[Recovered Thread: 85008]

[tmoreau]

So, your saying that there is absolutely no earthly lens capable of seeing footsteps on the moon? The rings of Saturn? What kind of lens are you saying it would take, one forty feet across? The idea is absurd.

Perhaps there is no complete system capable of that, but the limitation is not in the lens(!)?

The problem is not how much light enters the front of the lens, its what happens to it after that point. There is plenty of detail in the light but it gets destroyed incrementaly by all the things that happen to it on the way to the sensor/film/eye, or the sensor/film/eye cannot resolve all the detail availible.

To have a greatly enlarged blur (ie, the moon) the light must become blurred somehow. When and how does that happen? In the vacuum of space? In the earths atmosphere? In the lens elements? As the light is passes through the aperture?

You seem to be saying you need a larger aperture to get more detail. Very well, do 500mm lenses categorically have larger apertures than 800mm lenses? That single subjective observation you made proves nothing. The microscope comparison has merit, we know using apertures like f32 and f64 do dirty things with light that cause reduced resolution. Its still largely outside the scope of this discussion, though to try and bring it in you'd be saying that f2.8 on a 7mm lens vs f2.8 on a 300mm lens is... well I don't want to put words in your mouth...

"Hiigh School" Things that make you go hmm....

[DBB]

JimC wrote:

You're showing resolution limitations of the objectives used in those examples.

In the case of most current DSLR models using good quality lenses, the sensors are capable of outresolving the lenses.

If you want samples, just look at our review samples. You'll see cases where a model with a smaller sensor using a shorter actual focal length lens can outresolve a model with a larger sensor using a longer focal length lens. We have some of the same subjects in each review. That's not always the case, since we are starting to see some pretty absurd pixel counts in very small cameras.

Phil Askey over at dpreview.com performs resolution chart tests, too. Even an 8MP prosumer model like the Olympus C-8080Z can outresolve a 6MP Canon EOS-10D, and come very close to the EOS-20D.

Essentially my posts are aimed at showing that since the "Cropping factor" puts more pixels on the target, all things being equal, a camera with a 1.5 cropping factor will "out resolve" a camera with no cropping factor.

But this assumes that there are details to be "resolved."

It doesn't make much difference if your target is 100 yards away. So what if the "true" magnification is marginally greater? Who cares?

But once we get into the area of comparing gear aimed at true magnification, it does indeed make a difference in resolving power. More pixels on target will not resolve a blur. If true magnification allows the potential of seeing MORE detail then once again, all things being equal, more detail will be captured - resolved.

Thus my extreme Mars example with the 200x cropping factor or true 200 power magnification.

Why is it that ALL the sites dealing with this question are quick to say that "The focal lenght multiplier" is a misnomer?

You cannot resolve detail that is not there.

Dave

[JimC]

If you run into a situation where the sensor is outresolving the lens, yes you may see an improvement with a larger sensor, since the lens wouldn't need to be as good (lp/mm) if the photosites were spread out more, as compared to a sensor using a smaller portion of a lens.

But, with current DSLR models using good lenses in conditions most photographers use their cameras in, that's not the case.

The lenses are still capable of out resolving the sensors.

Are there conditions where a full frame model has some advantages? Sure. For example, if you want a shallower depth of field for any given aperture, focus distance and angle of view. Most users probably need the opposite (more depth of field). ;-)

Or, perhaps you want a wider lens. That's tough to get on a model using a smaller sensor.

We're currently seeing higher megapixel counts in full frame models. It's tough to keep noise down in a smaller sensor. But, just because photosites are larger for a given resolution sensor if the sensor is larger, doesn't mean that it's going to have better noise characteristics either. Look at noise levels from the Kodak full frame models as an example.

So, bottom line (again), you have to take each sensor/lens combination on a case by case basis.

[tmoreau]

DBB wrote:

Essentially my posts are aimed at showing that since the "Cropping factor" puts more pixels on the target, all things being equal, a camera with a 1.5 cropping factor will "out resolve" a camera with no cropping factor.

But this assumes that there are details to be "resolved."

If you add the qualifier that the sensor resolution is the same, I'd agree. Otherwise a 8mp APS vs 12mp FF could be the same pixels "on target" if the photosites are the same size. Cropping would happen in camera vs in photoshop, for the same results.

[DBB]

tmoreau wrote:

DBB wrote:

If you add the qualifier that the sensor resolution is the same, I'd agree. Otherwise a 8mp APS vs 12mp FF could be the same pixels "on target" if the photosites are the same size. Cropping would happen in camera vs in photoshop, for the same results.

My "Qualifier" is that a sensor with 1 gig of pixels AND a 24mm lens that is capable of handling that kind of sensor CANNOT match my 1100mm lens in resolving detail at 100 yards. You cannot resolve detail that the lens cannot see.

To the 24 mm lens, the flower which is my hypothetical target is nothing more then a pin head sized blur (if it is even that) while to the 1100mm lens it is 13 feet away.

Only with the 1100 mm lens would a croping factor be of any use, since more of the pixels would resolve what is actually visible as more then a minute blur.

This discussion transcends the cropping factor - True magnification is being attacked here as a more or less meaningless phrase if the lens and sensor are of a high enough quality.

No way

A highly resolved dot is still just a dot no matter how sharp the focus. This is the idea that people have trouble appreciating and which all the scientific links back up.

Dave

[JimC]

DBB wrote:

This discussion transcends the cropping factor - True magnification is being attacked here as a more or less meaningless phrase if the lens and sensor are of a high enough quality.

Dave:

I don't think anyone is trying to do that. You're the one coming up with examples you don't find in the real world when comparing DSLR models with smaller sensors compared to models with sensors the size of 35mm film. ;-)

Sure you can come up with theoritical examples of where a sensor can outresolve a lens, so that the lens is the limiting factor.

To repeat a post I made earlier (and it wasn't meant to imply that the lens could be as short as you wanted it to be and still outresolve a longer lens):

The bottom line is that you need to take each sensor/lens combination on a case by case basis to see what it's capable of resolving, with the way the image is being processed also coming into the equation.

But, with current technology used in DSLR models, a shorter focal length lens for a given angle of view with an APS-C sensor can resolve just as much detail as a longer focal length lens on a 35mm film size sensor, if the resolution of the sensor (how many photosites it has) is equivalent.

Will we reach a point where the sensors are outresolving the lenses? Sure we will, just like we have larger format film when that happens.

But, for all practical purposes, a DSLR model using an APS-C sensor with a 100mm lens will resolve just as much detail as a DSLR model with a 35mm film size sensor using a 150mm lens, if the resolution of the sensors is the same (number of photostites in the sensor), with equivalent light gathering ability (aperture, as rated in f/stop), for the amount of light the sensor receives, as long as you're using lenses of equivalent quality (good lenses can outresolve the sensors).

[tmoreau]

DBB wrote:

My "Qualifier" is that a sensor with 1 gig of pixels AND a 24mm lens that is capable of handling that kind of sensor CANNOT match my 1100mm lens in resolving detail at 100 yards. You cannot resolve detail that the lens cannot see.

To the 24 mm lens, the flower which is my hypothetical target is nothing more then a pin head sized blur (if it is even that) while to the 1100mm lens it is 13 feet away.

Only with the 1100 mm lens would a croping factor be of any use, since more of the pixels would resolve what is actually visible as more then a minute blur.

This discussion transcends the cropping factor - True magnification is being attacked here as a more or less meaningless phrase if the lens and sensor are of a high enough quality.

No way

A highly resolved dot is still just a dot no matter how sharp the focus. This is the idea that people have trouble appreciating and which all the scientific links back up.

Dave

How can you claim this? Why is it a dot? Does it look like a dot from close up? Does it look like a dot when using a telescope at 100 yards? Does it look like a dot in your viewfinder? To the naked eye? How does a flower "magicly turn into a dot" (please feel free to quote me)?

We know (you know now, because I'm telling you!) that there are satelites which can photograph the ground in such detail that they can read a persons wristwatch. Looking down from the space shuttle IOWA would be nothing but a dot, but somehow out of that "blur" these devices have resolved additional detail.

The 100 yard flower looks like a "dot" or a "blur" to your eye, because your eye can only resolve so much detail. The telescope you use to see it clearly has a lens four inches across, how is that?

The lens can see the detail, no matter if its a 28mm lens, a 7mm lens, or a 1100mm lens. If the lens destroys the detail in the few inches between the front element and the sensor, thats an entirely different matter!


Your entire theory is wrong and you have made no attempt at all to substantiate it using such troubled things as logic and fact.

[Mark47]

Tom LaPrise wrote:

It didn't take much to prove you wrong. Everyone here, with maybe one exception, has done that.

The NASA quote also says that the reason the HST sees more detail is because it's above the atmosphere and its distortion, not because it has higher magnification, which it doesn't.

No one has proved me wrong, they have simplysaid things that you apparently agree with, just like most of the world once believed the earth was flat; lots of people that dont know what they are talking about doesnt makesomething a fact.You are the only one that has been proved wrong by trying to suggest that light doesnt travel in waves when it is commonly known and easily referenced that it does.

You have used selective reasoning to put words into the mouths of NASA; that is not what they said at all. If you understood what they were saying, itis that being above the atmoshpere will ENHANCE the ability of a lens, if magnification wasnt a factor then they wouldnt have built it so big in the first place, they would just use a tiny lens and blow it up with software. "The bigger the lens the more light", being above the atmoshpere only enhaces this, you still need a bigger lens dont you. The bigger the lens the bigger the OPTICAL magnification, the more the optical magnification the more DETAIL that is taken in. It is the DETAIL that determines the quality of the image not the magnification.



Why do the makers of digital videos make a big deal out of the OPTICALmagnification as opposed to the digital? The reason is becausea video with a20 timesOPTICAL zoom with ten times DIGITAL zoom willproduce a better image thana camera with a 10 times optical zoom but 20 times digital zoom. They both have the same 200 times zoom factor but because one has a higher OPTICAL magnification it produces a better picture becuase the BIGGER lens takes in more DETAIL. This is why NASA built the hubble so big, because in their own words "The larger the telescope, the more light it can collect. The more light collected, the fainter and more distant the objects that can be observed". A BIGGER lens has more OPTICAL magnificationand as a result takes in MOREDETAIL of objects far away. This is why video camera makers make a big deal out of the OPTICALmagnification because optical magnification is superior to digital magnification because the bigger lens takes in more detail.

A 300mm lenshas more optical magnification than a 200mm lens. Putting a 200mm lens on a crop camera does not change the optical magnification it changes the DIGITAL magnification, it is still a 200mm lens withthe optical magnification power of a200mm lens. The difference in optical magnification is the amount of light it will take in from a distance, which is why video camera manufacturers make a big deal out of the OPTICAL magnification because the more optical magnification you have the more DETAIL you take in.Digital magnification can only enhance what the lens brings in, the more DETAIL it brings in the sharper the image, the bigger the optical magnification the more detail it has to work with.

If you want to think in terms of pixels, a 300mm lens will take in more "pixels" of the image than a 200mm lens. So it isnt that it is magnifying the image but taking more in. When you put a 200mm lens on a crop camera you are not taking in as many "pixels" as a 300mm lens, so you are not taking in as much detail. So while the 200mm lens may be equivelant to a 300mm on a crop, it is still not OPTICALLY the same.

[tmoreau]

I've been throwing around the term "real-world" and other practical implication a lot, so I'll try to substantiate my point a little. Please refer to the gigapixel project where they built a film based gigapixel (1,000 megapixels) camera and have used it to photograph all over the country. They have made prints tens of feet wide of exquisite detail. The lens?

Cliffs notes: 9x18" film, 215mm f22 lens with 100 degrees FOV (35mm equiv. about 20mm, lol:lol This page goes into more detail about the lens. Filter size is 155mm square (six inches).

They go into some detail about the physical limitation encountered, and its all about the bad things which happen to light as it passes through the various lens elements (ie, spherical abberation). They didnt mention that there wasnt enough detail contained in that six in wide space and had to increase the lens to...? Please refer to the sample pictures if you think a 215mm lens is unable to resolve enough detail for 1,000 megapixels. The lens they created fits on old military cameras, which is what they used for the body.

Is this consistent with your argument?

Oh, Mark, you really MUST learn the difference between digital magnification and using a smaller sensor of the same resolution as a larger sensor. Crawl before you walk, bud. So is the kit lens with a 300D digital rebel 6mp, and the lens sold with the 350d rebel XT a 8mp lens?

[tmoreau]

This picture is of an entire baseball stadium, individual people are "just a dot, a blur". Until you see the 100% crops!!!!!

I really don't see how you have an argument!