Hi there Tom
There is this article on 'Magnification' and macro at
http://www.cs.mtu.edu/~shene/DigiCam/Us ... ation.html
It's interesting, but technical, and I am trying to digest it. But before I do, I should like to have your expert opinion on it. Don't want to start believing in something and then later find out that it is fatally flawed.
For example, an excerpt from it says, "But, the image taken by the D100 plus a 1:1 capable 60mm Micro lens covers a larger area than that of the Nikon 4500. Is there something wrong? The answer is nothing is wrong here. But, why the 4500 with a magnification 0.43X can "magnify" higher than a 1:1 life-size image taken by the D100 plus 60mm Micro lens? The answer is: the sensor size of the D100 is larger than the sensor of the 4500."
And further down, "Yes, if we continue to pack more pixels to a 2/3" sensor, the pixel/mm count increases, and, as a result, the "macro" capability in this sense increases even though the lens magnification and image coverage do not change. Therefore, this is a problematic definition because macro capability does not come from pixel count. Those who promote this pixel/mm count as a measurement of macro capability usually have an argument like this: one can crop part of the image, because the increase of pixel count cropping would increase the magnification. Unfortunately, cropping is not part of the equation of magnification. Otherwise, one does not need any macro lens. A very high density and small sensor would do all the magic of an excellent macro lens."
Would really appreciate yr advice, Tom.
Best Regards
Gunn
Question for Tom
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twebster
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Hi ya' Gunn 
That is an excellent article. Magnification is a property of the lens regardless of the format recording the image. Life-size (1:1) is the same whether you record the image on a small digital sensor, a 35mm frame of film, or on a 4" x 5" sheet of film. The recording format simply dictates how large of an area is recorded in the image at a given image magnification.
The only point he trips over is the discussion of pixel density of the ccd or cmos array. Image magnification at the imaging plane is still independent of pixel density. You can think of pixel density the same as you can think of film grain. The smaller the film grain, the more details can be recorded in the image. The more dense the pixels in a given size of ccd/cmos array, the more the ccd/cmos array acts like fine-grained film and the more fine details will be recorded in the image. You don't take in pixel density to describe image magnification.
Best regards as always,
That is an excellent article. Magnification is a property of the lens regardless of the format recording the image. Life-size (1:1) is the same whether you record the image on a small digital sensor, a 35mm frame of film, or on a 4" x 5" sheet of film. The recording format simply dictates how large of an area is recorded in the image at a given image magnification.
The only point he trips over is the discussion of pixel density of the ccd or cmos array. Image magnification at the imaging plane is still independent of pixel density. You can think of pixel density the same as you can think of film grain. The smaller the film grain, the more details can be recorded in the image. The more dense the pixels in a given size of ccd/cmos array, the more the ccd/cmos array acts like fine-grained film and the more fine details will be recorded in the image. You don't take in pixel density to describe image magnification.
Best regards as always,
Tom Webster
Administrator
Phoenix "The Valley of the Sun", Arizona, USA
Think about this...maybe Murphy is an optimist!!!
Administrator
Phoenix "The Valley of the Sun", Arizona, USA
Think about this...maybe Murphy is an optimist!!!
Sorry for interrupting you, but I was thinking on this subject for some time...
I know, that a macro, 1:1 and other definitions does not appear with 35mm, but I still think that things go a bit different now and those definitions begin loosing their sence somehow. I think that the reasons for this are:
1. In the film time the choise of image formats was limited and does not change for a long period of time. So it was easy to know all the sizes and everyone interested in the subject can cleary understand what does 1:1 mean for 35 mm lens and for medium format, for example.
Now we have a new sensor coming out every day and to make things worse the size of sensor installed in a camera is not typically listed in specification. But how can one understand the meaning of magnification if the size of imaging device is not known? It became just a number without any meaning.
2. Now many people do use "prosumer" compact digital cameras which have fixed lenses. In 35 mm world there was many lenses aimed for single format - 24x36 mm, so comparing magnification of different lenses was adequate for comparing their macro possibilities. In the world of compact digital cameras it does not have a sence - one can not swap a lens betwen different cameras, and to compare the macro possibilities of different cameras one should take everything in consideration - lens, imaging device size and pixel count. Such camera is a complete and self-contained device and should be analysed as a whole thing.
For example Sony F88 have a 5MP sensor and minimal area of 36x20 mm and Pentax 750z just 30x40 mm. Do you think Sony allows you to make "better" macro images? No, because 750z have a 7MP sensor and image you will see on screen will actually have a larger magnification.
3. In film world there was no pixels. Final printed image may be as large or small as you like. Yes, there was limitations, but there was no way to tell exactly where the margin is. Now you can - you have pixels which will look bad if you will try to make them larger. This is what gives a sense for pixel/mm count - actually, pixel/mm is a device-independent measure of final magnification of the image you will be viewing as a final result with highest quality possible.
I understand that magnification is a property of a lens and this will never change, but this property should be left for lens designers, because in the current situation it became meaningless and even contraversal for the final customer.
Do you think Danny is thinking he is limited because he does not have a macro lens on his panasonic when shooting ants and flys? "Care for the images that come out of the box rather than for a box", it is what he is saying. We do not have compact digital cameras with 1:1 lenses, but that does not prevent many digital cameras to make images of things smaller than it is possible with 1:1 35 mm lens. I think if there will be a compact digital camera with 1:1 lens than we should better compare it with low-power microscopes, rather than with macro cameras
The definition of "macro" term is a bit more difficult problem, unless we are going to left it for a lens designers too... If we insist that macro is 1:1 and higher than we do not have any digital camera (not DSLR) with macro lens and this means that this term won't be used in this sence by general public. It means that another or even new term will be used or the meaning of "macro" will be changed.
WBR,
Sergey.
I know, that a macro, 1:1 and other definitions does not appear with 35mm, but I still think that things go a bit different now and those definitions begin loosing their sence somehow. I think that the reasons for this are:
1. In the film time the choise of image formats was limited and does not change for a long period of time. So it was easy to know all the sizes and everyone interested in the subject can cleary understand what does 1:1 mean for 35 mm lens and for medium format, for example.
Now we have a new sensor coming out every day and to make things worse the size of sensor installed in a camera is not typically listed in specification. But how can one understand the meaning of magnification if the size of imaging device is not known? It became just a number without any meaning.
2. Now many people do use "prosumer" compact digital cameras which have fixed lenses. In 35 mm world there was many lenses aimed for single format - 24x36 mm, so comparing magnification of different lenses was adequate for comparing their macro possibilities. In the world of compact digital cameras it does not have a sence - one can not swap a lens betwen different cameras, and to compare the macro possibilities of different cameras one should take everything in consideration - lens, imaging device size and pixel count. Such camera is a complete and self-contained device and should be analysed as a whole thing.
For example Sony F88 have a 5MP sensor and minimal area of 36x20 mm and Pentax 750z just 30x40 mm. Do you think Sony allows you to make "better" macro images? No, because 750z have a 7MP sensor and image you will see on screen will actually have a larger magnification.
3. In film world there was no pixels. Final printed image may be as large or small as you like. Yes, there was limitations, but there was no way to tell exactly where the margin is. Now you can - you have pixels which will look bad if you will try to make them larger. This is what gives a sense for pixel/mm count - actually, pixel/mm is a device-independent measure of final magnification of the image you will be viewing as a final result with highest quality possible.
I understand that magnification is a property of a lens and this will never change, but this property should be left for lens designers, because in the current situation it became meaningless and even contraversal for the final customer.
Do you think Danny is thinking he is limited because he does not have a macro lens on his panasonic when shooting ants and flys? "Care for the images that come out of the box rather than for a box", it is what he is saying. We do not have compact digital cameras with 1:1 lenses, but that does not prevent many digital cameras to make images of things smaller than it is possible with 1:1 35 mm lens. I think if there will be a compact digital camera with 1:1 lens than we should better compare it with low-power microscopes, rather than with macro cameras
The definition of "macro" term is a bit more difficult problem, unless we are going to left it for a lens designers too... If we insist that macro is 1:1 and higher than we do not have any digital camera (not DSLR) with macro lens and this means that this term won't be used in this sence by general public. It means that another or even new term will be used or the meaning of "macro" will be changed.
WBR,
Sergey.