Go Back   Steve's Digicams Forums > Digicam Help > General Discussion

Reply
 
Thread Tools Search this Thread
Old Mar 9, 2006, 9:47 PM   #81
Senior Member
 
tmoreau's Avatar
 
Join Date: Dec 2005
Posts: 477
Default

Lets take a lesson from the gigapixel project. With thier 100 degree FOV 215mm lens and 9x18" sheet of film, they are resolving between one and four BILLION pixels. Read that again. Ok, now if we took an 8x10" film and moved it closer to the lens (focusing, say, at 160mm instead) there would be 1-4 billion pixels availible for that film to resolve, if its up to the challenge.

Keep moving it closer, and you'll run into a point where there are four billion pixels smooshing through an f22 aperture. Notice that the forty or so pixels that make up the baseball arent a "dot", a "blur". Four billion pixels, one little bitty aperture, and you have the BALLS to say that a 200mm SLR lens can not resolve EIGHT MILLION PIXELS, no matter how well its built!!!!!!!

It is possible to take a picture of an apple where the apple fills the entire frame, and the picture contains detail down to the level seen in a microscope. This could be accomplised with a 24x36mm sensor and a 90mm macro lens, if both are of sufficient design. The properties of light are not the limiting factor, lens and sensor design are.



Oh, DBB, this quote cracks me up! "If you can't SEE tjhe details, no sensor will be able to resolve them."

Welcome to the center of the universe, where the world is flat and extends only to the horizon, only light that I can see exists, radio waves, gamma rays, infared light, and ultraviolet light do not exist. This is MY world, Mwuahahaha!!! (No offense, but really, how couldn't I say it? Have a little laugh with us).
tmoreau is offline   Reply With Quote
Old Mar 10, 2006, 12:23 AM   #82
Member
 
Join Date: Jan 2006
Posts: 91
Default

Quote:
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?

I think you need to think before you post silly statements like this, stick to facts and leave personal condescending arguments where they belong. You have not put together all the facts, just the ones you want. Of course if you use a camera with more megapixels you will get more detail that has nothing to do with anything as we are talking about comparisons between cameras with THE SAME resolution.



So please explain why video camera manufacturers make a fuss about the optical magnification? You have just ignored what I have said because it disagrees with you and maintained your half baked theory. According to your theory if NASA used a 300mm lens and a mega gigapixel camera they would get the same result as building the giant hubble telescope which is nonsense.

Yes your camera will get better results than a 8 megapixel because it has a more pixels. What you have neglected however is that if you took your camera and put a 100mm lens on it instead ofthe 50mmthe resolution would be even better and more detailed because of the higher OPTICAL MAGNIFICATION. This is why video camera manufacturers go to great lengths to promote the higher OPTICAL MAGNIFICATION because the more OPTICAL magnification the better the resolution, nothing to do with megapixels or sensors. if there was no difference between 10 times optical zoom and 20 times optical zoom no one would bother with it. More optical zoom meand BIGGER LENS. 300mm lens = BIGGER LENS than 200mm = more OPTICAL zoom.


Mark47 is offline   Reply With Quote
Old Mar 10, 2006, 12:40 AM   #83
Member
 
Join Date: Jan 2006
Posts: 91
Default

Quote:
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?

That is an invalid argument as I was comparing lenses not sensors, and you have said nothing here about comparisons of lenses only the relationship between one lens and one sensor. The fact is that camera manufacturers make a point of advertising the higher OPTICAL zoom as opposed to digital zoom. The 50mm lens was needed for the wide angle. If however you put a 1000mm lens on to your camera and then took a photo and then used the 50mm to photograph the same subject from the same point and crop and blow it up to be the same size as the 1000mm, which will contain the most detail? The 1000 mm obviously!
Mark47 is offline   Reply With Quote
Old Mar 10, 2006, 1:27 AM   #84
Member
 
YunusEmre's Avatar
 
Join Date: Mar 2006
Posts: 44
Default

Ahem, let me interrupt this discussion for a little while and ask you guys what you are exactly arguing about? I agree that optical zoom is better than digital zoom, I think everybody will agree to that, right?. We must keep in mind there is a limit to both.

Let me give you a few options,

1) D-SLR cameras with smaller than 35mm sensor crops the picture when used with a lense made for a 35mm sensor camera

2) A picture cropped in this manner will give the impression of grater magnification compared to the magnification with a camera with 35mm sensor using the same lens

3) A picture cropped as described in 1 may have more pixels than a picture that can be crated by cropping the picture of the same object taken with a 35mm sensor camera with the same lens even though the 35mm camera has more pixels.

I stated these, as I understand them. Which of these do you guys do not agree with and which do you agree with? Or is it something entirely different that you do not agree with?

Edit: doh! 35mm not 32mm
YunusEmre is offline   Reply With Quote
Old Mar 10, 2006, 4:00 AM   #85
Member
 
Join Date: Jan 2006
Posts: 91
Default

If you look at a painting of a tree, it will look like a tree with leaves and branches. If you look close up however, you can see that there are no actual leaves painted, it is just brush strokes that when viewed from far away will look like leaves because your mind fills in the blanks. It is the same in real life, if you look at trees from a mountain top, you cant see individual leaves, you cant see detail, it is just a composite put together by your mind. The same if you look at any tree from the ground, it is just a composite image thatgives the impression so you know what it is but without the detail.the image you see is actually created by your mind using information. The information it uses is the different wavelength of light that is absorbed by different matter. Different matter absorbs different wavelengths of light so your mine asigns a colour code to differentiate it. Matter itself is invisible. It doesnt take every single photon of light that hits the trees and put it into position, it instead just like the painting"fills in the blanks".

The further away from an object you are the more "blanks" there are to fill in as light is not coming to you perfectly parallel. it is like the picture projected onto a screen, the further you move the screen away, the bigger the picture. There is less picture per square inch, so there is less detail or less pixels. When you are looking at an object this means that there is less detail for your mind to create an image, so it has more "blanks" to fill in.

If a person is too far away from you, you will not be able to recognize them because the light coming to you from them, does not contain enough information to fill in all the blanks, so you get an impression or composite justlike the painting of a tree.

Get two magnifying glasses, one large (HIGH OPTICAL magnification)and one small (low OPTICAL magnification)and focus the light from the sun on to a piece of wood so that the diameter of the circle where it hits the wood is the same size for both. The larger magnifying glass (higherOPTICAL magnification)is going to burn the wood far easier because it has more light focused into the same size area. It is the same with lenses, the more OPTICAL MAGNIFICATION of the lens, the more light it is focusing intothe same area. Because it is focusing more light, it is bringing with it moredetail, so there are less "blanks" to fill in.

Suppose you were totake the two magnifying glasses and focus them so the circles are the same size. What you have is similar in design tothe focusing of a 200mm lens and a 300mm lens.The circle of light on the wood is the same size but the amount of light of the larger "magnifying glass" is far greater. The more light, the more information, the more information the less blanks to fill, the more detail you see.

So when someone says that a crop camera will make a 200mm lens the equivelant of a 300mm, it doesnt turn the 200mm lens into a 300mm lens. It doesnt make the small magnifying glass stronger so that it can burn through wood the same as the larger one. All it does is it uses less of the circle and blows it up more, which is digital magnification. This is why video camera makers make a big deal out of having larger OPTICAL zoom. Its not about magnification but the amount of light that is focused. The more optical zoom the bigger the magnifying glass the more it will "burn".
Mark47 is offline   Reply With Quote
Old Mar 10, 2006, 4:45 AM   #86
Moderator
 
Nagasaki's Avatar
 
Join Date: Jan 2004
Posts: 897
Default

Nobody is arguing that an optical zoom beats a digital zoom. With digital zoom you turn your 8Mp into a 4Mp or whatever.

What we are taling about is using an 8Mp camera to photograph a distant object. If I attach a 200mm lens to this camera will it have the same field of view as a 300mm lens on a 35mm camera yes. Will it provide sufficient light to the sensor to expose the scene yes. Finally and this is the point that you seem to disagree withwill it be able to resolve the scene in sufficient detailyes.

The 300mm lens may be able out resolve the 200mm lens but if they both out resolve the sensor that fact is irrelevant and undetectablein the resulting picture.
Nagasaki is offline   Reply With Quote
Old Mar 10, 2006, 7:41 AM   #87
Member
 
Join Date: Jan 2006
Posts: 91
Default

It seems that a number of people have been arguing that optical magnification has no effect, as they have been focusing on the resolution of the sensor, not undrestanding how the whole system works. The 200mm lens will not provide as much detail as the 300mm lens due to the optical characteristics. The difference will be small and probably not noticeable, for general photography, it will play a more significant role in longdistance. The point was, that the crop factor is being promoted as turning your 200mm lens into a 300mm lens, giving people the false impression that your lens is now "more powerful". If a squirrel is too far away for you to make it out properly at 200mm then using a crop camera isnt going to make it any bigger.

Suppose you see something in the woods amonst some leaves, its so far away you cant make it out. You try a 200mm lens on your 35 camera but still you cant make out what it is. Putting the 200mm lens onto your crop camera isnt going to bring the image "closer" to you so that you can make it out.

Long distance photography is like a jigsaw puzzle. You see someone in the distance but you cant make out who it isbecause your eyes dont pick up all the detail. You use a lens and the lens ads more pieces of the puzzle, so the person becomes a bit more recognizeable. You use a bigger lens and it brings in more pieces of the puzzle. This is why the hubble telescope is so big, to collect more pieces of the puzzle. When you use a bigger lens, you are not simply making the image bigger but obtaining more "pieces of the puzzle".

This is the main point I was making, was when something is a long distance away, to the point where it is unrecognizeable. The crop camera wont make it recognizeable by turning your 200mm lens into a 300mm. Not unless you increase the number of pixels, even then you are still getting a "composite" photo with details ommitted. having more pixels would be like taking a painting of a tree and increasing the size of the brush strokesto enable you to see it further away. It is still the same brush strokes but you have increased the size of them, rather than actually filled in more blanks. This is why the images from that megapixel camera are so crappy, they only digitally improve, not optically.

If you look at that diagram on the previous page, it hasnt accounted for the different amounts of light taken in by the more powerful lenses, it is only used as a means to illustrate the croping effect, not the optical quality, so is innapropriate to the point I was making.

Mark47 is offline   Reply With Quote
Old Mar 10, 2006, 8:19 AM   #88
Senior Member
 
tmoreau's Avatar
 
Join Date: Dec 2005
Posts: 477
Default

The fuss about optical magnification versus digital magnification is that with digital magnification your taking (for example) a 1mp image and enlarging it as you would in photoshop, by taking the center 600k pixels and enlarging them to fill the 1mp space. Your not using the native resolution of the sensor, your using LESS than the 1mp resolution. Optical magnification changes what the sensor takes in. Have you any idea what I'm talking about? I see no evidence of it in your posts. Simple concept. Your taking a pretty hard line on a topic that escapes your understanding.

The reason for using larger lenses and longer focal lengths is because of limitation in sensor/film/human eye resolution. Its that simple.

We could theoretically build the hubble over today, replace the 8 foot mirror with a 3 foot mirror, and replace the old tech sensor with something comparable to what you find in 7mp pocket cameras.

Oy, I just dont get how you can continue this nonsense. Putting a longer lens on the same camera increases optical magnification. You got that part right. Now, pour yourself into the discussion here, and realize thats not the topic. Welcome to page five, where have you been? Whats being debated is that a SHORTER lens can have MORE optical magnification, when your using a smaller and higher resolution sensor. The reason is that there is much more detail availible to be resolved in any given lens than current sensor technology is capable of. Making a smaller but higher pixel density sensor is not "digital zoom" as your posts imply.

Quote:
"if you look at trees from a mountain top, you cant see individual leaves, you cant see detail, it is just a composite put together by your mind."
At least your on the same page as Dave, in thinking that your eye is the most capable optical device made. Your stuck on the idea that your eye is NOT limited in resolution, that your expiriencing the limitations of light, not your own personal limitations.

Quote:
The crop camera wont make it recognizeable by turning your 200mm lens into a 300mm. Not unless you increase the number of pixels, even then you are still getting a "composite" photo with details ommitted.
You are assuming that camera 1 is 6mp, you increase to 8mp for camera 2, but by saying details are still omitted your saying that the lens is unable to resolve more than 6mp. How is the gigapixel lens able to resolve billions of pixels, then?

Here we go...
All magnification does (listen up, kids) is spreads out light that is too close together for the resolution of your sensor/film/eye. If four leaves on the tree fall into one pixel, you get one "dot" or "blur". Spread the light out a little and each leaf will fall on its own pixel. Spread it out a little more, and you will make out stems, then the shape of the leaf, then veins...

Whats another way to do this? Make the pixels smaller. We have the technology, our eyes are a fixed resolution so if WE want to see more detail the light must be spread out, but CCD sensors are not fixed in resolution, we continue to advance in this area.

Its tough for us to spread out the light without adding various types of distortion in the process, but were not so bad at it, and were getting better. Lens design is improving, but is already well ahead of sensor resolution, so the point is moot.

Thats all folks, I've had enough, thanks for playing!
tmoreau is offline   Reply With Quote
Old Mar 10, 2006, 9:24 AM   #89
DBB
Senior Member
 
Join Date: Jan 2004
Posts: 2,483
Default

The question here is the difference between "Resolving power" and "Magnification."

The cropping power magnifys the image without in any way increasing the resolution.

I have posted links to scientific explantions of this.

These links have been ignored.

My Dear Mr. T. Moreau.

With all due respect, you have repeatedly said that Mr. 47 is all alone on this. This is revealing. Reality is not decided by a majority vote.



Dave
DBB is offline   Reply With Quote
Old Mar 10, 2006, 9:29 AM   #90
Senior Member
 
tmoreau's Avatar
 
Join Date: Dec 2005
Posts: 477
Default

DBB wrote:
Quote:
The question here is the difference between "Resolving power" and "Magnification."

The cropping power magnifys the image without in any way increasing the resolution.
Very specific example then, Canon Rebel XT wtih a 35mm f/1.4L lens. What is the sensor resolution? What is the lens resolution?
tmoreau is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 11:43 AM.