04-07-2012, 02:39 PM
You said some things here that confuse me (i'm easily confused so no offense intended). A 0.95 lens is in fact a 0.95 lens whether it be on 4/3 camera or a 35mm camera. The thing is that if you put a lens designed for a 4/3 camera on a 35mm camera; the middle will read the same (I think); but the edges will read significantly less (I would say pitch black but that is not a given). The total amount of light if we include total area the light covered woudl be less with a lens designed for 4/3 but I believe the center would equally well light.
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I.e, it is not the smaller circle that allows for more light; though it is certainly easier to design for a bright small circle than a large bright circle <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='
' />
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The trick is when folks start throwing in worlds like dof, perspective, effective sensitivity and similar that the issue becomes more muddy. While a .95 lens on 4/3 allows for a faster shutter speed than a 1.4 lens on 35mm; does the larger sensor perform better with less light ? Does the larger lens allow for shallower dof (if that is your objective); Does ...
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Anyways I believe that this is why these conversations are a rat hole. The argument usually drifts from one comparison to another rather than the direct light/shutter speed ratio and because of this drift it becomes somewhat frustrating to some people.
[quote name='Plochmann' timestamp='1333774268' post='17352']
You do not understand for you do not ask. But why ask something if the answer does not help you. The Buddha once said... <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/tongue.gif' class='bbc_emoticon' alt='
' /> But there is nothing to interpret, the troll only said, the f-stop is so fast because the 4/3 sensor is so puny!! It was many a month ago.
And also you've read to swiftly. I never said anything about 4/3 lenses being smaller because they are more focused. You were right, that is nonsense <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/biggrin.gif' class='bbc_emoticon' alt='
' />
The rest is fine, but I don't think technically answers my question. Why is it that a smaller imaging circle allows for a lower f-stop number? The equation is the same mathematically. Focal length divided by diameter of iris opening. This common and overly simplified equation which I've read doesn't even actually relate to modern optics, is what is confusing. I've read that you have to use a trigonometric equation when dealing with complex elements. I've also read that a lens element's Focal length is something fixed by the shape of a the lens element and determined in factory, and the iris diameter would depend on the dimensions of a lens, neither of these say anything about the image circle.
What I'm trying to say is, if I take that 17mm 0.95 lens and somehow put it on a 135 camera and then go and take a light meter and read a gray card in a dark place, and it says expose to 0.95, so I go and open it all the way up and take a picture, would not it even on 135 film expose the gray card to be 40% when properly printed? I think so. It comes down to that maybe section you mention, the exposure.
In fact, whether or not you were trying to say I was wrong, which I can not figure from the semantics of what you wrote, I think it is a matter of focus. Focusing in the most simple terms is the converging of light rays to a point. If we were to take that lens, with a 0.95 aperture, but have to spread it out over a full frame the depth of field would be a lot less and the aperture value seems to also be affected somehow(for whatever mathematical reason or equation that we do not possess). How are size of the aperture opening and image circle related, is that the missing link.
Ahhh... I'll have to reread and edit this if it makes no sense. Wife and kid are having a hoot'nanny next to me. <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/blink.gif' class='bbc_emoticon' alt=':blink:' />
[/quote]
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I.e, it is not the smaller circle that allows for more light; though it is certainly easier to design for a bright small circle than a large bright circle <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/smile.gif' class='bbc_emoticon' alt='
' />-
The trick is when folks start throwing in worlds like dof, perspective, effective sensitivity and similar that the issue becomes more muddy. While a .95 lens on 4/3 allows for a faster shutter speed than a 1.4 lens on 35mm; does the larger sensor perform better with less light ? Does the larger lens allow for shallower dof (if that is your objective); Does ...
-
Anyways I believe that this is why these conversations are a rat hole. The argument usually drifts from one comparison to another rather than the direct light/shutter speed ratio and because of this drift it becomes somewhat frustrating to some people.
[quote name='Plochmann' timestamp='1333774268' post='17352']
You do not understand for you do not ask. But why ask something if the answer does not help you. The Buddha once said... <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/tongue.gif' class='bbc_emoticon' alt='
' /> But there is nothing to interpret, the troll only said, the f-stop is so fast because the 4/3 sensor is so puny!! It was many a month ago.And also you've read to swiftly. I never said anything about 4/3 lenses being smaller because they are more focused. You were right, that is nonsense <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/biggrin.gif' class='bbc_emoticon' alt='
' /> The rest is fine, but I don't think technically answers my question. Why is it that a smaller imaging circle allows for a lower f-stop number? The equation is the same mathematically. Focal length divided by diameter of iris opening. This common and overly simplified equation which I've read doesn't even actually relate to modern optics, is what is confusing. I've read that you have to use a trigonometric equation when dealing with complex elements. I've also read that a lens element's Focal length is something fixed by the shape of a the lens element and determined in factory, and the iris diameter would depend on the dimensions of a lens, neither of these say anything about the image circle.
What I'm trying to say is, if I take that 17mm 0.95 lens and somehow put it on a 135 camera and then go and take a light meter and read a gray card in a dark place, and it says expose to 0.95, so I go and open it all the way up and take a picture, would not it even on 135 film expose the gray card to be 40% when properly printed? I think so. It comes down to that maybe section you mention, the exposure.
In fact, whether or not you were trying to say I was wrong, which I can not figure from the semantics of what you wrote, I think it is a matter of focus. Focusing in the most simple terms is the converging of light rays to a point. If we were to take that lens, with a 0.95 aperture, but have to spread it out over a full frame the depth of field would be a lot less and the aperture value seems to also be affected somehow(for whatever mathematical reason or equation that we do not possess). How are size of the aperture opening and image circle related, is that the missing link.
Ahhh... I'll have to reread and edit this if it makes no sense. Wife and kid are having a hoot'nanny next to me. <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/blink.gif' class='bbc_emoticon' alt=':blink:' />
[/quote]