Relation between dust and aperture setting

Started 9 months ago | Questions
Photonique
New MemberPosts: 2
Like?
Relation between dust and aperture setting
9 months ago

Hi all,

this is my first post in this forum although I've been reading it since many years. I'm owning a D800 since 4 months now and I am very happy with it. However, I've had increasing issues with dust levels on my sensor. Anyway, my question is not related to how to remove such dust but I made an observation which I can't find an answer to:

When I take a photo of a bright white wall at high aperture number, say f22, I can clearly see a lot of dust particles. But when I set the aperture to f3.5, all dust particles are no longer visible. How can that be? I mean the dust will not change deepening on aperture setting. So it must have something to do with the light entering through the lens and hitting onto the particles. This phenomenon is also clearly visible when using life view mode.

Does anyone know why this is happening?

Thanks.

Photonique

ANSWER:
This question has not been answered yet.
Nikon D800
If you believe there are incorrect tags, please send us this post using our feedback form.
soloryb
Senior MemberPosts: 1,359Gear list
Like?
Re: Relation between dust and aperture setting
In reply to Photonique, 9 months ago

What you are experiencing is exactly why Nikon recommends that you keep the aperture below f/16 for the D800. That dust is there - whether or not it is observable at the wider apertures. As far as I know, this dust becomes more visible due to the increased diffraction occurring at f/16 and above. Lower resolution sensors don't show this but a 36-MP sensor will.

You have two basic choices here. Either you can shoot at below f/16 or live with the dust and remove it in post.

BTW, one of the steps that I use before cleaning is to take several de-focused shots of a uniform light background (I use a mat board) with the aperture set to f/16. Vary the distance so that the images are not all exactly the same. Then import them into Lightroom and use 'Visualize Spots' under the Spot Removal tool. Playing with the slider will bring out even the most minute dust particles on the sensor. Even after careful wet cleaning, it's almost impossible to eliminate all the spots, but you can get the worst of them off if you're diligent enough. Any spots remaining probably won't be visible in normal shooting below f/16, but in your case, keep repeating the cleaning until any dust becomes tolerable.

soloryb

Photonique wrote:

Hi all,

this is my first post in this forum although I've been reading it since many years. I'm owning a D800 since 4 months now and I am very happy with it. However, I've had increasing issues with dust levels on my sensor. Anyway, my question is not related to how to remove such dust but I made an observation which I can't find an answer to:

When I take a photo of a bright white wall at high aperture number, say f22, I can clearly see a lot of dust particles. But when I set the aperture to f3.5, all dust particles are no longer visible. How can that be? I mean the dust will not change deepening on aperture setting. So it must have something to do with the light entering through the lens and hitting onto the particles. This phenomenon is also clearly visible when using life view mode.

Does anyone know why this is happening?

Thanks.

Photonique

 soloryb's gear list:soloryb's gear list
Fujifilm FinePix X100 Nikon D800E Nikon AF-S Nikkor 24-70mm f/2.8G ED Nikon AF-S Nikkor 70-200mm f/2.8G ED VR II Nikon AF Fisheye-Nikkor 16mm f/2.8D +9 more
Reply   Reply with quote   Complain
kymarto
Contributing MemberPosts: 632
Like?
Re: Relation between dust and aperture setting
In reply to soloryb, 9 months ago

Same reason a shadow isn't visible on a cloudy day. At small apertures the light entering the lens acts much more like a point source than with wider apertures.

Reply   Reply with quote   Complain
SushiEater
Senior MemberPosts: 2,099Gear list
Like?
Re: Relation between dust and aperture setting
In reply to Photonique, 9 months ago
 SushiEater's gear list:SushiEater's gear list
Nikon D800E Nikon D810 Nikon AF-S Nikkor 16-35mm f/4G ED VR Nikon AF-S Nikkor 14-24mm f/2.8G ED Sigma 70-200mm F2.8 EX DG OS HSM +11 more
Reply   Reply with quote   Complain
jfriend00
Forum ProPosts: 11,131
Like?
Re: Relation between dust and aperture setting
In reply to Photonique, 9 months ago

When you shoot at a small aperture, the small aperture is excluding the light rays that come from the outer parts of the lens. As such you end up with only light rays that are of very similar angle through the lens. This means that the light rays hitting a given pixel on the sensor are generally all arriving in at approximately the same angle. This means that a dust particle that's on the glass above the sensor is going to cast a much stronger shadow on that particular pixel and thus it's effect will be quite noticeable.

If you shoot at a large aperture, the entire lens are is used to collect light and light arrives at a given pixel from many different angles. Because the light arrives from many different angles, the dust particle doesn't cast a very pronounced shadow on the pixels and thus you don't notice it as much.

It's the same reason why you use a large softbox to make soft shadows or no shadows (light comes from many different angles and thus doesn't make well defined shadows) and why a single point flash makes well defined shadows (light comes from only one angle to each point in the subject and thus casts a well defined shadow).

-- hide signature --
Reply   Reply with quote   Complain
michaeladawson
Veteran MemberPosts: 7,960Gear list
Like?
Re: Relation between dust and aperture setting
In reply to soloryb, 9 months ago

soloryb wrote:

What you are experiencing is exactly why Nikon recommends that you keep the aperture below f/16 for the D800. That dust is there - whether or not it is observable at the wider apertures. As far as I know, this dust becomes more visible due to the increased diffraction occurring at f/16 and above. Lower resolution sensors don't show this but a 36-MP sensor will.

Diffraction?  No.  You will see dust spots on a 6 MP camera and a 36 MP camera just as easily.  For small apertures the incoming light is coming almost all perpendicular from a small opening.  Wide apertures and the light is coming from all angles.

Similar to what someone else said...  stand a person near a wall. Shine a flashlight at them, look at the well defined shadow on the wall.  Now use a big wide light source if you can find one.  The wider the light source the less distinct the shadow becomes.

-- hide signature --

Mike Dawson

 michaeladawson's gear list:michaeladawson's gear list
Panasonic Lumix DMC-LX3 Nikon D200 Nikon D4 Nikon D800E Nikon AF-S Nikkor 70-200mm f/2.8G ED VR +17 more
Reply   Reply with quote   Complain
SushiEater
Senior MemberPosts: 2,099Gear list
Like?
Re: Relation between dust and aperture setting
In reply to jfriend00, 9 months ago

jfriend00 wrote:

When you shoot at a small aperture, the small aperture is excluding the light rays that come from the outer parts of the lens. As such you end up with only light rays that are of very similar angle through the lens. This means that the light rays hitting a given pixel on the sensor are generally all arriving in at approximately the same angle. This means that a dust particle that's on the glass above the sensor is going to cast a much stronger shadow on that particular pixel and thus it's effect will be quite noticeable.

If you shoot at a large aperture, the entire lens are is used to collect light and light arrives at a given pixel from many different angles. Because the light arrives from many different angles, the dust particle doesn't cast a very pronounced shadow on the pixels and thus you don't notice it as much.

Not even close. Regardless of aperture used the entire lens collects the light. At large aperture light hitting the sensor is straight (er) and at small aperture light is at the angle scattered more thus you get diffraction. It works exactly the same as your eyes. The more you squint the more you see in focus (DOF) but squinting does not prevent seeing less. No matter what your entire pupil collects light you see. The brighter the light the more pupil contracts.

It's the same reason why you use a large softbox to make soft shadows or no shadows (light comes from many different angles and thus doesn't make well defined shadows) and why a single point flash makes well defined shadows (light comes from only one angle to each point in the subject and thus casts a well defined shadow).

The soft box makes light to go around the object and it doesn't have to be large but the larger it is the more light goes around. And it is not the only reason. Bouncing light can eliminate shadows too by simply throwing light on the shadows.

 SushiEater's gear list:SushiEater's gear list
Nikon D800E Nikon D810 Nikon AF-S Nikkor 16-35mm f/4G ED VR Nikon AF-S Nikkor 14-24mm f/2.8G ED Sigma 70-200mm F2.8 EX DG OS HSM +11 more
Reply   Reply with quote   Complain
jfriend00
Forum ProPosts: 11,131
Like?
Re: Relation between dust and aperture setting
In reply to SushiEater, 9 months ago

SushiEater wrote:

jfriend00 wrote:

When you shoot at a small aperture, the small aperture is excluding the light rays that come from the outer parts of the lens. As such you end up with only light rays that are of very similar angle through the lens. This means that the light rays hitting a given pixel on the sensor are generally all arriving in at approximately the same angle. This means that a dust particle that's on the glass above the sensor is going to cast a much stronger shadow on that particular pixel and thus it's effect will be quite noticeable.

If you shoot at a large aperture, the entire lens are is used to collect light and light arrives at a given pixel from many different angles. Because the light arrives from many different angles, the dust particle doesn't cast a very pronounced shadow on the pixels and thus you don't notice it as much.

Not even close. Regardless of aperture used the entire lens collects the light. At large aperture light hitting the sensor is straight (er) and at small aperture light is at the angle scattered more thus you get diffraction. It works exactly the same as your eyes. The more you squint the more you see in focus (DOF) but squinting does not prevent seeing less. No matter what your entire pupil collects light you see. The brighter the light the more pupil contracts.

Sorry, dude but you just don't appear to understand here. Why do you think large aperture lenses have much bigger optics. It's because the EXTRA light for the larger aperture comes from collecting more light with the larger lens. When you then take a large aperture lens and use a small aperture with it, you are restricting light so that only light from a narrower set of angles (through the central part of the lens) is actually used, the other light rays are blocked by the aperture.

FYI, squinting DOES restrict the light. It narrows down your eye aperture so not as much light gets in and thus only light from a narrower angle gets in to the eye that is easier to focus and has more DOF. When the aperture of the eye contracts, it's blocking light just like when the aperture in the elns.

It's the same reason why you use a large softbox to make soft shadows or no shadows (light comes from many different angles and thus doesn't make well defined shadows) and why a single point flash makes well defined shadows (light comes from only one angle to each point in the subject and thus casts a well defined shadow).

The soft box makes light to go around the object and it doesn't have to be large but the larger it is the more light goes around. And it is not the only reason. Bouncing light can eliminate shadows too by simply throwing light on the shadows.

You are so wrong here. Light travels in straight lines. It NEVER goes "around" an object (except for diffraction which is not what we're talking about here). The softbox works because the light comes from many different sources at many different angles, thus the light can't form a sharp shadow boundary.

-- hide signature --
Reply   Reply with quote   Complain
SushiEater
Senior MemberPosts: 2,099Gear list
Like?
Re: Relation between dust and aperture setting
In reply to jfriend00, 9 months ago

jfriend00 wrote:

SushiEater wrote:

jfriend00 wrote:

When you shoot at a small aperture, the small aperture is excluding the light rays that come from the outer parts of the lens. As such you end up with only light rays that are of very similar angle through the lens. This means that the light rays hitting a given pixel on the sensor are generally all arriving in at approximately the same angle. This means that a dust particle that's on the glass above the sensor is going to cast a much stronger shadow on that particular pixel and thus it's effect will be quite noticeable.

If you shoot at a large aperture, the entire lens are is used to collect light and light arrives at a given pixel from many different angles. Because the light arrives from many different angles, the dust particle doesn't cast a very pronounced shadow on the pixels and thus you don't notice it as much.

Not even close. Regardless of aperture used the entire lens collects the light. At large aperture light hitting the sensor is straight (er) and at small aperture light is at the angle scattered more thus you get diffraction. It works exactly the same as your eyes. The more you squint the more you see in focus (DOF) but squinting does not prevent seeing less. No matter what your entire pupil collects light you see. The brighter the light the more pupil contracts.

Sorry, dude but you just don't appear to understand here. Why do you think large aperture lenses have much bigger optics.

First of all don't call me dude. It is not polite.

Second of all large aperture lenses have much bigger optics because small lenses don't collect as much light as larger lenses. For the same reason the last element of the lens has to be larger too.

It's because the EXTRA light for the larger aperture comes from collectig more light with the larger lens. When you then take a large aperture lens and use a small aperture with it, you are restricting light so that only light from a narrower set of angles (through the central part of the lens) is actually used, the other light rays are blocked by the aperture.

Again, not even close. Regardless of the aperture the front element collects all of the light.

I am not talking about quantity of the light, I am talking about just light. Of course, if you close aperture less light coming in but all of the view coming in anyway. This light just being angled otherwise you would see nothing more than the aperture opening on the sensor.

Do this (this is an old trick), glue a small mailing stamp on the front element. Take a picture. See if the stamp is in the picture. I have a lens with lots of dust behind the front element. Never seen it in the pictures.

And squinting does not make less light going in to your eye because you are not covering the pupil.

If you squint your iris does not get larger, indication of the less light. Only your pupil collect light not he whole eye. Stand in front of the mirror and see for yourself.

The soft box makes light to go around the object and it doesn't have to be large but the larger it is the more light goes around. And it is not the only reason. Bouncing light can eliminate shadows too by simply throwing light on the shadows.

You are so wrong here. Light travels in straight lines.

But it also bends and goes around.

Take two objects. The disk and the ball of the same diameter.

Shine the light on the ball. If you are correct light should produce the same shadow as the disk.

Nope!!!! Light will go around the ball and produce smaller shadow.

It NEVER goes "around" an object (except for diffraction which is not what we're talking about here). The softbox works because the light comes from many different sources at many different angles, thus the light can't for a sharp shadow boundary.

Of course it does. Light is a stream just like liquids and air. That is how air dynamics of the car works.

Take a ball and light up the candle behind it. Now blow strong stream of air on the ball and candle will go out.

Or do this, position the object 1 foot from the wall and shine the light on it. you should see harsh shadow. Now move the object another foot away and shadow gets smaller. Same light, same object. Why? Because light bends around the object and lightens the shadow.

And if you don't believe me just Google.

 SushiEater's gear list:SushiEater's gear list
Nikon D800E Nikon D810 Nikon AF-S Nikkor 16-35mm f/4G ED VR Nikon AF-S Nikkor 14-24mm f/2.8G ED Sigma 70-200mm F2.8 EX DG OS HSM +11 more
Reply   Reply with quote   Complain
jjnik
Senior MemberPosts: 1,293Gear list
Like?
Re: Relation between dust and aperture setting
In reply to SushiEater, 9 months ago

SushiEater wrote:

jfriend00 wrote:

SushiEater wrote:

jfriend00 wrote:

When you shoot at a small aperture, the small aperture is excluding the light rays that come from the outer parts of the lens. As such you end up with only light rays that are of very similar angle through the lens. This means that the light rays hitting a given pixel on the sensor are generally all arriving in at approximately the same angle. This means that a dust particle that's on the glass above the sensor is going to cast a much stronger shadow on that particular pixel and thus it's effect will be quite noticeable.

If you shoot at a large aperture, the entire lens are is used to collect light and light arrives at a given pixel from many different angles. Because the light arrives from many different angles, the dust particle doesn't cast a very pronounced shadow on the pixels and thus you don't notice it as much.

Not even close. Regardless of aperture used the entire lens collects the light. At large aperture light hitting the sensor is straight (er) and at small aperture light is at the angle scattered more thus you get diffraction. It works exactly the same as your eyes. The more you squint the more you see in focus (DOF) but squinting does not prevent seeing less. No matter what your entire pupil collects light you see. The brighter the light the more pupil contracts.

Sorry, dude but you just don't appear to understand here. Why do you think large aperture lenses have much bigger optics.

First of all don't call me dude. It is not polite.

Second of all large aperture lenses have much bigger optics because small lenses don't collect as much light as larger lenses. For the same reason the last element of the lens has to be larger too.

It's because the EXTRA light for the larger aperture comes from collectig more light with the larger lens. When you then take a large aperture lens and use a small aperture with it, you are restricting light so that only light from a narrower set of angles (through the central part of the lens) is actually used, the other light rays are blocked by the aperture.

Again, not even close. Regardless of the aperture the front element collects all of the light.

I am not talking about quantity of the light, I am talking about just light. Of course, if you close aperture less light coming in but all of the view coming in anyway. This light just being angled otherwise you would see nothing more than the aperture opening on the sensor.

Do this (this is an old trick), glue a small mailing stamp on the front element. Take a picture. See if the stamp is in the picture. I have a lens with lots of dust behind the front element. Never seen it in the pictures.

And squinting does not make less light going in to your eye because you are not covering the pupil.

If you squint your iris does not get larger, indication of the less light. Only your pupil collect light not he whole eye. Stand in front of the mirror and see for yourself.

The soft box makes light to go around the object and it doesn't have to be large but the larger it is the more light goes around. And it is not the only reason. Bouncing light can eliminate shadows too by simply throwing light on the shadows.

You are so wrong here. Light travels in straight lines.

But it also bends and goes around.

Take two objects. The disk and the ball of the same diameter.

Shine the light on the ball. If you are correct light should produce the same shadow as the disk.

Nope!!!! Light will go around the ball and produce smaller shadow.

It NEVER goes "around" an object (except for diffraction which is not what we're talking about here). The softbox works because the light comes from many different sources at many different angles, thus the light can't for a sharp shadow boundary.

Of course it does. Light is a stream just like liquids and air. That is how air dynamics of the car works.

Take a ball and light up the candle behind it. Now blow strong stream of air on the ball and candle will go out.

Or do this, position the object 1 foot from the wall and shine the light on it. you should see harsh shadow. Now move the object another foot away and shadow gets smaller. Same light, same object. Why? Because light bends around the object and lightens the shadow.

And if you don't believe me just Google.

Wow - virtually everything you just threw out (or maybe a better word would be threw up) about the behavior of light is completely wrong!

 jjnik's gear list:jjnik's gear list
Nikon D4s Nikon D700 Nikon D800E Nikon 1 AW1 Nikon AF-S Nikkor 24-70mm f/2.8G ED +11 more
Reply   Reply with quote   Complain
jfriend00
Forum ProPosts: 11,131
Like?
Re: Relation between dust and aperture setting
In reply to SushiEater, 9 months ago

SushiEater wrote:

jfriend00 wrote:

SushiEater wrote:

jfriend00 wrote:

When you shoot at a small aperture, the small aperture is excluding the light rays that come from the outer parts of the lens. As such you end up with only light rays that are of very similar angle through the lens. This means that the light rays hitting a given pixel on the sensor are generally all arriving in at approximately the same angle. This means that a dust particle that's on the glass above the sensor is going to cast a much stronger shadow on that particular pixel and thus it's effect will be quite noticeable.

If you shoot at a large aperture, the entire lens are is used to collect light and light arrives at a given pixel from many different angles. Because the light arrives from many different angles, the dust particle doesn't cast a very pronounced shadow on the pixels and thus you don't notice it as much.

Not even close. Regardless of aperture used the entire lens collects the light. At large aperture light hitting the sensor is straight (er) and at small aperture light is at the angle scattered more thus you get diffraction. It works exactly the same as your eyes. The more you squint the more you see in focus (DOF) but squinting does not prevent seeing less. No matter what your entire pupil collects light you see. The brighter the light the more pupil contracts.

Sorry, dude but you just don't appear to understand here. Why do you think large aperture lenses have much bigger optics.

First of all don't call me dude. It is not polite.

Second of all large aperture lenses have much bigger optics because small lenses don't collect as much light as larger lenses. For the same reason the last element of the lens has to be larger too.

It's because the EXTRA light for the larger aperture comes from collectig more light with the larger lens. When you then take a large aperture lens and use a small aperture with it, you are restricting light so that only light from a narrower set of angles (through the central part of the lens) is actually used, the other light rays are blocked by the aperture.

Again, not even close. Regardless of the aperture the front element collects all of the light.

I am not talking about quantity of the light, I am talking about just light. Of course, if you close aperture less light coming in but all of the view coming in anyway. This light just being angled otherwise you would see nothing more than the aperture opening on the sensor.

Do this (this is an old trick), glue a small mailing stamp on the front element. Take a picture. See if the stamp is in the picture. I have a lens with lots of dust behind the front element. Never seen it in the pictures.

And squinting does not make less light going in to your eye because you are not covering the pupil.

If you squint your iris does not get larger, indication of the less light. Only your pupil collect light not he whole eye. Stand in front of the mirror and see for yourself.

The soft box makes light to go around the object and it doesn't have to be large but the larger it is the more light goes around. And it is not the only reason. Bouncing light can eliminate shadows too by simply throwing light on the shadows.

You are so wrong here. Light travels in straight lines.

But it also bends and goes around.

Take two objects. The disk and the ball of the same diameter.

Shine the light on the ball. If you are correct light should produce the same shadow as the disk.

Nope!!!! Light will go around the ball and produce smaller shadow.

It NEVER goes "around" an object (except for diffraction which is not what we're talking about here). The softbox works because the light comes from many different sources at many different angles, thus the light can't for a sharp shadow boundary.

Of course it does. Light is a stream just like liquids and air. That is how air dynamics of the car works.

Take a ball and light up the candle behind it. Now blow strong stream of air on the ball and candle will go out.

Or do this, position the object 1 foot from the wall and shine the light on it. you should see harsh shadow. Now move the object another foot away and shadow gets smaller. Same light, same object. Why? Because light bends around the object and lightens the shadow.

And if you don't believe me just Google.

Ignoring diffraction effects and extraordinary things that might happen in space with large bodies like planets, neither of which I think we're talking about here, light in a constant medium (like air) travels in a straight line. As long as you insist otherwise, it is not worth discussing further with you.

If you want to share a reference on the ball and disk that shows light bends and it's not purely a diffraction effect, then folks could take a look.

Oh, by the way why do YOU think that a small aperture makes dust particles more visible if it's not for the reasons I've outlined.

-- hide signature --
Reply   Reply with quote   Complain
SushiEater
Senior MemberPosts: 2,099Gear list
Like?
Re: Relation between dust and aperture setting
In reply to jfriend00, 9 months ago

Ignoring diffraction effects and extraordinary things that might happen in space with large bodies like planets, neither of which I think we're talking about here, light in a constant medium (like air) travels in a straight line. As long as you insist otherwise, it is not worth discussing further with you.

If you were correct than light shining on the object would create well dined shadow. But it doesn't.

Even laser shined on the moon would produced very large circle there. Not so straight line, is it.

If you want to share a reference on the ball and disk that shows light bends and it's not purely a diffraction effect, then folks could take a look.

Oh, by the way why do YOU think that a small aperture makes dust particles more visible if it's not for the reasons I've outlined.

For the same reason you see sharper when you squint.

 SushiEater's gear list:SushiEater's gear list
Nikon D800E Nikon D810 Nikon AF-S Nikkor 16-35mm f/4G ED VR Nikon AF-S Nikkor 14-24mm f/2.8G ED Sigma 70-200mm F2.8 EX DG OS HSM +11 more
Reply   Reply with quote   Complain
Araldite
Regular MemberPosts: 352Gear list
Like?
Re: Relation between dust and aperture setting
In reply to SushiEater, 9 months ago

If the sun sets below the horizon why do we still have some light ?? Black holes can distort light, so why can't we have a small distortion on earth or bending of the light rays?

 Araldite's gear list:Araldite's gear list
Panasonic Lumix DMC-LF1 Canon EOS 70D Canon EF-S 15-85mm f/3.5-5.6 IS USM Canon EF-S 55-250mm f/4-5.6 IS STM Adobe Photoshop Elements 10 +2 more
Reply   Reply with quote   Complain
SushiEater
Senior MemberPosts: 2,099Gear list
Like?
Re: Relation between dust and aperture setting
In reply to jfriend00, 9 months ago

Do you see harsh shadows? And she is sitting few inches from the wall.

This is why.

 SushiEater's gear list:SushiEater's gear list
Nikon D800E Nikon D810 Nikon AF-S Nikkor 16-35mm f/4G ED VR Nikon AF-S Nikkor 14-24mm f/2.8G ED Sigma 70-200mm F2.8 EX DG OS HSM +11 more
Reply   Reply with quote   Complain
SushiEater
Senior MemberPosts: 2,099Gear list
Like?
Re: Relation between dust and aperture setting
In reply to Araldite, 9 months ago

Araldite wrote:

If the sun sets below the horizon why do we still have some light ??

Because what you see where you are is not what actually happens. Sun still shines on the atmosphere and light reflects in to your location.

Black holes can distort light, so why can't we have a small distortion on earth or bending of the light rays?

Since black holes are theory I can't comment.

 SushiEater's gear list:SushiEater's gear list
Nikon D800E Nikon D810 Nikon AF-S Nikkor 16-35mm f/4G ED VR Nikon AF-S Nikkor 14-24mm f/2.8G ED Sigma 70-200mm F2.8 EX DG OS HSM +11 more
Reply   Reply with quote   Complain
kentak
Junior MemberPosts: 36
Like?
Re: Relation between dust and aperture setting
In reply to SushiEater, 9 months ago

SushiEater wrote:

Ignoring diffraction effects and extraordinary things that might happen in space with large bodies like planets, neither of which I think we're talking about here, light in a constant medium (like air) travels in a straight line. As long as you insist otherwise, it is not worth discussing further with you.

If you were correct than light shining on the object would create well dined shadow. But it doesn't.

Even laser shined on the moon would produced very large circle there. Not so straight line, is it.

If you want to share a reference on the ball and disk that shows light bends and it's not purely a diffraction effect, then folks could take a look.

Oh, by the way why do YOU think that a small aperture makes dust particles more visible if it's not for the reasons I've outlined.

For the same reason you see sharper when you squint.

jfriend00's answer and reasoning are correct.

Here is a link that shows an explanatory diagram.

dust and aperture

It's because dust lies on the filters above the actual photosites that aperture makes a difference--due to light rays coming more directly at small apertures and from wider angles at large apertures.

If dust were able to lie directly on the sensor, thus blocking all light to given pixels, then aperture would make little or no difference and dust would be visible and distinct no matter the aperture.

Reply   Reply with quote   Complain
SushiEater
Senior MemberPosts: 2,099Gear list
Like?
Re: Relation between dust and aperture setting
In reply to kentak, 9 months ago

I posted the same exact link in my very first post in this thread 5 hours ago.

The way I understand what he is saying is that light is coming from different angles if aperture is smaller and that is why we see more dust which is not correct.

 SushiEater's gear list:SushiEater's gear list
Nikon D800E Nikon D810 Nikon AF-S Nikkor 16-35mm f/4G ED VR Nikon AF-S Nikkor 14-24mm f/2.8G ED Sigma 70-200mm F2.8 EX DG OS HSM +11 more
Reply   Reply with quote   Complain
jjnik
Senior MemberPosts: 1,293Gear list
Like?
Re: Relation between dust and aperture setting
In reply to SushiEater, 9 months ago

SushiEater wrote:

Do you see harsh shadows? And she is sitting few inches from the wall.

This is why.

That's about reflected light, not light bending around an object - as that doesn't happen, with the exception of gravitational lensing around massive objects - Amanda Tapping certainly not qualifying as one!!

 jjnik's gear list:jjnik's gear list
Nikon D4s Nikon D700 Nikon D800E Nikon 1 AW1 Nikon AF-S Nikkor 24-70mm f/2.8G ED +11 more
Reply   Reply with quote   Complain
kentak
Junior MemberPosts: 36
Like?
Re: Relation between dust and aperture setting
In reply to SushiEater, 9 months ago

SushiEater wrote:

I posted the same exact link in my very first post in this thread 5 hours ago.

The way I understand what he is saying is that light is coming from different angles if aperture is smaller and that is why we see more dust which is not correct.

No, he said the opposite in his first post in the thread: Light arrives at the dust/sensor at narrower angles with small apertures and from wider angles with large apertures.

Thus, if you two are in agreement, the matter can be settled. Cool.

And, yes, I did miss your link. I think it explains the issue pretty well.

Reply   Reply with quote   Complain
jjnik
Senior MemberPosts: 1,293Gear list
Like?
Re: Relation between dust and aperture setting
In reply to SushiEater, 9 months ago

SushiEater wrote:

I posted the same exact link in my very first post in this thread 5 hours ago.

The way I understand what he is saying is that light is coming from different angles if aperture is smaller and that is why we see more dust which is not correct.

it's the opposite - smaller physical apertures (high f numbers) prevent the light coming in from many different angles making for a pinhole camera effect with larger DOF - so your dust bunnies become more obvious as they are in focus!

 jjnik's gear list:jjnik's gear list
Nikon D4s Nikon D700 Nikon D800E Nikon 1 AW1 Nikon AF-S Nikkor 24-70mm f/2.8G ED +11 more
Reply   Reply with quote   Complain
Keyboard shortcuts:
FForum MMy threads