Aperture and Field of View

[pzkpfw]

OK, so step 3, note that with the lasers themselves turned off, and the scene lit by some other source, the "lasers" may as well just be "toasters", because you're not talking about the beams emitted, you're talking about the devices themselves.

So, as per post #2, the aperture won't stop you seeing any of the devices, but it will affect how much light from them gets to the screen. Note four paths from the toasters to the lens shown here, but 2 paths to the screen. The aperture has affected how much light gets through, but not the field of view.

(A but hurriedly drawn, sorry. Gotta go out soon.)

 

Step 4 then gets a bit complicated.

If you turn the lasers on, but keep the "other" light on also, you'd still see the five laser devices, but now you'd also see three red spots of the laser light; two of the beams are being blocked by the diaphragm (depending on the opening size). The lasers (when turned on) are just demonstrating how some paths of the light get blocked, but some don't.

Edited December 3, 2017 by pzkpfw
Numbers

[Strange]

29 minutes ago, Dalo said:

nope. I do mean off.

So you mean:

2) Let us turn all lasers off.

3) I suppose that everybody will agree with me that, even if the diaphragm is put at the same position as in in my diagram, all five lamps will be visible from the screen position, whatever the aperture?

In which case: no. How the *%^# will they be visible if they are off?

16 minutes ago, pzkpfw said:

because you're not talking about the beams emitted, you're talking about the devices themselves.

Hmmm. I wonder if that is the source of the confusion.... it would explain all the bizarre contradictory statements about beams vs sources being visible or not. And might even make sense of the "things become visible with the filter" (although I can't quite see how).

 

[Outrider]

On 12/1/2017 at 10:06 AM, Dalo said:

As you can see, the sky is completely dark, all the sun rays having been absorbed, leaving only the sun itself.

So you can see the sun with all the suns rays absorbed?

[Dalo]

27 minutes ago, pzkpfw said:

OK, so step 3, note that with the lasers themselves turned off, and the scene lit by some other source, the "lasers" may as well just be "toasters", because you're not talking about the beams emitted, you're talking about the devices themselves.

So, as per post #2, the aperture won't stop you seeing any of the devices, but it will affect how much light from them gets to the screen. Note four paths from the toasters to the lens shown here, but 2 paths to the screen. The aperture has affected how much light gets through, but not the field of view.

(A but hurriedly drawn, sorry. Gotta go out soon.)

 

Step 4 then gets a bit complicated.

If you turn the lasers on, but keep the "other" light on also, you'd still see the five laser devices, but now you'd also see three red spots of the laser light; two of the beams are being blocked by the diaphragm (depending on the opening size). The lasers (when turned on) are just demonstrating how some paths of the light get blocked, but some don't.

You are right that turning the lasers off and using an extra source of light needlessly complicates the whole picture. I really felt that Strange had expressed all possible objections to my experiment, and I did not feel like starting the whole discussion again. So I looked for variation to make the difference clear between the sources of light as illuminated objects, and the beams that come out of them, just like the analogy of the mini suns that shine all in one and the same direction.

Because of a new setup, I have to be more careful in the description of the different steps. 

1) same diagram as before. Diaphragm also at same position.

2) extra light. Lasers off.

3) all lasers, which could as well be roasters, are visible from screen.

4) extra light off. Lasers on. Only three beams go through diaphragms

5) five bright spots visible from screen.

 

5 minutes ago, Outrider said:

So you can see the sun with all the suns rays absorbed?

The picture of the sun through a filter is used as an analogy for the laser lamps that are visible even though their beams are blocked. 

Edited December 3, 2017 by Dalo

[pzkpfw]

Step 5 - wrong. How do you get the five bright spots if 2 of the beams are blocked?

 

[Strange]

12 minutes ago, Dalo said:

So I looked for variation to make the difference clear between the sources of light as illuminated objects, and the beams that come out of them, just like the analogy of the mini suns that shine all in one and the same direction.

So all this time your lasers have been illuminated by another source. Even though your video was done in the dark, and I explicitly said there was no other source of light. 

And then you complain when people don't understand you! 

13 minutes ago, Dalo said:

just like the analogy of the mini suns that shine all in one and the same direction.

You still haven't explained why you suddenly switched to mini suns that shine in one direction" instead of lasers. Presumably this means something different to you but you haven't said (and no one guess) what it is.

[Dalo]

5 minutes ago, Strange said:

So all this time your lasers have been illuminated by another source. Even though your video was done in the dark, and I explicitly said there was no other source of light. 

And then you complain when people don't understand you! 

You still haven't explained why you suddenly switched to mini suns that shine in one direction" instead of lasers. Presumably this means something different to you but you haven't said (and no one guess) what it is.

NO! THE LASERS ARE THE ONLY SOURCE OF LIGHT WHEN THEY ARE TURNED ON!

MINI SUNS ARE AN ANALOGY!

 

Edited December 3, 2017 by Dalo

[Strange]

No what? 

(Another annoying habit: ambiguous replies. I don't know which statement you are responding to. And I don't know what "no" means as a response to any of them.)

[pzkpfw]

4 minutes ago, Dalo said:

NO! THE LASERS ARE THE ONLY SOURCE OF LIGHT WHEN THEY ARE TURNED ON!

MINI SUNS ARE AN ANALOGY!

 

Step 5 (of your latest set) is still wrong.

Edited December 3, 2017 by pzkpfw

[Dalo]

Just now, pzkpfw said:

Step 5 (of your latest set) is still wrong.

That is the whole point of the discussion and the result that Strange and I had arrived at. He agrees with you. I do not, that is the reason for my experiment. You think that it is superfluous, I do not. We could go on forever, you will not change your mind and I will not change mine. Let us wait until I am in a position to perform the experiment myself, or until somebody else does it.

[Strange]

15 minutes ago, Dalo said:

NO! THE LASERS ARE THE ONLY SOURCE OF LIGHT WHEN THEY ARE TURNED ON!

So what have you now introduced another light-source that allows us to see the lasers when they are off. I thought this was to explain why you previously said that you could see the source when the beam was blocked. 

So, please, can we get rid of this extra light. We don't care about being able to see the laser equipment or what make they are.

We just want to understand why you think you can see the laser light when it is blocked by the diaphragm

 

15 minutes ago, Dalo said:

MINI SUNS ARE AN ANALOGY!

Why use an analogy when the "real thing" (laser) is good enough. It just confuses the issue. 

6 minutes ago, Dalo said:

That is the whole point of the discussion and the result that Strange and I had arrived at. He agrees with you. I do not, that is the reason for my experiment. You think that it is superfluous, I do not. We could go on forever, you will not change your mind and I will not change mine. Let us wait until I am in a position to perform the experiment myself, or until somebody else does it.

Can you explain how or why you think you can see the beams of light when they are blocked? Have you never heard of shadows? Can you see through walls?

Can you explain whether you think the lens is significant to this? Or can you still see the blocked beam in this version:

On 01/12/2017 at 5:20 PM, Strange said:

Dalo, which parts of the experiment are important? Could we do without the lens and the sensor/film? Could we reduce the setup to two lasers and a partial obstruction:

lasers     aperture      filter
              |
O------------ |             :
              |             :              (> observer
O---------------------------:-------
                            :
                            :

Will the observer see one or two light sources? Will this change if the filter is removed?

Edited December 3, 2017 by Strange

[pzkpfw]

43 minutes ago, Dalo said:

That is the whole point of the discussion and the result that Strange and I had arrived at. He agrees with you. I do not, that is the reason for my experiment. You think that it is superfluous, I do not. We could go on forever, you will not change your mind and I will not change mine. Let us wait until I am in a position to perform the experiment myself, or until somebody else does it.

There is no discussion if you can't explain (or diagram, or whatever) why you think your result would occur.

Why would you see all five spots?

(If you think that your step 5 would show 5 spots, given your step 4; it should be possible for you to draw a diagram showing the path you think the light is taking. Does the light do a loop-de-loop? A figure 8? How do you see all five spots when, given your step 4, two of the beams were blocked?)

Edited December 3, 2017 by pzkpfw

[Outrider]

1 hour ago, Dalo said:

The picture of the sun through a filter is used as an analogy for the laser lamps that are visible even though their beams are blocked. 

That doesn't answer my question. 

So you can see the sun with all the suns rays absorbed? Yes or no? 

[Klaynos]

7 hours ago, pzkpfw said:

There is no discussion if you can't explain (or diagram, or whatever) why you think your result would occur.

Why would you see all five spots?

(If you think that your step 5 would show 5 spots, given your step 4; it should be possible for you to draw a diagram showing the path you think the light is taking. Does the light do a loop-de-loop? A figure 8? How do you see all five spots when, given your step 4, two of the beams were blocked?)

I see we've actually gotten somewhere. 

If dalo would answer this question his misunderstanding would probably become apt clearer to us. 

Well done. 

[John Cuthber]

11 hours ago, studiot said:

Because Dalo want's to display an image on the screen, not burn a hole in it ??

 

Very smart.

However, it's not how a lens forms an image, and it explains why this thread is getting nowhere.

PZKPFW got it right last Thursday

On 11/30/2017 at 7:07 PM, pzkpfw said:

This whole 5 laser thing still seems like a pointless diversion, as I think Dalo has misunderstood post #2 (which he seemed to accept).

Dalo, the diagram showed how light from one point on the source travels multiple paths to the lens. So the diaphram blocks some of the light from points on the source, but not all. Note how in post #2 the diaphram does not cut off the head of the stick figure; just some of the light from the head. I've slightly expanded the diagram, possibly wasting my time.

Your five lasers do not replicate what happens for general photo taking, as we don't get single sources of light from the source we are photographing. e.g. there won't be a single ray of light from the head of the stick figure to the lens.

 

[Strange]

1 minute ago, John Cuthber said:

PZKPFW got it right last Thursday

But Dalo rejects that as irrelevant to his (new) question. It is no longer about field of view, but some bizarre misunderstanding about the visibility of lasers. As far as I can tell the lens is irrelevant. But it is hard to know because it is nearly impossible to get a straight answer from Dalo (deliberately ortherwise, I don't know).

9 hours ago, Dalo said:

The picture of the sun through a filter is used as an analogy for the laser lamps that are visible even though their beams are blocked.

But it is a terrible analogy. There is nothing blocking the light from the sun and it is nota unidirectional source. Your analogy has nothing common with the actual case.

If you take a picture of the Sun behind a tree (equivalent to the beam being blocked by the diaphragm) does it become visible when you add a filter?

 

[John Cuthber]

23 minutes ago, Strange said:

But it is hard to know because it is nearly impossible to get a straight answer from Dalo

That too, is a major contributor to the lack of progress in this thread.

[studiot]

3 hours ago, John Cuthber said:

15 hours ago, studiot said:

Because Dalo want's to display an image on the screen, not burn a hole in it ??

 

Very smart.

However, it's not how a lens forms an image, and it explains why this thread is getting nowhere.

I think you misunderstand both Dalo and pzkpfw's diagram.

 

Here is a kodak carousel projector calculator which shows the truth.

 

For instance the focal length of a lens to project a 2m image  on a screen 5 metres away is 86mm

 

Kodak projector lenses are in the range 75mm to 200mm focal length, and zoom between these values to focus at a fixed screen.

 

 

Note that projectors usually achieve Dalo's parallel ray requirement with a collimator between the light source and the slide.

 

Note that projector greatly magnify the object in the mage, whereas cameras greatly reduce the object size in the image on film or sensor.

Damm I lost all my text again

 

https://www.digitalslides.co.uk/wp-2013/faq-items/what-focal-length-lens-do-i-need-for-my-slide-projector/

 

 

 

[John Cuthber]

1 hour ago, studiot said:

Damm I lost all my text again

Unfortunately, it came back.

Do you work for Kodak?

If not I can't see why you posted the link there.

None of what you  posted does anything to help the discussion about apertures.

The calculation they do is correct, but has nothing to do with the point in hand.

You put the screen at the focus- that's why the projector lets you move the lens back and to in order to get the focus where the screen is.

The focus is not 86 mm from the lens (It only would be if the slide was an infinitely long way from the lens.)

[Dalo]

A favorite police interrogation technique is to keep asking the same thing over and over again, and grasp any change in formulation, however innocuous, in shaking the suspect's confidence. The aim is not so much the search of truth as intimidation.

It is a technique often used in this forum. Combined with  coordinated personal attacks from different fronts they are very effective in at least destroying the credibility of the poster.

These are means that are also used in "dirty" political campaigns. But then, as Phi said somewhere, scientists  (and would-be scientists) are just normal people, so we should not be surprised if they react just like anybody else.

I will not keep defending myself and my views when it is obvious that everything has been said. There is no way for me to ever satisfy the objectors unless I express my deepest apologies and culpability.

To the objectors I say: Don't hold your breath.

Edited December 3, 2017 by Dalo

[Strange]

Asking you for clarification, when you alternate between randomly changing the scenario and refusing to answer, is not a personal attack. Pouting out that you behave like that is not a personal attack either. 

[Phi for All]

57 minutes ago, Dalo said:

A favorite police interrogation technique is to keep asking the same thing over and over again, and grasp any change in formulation, however innocuous, in shaking the suspect's confidence. The aim is not so much the search of truth as intimidation.

It is a technique often used in this forum. Combined with  coordinated personal attacks from different fronts they are very effective in at least destroying the credibility of the poster.

!

Moderator Note

The resemblance wouldn't have a chance to form if you could explain the problems you have with mainstream science so the membership can understand what you're questioning. Questions for clarity, interrogations even, these are all part of the scientific method. But the "favorite police interrogation technique" resemblance is because you don't seem to be taking anything said on board. You still make the same mistakes, and by now it looks pretty willful, like you just want to make people waste their time explaining what you should have learned in school. You act like you're some kind of pioneer, when all everyone sees is someone unwilling to be clear about exactly what they don't understand about basic science. 

Not sure what to do with you. If it looked like you were trying to learn, we'd give you all the time in the world. As it is, you just keep rowing your canoe out of reach while claiming to want to board the ship. People are very patiently throwing you lines, which you watch sail past without grabbing onto. Now you claim instead they're using police tricks, and coordinating personal attacks. I think you need to take a vacation, re-read ALL of your threads, absorb the replies, and mark the difference between criticizing your ideas or thought processes and attacking you personally.

 

[Endy0816]

You've got this situation going on for an aperture.

If you start out with a million photons coming off of the object; only a fraction of them will be at an angle such that they'll pass through the aperture.

The more photons you allow in(larger aperture) the brighter your image but you also start seeing overlap(less clarity).

 

FOV remains the same because to photons even a tiny hole is like a train tunnel to a sparrow. Plenty of room to fly on through.

 

 

 

Edited December 3, 2017 by Endy0816

[pzkpfw]

2 hours ago, Dalo said:

... I will not keep defending myself and my views when it is obvious that everything has been said. There is no way for me to ever satisfy the objectors unless I express my deepest apologies and culpability. ...

It's not about "defending", it's about "discussion". Nobody wants your apologies, we want to understand why you think what you do, and help you.

You wrote:

4) extra light off. Lasers on. Only three beams go through diaphragms

5) five bright spots visible from screen

Nobody here understands how you get step 5 after 4.

It's very simple, all you need to do is draw a diagram showing how you can see all five spots in step 5. What path is the light following? (Move the discussion along, instead of getting upset and defensive.)

Your earlier diagram is a good start. 

 

Edited December 3, 2017 by pzkpfw

[studiot]

5 hours ago, John Cuthber said:

1 )Unfortunately, it came back.

2) Do you work for Kodak?

3) If not I can't see why you posted the link there.

4) None of what you  posted does anything to help the discussion about apertures.

5) The calculation they do is correct, but has nothing to do with the point in hand.

6) You put the screen at the focus- that's why the projector lets you move the lens back and to in order to get the focus where the screen is.

7) The focus is not 86 mm from the lens (It only would be if the slide was an infinitely long way from the lens.)

1) Why unfortunately? Is this personal?

2) No

3) Neither pzkpfw's nor Kodak's image formation on a screen show the screen at the focal distance from the lens optical centre.

4) I didn't suggest it did, I was going to post some very excellent pictures from Nikon about that.

5) If Kodak's calculation is correct (suprise suprise) why are you bitching about it?

6) It's basic that you can start a fire by focusing the Sun's rays onto an imflammable substance with a converging lens.
That is what happens if you put the substance at the focus of the lens. A project wants to make the image (much) larger, a camera wants to make it (much) smaller

7) The focal distance is determined by the lens not the light approaching it. If Kodak say their lens has a focal distance of 86 mm I would rather believe them than you, without much stronger evidence than personal attack.

2 hours ago, Phi for All said:

As it is, you just keep rowing your canoe out of reach while claiming to want to board the ship. People are very patiently throwing you lines, which you watch sail past without grabbing

 

I particularly liked this +1

 

and +1 tp pzkpfw for all the hard (and good) work put in on this thread.