and have been mentioned, eric).

Here is what nospam has written in this thread so far:

1. it's built to withstand it, usually with a sapphire crystal lens
cover or similar.
....
mostly because digital is much better than film, particularly when
it's mixed with highly sophisticated image processing.

2. no.

3. actually no.

a scratch on a tiny lens would be much more than a 'mild diffusion
filter', and it's actually *very* difficult to scratch the lens
because it has a protective cover (usually sapphire crystal),
which does not scratch easily, even if one tries.

4. i'm sure you do, but that doesn't mean you understand it.

there's a very big difference between a scratch on a cellphone
lens versus a scratch on an slr lens, for reasons that should be
immediately obvious.

there are also other factors involved as to why smartphone cameras
do as well as they do (and have been mentioned, eric).

5. yes it most certainly is.

It's the ancient laws of optics. Several people have already
given the correct explanation.

they might think they have, but they have not, and the 'ancient
laws of optics' actually say the *opposite* of what you think they
do.

I expect you to say "no". If you really believe that it is
modern technology please explain what the technology is and how
it works.

i already did.

Extracted from this is the valid point that cellphone lenses tend not
to be scratched because they are behind a layer of saphire crystal
glass.

nospam has also done some hand waving which says in effect 'modern
technology is wunnerful' and leaves it at that. This is what he claims
has already "been mentioned" and comprises his explanation of "what
the technology is and how it works."
--

Regards,

Eric Stevens

In article , Eric Stevens
wrote:

Perhaps it's to do with something like the focal length or depth of
focus?

Simple, the image focal point is nowhere near the scratched area so it
behaves more or less like a very mild diffusion filter at worst.

no.

Yes. I see this question all the time dealing with camera lenses.

i'm sure you do, but that doesn't mean you understand it.

there's a very big difference between a scratch on a cellphone lens
versus a scratch on an slr lens, for reasons that should be immediately
obvious.

there are also other factors involved as to why smartphone cameras do
as well as they do (and have been mentioned, eric).

Here is what nospam has written in this thread so far:

1. it's built to withstand it, usually with a sapphire crystal lens
cover or similar.
....
mostly because digital is much better than film, particularly when
it's mixed with highly sophisticated image processing.

2. no.

3. actually no.

a scratch on a tiny lens would be much more than a 'mild diffusion
filter', and it's actually *very* difficult to scratch the lens
because it has a protective cover (usually sapphire crystal),
which does not scratch easily, even if one tries.

4. i'm sure you do, but that doesn't mean you understand it.

there's a very big difference between a scratch on a cellphone
lens versus a scratch on an slr lens, for reasons that should be
immediately obvious.

there are also other factors involved as to why smartphone cameras
do as well as they do (and have been mentioned, eric).

5. yes it most certainly is.

It's the ancient laws of optics. Several people have already
given the correct explanation.

they might think they have, but they have not, and the 'ancient
laws of optics' actually say the *opposite* of what you think they
do.

I expect you to say "no". If you really believe that it is
modern technology please explain what the technology is and how
it works.

i already did.

Extracted from this is the valid point that cellphone lenses tend not
to be scratched because they are behind a layer of saphire crystal
glass.

read it again and extract the other key point.

In article ,
RichA wrote:


Simple, the image focal point is nowhere near the scratched area so it
behaves more or less like a very mild diffusion filter at worst.

no.

Yes. I see this question all the time dealing with camera lenses.

i'm sure you do, but that doesn't mean you understand it.

there's a very big difference between a scratch on a cellphone lens
versus a scratch on an slr lens, for reasons that should be immediately
obvious.

Deep DOF?

that has nothing to do with scratches

In article ,
RichA wrote:


there's a very big difference between a scratch on a cellphone lens
versus a scratch on an slr lens, for reasons that should be immediately
obvious.

Deep DOF?

that has nothing to do with scratches

Deep DOF might make dirt or scratches on surfaces far from the focal plane
have GREATER impact on the image than if the camera had a large sensor and
shallow DOF. This is WHY people stop-down lenses when looking for evidence
of sensor dust.

no

On Thu, 31 May 2018 18:51:55 -0400, nospam
wrote:

In article , Eric Stevens
wrote:

Perhaps it's to do with something like the focal length or depth of
focus?

Simple, the image focal point is nowhere near the scratched area so it
behaves more or less like a very mild diffusion filter at worst.

no.

Yes. I see this question all the time dealing with camera lenses.

i'm sure you do, but that doesn't mean you understand it.

there's a very big difference between a scratch on a cellphone lens
versus a scratch on an slr lens, for reasons that should be immediately
obvious.

there are also other factors involved as to why smartphone cameras do
as well as they do (and have been mentioned, eric).

Here is what nospam has written in this thread so far:

1. it's built to withstand it, usually with a sapphire crystal lens
cover or similar.
....
mostly because digital is much better than film, particularly when
it's mixed with highly sophisticated image processing.

2. no.

3. actually no.

a scratch on a tiny lens would be much more than a 'mild diffusion
filter', and it's actually *very* difficult to scratch the lens
because it has a protective cover (usually sapphire crystal),
which does not scratch easily, even if one tries.

4. i'm sure you do, but that doesn't mean you understand it.

there's a very big difference between a scratch on a cellphone
lens versus a scratch on an slr lens, for reasons that should be
immediately obvious.

there are also other factors involved as to why smartphone cameras
do as well as they do (and have been mentioned, eric).

5. yes it most certainly is.

It's the ancient laws of optics. Several people have already
given the correct explanation.

they might think they have, but they have not, and the 'ancient
laws of optics' actually say the *opposite* of what you think they
do.

I expect you to say "no". If you really believe that it is
modern technology please explain what the technology is and how
it works.

i already did.

Extracted from this is the valid point that cellphone lenses tend not
to be scratched because they are behind a layer of saphire crystal
glass.

read it again and extract the other key point.

I would rather leave it to the author. What do you regard as the other
key point?
--

Regards,

Eric Stevens