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Old Apr 18, 2007, 1:29 AM   #21
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Gazander wrote:
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magnification remains the same but fov changes...?

Correct

if 3:2 aspect ratio is maintained, and you print a 35mm and dslr pic, both with the same 50mm lens.... won't the DSLR pic appear more zoomed in?

Also correct, but the appearance of the subject as "larger" is only relative to the amount of background in the frame. Let's say that you take a shot with your DSLR. You put the shot up on your computer in your image editing software. You use your crop tool at the preset of 6x4 (to keep the aspect ratio constant). You have a subject that is 500x500 pixels in the center of the frame. Now you crop with the cropping tool so that you crop away an equal amount from each side to make the new size of the total pic 2/3 of it's original dimensions. The 500x500 subject is still 500x500 pixels, but occupies a larger percentage of the frame -- it appears to be 1.5x larger, but it's still 500x500.

When you use a longer focal length lens. shooting at the same distance, the subject's image on the sensor is actually larger. IIRC, the size difference is linear, so if you shoot the same subject from the same distance, the size of a 10x10 subject with a given FL lens will be 20x20 when taken with a lens with a FL twice of the first.

As for DA vs FA, i think a "standard" lens for 35mm camera is about 43mm, i define this as being able to look, one eye open and one eye in the viewfinder and not notice an appreciable difference in FOV between each eye.

Again, IIRC, the "standard" lens for a 35mm camera was established mathematically by making the focal length equal to the diagonal of the film frame. This is about 43mm for a 35mm cameral. When Leica was designing 35mm cameras, they found that 50mm of premium quality were easier and more economical to design and manufacture, so they made the "standard" lens 50mm. Other manufacturers later adopted the Leica "standard".

I don't know this for a fact, but I read it somewhere a very long time ago, and I always found it to be believable since to my eye, about 70mm matches my vision more closely and I definitely think that everyone sees differently.

I know the 50mm is NOT like that, not even close on my DL. Since the 40mm is close to the ideal 43mm, will it match the human FOV or will it be out of whack like the 50mm?

If it's really imortant, I think that you should get ahold of a zoom that includes all the focal lengths that might match your vision, maybe like a 28-105 and see which focal length most closely matches what you see. Once you've found it, get yourself the fastest lens of quality at that focal length (or close) that you can afford. I don't personally put much stock in this definition of a standard lens, so I just look at the coverage that a wide lens will give me, and use a wide zoom that will cover it. For a "standard" lens, I'll go with an FA 50 1.4 or F 50 1,7, not because it matches my eyes, but because of the speed and optical quality.

By the crop factor the lens to get the "ideal" 43mm is a 28mm lens or thereabout.

I don't really think that there is an "ideal" lens -- I use different lenses for different purposes. If you use the appropriate coverage lens, then you should get the results that you're looking for.

Now i just went and confused myself again.

Join the club. . .:-)
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Old Apr 18, 2007, 1:48 AM   #22
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NonEntity1 wrote:
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This is my sticking point with this as well. I understand that there is no magnification factor and the image on the sensor or film is the same size, just with more background. But if I actually print a 4x6 of each shot, the picture from the digital should look more zoomed in to my way of thinking.

Correct, in a way. It looks and is bigger, but this is not due to image on the sensor being bigger, it's because you've enlarged it by a factor of 1.5 to make it fit the 4x6 paper. If you cropped the print as in Tom's example, then you'd have the results of equal enlargement of each image.

This really does not matter a great deal to me as my interest in photography began with a digital SLR (indeed, with my point and shoot 35mm I was under the impression that higher ISO numbers simply meant "better" because ISO 400 film cost more than ISO 100 film). So I don't have to do any frame of reference to compare to anyhow.

Then I say go with that -- I pretty much now think in terms of an APS-C sensored camera [email protected] is "wide", @28mm - @60mm is "normal", out to about 150 is short tele, out to about 500 is long tele, and over 500 is extreme tele (and very neat:-)). Make having no previous frame of reference a benefit. Make your own "standards", as long as you understand them, then they will help you choose the correct lens for the job at hand. If it works for you, it really doesn't matter how others view it.


But it seems to me that some of the confusion here is whether you are thinking of the "captured" image or "printed" image when discussing the crop factor. Unless I am missing something and I am still lost?

See the first paragraph in this post
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Old Apr 18, 2007, 3:24 AM   #23
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None of what's being said here is necessarily untrue, but it does over-complicate something that is rather simple.

If two guys go out shooting birds, one guy has a 35mm film camera with a 150mm lens, and the other has an Olympus DSLR with a 2x crop factor with a 150mm lens, the guy with the Olympus will capture images of birds that are twice as wide and twice as high, roughly 4 times as detailed. It will have the same field of view as a 300mm lens on a 35mm film camera, or a 150mm lens with a 2x teleconverter on a 35mm camera.

Some would say that because the 2x crop factor results in details becoming twice as wide, that could be called magnification. Some may disagree because the actual surface area being used by the sensor is still the same as what is used by the film. The way I see it, that's like saying a magnifying glass doesn't magnify because the thing you're looking at stays the same size, you're just focusing on a smaller piece of paper.

A 2x crop factor is effectively the same as using a 2x teleconverter on a 35mm film camera. I suppose that some could argue that a teleconverter doesn't magnify either, or that a 35mm negative captures the same level of detail as 4 Olympus sensors laid out in a grid, but I have a hard time seeing either argument as reasonable.
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Old Apr 18, 2007, 3:35 AM   #24
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Corpsy wrote:
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None of what's being said here is necessarily untrue

If two guys go out shooting birds, one guy has a 35mm film camera with a 150mm lens, and the other has an Olympus DSLR with a 2x crop factor with a 150mm lens, the guy with the Olympus will capture images of birds that are twice as wide and twice as high, roughly 4 times as detailed.
Well that is not entirely true either.....

Yes it appears as a 300mmm lens BUT DETAIL.... no not really as you are only caputing half what the lens actually is collecting.... the rest of the image is be spread outside the sensor area.

Now for a high F/stop (where light is more direct concentrated) not as true but wide open there is a difference.... some detail or at least exposure value will be lost, because those rays from the outer lens are being lost.

This is the excuse for DA lenses where the image circle is shrunk for digital (sub FF), so while no FL difference... ALL the light (and redundant detail when wide open) is being concentrated in the image/sensor area.

This is all diquised by automation.... may still say max aperture, but you will see a higher shutter from a DA lens than a FF lens for a given (espec) max F/stop.
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Old Apr 18, 2007, 4:59 AM   #25
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Hayward wrote:
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Corpsy wrote:
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None of what's being said here is necessarily untrue

If two guys go out shooting birds, one guy has a 35mm film camera with a 150mm lens, and the other has an Olympus DSLR with a 2x crop factor with a 150mm lens, the guy with the Olympus will capture images of birds that are twice as wide and twice as high, roughly 4 times as detailed.
Well that is not entirely true either.....

Yes it appears as a 300mmm lens BUT DETAIL.... no not really as you are only caputing half what the lens actually is collecting.... the rest of the image is be spread outside the sensor area.

Now for a high F/stop (where light is more direct concentrated) not as true but wide open there is a difference.... some detail or at least exposure value will be lost, because those rays from the outer lens are being lost.

This is the excuse for DA lenses where the image circle is shrunk for digital (sub FF), so while no FL difference... ALL the light (and redundant detail when wide open) is being concentrated in the image/sensor area.

This is all diquised by automation.... may still say max aperture, but you will see a higher shutter from a DA lens than a FF lens for a given (espec) max F/stop.
As far as "DETAIL", I'm not talking about detail the lens sees, but rather actual image detail on the captured photograph. When the Pentax SMCP-FA 50mm f/1.4 is used on a 35mm film camera it's a given that it captures a 50% wider field of view than if used on the Pentax K10D, but are you arguing that on a 35mm film camera it will also capture all the resolution of what is being cropped, producing what is effectively a 22 megapixel image? The fact is, all the light coming through the lens may hit the 35mm negative, but detail is still lost due to the fact that film isn't perfect.

In my example I didn't say both people were using the same lens, only that both lenses were 150mm. I suppose if it's an Olympus it would just be assumed that the lens is designed for digital, but that isn't even the point. A DSLR can pull the same level of detail from a DA lens as it can from a decent FF lens, regardless of what shutter speed is used. In fact, I doubt many would claim the Digital Rebel XT captures more detail with it's kit lens than with an L series lens.
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Old Apr 18, 2007, 5:52 AM   #26
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Corpsy wrote:
Quote:
Hayward wrote:
Quote:
Corpsy wrote:
Quote:
None of what's being said here is necessarily untrue

If two guys go out shooting birds, one guy has a 35mm film camera with a 150mm lens, and the other has an Olympus DSLR with a 2x crop factor with a 150mm lens, the guy with the Olympus will capture images of birds that are twice as wide and twice as high, roughly 4 times as detailed.
Well that is not entirely true either.....

Yes it appears as a 300mmm lens BUT DETAIL.... no not really as you are only caputing half what the lens actually is collecting.... the rest of the image is be spread outside the sensor area.

Now for a high F/stop (where light is more direct concentrated) not as true but wide open there is a difference.... some detail or at least exposure value will be lost, because those rays from the outer lens are being lost.

This is the excuse for DA lenses where the image circle is shrunk for digital (sub FF), so while no FL difference... ALL the light (and redundant detail when wide open) is being concentrated in the image/sensor area.

This is all diquised by automation.... may still say max aperture, but you will see a higher shutter from a DA lens than a FF lens for a given (espec) max F/stop.
As far as "DETAIL", I'm not talking about detail the lens sees, but rather actual image detail on the captured photograph. When the Pentax SMCP-FA 50mm f/1.4 is used on a 35mm film camera it's a given that it captures a 50% wider field of view than if used on the Pentax K10D, but are you arguing that on a 35mm film camera it will also capture all the resolution of what is being cropped, producing what is effectively a 22 megapixel image? The fact is, all the light coming through the lens may hit the 35mm negative, but detail is still lost due to the fact that film isn't perfect.

In my example I didn't say both people were using the same lens, only that both lenses were 150mm. I suppose if it's an Olympus it would just be assumed that the lens is designed for digital, but that isn't even the point. A DSLR can pull the same level of detail from a DA lens as it can from a decent FF lens, regardless of what shutter speed is used. In fact, I doubt many would claim the Digital Rebel XT captures more detail with it's kit lens than with an L series lens.
Yeah you are right I just blew high school Physics..... :shock: (Hey its only been 20 something years )

DA leses are EXACTLY the same f/ value just smaller and cheaper (though they really aren't the later) but all the light is being concentrated on the sensor with no spill over so in a dots per inch sort of sense they for the format do have more detail.... though less versatility should you ever want to use them on a film or a FF digital camera.
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Old Apr 18, 2007, 12:12 PM   #27
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Corpsy wrote:
Quote:
None of what's being said here is necessarily untrue, but it does over-complicate something that is rather simple.

If two guys go out shooting birds, one guy has a 35mm film camera with a 150mm lens, and the other has an Olympus DSLR with a 2x crop factor with a 150mm lens, the guy with the Olympus will capture images of birds that are twice as wide and twice as high, roughly 4 times as detailed. It will have the same field of view as a 300mm lens on a 35mm film camera, or a 150mm lens with a 2x teleconverter on a 35mm camera.

Some would say that because the 2x crop factor results in details becoming twice as wide, that could be called magnification. Some may disagree because the actual surface area being used by the sensor is still the same as what is used by the film. The way I see it, that's like saying a magnifying glass doesn't magnify because the thing you're looking at stays the same size, you're just focusing on a smaller piece of paper.

A 2x crop factor is effectively the same as using a 2x teleconverter on a 35mm film camera. I suppose that some could argue that a teleconverter doesn't magnify either, or that a 35mm negative captures the same level of detail as 4 Olympus sensors laid out in a grid, but I have a hard time seeing either argument as reasonable.
Hi Corpsy,

I'm probably not getting what you're saying here, but it seems like you're claiming that a smaller sensor will have more resolution than film twice its size. This does not compute for me. If all things are equal (lens, technique, etc.), I would think the larger format will capture more detail, just because it's larger and there has to be a limit to how many individual sensor sites that can be packed into a given area, in addition to a limit to each individual site's ability to discriminate from adjacent sites. I would think that individual "grains" of silver oxide would be smaller than individual sensor sites on a digital sensor, and would thus be more densely packed, allowing greater resolution.

The offshoot of your statement would be that there is no resolution advantage to going with a larger format, and it would follow that an 4/3 format image would be capable of greater enlargement than 35mm film without loss of detail. It would follow that a full frame 35mm digital camera would outresolve a 645 film camera. I can't see how this would be, and I'd think that medium format film shooters would definitely disagree.

Teleconverters do magnify. There is no way that the length of a TC is sufficient to increase the focal length of a lens without magnification. My Tamron SP 300/2.8 with the 1.4x TC is considerably shorter than the Tamron SP 400/4 though they share the same effective FL and max aperture. With the two stacked TCs like I've been using, it's considerably smaller than I think it would be possible to make a 714mm f6.7.

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Old Apr 18, 2007, 1:23 PM   #28
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I think some are still confused between Field of View and magnification.

Teleconverter magnifies the image, so a 300mm lens becomes a 600mm lens with a 2x converter - note "converter"

The 1.5x crop factor only affects the Field of View. The 300mm lens still has a focal length on 300mm, but the FoV ie the bit you can see has narrowed to the equivalent of a 450mm lens.

Going from maybe 180 degrees view with a fisheye to around 6 degrees with a long prime.


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Old Apr 18, 2007, 2:42 PM   #29
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snostorm wrote:
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Hi Corpsy,

I'm probably not getting what you're saying here, but it seems like you're claiming that a smaller sensor will have more resolution than film twice its size. This does not compute for me. If all things are equal (lens, technique, etc.), I would think the larger format will capture more detail, just because it's larger and there has to be a limit to how many individual sensor sites that can be packed into a given area, in addition to a limit to each individual site's ability to discriminate from adjacent sites. I would think that individual "grains" of silver oxide would be smaller than individual sensor sites on a digital sensor, and would thus be more densely packed, allowing greater resolution.

The offshoot of your statement would be that there is no resolution advantage to going with a larger format, and it would follow that an 4/3 format image would be capable of greater enlargement than 35mm film without loss of detail. It would follow that a full frame 35mm digital camera would outresolve a 645 film camera. I can't see how this would be, and I'd think that medium format film shooters would definitely disagree.

Teleconverters do magnify. There is no way that the length of a TC is sufficient to increase the focal length of a lens without magnification. My Tamron SP 300/2.8 with the 1.4x TC is considerably shorter than the Tamron SP 400/4 though they share the same effective FL and max aperture. With the two stacked TCs like I've been using, it's considerably smaller than I think it would be possible to make a 714mm f6.7.

Scott

I am indeed claiming that a smaller digital sensor will have more resolution than film twice it's size. The Canon S3IS takes a sharp 6mp image using a sensor that has less than 1/10th the surface area of 35mm film. You can try to claim that a photo taken with standard 35mm film has roughly the same resolution as a 60 megapixel digital camera, but the fact of the matter is that a 6mp DSLR has at least as much resolution as 35mm film if not more.

http://www.luminous-landscape.com/reviews/cameras/d60/d60.shtml

http://www.luminous-landscape.com/re..._vs_film.shtml

Nothing I've stated could be logically carried forward to the conclusion in your second paragraph. Larger film formats certainly capture more detail than smaller ones, the same way that larger sensors can capture more detail and dynamic range. Digital sensors are simply a different technology than film, one that has been evolving in resolution and sensitivity since it's inception.

As for your third paragraph, I of course agree that teleconverters magnify. My point was that if using a 35mm film camera with a 2x teleconverter on a 150mm lens magnifies it into being 300mm equivalent, then a 2x crop factor that achieves the same result could also be called magnification.

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Old Apr 18, 2007, 3:06 PM   #30
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Dal1970 wrote:
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I think some are still confused between Field of View and magnification.

Teleconverter magnifies the image, so a 300mm lens becomes a 600mm lens with a 2x converter - note "converter"

The 1.5x crop factor only affects the Field of View. The 300mm lens still has a focal length on 300mm, but the FoV ie the bit you can see has narrowed to the equivalent of a 450mm lens.

Going from maybe 180 degrees view with a fisheye to around 6 degrees with a long prime.


Darren
A teleconverter magnifies an image by focusing on a smaller field of view. If a DSLR produces the same FOV with the same level of detail via the crop factor, why can that not be called magnifying? The way I see it, magnification is defined by the actual result, not by the methods used to achieve that result.
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