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Author Topic: Infinity VS. Depth of Field  (Read 10567 times)
semillerimages
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« on: June 28, 2005, 09:03:17 PM »
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Nor was I referring to you. Sheesh.

*steve
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semillerimages
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« Reply #1 on: June 29, 2005, 01:52:33 AM »
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Intellectual superiority also entails one understanding the deficiencies in explaining a subject not perfectly understood by a layman.

You know what the poster meant about focusing beyond infinity.
You responded like a jack ass.

Stating the obvious.

It's a sorry state here that courtesy, civility and understanding cannot be the first step forward.

The put it in a way you *might* understand.
Speak only if you have something nice to say otherwise you pollute a great forum for learning by your insipid ways.

*steve
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dazzajl
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« Reply #2 on: June 29, 2005, 04:51:15 PM »
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Ok guys,

try and put down the text books for a minute and think about this from the point of using a camera and not talking about it.

Look at it this way.......

Set up a camera on a tripod and start walking away from it. After one pace you will probably be at the closest point the lens can focus. After another 10 paces, perhaps half way around the travel of the focus ring. At some point not long after that the lens will need to be set at infinity to have you on the focus plane.

If you keep walking past this point..... Yup... you are beyond infinity. IN THE TERMS OF THE ORIGINAL QUESTION
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Jonathan Wienke
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« Reply #3 on: June 30, 2005, 12:34:51 AM »
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If you keep walking past this point..... Yup... you are beyond infinity. IN THE TERMS OF THE ORIGINAL QUESTION
No you're not. Infinity can be approached, but you can't go beyond it.

What sort of fish is best for hammering lag bolts into concrete?
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Tim Gray
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« Reply #4 on: June 30, 2005, 09:30:14 AM »
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FWIW - last night I took my 50mm 1.4 and no matter how far away I tried to focus, there was always a small amount of latitude to move the focus from the AF point to the point where the focus ring stopped.  Didn't try on any other lenses though and that might be peculiar to my copy.
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Eric Myrvaagnes
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« Reply #5 on: June 30, 2005, 11:15:57 AM »
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I think the solution to this squabble is to allow into the lexicon the new word that dazzajl has coined: "infinty."

I propose that henceforth (at least on this thread), "infinity" shall mean what it has meant for many centuries -- the point that is beyond anything else; while "infinty" (without the third "i") shall mean pretty gosh-darn far away, or as far away as I am interested in at the moment.

But, since "infinty" looks so much like "infinity", the difference might be made clearer by using instead the term "dazzajl-infinty".

Eric
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-Eric Myrvaagnes

http://myrvaagnes.com  Visit my website. New images each season.
cookielida
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« Reply #6 on: June 28, 2005, 04:48:01 PM »
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Hello all!
OK, this is the question:
Does depth of field have any effect when taking a picture of subjects that all of them are beyond the infinity range? Is the aperature have any effect on the details results in such a situation?
hope you understand the question
10x
Cookielida
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BlasR
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« Reply #7 on: June 28, 2005, 10:05:31 PM »
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It's a tough question, because the word "infinity" can mean different things in different contexts.
In this context, such "infinity" concepts do exist but there are more than one of them, since not all infinite sets have the same size. So there does not exist any one single "infinity" concept; instead, there exists a whole collection of things called "infinite cardinal numbers".
In other words, the question is: does there exist some topological space (that is, a set of objects plus a definition of what convergence means) which, as well as including the familiar real numbers we are used to, also includes an "infinity" concept to which some sequences of real numbers converge?
Just take the photos good or bad is a photo

BlasR
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Jonathan Wienke
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« Reply #8 on: June 29, 2005, 01:46:14 AM »
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The only entitity I'm aware of that regularly visits "beyond infinity" is Buzz Lightyear. And I'm fairly sure that my earlier comment would fall under the category of stating the obvious as well. If you see a woman with her skirt unintentionally tucked into her panties, pointing it out may embarass her, but not pointing it out will result in even more embarassment in the long run. But sometimes she'll hate you for pointing it out anyway. "Subjects beyond infinity range" definitely qualifies as an intellectual panty tuck.
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dazzajl
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« Reply #9 on: June 29, 2005, 04:53:00 PM »
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DOH!!

Double post
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Jonathan Wienke
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« Reply #10 on: June 30, 2005, 12:30:59 AM »
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Once you are focused on this infinty distance, anything beyond that (no matter how far) will be covered by the plane of focus. Hyperfocal distance has absolutley nothing to do with it.

In fact, if you want to get into the whole techy debate thing, there is no such thing as hyperfocal distance as there is really no such thing as depth of field.
This statement is completely incorrect. Like I said, what you're talking about is a function of the hyperfocal distance. There is no such thing as the "infinity distance" you're talking about, only hyperfocal distance, which does vary depending on aperture, focal length, and one's definition of "in focus" which is tied to the CoC value you use. If you doubt this, there are numerous DOF calculators on the net you can consult to confirm what I'm saying. If you look up any glossary of terms related to optics, you'll find mention of hyperfocal distance, but you will not find any mention of infinity distance. It does not exist. It is a figment of your imagination.
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Jonathan Wienke
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« Reply #11 on: June 30, 2005, 09:20:50 AM »
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The question was about objects BEYOND THIS POINT. Objects that are BEYOND (the point that the scale on the lens calls) INFINITY.
No, it all goes back to your persisting in the totally made-up and absolutely incorrect use of "infinity distance" to describe hyperfocal distance. You have made up your own description of hyperfocal distance which is a patently obvious contradiction of the word "infinity" and are persisting in that foolishness even after having had the correct term and how to calculate it pointed out to you more than once. If you actually bothered to check into a DOF calculator, you would learn why the infinity mark on the EF 17-40/4L is just past the 1m mark, but on the EF 135/2L the distance scale goes to 10m before the infinity mark. I'll give you a big hint: the hyperfocal distance for the 17-40 happens to be a lot shorter than that of the 135. Just because you insist on calling a derivation of hyperfocal distance "infinity distance" doesn't make it so, any more than someone calling you a "gender-confused goat tapeworm" would make you one. The act of someone writing or speaking that phrase directed at you would not magically transform you into something disgusting living in a goat's bowels.

In case you haven't noticed, the distance marks crowd closer together on any given lens' focus scale as the scale approaches infinity. On the 17-40, the interval between the 1 and 1.5 foot marks is nearly twice that between the 1.5 and 3 foot marks. The interval between 3 and infinity is smaller yet. But the infinity mark still corresponds to infinity distance, not 45 feet. Mounted on a body with sufficiently precise AF, and given a sufficiently magnified view of the focus scale you would discover that that there is a very small but measurable focus position difference between 45 feet and something closer to infinity, like the sun, or a mountain peak 50 miles away. At some point the difference in focus position and true infinity becomes too small to measure, and people don't bother any more. But that doesn't mean that the lens has an "infinity distance" which is some clearly defined distance less than infinity, it just means someone has made an executive decision regarding how many focus distance marks can be practically crowded in next to the infinity mark.
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dazzajl
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« Reply #12 on: June 30, 2005, 11:19:13 AM »
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If the world at large can benifit from the awful typing of this poor snapper, then glad to be of service.  ::  :laugh:
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Jack Flesher
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« Reply #13 on: June 28, 2005, 04:58:39 PM »
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You cannot have any object BEYOND infinity, thus your question makes no logical sense.
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semillerimages
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« Reply #14 on: June 28, 2005, 08:51:57 PM »
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Cookielida,

If it makes you feel any better, I often have a good laugh at the high and mighty tone that some members of this forum use when addressing questions from others. Some here have an excellent grasp of the technical, but fail miserably in the public relations realm. It's unfortunate, because there are plenty of people who most likely could learn a few things from the expertise of the some of the members, but the attitudes put forth by these people are quite horrendous.

*steve
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semillerimages
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« Reply #15 on: June 28, 2005, 10:50:46 PM »
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Ahh heck-o-rama batman.

The comment was intended for jon, I thought I made my comment clear enough...

No offense to anyone else and actually no offense to jon either, just stating the obvious.

*steve
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Jonathan Wienke
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« Reply #16 on: June 29, 2005, 02:37:31 AM »
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You know what the poster meant about focusing beyond infinity.
You responded like a jack ass.

Stating the obvious.

It's a sorry state here that courtesy, civility and understanding cannot be the first step forward.
I merely pointed out that the original poster's patently silly misuse of "beyond infinity" was most likely occasioning laughter at his/her expense. Which is both obvious, and true. And then answered the question he/she probably meant to ask. I did not use any insulting terms like "stupid", "dumb", "moron", or even "ignorant", which one could certainly argue is relevant and applicable.

On the other hand, you compared me to a "jack ass". Who is being rude and insulting here?
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dazzajl
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« Reply #17 on: June 29, 2005, 05:00:16 AM »
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No I mean the infinity distance.

Lets say that a hypothetical lens reads infinity as 45 feet, everything at 45 feet or beyond will be sharp with the lens set to infinty, rather than the hyperfocal distance.
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Jack Flesher
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« Reply #18 on: June 29, 2005, 08:17:09 AM »
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You know what the poster meant about focusing beyond infinity.
Well I sure don't, so please enlighten me...
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Tim Gray
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« Reply #19 on: June 29, 2005, 04:25:45 PM »
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Of course you can have "beyond infinty", when in the context of distance from a lens. Every lens has a point at which further distances from the lens are no longer relevant in terms of focus. This distance is called infinty. It is not a real infinity and hence may lead to some confusion.
No - not true. See this link to the DOF calc

For the far focus point the calculation divides by the Hyperfocal Distance minus the focus distance. When that = 0 you have infinity. Actually, if I remember my highschool math division by 0 technically not inifinity, but simply "undefined".

The hyperfocal distance is defined as the distance such that everything from 1/2 that distance to infinity is acceptably sharp. Infinity is used in the normal sense of nothing bigger than.

The only context that's meaningful here is the context of "in focus" and once you start to change the technical meaning of the words it becomes very difficult to communicate meaningfully.
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