City - Zagreb State - CROATIA Country - UF Old Timers
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Adrijana, is a friend of mine studing and living in Zagreb. I'd use the chance here to thank her for all. and the oblivious, unrecorded time- of which no one might be aware! :D
I would wish to have you explaining me this on practice, even though there's a great theoritical explanation of this phenomena. I will remember this, we'll talk again about it some day (i mean, i will listen to you).
Such negative apertures are really very usual too. In electron microscopy for example, since the electron "rays" tend to "diverge" because the electrons have negative charge and thus repel each other.
So, perhaps a possible interpretation could be that the optical properties of such a lens are such that the image is constructed under a virtual repulsion of all photons against each other in the light ray. Since photons are bosons they can't do that in a space with positive distances. So we, again, can say that such a lens distorts space in the sence of taking the negative candidate of the square root that represents distance. No problem, that's only a bijective mapping!
I think those ol' sods in NASA and Leica and Hasselblad have that already, Visar! They keep it as a secret since at least 45 years! ;-)
Seriously now, I miss some point here, since I don't see any kind of matter travelling. It's only light that travels, and that is allowed to travel with c in space. (What space? That's another question ;-)) Antimatter can (and does) quite peacefully exist in our space, until it gets to meet some matter and get annihilated to radiation. (Think of positrons.)
A lens with a negative focal length (not aperture) is actually each an every normal biconcave lens, since it constructs a virtual image in front of it and not behind it. So we had to place the film in front of the lens and not behind it, in order to get an image.
Now, keep the focal length positive and let the aperture go below 0. Then, the image has to be generated behinf the lens, since the focal length is > 0. But the aperture is negative. And at the same time (see attachment):
f=u/(1.22*lambda*(m+1))
where f is the aperture stop, lambda is the wavelength of light, and m is the magnification. So, if f is negative, then we have many possilities to make the right hand side also negative.
We can say that u is negative, and lambda and m are positive. Then, one way to achieve a negative u is to invert space itself on the coordinates origin (middle of lens). Any distance in front of you is now distance behind you, and you could seemlesly photography people behind you! Interersting case for espionage! ;-) The other way is to achieve this is to say that your virtual lens stands behing the object which stands in front of you, and so you capture the backside of some object in front of you. Great case too! Still we are in euclidian space. A distance is a square root of sums od squares here. The square root of, say 4, is 2 *and* -2. Until now we dealt with the positive roots. OK, now we go for the negative roots!
Or we can say that lambda, light's wavelength is 0. Insane case for Perry Rhodan, and I still don't figure out this space. Seems to be... exquisite! It includes energies < 0, which is quite normal, but also negative curvatures, which is, well, not so normal! ;-)
We can say that -oo < m < -1, and u and lambda < 0, which again can be reduced to the first case.
Or we can also say that u, lambda < 0, and -oo < m < -1. Errm... I leave that for later on! ;-)
The annals of photographic mathematics, that is! ;-)
OK- i wish we had means to plunge into the realms of discovery!! I thought that f1:1 would be equal to what the eye can see on whatever light condition!? eye being here the reference. Now, i have also only heard of lenses that as you discribe as wet dreams of all photographers, including me there amongst those topwishers! ;) though, i never saw or shot with one!
the idea of having a minus/ negative aparture, is absolutely thrilling to me and i feel sparkls on my eyes too. and i have thought of it. and i found it mathematically, as you have also described in your message, working. but, (that big fat *but* as you say), it sounds to something like the matter reaching the speed of light, thus it is no matter anymore- but antimatter. it passes onto a level practically unknown to us but theorically passible. I guess, i am getting mathematically confused, as it seems those calculations are surpassing my logical imagination- therefore, a whole new beginning for the photographic era is about to begin!? how about proposing this project to NASA, or Leica company, or...!?
And now for my wishful thinking that didn't fit the maximun length of the messages.
As known, the f/stop is simply the ratio of aperture diameter to focal length. Now, any lens covers some certain range of f/stops. Opening the aperture wider and wider is simply going to smaller denominators of that ratio, which allows for more light to pass through on its way to the film or CCD. And so we come to f/1, which says that the aperture diameter is exactly as large as the focal length? Now, that's already a light giant of a lens, but it goes even higher. There are lenses around that reach f/0.5 ( = f*2 !!!) or even f/0.33 (= f*3 !!!!!) Which is already stunning (and a wet dream of every photographer).
The other direction is of course to make that ratio smaller and smaller, which is a great thing for big DoF and also less light to pass through. Following that direction we go to f/12... f/22, and so on, and that series of ratios tends towards 0 in case of an aperture diameter that is really tiny tiny tiny. Thinking of it independently of "reality" (no problem for a mathematician! ;-)) we end up with, say f/(large number). But no matter how large the demonator is, the ratio f/something can't be less than 0. (Remember my arrrfff for stops less than 0, i.e *negative*? ;-))
So let's continue thinking abstractly. What would a negative f-stop mean? It would imply a less than 0 diameter of the aperture! Hey, now that I name a revolution! A negative length! It appears quite naturally in many metric spaces. But what would that mean in our usual euclidean metric? Hmm, I must think of that - and my eyes are shining insanely now! I conjecture that it would mean a complete inversion, and that not only for left-right but also for... front and back!!! You could capture what is *behind* some optical obstacle! And you could make portraits of people that stand with their backs turned on you! Heheee!!! (Sinister smile here!)
But I must examine the consequences exactly. As we know, mathematics doesn't really care about possibilities of realisation/production of such lenses, ey? ;-) Much like saying, when two people go into an emoty building, and three come out of the same building later on, then: If one person goes into the bulding then the building is... empty!! :-D
And thanks a lot for the fruitful ongoing exchange!
Such results of pushes are indeed not really exactly foreseeable. You only get the "feeling" of what the result will be like in "average". But indeed not really exactly. And many times you just keep on trying, studying the results, making some conslusions, and there you go for yet another try until it really works. It can be fun but it can also get on your nerves - I know! ;-)
I used the word "negative" not as a description of quality, but simply as less than 0. It wasn't absolutely clear to me that you meant f/3 *less* than "normal", and that the minus sign only denoted that *less than*. So I was wondering if you mean perhaps an aperture of really -f/3, which would be a revolution to me. Unfortunately no revolution this time! ;-) And fortunately we are in our usual trusted fields of apertures! I think that there was also wishful thinking in my wondering. You'll see why at the end of the message.
So, after having understood exactly what you mean, I must say that I would also prefer a narrower aperture for greater DoF and thus greater range of detailed depth. A bit less light is more than acceptable to me if the details come up properly. Except of course if there is some intention for a "heavely feeling", as you said - I must lough again here! I know what you mean! Or perhaps if there is the danger of underexposure and loss of details because of that. But that's then a chapter for itself - how to get details when the light is simply too low.
About the pixelated-echoed behavior of some details sometimes, this was exactly why I asked! I have sometimes the same problems with my scanner. In such cases I go to higher scanning resolution, but to a higher scanning resolution that is *not* an integer multiple of the resolution at which the problem appears. For example, when this problem appears at a scanning resolution of 1200ppi, it will disappear at, say, 1800ppi, but *reappear* at 2400 ppi, or 3600ppi, etc - and that's funny! It is funny because it only affects *some* parts of the image, and because it keeps returning at those integer multiples. When such things appear, it always smells after resonance. This really seems to be resonance of the scanning resolution with the resolution of something real existing. I tip on the degree of "fineness" of the details of the image in that specific region. The same reason for the Moivre patterns that appear sometimes. I examine that further.
I usually set my camera on AV (aparture priority). that adjusts the light SP (shutter speed) for me. as you said, the pushing of aces from 100 to 200, or other number, one gains in grain and the results are really unforeseen- but certainly not as they would be if one did not push them.
I do not think i said there's something negative in pushing -1/3 less stop. I would rather keep a few details underexposed rather than losing them by overexposure- unless i want to reach some heavenly feeling ;).
as for that picelated- echoed behaviour, as your putting it, you have to pardon my ignorance when it comes to that. though i know for sure, that it is not due to the uploading size and the UF resize- as i uploaded in a ratio of 700 x 500; and it is not oversharpened- so the only possibility is the scanning. do you have any idea of how to get rid of that, or is it ok that way?
once more, thanks for the inquirie and the thoroghness in analysing my photos.
Hi Visar, and thanks for the details on how you got the image. The push 200->400 (or even higher) is good for strengthening grain on film images, which I consider one of the most fascinating things in analog photography. (But the pushed frame has to be also processed accordingly, i.e. not as 200) I do that quite often too. Quite surprised to see no grain on this.
But what is a -0.3333 stop? Why is it negative? Or did you mean that you shoot with an f stop of one third *less* than what the camera "would decide"? In this case it would mean to cheat the sensitivity to the double of the used film, which then halves the amount of light that hits the film frame. And also a change of the aperture in such a way (0.3333 = 1/3 stop less) that the amount of light gets again doubled back if the "original decision" of the camera would be approx. f/1.14. Any "original camera decision" of wider than f/1.14 more than doubles the amount of light that hits the frame, and so you get overexposure. And any "original decision" of narrower than f/1.14 less than doubles that light which results in underexposure. Since your Canon 28-135 IS USM covers starts from 1:3.5-1/5.6 the image should be underexposed, but it isn't. So, did you perhaps also set a slower shutter speed for letting some additional amount of light to hit the film frame? That would explain the motion blur of Adrijana. But she stood at the right place, really. So, reluctance has also its benefits! ;-)
I attached also the marked-up image. The letters of "National Geographic" and the window frames of the building exhibit that kind of "pixelated-echoed" behavior that comes either from oversharpening, or from scanning, or from automatic downscaling of uploaded images bigger than 850x850 in UF. The downscaling algorithms of PS do a much better job for that, but are also slower. Perhaps its better to downscale images first - at least I have better results with manual downscaling in PS before uploading.
As about that game, well, I think that the recorded melting times are going to get shorter and shorter as the years are passing by. Which could make refrigerators even more necessary for cooling things. Which would raise the amount of needed electric energy. Which could make necessary to burn even more oil. Which spits out more C02 to the atmosphere - hmmm... Nice expectations! ;-)
Thanks for the thorough comment on this shot Nick. No, it is not due to oversharpening. It is because that day i wanted to try something new. I cheated the camera (it is film, no digital) by raising the aces to 400 from its original scale of 200. In addition, i usually take shots with -0.3333! stops. that way i gain in speed and also preserve details by not overexposing them while trying to get just enough of the main subject.
I do absolutely agree with you with respect to the composition suiting cityscape images; that way the compositions turn creative in the positioning the subjects as well as much of the scenery around. I was taking a shot of this yellow frame, which was put there by National Geographic- that was a message for the global warming (they put a massive ice within the frame- and made a game, as when the ice is gonna melt; whoever sends a message with the most accurrate time was gonna win a great deal of money), and then Adrijana was reading something and reluctant to what i was doing. I called her name, and she turned, and so I got a very spontaneous shot of her, of which I am thankful to her reluctance, and yet i have the shot which i intended to take. beside, on where she stands there couldn't be anything of more importance than her?!
Great details on the city and its unimaginably complicated, yet familiar structure. I find that the unbalanced, de-centered composition is always best suited for the needs of the city. I only wish that the pixelation phenomena would be absent here - was that from downscaling or oversharpening it, Visar?
Adrijana stands exactly at the right place, on the implicit leading line from her over the yellow case to the building on the background. A bit of motion blur on her, but still strong enough as a moment frozen for all times.
That bright yeloow is such a good contrast to the rest of the rather dusty earthy colors of the city. It pops in front of the image, it says "Here!" Almost as strong as those B&W images with only a single object in colors. Good approach for that with camera/lens only.
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{K:127263} 5/1/2008
