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D-SLR Maginfication Fallacy

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bradley phillip said:
Wow, this whole thread's on fire!! :)

Thanks for the thought-provoking discussion, Chris.
Click to expand...
Anytime :-)
Member said:
Member said:
A D30 shooter with a 100 mm lens would stand in the same place as a
35 mm shooter with a 160 mm lens, ergo the same perspective.
Click to expand...
Yes, you've read the implication in my earlier post correctly. I
believe there would be a difference between the image captured with
a D30 @ 100mm and with a 35mm at 160 from the same place. I'll
explain:

1) The depth of focus offered by the two views would be different
(the 160mm would offer less depth of focus than the 100mm).
Click to expand...
Depth of field is a big can of worms and it's difficult to get consensus. There are many sources of confusion because it makes a difference whether you talk about the aperture size relative to the lens (i.e. "f-numbers"), or absolute aperture, and the size you enlarge the print by. People have done the arithmentic and mathematics before in these forums, but in the simple case you care correct.
Member said:
2) To get exactly the same "telephoto compression", or let me put
it more preciseley-- to get exactly the same perspective between
objects at various distances in your image, you'd have to stand in
different places with the two different focal lengths.
Click to expand...
This is wrong. Perspective has nothing to do with the focal length of the viewing device. It is a function of where the veiwer stands, and nothing else.
Member said:
If you
stood in the same place, the difference in perspective would be
greater the closer the objects were to the camera. (i.e. no
difference at "infinity").
Click to expand...
No it wouldn't. Perspective is simply the way things look bigger and obscure more of the background the closer you stand to them. It happens because light travels in straight lines. If you have a nearby building obscuring a different mountain, the only way you will be able to see more of the mountain, while keeping the building in frame, is to move backwards. Putting a longer lens on won't suddenly make the light from the mountain curve round the building.

People often talk about "telephoto compression" without really thinking about what it means. What appears compressed is the distance between objects. In other words, the distance between objects looks smaller when they are using a long telephoto lens. As we know from experience, the reason big things look small is because they are a long way away (this is perspective). The reason people associate this effect with telephoto lenses is because telephoto lenses have a narrower field of view, and so the photographer has to stand further away from the subject to fit it all in.
 
Exactly Chris,

Well said. If you take a photo with a 20mm, curbside, 7 feet away from a large building - - - you would need to place yourself nearly 14 feet away in the center of the road, and about 7 feet below the surface of the road to get the same shot with a 28mm lens (all on 35mm format). You would also need to stop down at least one more stop to be close in dof.
Chris Brown said:
Mastrianni said:
No, period. Done it, and do it all the time. Please don't get back
into perspective, and distance from subject. Read other posters for
that. They are correct in talking about "perspective, compression,
or whatever you want to call it", in reference to subject to lens
distance. But due to the increased DOF inherent in wide angle
lenses, the same "perspective" may be achieved in the final image
by adjusting angle to subject plane when altering the "distance".
Click to expand...
Utter rot. The only way you can possibly get the same image from a
differnt position is if everything in your frame is in exactly the
same plane, perpendicular to the lens axis.

If you have objects in different planes then it is not physically
possible to get the same image standing in two different places.

Try an experiment, looking at this text now, close one eye and put
your finger in front of the other eye so that it is obscuring some
of the text. Now move your head backwards, keeping the finger in
the same place. Notice how more of the text becomes visible. This
is the "perspective compression" that people like to talk about.
You really think you're going to be able to hide that text again
from a distant position by changing lenses?

You stated that you can get exactly the same image from two
different spots. You are simply wrong, there's nothing more to it.
Click to expand...
 
Matti J. said:
Thank you Will. Exactly what I meant in my post: perspective, DOF
etc. are more or less changed.
Click to expand...
Matti,

It's too bad trying to mask off the film gate in a 35mm SLR with tape is likely to damage the shutter curtains otherwise it would be easy to show the results of using "smaller" film (or sensors). This is more high-school physics than advanced optics.

I don't remember all this fuss when APS came out, tho'. It's got to be some psychological thing about not wanting to trade "magnification", which thought to be good for "cropping", which is perceived to be "bad" when one spends many $K for something like a D30 or D1x or whatever.

Will
 
Take a look at Ansel Adams Photographic Techniques Book I, pages 84 - 85.

Here, it is quite clear that if you zoom in or out at the SAME POSITION the crop will be identical throughout the image.

If you CHANGE POSITION YOU CHANGE THE IMAGE, the subject may fill the same space, but the perspective, the way the subjects relate to each other in the image WILL BE DIFFERENT.

But dont take my word for it, take Ansel's:



So please, People, take a close look at what you "know". Yes it may seem that you "get closer" but you dont, you just get a smaller picture.

Dont think you can go to your local zoo with a 300mm lens and be able to "see" what a 450mm does. The animals will be just as far away through the view finder.

Good luck, I know its tough getting this all sorted out, but dont distress as many pros dont have it "down" completely yet either.

johnny
 
Larry,

You are absolutely correct. And my words are just words, but images are images. Two different things.

Thanks
Mastrianni
lhsmith said:
The preferred "look" of certain lenses, as discussed by you and
Danny, has given me a thought-or-two.
(I realize we have drifted a bit from the original thread-question
here, but what's new about that, ...right? :-)

I don't believe that I have a "preferred lens look". In my personal
approach, I enjoy 'discovering' some aspect of natural beauty, and
then "exploring" the various opportunities to best "capture" the
perceived beauty with my camera.

Within the existing physical limitations, I will most likely move
forward/back, up/down, side ways, ...whatever. Then, when I've
found THE (or one-of THE) place from which the scene looks the
best, I try to pick the lens that will most nearly crop "in-camera"
the scene with little "cutting-room floor" losses. (This to make
the most use of 35mm resolution for larger prints).

Capturing the beauty as it exists in nature is my goal, not to
"create" something pleasing via "the look" of a particular lens,
etc. The focal-length lens that frames the picture I want from
where I want it done, is my "preferred" lens.

I don't fault others who approach things differently, and I don't
believe I'm fanatical about the issue of "found"
rather-than-created beauty, but it's what I choose to pursue and
find satisfaction in recording.

"To each his own" means we'll always have something interesting and
different to learn/discuss here, no?

Larry
Mastrianni said:
This is true, and what I was trying to get across. If you like the
"look" of images from a certain lens on 35mm, you will probably
like that "look" on a DSLR. You may have to adjust distance, and
hence angle and aperture, but it is possible to learn to adjust
your shooting style to your DSLR's idiosyncracies, without
replacing your whole lens collection, and still maintain that
"look". Tele's are another whole deal. You can only "compress" or
"flatten" an image so much before the variance is so
inconsequential it is irrelevant to the final image. Is there a
theoretical difference? Yes, and I admitted as much. But at what
price does everyone want to apply theory when there is no visible
intrisic value? If you don't have the room to move, then by all
means, get a wider lens. If you're shooting birds and can't get
closer, then by all means get a longer focal length. But I do
believe that most people who went from 20mm to 17mm (or 14mm), did
so unnecessarily. They could have attained the same image with
their old 20mm. And the "look" of a 14mm is very different from a
20mm, no matter what camera you put it on. So I would think that
would open up another whole can of worms. Maybe good, maybe bad,
depending on your personal vision. I use only 2 focal lengths in my
work. I have experienced pretty much every focal length, but
settled on these 2, as it is how I "see". Those same focal lengths
are used on both film and digital. (my medium format lenses are
different) I don't have a problem, and would not expect everyone to
do as I do. But I was trying to make the point that a 50mm lens on
a D30/D1 is not TRULY an 80mm lens. We can debate why endlessly,
but you said it best: it's a "different look". Unless cropping is
the same, aperture is adjusted to give same DOF, and angle of lens
to subject plane is adjusted, (the variable everyone disregards,
but is more sensitive to variations the wider you go...literally by
inches), you will not acheive the same results by using a
multiplier in reference to "focal length".

Good Night All
Mastrianni
Danny Odum said:
There is also a different look that wider lenses give. Sometimes
you can't move far enough away.
Click to expand...
Click to expand...
Click to expand...
 
Will Perlis said:
I don't remember all this fuss when APS came out, tho'. It's got
to be some psychological thing about not wanting to trade
"magnification", which thought to be good for "cropping", which is
perceived to be "bad" when one spends many $K for something like a
D30 or D1x or whatever.

Will
Click to expand...
Will,

How many of the "APS" people had multi-thousands$ worth of lens designed to cover the 35mm format, and were trying to use them to best advantage on those APS cameras, with the intent to make fairly large prints from the resulting images?

And how many of them had selected these lenses (AND suffered the expense of their purchase) to give the specific "range"(wide/standard/telephoto) of capabilities they desired?

Rhetorical questions, of course, ... I don't think there's any mystery here.It seems to me that the "psychological thing" is plainly-and-simply the desire of people who HAVE met the above conditions desiring to use their equipment-investment AS INTENDED, combined with the potential of (D-30, or so) QUALITY sensors which use that full lens coverage, to make possible the substitution of 35mm-size DIGITAL equipment , giving the best-possible large prints FROM THIS FORMAT.

(If the edge-quality of the lenses becomes the "limiting-factor", when the hi-res/full-frame sensors are "up-to-snuff", ...then that will be the NEXT "bridge to cross". But anyone will be free to use, AT THEIR DISCRETION, the same cure being "forced" on us today,...CROP before printing, if they want to use only the "center"-performance of their lenses.

Those with (let's say) the 200/1.8 L may not need to do much of this. (I'm not one of them , ...just a jealous wannabe:-)

Larry
 
Hello Brad,

Thanks for the quick overview, I wasn't however unclear about the technical functionality I LOVE the performance of my standard EOS lenses on the D30... I'm using the best part of already good glass ot YES get BETTER pictures.... Yes everyone is closer thats fine... Yes it narrows my WIDES, but for that I'll just take multiple frames and stich them together... SO I can have is I want it a 5mm lens without distortion...

Scott...
bradley phillip said:
Scott,

You're right in that what you see is what you get when using an
SLR. That is true. The problem arises if you compare what you see
from the SAME lens on a D30, and say, a EOS 30 (Elan 7e).

Say you buy yourself a spiffy new 300/2.8-- hook it up to the EOS
30, and it'll give you the field of view of a 300mm lens... No
surprises there.

But when you slap it onto a D30 and look through the viewfinder,
the you'll see much, much more magnification, FROM THE SAME LENS!
It'll be acting like a 480mm would on the EOS 30. That's right,
the people in the distance will "be closer" than they were on the
film camera.

You might say COOL! a 480/2.8 for the price of a 300/2.8!! (The
apeture stays the same)... It's like some kind of magic
teleconverter!!

But it's actually not so cool at the other end of things... In the
wide end. Nature photographers frequently shoot wide angles, and
ultrawides like the 17-35/2.8 become rather ordinary 27-56 when
attached to the D30.

So people would like 2 things: the mm they paid for and the
coverage they paid for in their lenses.

Hope that makes it a bit clearer, at least.

bradley phillip
Click to expand...
 
Johnny,

Very nice book. But if you look at the example, it uses lenses that are extremely different (105 & 50) to illustrate a point. Nowhere did I say that you could emulate a 20mm lens with a 85mm lens. I said that I can create the same/near identical image on a 35mm & DSLR using the same lens, especially if it is a tele lens, but even with a 20mm lens with little or no difference in the image. The wide angle will also require a change in angle to plane of subject, but will still appear wide angle in nature (distorted perspective). The differential between 17mm on DSLR & 20mm on 35mm will be moot. Do I think there is a difference? Of course I do. Does it really matter, and is it really necessary to change lenses? Not for me.
Thanks
Mastrianni
johnny said:
Take a look at Ansel Adams Photographic Techniques Book I, pages 84
  • 85.
Here, it is quite clear that if you zoom in or out at the SAME
POSITION the crop will be identical throughout the image.

If you CHANGE POSITION YOU CHANGE THE IMAGE, the subject may fill
the same space, but the perspective, the way the subjects relate to
each other in the image WILL BE DIFFERENT.

But dont take my word for it, take Ansel's:



So please, People, take a close look at what you "know". Yes it may
seem that you "get closer" but you dont, you just get a smaller
picture.

Dont think you can go to your local zoo with a 300mm lens and be
able to "see" what a 450mm does. The animals will be just as far
away through the view finder.

Good luck, I know its tough getting this all sorted out, but dont
distress as many pros dont have it "down" completely yet either.

johnny
Click to expand...
 
Larry & Matti,

I already said if you are in a situation where you cannot move, then of course you need to change lenses. In the studio or on location, (for me), I have not encountered that problem. But I still believe that it would behoove MOST photographers to learn to address their perceived problems with creative solutions, not with changing lenses. But if you need more room, you need more room. Change lenses.
Sincerely
Mastrianni
Matti J. said:
Mastrianni said:
....
(of course dependent on distance to subject). Again, I have no
problems with using a, for instance, 85mm interchangably between a
film and DSLR. Again, I adjust my distance and aperture
accordingly, and voila, the final uncropped images from either film
or DSLR are THE SAME. This is real world usage, but does not
totally discount theory in any way. But it does relegate theory to
its proper place in image production: if it doesn't show up on the
final uncropped image, it don't matter. Uh...period.
Sincerely
Mastrianni
Click to expand...
Dear Mastrianni,

I think you are still slightly missing the point. We are talking
about the ouput of the lens + body combination. By succesting that,
you can "always" move your position i.e. changing your distance
from the subject and thus deal with the different zoom range
characteristics is unnecessarily confusing the actual phenomena.

I cannot make this more clear (and ackward) than this: suppose you
are on the top of a narrow tower where there is little or no room
for moving yourself while shooting. Now consider the lens + body
output. There IS an undisputable difference! You cannot change that
my moving around.

Tele lenses and zooms are for getting the picture from where you
are. By changing your position you are changing your perspective
relative to your surroundings. And that's a different story.

Cheers,
Matti J.
Click to expand...
 
Anyone able to explain why digital sensors must be so small? Not just the factory spiel, but some reason why you can't cover a 35mm frame with pixels.
lhsmith said:
Will Perlis said:
I don't remember all this fuss when APS came out, tho'. It's got
to be some psychological thing about not wanting to trade
"magnification", which thought to be good for "cropping", which is
perceived to be "bad" when one spends many $K for something like a
D30 or D1x or whatever.

Will
Click to expand...
Will,

How many of the "APS" people had multi-thousands$ worth of lens
designed to cover the 35mm format, and were trying to use them to
best advantage on those APS cameras, with the intent to make fairly
large prints from the resulting images?

And how many of them had selected these lenses (AND suffered the
expense of their purchase) to give the specific
"range"(wide/standard/telephoto) of capabilities they desired?

Rhetorical questions, of course, ... I don't think there's any
mystery here.It seems to me that the "psychological thing" is
plainly-and-simply the desire of people who HAVE met the above
conditions desiring to use their equipment-investment AS INTENDED,
combined with the potential of (D-30, or so) QUALITY sensors which
use that full lens coverage, to make possible the substitution of
35mm-size DIGITAL equipment , giving the best-possible large prints
FROM THIS FORMAT.

(If the edge-quality of the lenses becomes the "limiting-factor",
when the hi-res/full-frame sensors are "up-to-snuff", ...then that
will be the NEXT "bridge to cross". But anyone will be free to use,
AT THEIR DISCRETION, the same cure being "forced" on us
today,...CROP before printing, if they want to use only the
"center"-performance of their lenses.

Those with (let's say) the 200/1.8 L may not need to do much of
this. (I'm not one of them , ...just a jealous wannabe:-)

Larry
Click to expand...
 
Danny,

I'm with you. My knowledge of such things is so limited that I tend to take a simplistic view.

Think "tile-floor". Bigger floor? Add more tiles!

What's the big deal? (Must be one, ...but I sure don't know what it is :-)

Larry
Danny Odum said:
lhsmith said:
Will Perlis said:
I don't remember all this fuss when APS came out, tho'. It's got
to be some psychological thing about not wanting to trade
"magnification", which thought to be good for "cropping", which is
perceived to be "bad" when one spends many $K for something like a
D30 or D1x or whatever.

Will
Click to expand...
Will,

How many of the "APS" people had multi-thousands$ worth of lens
designed to cover the 35mm format, and were trying to use them to
best advantage on those APS cameras, with the intent to make fairly
large prints from the resulting images?

And how many of them had selected these lenses (AND suffered the
expense of their purchase) to give the specific
"range"(wide/standard/telephoto) of capabilities they desired?

Rhetorical questions, of course, ... I don't think there's any
mystery here.It seems to me that the "psychological thing" is
plainly-and-simply the desire of people who HAVE met the above
conditions desiring to use their equipment-investment AS INTENDED,
combined with the potential of (D-30, or so) QUALITY sensors which
use that full lens coverage, to make possible the substitution of
35mm-size DIGITAL equipment , giving the best-possible large prints
FROM THIS FORMAT.

(If the edge-quality of the lenses becomes the "limiting-factor",
when the hi-res/full-frame sensors are "up-to-snuff", ...then that
will be the NEXT "bridge to cross". But anyone will be free to use,
AT THEIR DISCRETION, the same cure being "forced" on us
today,...CROP before printing, if they want to use only the
"center"-performance of their lenses.

Those with (let's say) the 200/1.8 L may not need to do much of
this. (I'm not one of them , ...just a jealous wannabe:-)

Larry
Click to expand...
Click to expand...
 
Will,

Let me rephrase perspective; that wide angle distorted near/far look. I never said DOF was perspective. I said due to the inherent deep DOF of wide angle, you could "emulate in reality", (as opposed to theory), the same "look", whether using, (for example) 24mm or 28mm. (I beleive I said 17mm & 20mm), with little aperture adjustment. With a little change in angle of view to subject, the photos will appear to have been taken with the same lens. You can say "no way" from now till dooms day. (and in theory you would be right), but in real world you are still incorrect. Is every centimeter of measurement of object placement in reference to each other the same? Well if you do that sort of thing, no. But you will find the "look" of the image identical.

I certainly didn't mean to upset everyone,or discount their methods. I meant only to suggest that many would be better served saving their money and not going out to buy a lens that's a couple of mm wider because of a format differential. For most, it would be inconsequential to their real world technique or output. But hey, if you feel you need it, then I guess you do.
Sincerely
Mastrianni
Will Perlis said:
Mastrianni said:
... But due to the increased DOF inherent in wide angle
lenses, the same "perspective" may be achieved in the final image
by adjusting angle to subject plane when altering the "distance".
Click to expand...
Nope. DOF has nothing to do with "perspective". DOF has to do
with the perceptable onset of the fuzzies, not with big people in
front of little mountains, or vice versa.

(There's an effect called "aerial perspective" which has to do with
atmospheric blurring, which people interpret as indicating
something is far away, but that's not what anyone is talking about
here. You can see that used frequently in movies when they shoot
planes approaching a city or a car coming down a long straight
road, and they zoom to keep the size of the plane or car relatively
constant.)

And yes, I've done the experiments.

Will
Click to expand...
 
The limited understanding of micro-electronics I have is: smaller is more expensive and harder to do. I understand that each pixel well must capture detailed enough info to facimilate film. But that only makes me wonder why not 8 million instead of 5 to get the right size?

Like I said before, the industry made a mistake by not standardizing early. We all get to pay for it now by buying 15mm lenses to be 22mm lenses. I remember just 10 years ago that a 15mm was a rental lens for most people.
lhsmith said:
I'm with you. My knowledge of such things is so limited that I tend
to take a simplistic view.

Think "tile-floor". Bigger floor? Add more tiles!

What's the big deal? (Must be one, ...but I sure don't know what it
is :-)

Larry
Danny Odum said:
lhsmith said:
Will Perlis said:
I don't remember all this fuss when APS came out, tho'. It's got
to be some psychological thing about not wanting to trade
"magnification", which thought to be good for "cropping", which is
perceived to be "bad" when one spends many $K for something like a
D30 or D1x or whatever.

Will
Click to expand...
Will,

How many of the "APS" people had multi-thousands$ worth of lens
designed to cover the 35mm format, and were trying to use them to
best advantage on those APS cameras, with the intent to make fairly
large prints from the resulting images?

And how many of them had selected these lenses (AND suffered the
expense of their purchase) to give the specific
"range"(wide/standard/telephoto) of capabilities they desired?

Rhetorical questions, of course, ... I don't think there's any
mystery here.It seems to me that the "psychological thing" is
plainly-and-simply the desire of people who HAVE met the above
conditions desiring to use their equipment-investment AS INTENDED,
combined with the potential of (D-30, or so) QUALITY sensors which
use that full lens coverage, to make possible the substitution of
35mm-size DIGITAL equipment , giving the best-possible large prints
FROM THIS FORMAT.

(If the edge-quality of the lenses becomes the "limiting-factor",
when the hi-res/full-frame sensors are "up-to-snuff", ...then that
will be the NEXT "bridge to cross". But anyone will be free to use,
AT THEIR DISCRETION, the same cure being "forced" on us
today,...CROP before printing, if they want to use only the
"center"-performance of their lenses.

Those with (let's say) the 200/1.8 L may not need to do much of
this. (I'm not one of them , ...just a jealous wannabe:-)

Larry
Click to expand...
Click to expand...
Click to expand...
 
How'd you figure out these angles empirically? Aside from lens distortions, the FOV angle should be reduced by 1.6 (yours are from 1.54-1.58). There's a tendency for a little bit of error when measuring angle empirically because most people take pictures of markings on a flat object (e.g. take a picture of a ruler). If you use that method, the flat object has to be exactly parallel to the film/sensor plane to get an accurate measurement.
bradley phillip said:
FWIW, field of view figures are usually given across the diagonal
of the frame... I tried it H and V, but none of them are a factor
of 1.6...

Empirically,

50mm on a 36x24mm frame gives the following fields of view:
  • Diagonal: 46.8 o
  • Horiz: 39.6 o
  • Vert: 27.0 o
50mm * 1.6 = 80mm:
  • Diagonal: 30.3 o
  • Horiz: 25.4 o
  • Vert: 17.1 o
I couldn't see any "1.6" factors between any of the fields of view...

bradley phillip
dave said:
Does that mean that if the angle of coverage of a 50mm 1.4 is 46
degrees that it will then be reduced if used on a D-30 to 46/1.6 or
28.75 degrees?
Click to expand...
Click to expand...
 
Mastrianni said:
Larry & Matti,
I already said if you are in a situation where you cannot move,
then of course you need to change lenses. In the studio or on
location, (for me), I have not encountered that problem. But I
still believe that it would behoove MOST photographers to learn to
address their perceived problems with creative solutions, not with
changing lenses. But if you need more room, you need more room.
Change lenses.
Sincerely
Mastrianni
Click to expand...
Cropping factor is nothing to do with changing lenses. Nothing at all. Changing zoom range was just an efford (hopeless, as I see now) to make you (and me too) realize the difference in the image characterics of various size imagers (or film frame) and cropping factor. You may or may not think this is hair splitting. It is no use of entering this discussion, if someone don't find the original message on cropping vs. magnifying factor intellectually interesting. Yes, we may shoot and point, frame carefully, adjust aperture and be happy with it. But here we are talking about the details of the lens/imager combinations and their fine differencies. Which there are but you happened to disrecard them or just don't care.. because...well... you just don't care. And that's fine too.
Mastrianni said:
Matti J. said:
Mastrianni said:
....
(of course dependent on distance to subject). Again, I have no
problems with using a, for instance, 85mm interchangably between a
film and DSLR. Again, I adjust my distance and aperture
accordingly, and voila, the final uncropped images from either film
or DSLR are THE SAME. This is real world usage, but does not
totally discount theory in any way. But it does relegate theory to
its proper place in image production: if it doesn't show up on the
final uncropped image, it don't matter. Uh...period.
Sincerely
Mastrianni
Click to expand...
Dear Mastrianni,

I think you are still slightly missing the point. We are talking
about the ouput of the lens + body combination. By succesting that,
you can "always" move your position i.e. changing your distance
from the subject and thus deal with the different zoom range
characteristics is unnecessarily confusing the actual phenomena.

I cannot make this more clear (and ackward) than this: suppose you
are on the top of a narrow tower where there is little or no room
for moving yourself while shooting. Now consider the lens + body
output. There IS an undisputable difference! You cannot change that
my moving around.

Tele lenses and zooms are for getting the picture from where you
are. By changing your position you are changing your perspective
relative to your surroundings. And that's a different story.

Cheers,
Matti J.
Click to expand...
Click to expand...
 
Thanks for the great reference. I would have been nice if the text was more readable (somebody want to try GF on the text? just kidding :-)).

People should note that in the top set of picture it shows how the perspective is the SAME with the crops enlarged to the same area shown below each picture.

In the second set of pictures, the forground subject is kept the same size via MOVING the camera and changing the focal length.

Karl
Mastrianni said:
johnny said:
Take a look at Ansel Adams Photographic Techniques Book I, pages 84
  • 85.
Here, it is quite clear that if you zoom in or out at the SAME
POSITION the crop will be identical throughout the image.

If you CHANGE POSITION YOU CHANGE THE IMAGE, the subject may fill
the same space, but the perspective, the way the subjects relate to
each other in the image WILL BE DIFFERENT.

But dont take my word for it, take Ansel's:



So please, People, take a close look at what you "know". Yes it may
seem that you "get closer" but you dont, you just get a smaller
picture.

Dont think you can go to your local zoo with a 300mm lens and be
able to "see" what a 450mm does. The animals will be just as far
away through the view finder.

Good luck, I know its tough getting this all sorted out, but dont
distress as many pros dont have it "down" completely yet either.

johnny
Click to expand...
Click to expand...
 
Mastrianni said:
Will,
Let me rephrase perspective; that wide angle distorted near/far
look. I never said DOF was perspective. I said due to the inherent
deep DOF of wide angle, you could "emulate in reality", (as opposed
to theory), the same "look", whether using, (for example) 24mm or
28mm. (I beleive I said 17mm & 20mm), with little aperture
adjustment. With a little change in angle of view to subject, the
photos will appear to have been taken with the same lens. You can
say "no way" from now till dooms day. (and in theory you would be
right), but in real world you are still incorrect. Is every
centimeter of measurement of object placement in reference to each
other the same? Well if you do that sort of thing, no. But you will
find the "look" of the image identical.
I certainly didn't mean to upset everyone,or discount their
methods. I meant only to suggest that many would be better served
saving their money and not going out to buy a lens that's a couple
of mm wider because of a format differential. For most, it would be
inconsequential to their real world technique or output. But hey,
if you feel you need it, then I guess you do.
Sincerely
Mastrianni
Click to expand...
The difference in DOF output is highly relatated to the imager sizes. Large area digital imagers would make a (huge) difference in the DOF control. As many of us can appreciate, the 1.6 cropping factor i.e. the quite wide area of D30 imager is not actually "that bad". The usage of the quality Canon lenses indeed give enough shallow DOF if vere needed. And the control even increases when imagers (hopefully) get even larger (in the prosumer DCs to be exact).

Matti J.
 
For a particular lens;
The DOF characteristics remain the same.
The minimum focusing distance remains the same.
All intrisic characteristics (MTF, barrel distortion, etc.), remain the same.
The only things that change are;
Field of View
Magnification (because minimum focusing distance REMAINS THE SAME)

I know it seems confusing because people continue to refer to a 50mm as an 80mm, but it is only an 80mm in terms of FIELD OF VIEW!

Whew. Hope this helps. Phil is correct in referring to it as a cropping factor.

Everyone continues to harp on how bad this is for wide angle. But it really can be turned to an advantage. For instance, if you want to do a wide angle near/far shot (main subject is very close to lens, with panoramic view of background), you can actually fill up more of the frame with near subject because your minimum focusing distance DID NOT CHANGE. Creative opportunities abound. I don't know anyone who thinks medium format is restrictive (lens wise), because an 80mm on that format really behaves differently than an 80mm on a 35mm camera. You must just think differently for that particular tool, and take advantage of each one's optical idiosyncracies.

Matti,

The above was my original response, before we veered off topic. Additionally, I responded to the questioning of my methods and imaging philosophy. It is not necessary for you to agree with those philosophies, and everyone who would like to continue to apply every iota of theory, valid as it may be, to every shot they take, is more than welcome in my book to do so. They will hear no argument from me. Some are of the bent that no portrait can be taken without using a medium tele. I happen to disagree. Some believe you cannot do landscape without ultra wide angle, or large format. I disagree. You will note in the last paragraph that I acknowledge the differences in format size, but choose to take advantage of it as such, and disregard any supposed limitations. But then, that's my askewed philosophy. As another poster said to me, "that's utter rot". So be it.
Sincerely
Mastrianni
 
This physical size of censors talk has been covered quite nicely elsewhere but...

Cut silicon disk into, let's say, nine large area imager chips.

And now cut the same size silicon disk into 25 small area imager chips.

If there is only one defect dot on the silicon disk, how many imager chips are likely to be defective? One out of nine large imagers (11 % defective) and one out of 25 small imagers (4% defective).

If four imager chips on both discs are affected, 44 % vs. 16% of the chips are wasted.

Defectives rate combined with the total output of the single silicon disk, nine against 25, the yield from the production is highly different and so is the cost of single imager.

Cheers,
Matti J.
Danny Odum said:
Like I said before, the industry made a mistake by not
standardizing early. We all get to pay for it now by buying 15mm
lenses to be 22mm lenses. I remember just 10 years ago that a 15mm
was a rental lens for most people.
lhsmith said:
I'm with you. My knowledge of such things is so limited that I tend
to take a simplistic view.

Think "tile-floor". Bigger floor? Add more tiles!

What's the big deal? (Must be one, ...but I sure don't know what it
is :-)
Larry
Danny Odum said:
Anyone able to explain why digital sensors must be so small? Not
just the factory spiel, but some reason why you can't cover a 35mm
frame with pixels.
Click to expand...
Click to expand...
Click to expand...
 
Mastrianni said:
For a particular lens;
The DOF characteristics remain the same.
The minimum focusing distance remains the same.
All intrisic characteristics (MTF, barrel distortion, etc.), remain
the same.
The only things that change are;
Field of View
Magnification (because minimum focusing distance REMAINS THE SAME)

I know it seems confusing because people continue to refer to a
50mm as an 80mm, but it is only an 80mm in terms of FIELD OF VIEW!

Whew. Hope this helps. Phil is correct in referring to it as a
cropping factor.

Everyone continues to harp on how bad this is for wide angle. But
it really can be turned to an advantage. For instance, if you want
to do a wide angle near/far shot (main subject is very close to
lens, with panoramic view of background), you can actually fill up
more of the frame with near subject because your minimum focusing
distance DID NOT CHANGE. Creative opportunities abound. I don't
know anyone who thinks medium format is restrictive (lens wise),
because an 80mm on that format really behaves differently than an
80mm on a 35mm camera. You must just think differently for that
particular tool, and take advantage of each one's optical
idiosyncracies.

Matti,
The above was my original response, before we veered off topic.
Additionally, I responded to the questioning of my methods and
imaging philosophy. It is not necessary for you to agree with those
philosophies, and everyone who would like to continue to apply
every iota of theory, valid as it may be, to every shot they take,
is more than welcome in my book to do so. They will hear no
argument from me. Some are of the bent that no portrait can be
taken without using a medium tele. I happen to disagree. Some
believe you cannot do landscape without ultra wide angle, or large
format. I disagree. You will note in the last paragraph that I
acknowledge the differences in format size, but choose to take
advantage of it as such, and disregard any supposed limitations.
But then, that's my askewed philosophy. As another poster said to
me, "that's utter rot". So be it.
Sincerely
Mastrianni
Click to expand...
Thank you for your reply, Mastrianni. I'll let it be for now.

Happy shooting,
Matti J.
 
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