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Old Mar 13, 2006, 12:12 PM   #141
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Interlude, part II

Good point, I'll have to keep that in mind as I continue. There are plenty of things that shouldn't work in theory, but actually do. I think another example is that of a bumble bee, and how aerodynamicaly they should not be able to fly.

So far I'm focusing on theoretical maximums, since it (at this point) seems like that's a real boundry. It also clips our silly early exaples of astrophotography right out of the discussion, its useful to exagerate things to make small differences easier to "see" as they do in finite element analysis (where you see a skyscraper swinging sixty feet side to side in a discovery channel animation), but you have to do so with some discretion or disclaimers (I tried just that, but it seemed to cause confusion).

At any rate, I figure if we can determine theoretical maximums we can then try to plot the relatively small "real" differences along that scale. In the end, as we all already know, a cheap lens and a good lens have such a huge difference that all discussion of what's possible may seem irrelevant. The biggest reason I think it IS relevant, is the digicam segment of the market where a permanently fixed lens is designed as part of the whole camera system. Its this segment where engineers have the most freedom to push the limits, I think.

[edit] Lol, here's a bit about the bumblebee

"Often, the statement is made in a distinctly disparaging tone aimed at putting down those know-it-all scientists and engineers who are so smart yet can't manage to understand something that's apparent to everyone else."

Fitting, but I like this one,

"In some sense, the story has done its share to inspire further research. In recent years, scientists have tackled the problem of insect flight from a number of different angles and gained new insights into the complexities of powered flight."
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Old Mar 13, 2006, 9:38 PM   #142
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Since I haven't bothered to go over everything step by step, I'm only offering the hesitant opinion that there may be a couple small errors in all that difficult work.

FOV is being used where it seems it should be aperture. I find myself trying to imagine a 800mm lens on a 35mm camera, with f/2.8, which ends up being 10mm across. Across where? The f/D ratio suggests it needs to be 265mm objetive diameter. Carry that around. :evil:

In you TV example, you measure the slots in the shadow mask in the horizontal plane, and then use that figure for diagonal resolution. Should be horizontal.

Interesting, though.

brian
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Old Mar 13, 2006, 10:44 PM   #143
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I was wondering when someone would call me on that. What I really wanted to say, was to make the point of the minimum resolution needed to discern the three colors rather than a white spot (though I didnt state it that way). I figure that a pixel measuring aproximatly diaganolly the same size will give enough horizontal size to make that distinction.

Glad to know your paying attention!

The 10mm measurement was for the tiny camera with a 28mm lens, the big-gun would as you say be around 300mm, a BIG chunck of glass for sure. I've seen lens specs listed well over ten pounds, and I know I want nothing to do with that kind of monster. Without knowing the aperture we can't figure the lens size, which is why I listed it, but interestingly it dosent seem to figure into the calculations. I'm looking into that, since it seems quite odd.

I want to churn over my data so far, and try to get any errors to the surface, then draw some conclusions and move onto wherever the keyboard takes me next.
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Old Mar 14, 2006, 3:50 AM   #144
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A scientific explantion is one that is logical, not one that uses words or phrases that appear "scientifically technical", that is called jargon. Jargon is something that people that have week arguments fall back on to make it look like they know what they are talking about. The more "scientific" it sounds the more it sounds like you must know what you are talking about and that it must be correct because you are only repeating something that has already been proven by science. I have seen it a thousand times before. Another one that I see weak after week, is people that pick up on spellig mistakes or typig errors and make a big deal out of them.

You seem to be saying that the resolving power of lenses is the same no matter the focal length. I dont dispute that. That is not the issue. What you are failing to appreciate and address is the properties of light.

suppose you have two cameras in two rooms both 300mm on 35mm cameras both focused on a coin so that it fills the entire FOV. In one of the rooms it is completely dark, zero light, the other is lit brightly. Can you see both coins the same? Can you take a photograph of both? No. So from this we gather that the resolving ability of a lens is only PART of the equation. The other part of the equation is that it is the light coming into the lens that also determines the final picture. If you had your 30giga pixel camera in that dark room, would it be able to resolve a picture? No, because there is zero light, and when there is zero light, there can be no picture. Therefore what needs to be looked at is the light coming into the camera and how that may be affected. The resolving power of the lens is not will effect this, this is why I said you are arguing about the wrong subject.

Now suppose we ad a tiny bit of light into the room. Lets say it is just one photon of light bouncing around the room. This one photon of light hits the coin, and then flies into the lens. Can we see the whole coin yet? NO From this we can gather that even though light hits an object, it wont make the entire object visible will it? Therefore in order to see the entire object we need for light to hit the entire object, not just one part of it.
Lets suppose that to see the entire coin we need ten million light photons to hit it and for each and every one of those light photons to enter the lens. We have our modified particle accelerator that can shoot individual particles of light aimed at the coin. It fires ten million photons that hit the coin which then enter the lens, (redirected via a mirror) now can we see the entire coin. Yes, we can see the entire coin.
Now lets use two accelerators. One of them will fire 5million photons at the coin, while the other will fire 5 million at the lens directly. The 5 million are targetted at specific points. Some will hit the nose of the face on the coin, some will hit the hair, some on the chin, and some on every second letter. They hit the coin and then enter the lens. Can we see the entire coin? No we only see the parts of the coin where the light actually hits. We still have a total of 10million photons of light which still allow you to expose the sensor, but only 5 million of those photons are actually coming from the source, the other 5million are coming from elsewhere, they are blanks, they are AMBIENT light.
The further away you are from an object, the less light you are seeing from the actual object, and the more AMBIENT light you are seeing in the mix. therefore the closer you are to the object, the more direct light you are getting, and the less ambient light. This is because light does not travel in parallel lines, if it did, your field of view would now change no matter how far back you went. At the same time as light is "bouncing" off the object you are also getting light from the sun mixing in, therefore "diluting" the light coming from the object. In any given sqaure inch of light, the further you get away from the object, the more ambient light photons there are compared to the number of light photons that have actually been in contact with the object.
So before we go on, do you have any problem with this concept?

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Old Mar 14, 2006, 9:06 AM   #145
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Quote:
You seem to be saying that the resolving power of lenses is the same no matter the focal length. I dont dispute that. That is not the issue. What you are failing to appreciate and address is the properties of light.
Read it again, you missed something. I am talking entirely about resolving power of the lens but thats not exactly the conclusion I was going to draw from the facts I dug up. I am finding that a lens of X° angle of view will resolve details at a given minimum size on the focal plane no matter the focal length, however, a longer focal length creates a larger image circle (therefore, more 'pixels' of the same size are being resolved by the lens). A wider angle of view resolves smaller details at the focal plane (again, regardless of focal length).

Please state the problem that you are trying to adress, I think it is different than mine. The problem that I am adressing is this (hey, if your interested in something else, thats fine. But your post sugests that I'm a screw up for ignoring your problem... whatever it is?):

Quote:
The purpose of the following is to determine the theoretical limitations of a perfectly constructed lens, and if you can achieve as good results with a shorter focal length as you would with a longer focal length, all else being equal.
Pretty clear, no? I'm talking about resolution, not exposure. Please clarify the subject you are adressing between focal lengths, because I dont understand it and it seems to change with every post (probably because I don't understand).

Quote:
I said you are arguing about the wrong subject.
Different, I believe, but how is different wrong? Could we both discuss separate issues here, is there room for that? I'd adress your points, if I knew what point you were trying to make. As it is, if I try to counter your side of the discussion were going to go around in circles "no, I mean this" and "but that will affect..", know what I mean? It almost sounds like your not interested in lens resolution, but brightness as it relates to exposure, is this correct? If so, then aperture is critically important, but I don't see any mention of it in your post. Please help me out, and clear up the confusion.
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Old Mar 14, 2006, 11:16 AM   #146
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Mark47 wrote:
Quote:
...In any given sqaure inch of light, ...
To use that measure, you will have to rewrite pretty much all of physics. Even Newtonian physics does not talk about light being measured in terms of area.

Mark47 wrote:
Quote:
... We have our modified particle accelerator that can shoot individual particles of light ...
Interesting. You claim that light can be accelerated? That means that light cantravel at some speed other than the speed of light. Even more rewriting of physics.
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Old Mar 14, 2006, 11:44 AM   #147
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that it must be correct because you are only repeating something that has already been proven by science.
There's a scary implication there, that your tying to make a point that can not, or at least has not, been proved by science.

Quote:
We have our modified particle accelerator that can shoot individual particles of light aimed at the coin.
Whoa, that sounds relevant! I dont think many people go about photography by using particle accelerators to "shoot" light at things. Why don't we stick with examples that we might actually encounter in our own backyards.
Quote:
therefore the closer you are to the object, the more direct light you are getting, and the less ambient light.
You make big leap from misusing particle accelerators to photographing a tree in my back yard, or the headlights of my car. I really can't draw any useful conclusions from that. It seems that your saying that one form of light got hungry and ate the other. As far as I know, light cannot act upon other light.

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This is because light does not travel in parallel lines, if it did, your field of view would now change no matter how far back you went.
Not paralell, but straight. If light does not travel in a straight line, can you explain the way it does travel? I'm thinking of a word, can you guess what it is? Cone. This is a useful word, we can apply numbers, formulas, and concepts to it, expanding as we go (Ha, I crack me up!).

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Old Mar 14, 2006, 4:28 PM   #148
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Quote:
Quote:
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... We have our modified particle accelerator that can shoot individual particles of light ...
Interesting. You claim that light can be accelerated? That means that light cantravel at some speed other than the speed of light. Even more rewriting of physics.

So you and junior scientist here actually believe that a particle accelerator could be used to fire a photon of light at a coin in a room and that you could photograph it:?. Wow, no wonder you cant grasp anything.
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Old Mar 14, 2006, 4:31 PM   #149
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Quote:
wrote:
Quote:
...In any given sqaure inch of light, ...
To use that measure, you will have to rewrite pretty much all of physics. Even Newtonian physics does not talk about light being measured in terms of area.

Then obviously I must mean something else then, therefore you obviously dont understand, so why reply to something that is over your head?

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Old Mar 14, 2006, 4:38 PM   #150
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Quote:
Quote:
Quote:
This is because light does not travel in parallel lines, if it did, your field of view would now change no matter how far back you went.
Not paralell, but straight. If light does not travel in a straight line, can you explain the way it does travel? I'm thinking of a word, can you guess what it is? Cone. This is a useful word, we can apply numbers, formulas, and concepts to it, expanding as we go (Ha, I crack me up!).

Why dont you get yourself a dictionary and look up the difference between parallel and straight. Did I say light does not travel in straight lines? Where did you get that, and why bring up something so irrelevant.
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