The limitation comes from the lens resolution. There's a point where more megapixels simply becomes a burden without bringing any perceivable benefit at all. I personally believe with 35mm, it is probably around 20 megapixels. Of course, there is not a clear cut off line, but a gradual approximation.
With 35mm full frame, the first critical point of megapixel arrives at 4M. I will show you why below. Before reaching that point, any increase of number of megapixel resulting a quite strict one-to-one increase of resolution. For example, 2M quite literally has twice as much much resolution as 1M. After that, this will start to degrade. For the matter of better communication, consider a coefficient called ratio between the perceivable resolution increase and the pixel number increase. This ratio is practically 1/1 before the number of pixels is 4M, but starts to fall off gradually after that. My estimate is that it would fall to less than 0.5 when the number of pixels reaches 10M, and probably less than 0.1 at 20M. I'm pretty certain that this ratio approaches 0 by 40M. What that means is that after 10M, the perceivable resolution increase one receives from every 1M increase of megapixels is less than .5M, and after 20M, the perceived resolution increase for every 1M is less than .1M. As a practical matter, after 20M, the more megapixels simply become "the Emperor's new cloth" which really is not there to be seen. It just makes some people happy. And I'm talking about full frame 35mm. For APS sensors, the number is even smaller.
All that is because the inherent limitation of the lens resolution. Take 35mm full frame. I'll use approximation to simplify the explanation. Suppose there are N columns (or rows) of photosites for every 1mm. The total number of pixels of a full frame 35mm sensor is then (Nx36)x(Nx24), which is roughly 1000N^2 (pixels). Now, good 35mm lenses usually have excellent MTF at 30 line pairs per millimeter. Especially at the center of the frame, a good 35mm lens can have 80% or above MTF at 30 line pairs per millimeter. So it is reasonable to take 30 line pairs per millimeter as a baseline. A sensor that matches this resolution would have N=2x30 (two photosites for each line pair), and correspondingly the total number of pixels of 1000xN^2 = 1000x60^2, which is approximately 4M (or slightly less). This tells you two sides of the story. First, on a 35mm full frame sensor, before the number of pixels reaches 4M, most lenses have enough resolving power to take full advantage of the more pixels. Second, when the number of pixels goes beyond 4M, most lenses will not be able to fully take advantage of the increase of the pixels.
That of course doesn't mean that after 4M, the increase of the pixel numbers will have no benefit at all. They still do, but will not have the full benefit due to the lens resolution limitation.
For example, suppose you have a lens that has an MTF value of 50% (or MTF50) at 50 line pairs/mm (meaning that at this resolution, the lens delivers a perceivable contrast of only 50% of the full contrast, i.e., losing 50% of contrast). A sensor that matches this resolution would have N=2x50=100, and correspondingly a total number of pixels of 1000xN^2 = 1000x100^2 = 10M. That means, with this lens, a 10M sensor is able to represent each line pair with two columns/rows of photosites, but with a loss of 50% of contrast at such resolution. It could be said that at this level, you are only getting 50% of the perceivable resolution out of the increased number of pixels.
Now, those who are familiar with lens tests will tell you that a 35mm lens with an MFT50 at 50 line pairs/mm is a very good lens. For 35mm full frame, this is about 1200 lp/picture height.
With a 20M sensor, you need a lens that has an MTF50 with 70 lp/mm or an equivalent of 1700 lp/picture height for full frame. This is already surpassing the optimal resolution (center of the frame with a stopped down aperture) of even the best prime lenses. And we are talking about MTF with a 50% loss of contrast here.
Overall, even with a full frame, going from 10M to 20M has less than 50% increase in perceivable resolved pixels even with the best lenses. You're certainly not doubling the resolved pixels there. Of course, even an increase of 50% can be important for some people who (1) actually need a greater resolution; and (2) actually have possession to the top lenses and use them. On the other hand, with the same technology, going from 10M to 20M will lose at least one full stop of the ISO performance. I have no problem with people's preferences. I just have a problem with people making choices without the necessary information and understanding.
Still, one could make a rational (albeit discounted) argument for 20M for a full frame sensor. But beyond that, it certainly looks like an Emperor's new clothes to me, unless they suddenly come up with drastically better optics, which is extremely unlikely.
Besides, unless you want to make prints larger than 30 inches, you really don't benefit from more than 20M anyway even if you had a lens that could resolve more. And you're not getting those large files as a freebie. They impose a heavy tax on your computer system.
Showing posts with label Guides. Show all posts
Showing posts with label Guides. Show all posts
Friday, January 23, 2009
Understanding Resolution - Do You Need More Pixels?
Tuesday, May 27, 2008
Aerial Photography
Viewing photographs which are taken from a good, unique point of view is one of the most fascinating things in the world of photography. This is what we refer to as aerial photography.
Origins
Aerial photography is formally defined as photograph taking from an overhead viewpoint by using cameras that are mounted on an airborne tool such as a balloon, an aircraft, a kite, a skydiver and other similar tools. The art of aerial photography was first developed by Nadar, a French airman back in 1858. During the Second World War, aerial photography found a niche in military operations. Aerial photographs were used in spying and in the assessment of the battle ground. These photographs provided updated and realistic impressions of the topography and current situation in a certain area.
Uses of Aerial Photographs
There are many conceived and actual uses for pictures which are taken from above. Aerial photographs are actually used in the construction of topographic maps, in cartography, planning land use, archeology, production of movies, espionage, environmental studies, commercial advertising and in other fields.
The use of technology has also crawled into the field of aerial photography. Advances in radio technology has allowed for the use of aircraft models which are controlled by radio in the conduct of low-altitude photography. This is mainly used in advertising for the real estate business. This is because manned aircrafts are not allowed to fly low altitudes in populated locations. This task can be done by these radio-controlled aircraft models and they do the job very well.
Public Domain
Aerial photographs are considered public domain, because the pictures are taken from aerial views which are considered public places.
There are many ways to view aerial photographs on-line. One of the most popular ones is the Google Earth by Google. Google Earth provides satellite imagery as well as aerial photos of the planet. You can actually use the service to be able to search for different places in a certain area such as parks, restaurants, schools and hotels. It can also be used to be able to track down the best routes for reaching a certain location. You can also view the aerial photographs in different angles by tilting and rotating them.
These are some basic things about aerial photography. If you are interested in learning more about this topic, you can browse through some basic materials at the local library or use the Internet to get more information about it. Technorati Profile
Origins
Aerial photography is formally defined as photograph taking from an overhead viewpoint by using cameras that are mounted on an airborne tool such as a balloon, an aircraft, a kite, a skydiver and other similar tools. The art of aerial photography was first developed by Nadar, a French airman back in 1858. During the Second World War, aerial photography found a niche in military operations. Aerial photographs were used in spying and in the assessment of the battle ground. These photographs provided updated and realistic impressions of the topography and current situation in a certain area.
Uses of Aerial Photographs
There are many conceived and actual uses for pictures which are taken from above. Aerial photographs are actually used in the construction of topographic maps, in cartography, planning land use, archeology, production of movies, espionage, environmental studies, commercial advertising and in other fields.
The use of technology has also crawled into the field of aerial photography. Advances in radio technology has allowed for the use of aircraft models which are controlled by radio in the conduct of low-altitude photography. This is mainly used in advertising for the real estate business. This is because manned aircrafts are not allowed to fly low altitudes in populated locations. This task can be done by these radio-controlled aircraft models and they do the job very well.
Public Domain
Aerial photographs are considered public domain, because the pictures are taken from aerial views which are considered public places.
There are many ways to view aerial photographs on-line. One of the most popular ones is the Google Earth by Google. Google Earth provides satellite imagery as well as aerial photos of the planet. You can actually use the service to be able to search for different places in a certain area such as parks, restaurants, schools and hotels. It can also be used to be able to track down the best routes for reaching a certain location. You can also view the aerial photographs in different angles by tilting and rotating them.
These are some basic things about aerial photography. If you are interested in learning more about this topic, you can browse through some basic materials at the local library or use the Internet to get more information about it. Technorati Profile
Monday, May 19, 2008
How A Digital Camera Works
Digital cameras come in a variety of different shapes and sizes. Different brands of digital cameras also offer users an array of features designed to make each and every shot fantastic. Despite the numerous features offered by digital cameras, manufacturers still manage to create products that are simple enough for a child to use.
Day by day digital cameras are becoming a well-known fixture in most homes across the globe. In fact, most of the people around the world own one and use it on a regular basis. Digital cameras have also been incorporated into a variety of technical gadgets that have been integrated into the lifestyle of people everywhere.
PDA devices as well as cellular phones are just some of the technological devices that have a digital camera feature. Despite being an add-on feature, the digital camera device installed in these gadgets fair relatively well compared to detached models.
As a matter of fact the memory used for digital cameras, detached models or otherwise, can easily be upgraded using memory cards. The added memory will certainly come in handy because most digital cameras can also be used to take video clips.
There are numerous brands of digital cameras available on the market today. Mainstream electronic brands like Nikon, Kodak, Canon and Olympus are just some of the manufacturers of conventional 35mm cameras who have jumped on the bandwagon to create their own lines of digital cameras. Other famous brands that manufacture digital cameras include Panasonic, Casio and Sony.
Basic Features of Digital Cameras to Consider
Regardless of brand names, digital cameras have the same basic features that any consumer should know and consider before buying one. Even though digital cameras are generally a point and shoot device, certain features can often single out a particular brand or model. A good example of this is the term megapixel, which became known when digital cameras were introduced in the market.
Megapixels, which means millions of pixels, measure the quality and size of a digital camera. Pixels refer to the dots that make up a picture. Therefore a digital camera that has about a 5-megapixel resolution will produce better quality pictures compared to a 3-megapixel digital camera.
Moreover, photos taken with a digital camera that offers greater megapixels can be enlarged safely without sacrificing the quality of the picture. Average digital cameras with less than 3 megapixels often forfeit the clarity of the picture once it is enlarged. Unfortunately, there is a downside to using a digital camera with greater megapixels as they consume more of the camera’s memory.
The zoom function of a digital camera is another feature that most consumers should consider. There are generally two types of zoom features for many of the digital cameras on the market today. The optical zoom feature is common in devices without permanent lenses. The user can simply zoom and focus on the subject to be photographed.
A digital zoom feature is similar to using an editing software program for images. In most cases, a digital camera may offer both types of zoom features. Most digital camera users recommend concentrating on the optical zoom feature to validate the quality of the device.
What to Look for In a Digital Camera
A digital camera generally has an LCD screen. This wide screen replaces the small aperture in conventional cameras through which you look into before taking the shot. The LCD screen allows the photographer to view the picture while taking it to see how it would appear in reality.
Digital cameras have memory stick slots where memory sticks are inserted. Unfortunately, memory is another major consideration that many consumers often overlook. For the most part it is because digital cameras that require larger memory can be quite expensive.
On the whole, many of the digital cameras of today make use of rechargeable batteries. Consumers should check if the particular brand they wish to purchase comes with a charger. If not, then you need to purchase it separately.
Downloading pictures taken with the digital camera is another factor that need to be considered. In most cases, many digital cameras can easily be connected to a desktop computer using a USB port. Through this connection, a user may download the pictures taken with the camera into the computer’s hard drive for printing or editing.
Day by day digital cameras are becoming a well-known fixture in most homes across the globe. In fact, most of the people around the world own one and use it on a regular basis. Digital cameras have also been incorporated into a variety of technical gadgets that have been integrated into the lifestyle of people everywhere.
PDA devices as well as cellular phones are just some of the technological devices that have a digital camera feature. Despite being an add-on feature, the digital camera device installed in these gadgets fair relatively well compared to detached models.
As a matter of fact the memory used for digital cameras, detached models or otherwise, can easily be upgraded using memory cards. The added memory will certainly come in handy because most digital cameras can also be used to take video clips.
There are numerous brands of digital cameras available on the market today. Mainstream electronic brands like Nikon, Kodak, Canon and Olympus are just some of the manufacturers of conventional 35mm cameras who have jumped on the bandwagon to create their own lines of digital cameras. Other famous brands that manufacture digital cameras include Panasonic, Casio and Sony.
Basic Features of Digital Cameras to Consider
Regardless of brand names, digital cameras have the same basic features that any consumer should know and consider before buying one. Even though digital cameras are generally a point and shoot device, certain features can often single out a particular brand or model. A good example of this is the term megapixel, which became known when digital cameras were introduced in the market.
Megapixels, which means millions of pixels, measure the quality and size of a digital camera. Pixels refer to the dots that make up a picture. Therefore a digital camera that has about a 5-megapixel resolution will produce better quality pictures compared to a 3-megapixel digital camera.
Moreover, photos taken with a digital camera that offers greater megapixels can be enlarged safely without sacrificing the quality of the picture. Average digital cameras with less than 3 megapixels often forfeit the clarity of the picture once it is enlarged. Unfortunately, there is a downside to using a digital camera with greater megapixels as they consume more of the camera’s memory.
The zoom function of a digital camera is another feature that most consumers should consider. There are generally two types of zoom features for many of the digital cameras on the market today. The optical zoom feature is common in devices without permanent lenses. The user can simply zoom and focus on the subject to be photographed.
A digital zoom feature is similar to using an editing software program for images. In most cases, a digital camera may offer both types of zoom features. Most digital camera users recommend concentrating on the optical zoom feature to validate the quality of the device.
What to Look for In a Digital Camera
A digital camera generally has an LCD screen. This wide screen replaces the small aperture in conventional cameras through which you look into before taking the shot. The LCD screen allows the photographer to view the picture while taking it to see how it would appear in reality.
Digital cameras have memory stick slots where memory sticks are inserted. Unfortunately, memory is another major consideration that many consumers often overlook. For the most part it is because digital cameras that require larger memory can be quite expensive.
On the whole, many of the digital cameras of today make use of rechargeable batteries. Consumers should check if the particular brand they wish to purchase comes with a charger. If not, then you need to purchase it separately.
Downloading pictures taken with the digital camera is another factor that need to be considered. In most cases, many digital cameras can easily be connected to a desktop computer using a USB port. Through this connection, a user may download the pictures taken with the camera into the computer’s hard drive for printing or editing.
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