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Old Mar 15, 2006, 7:52 PM   #1
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Can someone please explain? I keep reading about Full frame or FF, APS, APS-C, 2:3 format and four third 4:3 format. I thinkI have some understanding of what this means but I really don't completely understand it.

It would be great to understand what actual size of digital sensors and cameras are being refereed to here?

What are the pros and cons of each format and who makes DSLR based on these formats?
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Old Mar 16, 2006, 12:15 AM   #3
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Rey, Great links! Thanks. But they still didn't talk about the four third size sensor and cameras. Who makes them and what are their advantages or disadvantages?
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Old Mar 16, 2006, 3:07 AM   #4
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The best know manufacturer of 4/3 camers is Olympus.



http://www.steves-digicams.com/2005_reviews/e500.html
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Old Mar 16, 2006, 12:22 PM   #5
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Remember Y2K? We got ourselves into a lot of trouble because computer designers thought it would always be the 1900's. Well, one day, the century changed.

If we (as a photographic community) werent so near-sighted, we'd have ignored the focal length of our lenses and marked them in angle of view. Then, when a different format came along, we be comparing apples to apples in terms of how we use our equipment and what results we expect.

The other part of the equation is aspect ratio, look at a 4x6 print and an 8x10 print... their width to length ratio is different (this is what 3:2 or 4:3 refers to).

I put together this chart to make it easier to compare different formats, fields of view, and focal lengths. While the APS sized sensors vary from canon to nikon to pentax (etc.), its not a really big variation.


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Old Mar 16, 2006, 3:32 PM   #6
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tmoreau wrote:
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Remember Y2K? We got ourselves into a lot of trouble because computer designers thought it would always be the 1900's. Well, one day, the century changed.

If we (as a photographic community) werent so near-sighted, we'd have ignored the focal length of our lenses and marked them in angle of view. Then, when a different format came along, we be comparing apples to apples in terms of how we use our equipment and what results we expect.

The other part of the equation is aspect ratio, look at a 4x6 print and an 8x10 print... their width to length ratio is different (this is what 3:2 or 4:3 refers to).
The formats we use are arbitrary and don't have a scientific meaning. There is no optimal film size or film format. At present, technology is closing in on the ability of 35 mm format lenses to resolve images on ourt sensors. Meaning that pretty soon, the sensor will be able to give more detail then the lens can provide.


As pointed out above; the expression "aspect ratio" still retains meaning and describes what the proportions of an uncropped image will look like when printed.

In other words, the film world, err, uses film and this film is of a certain physical size and proportion. There's no scientific reason to continue using any particular size. It's a legacy.

And of course, focal lenght still retains it's meaning - It's meaning being how "physically" close close we are getting to the target subject - whereas the angle of view is a reflection of how "apparently" close we are getting to the target.

For example, with my 500mm lens, shooting 35mm film, the resulting full sized printed image is smaller then the same lens shooting with my 1.5 camera. This is because the 1.5 sensor "crops" the image in camera. When printed, naturally it appears larger, since I am in fact printing a crop at 100 percent.

Yet looking through the viewfinder, I can see no magnification over the film camera, just a narrower field of view. This is a concept that Mr. Moreau does not comprehend.

Thus, professional microscopes provide two means of determining the power of a lens, and perhaps it's time we used that in photography as well. The NA and the magnification. Or as they express this point:

"Magnification is how much an image is enlarged under a microscope. Resolution is the amount of detail you can see. If you can magnify an image without increasing its resolution, that's empty magnification. We usually think in terms of the magnification of a microscope, but resolution is even more important. A greatly enlarged blur is still a blur."

"Resolution is usually expressed in terms of the minimum distance observable between two objects. The smaller the distance that can be seen between two objects, the better the magnification. The resolvable distance for an objective lens is 0.61 l/N.A., where l is the wavelength of the light and N.A. is a property of the lens called the "numerical aperture."

"Numerical aperture is a measure of the angle of the cone of light that can enter the objective lens. The bigger the N.A. the better, since N.A. is in the denominator of the equation. But each lens has a limit to its N. A. The objective lenses of many microscopes has the maximum N.A. inscribed on it."

Dave
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Old Mar 16, 2006, 5:47 PM   #7
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tmoreauand DBB,

Great chart and good explanation. I think I am getting some understadning of this mess of formats now. It looks like there is no obvious advantage to any of these formats and they are arbitrary. Just evaluate each SLR camera on its own merits will be the way to go without paying attention to the sensor size.
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Old Mar 16, 2006, 6:38 PM   #8
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harana wrote:
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tmoreau and DBB,

Great chart and good explanation. I think I am getting some understadning of this mess of formats now. It looks like there is no obvious advantage to any of these formats and they are arbitrary. Just evaluate each SLR camera on its own merits will be the way to go without paying attention to the sensor size.
Yes, as far as that goes, the user should compare the image quality, ease of use, their existing (if any lenses) in making this decision.

The really GOOD news, is that there are many good cameras out there, and it is difficult to go "wrong" in todays competitive atmosphere.

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Old Mar 17, 2006, 7:01 PM   #9
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Quote:
For example, with my 500mm lens, shooting 35mm film, the resulting full sized printed image is smaller then the same lens shooting with my 1.5 camera. This is because the 1.5 sensor "crops" the image in camera. When printed, naturally it appears larger, since I am in fact printing a crop at 100 percent.

Yet looking through the viewfinder, I can see no magnification over the film camera, just a narrower field of view. This is a concept that Mr. Moreau does not comprehend.
You just can't let go can you? You abandoned the thread where I stomped all over your lack of logic and now your going to throw around abstract theory of resolution/magnification in a thread where a newbie is simply tring to understand how one piece of equipment helps them take pictures compared to another? Your not much better than Mark.

Also, the formats aren't arbitrary, just obscure.
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Old Mar 18, 2006, 6:20 AM   #10
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Keep it civil guys. It's OK to disagree. But, let's have pleasant discussions without throwing flames. ;-)


harana

As you can see, there are a number of sensor sizes being used in digital cameras.

There are pros and cons to any of them.

When you use a larger sensor, you have a wider angle of view for any given focal length lens (less apparent magnification)

When you use a smaller sensor, you have a narrower angle of view for any given focal length lens (more apparent magnification).

With film, you have the same issues. If you use film that's smaller than 35mm, you'll have a narrower angle of view for any given focal length. If you use film that's larger than 35mm, you'll have a wider angle of view for any given focal length.

For non-DSLR models, manufacturers typically publish "35mm equivalent" information so that you can see how models compare from an angle of view perspective.

That's mostly because 35mm cameras are so popular (so that buyers have a better understanding of how angle of view compares between models).

Whether or not they are equivalent in other ways has been a subject of debate here. The angle of view differences are what most users are concerned with.

If you look at the focal lengths marked on the lenses of the smaller digital cameras, you'll see that the actual focal lengths are very short compared to the published "35mm equivalent" focal lengths.

Since you have a narrower angle of view with a smaller sensor, that allows manufacturers to make much smaller cameras that have the same angle of view as a much larger camera.

There are other differences besides angle of view. For example, depth of field is based on actual focal length, aperture and focus distance.

Because smaller sensors can use a much shorter focal length lens for any equivalent angle of view, you have much greater depth of field for any given aperture and focus distance. This can be a good thing if you want more depth of field, or a bad thing if you want less depth of field for helping a subject stand out from distracting backgrounds by using large apertures.

In addition, using a smaller sensor means that you'll have smaller photosites for each pixel compared to a larger sensor with the same number of photosites.

Since the surface area is smaller with smaller photosites, less light strikes them and the signal generated isn't as strong. That usually means that more amplification is needed for equivalent ISO Speed sensitivty, and amplifcation adds noise. That's why most models with smaller sensors have more limited ISO speeds available to them and tend to have higher noise levels as ISO Speeds are increased.

But, you still need to take each camera on a case by case basis, as improvements in technology are constantly being made. For example, we're seeing some pretty sophisticated microlens designs now with newer sensors, where a tiny lens over each photosite helps to amplify the light getting to them.

No one choice is going to be perfect for every user in every condition, especially given size, weight and cost concerns.


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