ideal portrait lens

[rizla]

Hi all,
i'm a new member and this is my first post, so please be gentle with me!
I've just purchased a 300d and wanted to know what you guys thought about portrait len's. As i'm a very keen angler,Most of my photography is head and shoulders shots,holding a carp up to my chest, sometimes in bad light.

regards
rizla

[JAB1]

You might consider the Canon 100mm macro lens...it has gotten rave reviews as a good portrait lens AND you can use it for macro work....I love this lens!!! Crystal clear and sharp, quiet....

[Vegas Poboy]

A good choice is the 50mm @ 1.8 its cheap and sharp plus it will give you 80mm f1.8 on digital cameras due to the 1.6x factor.

[Malaxos1]

I have the D Rebel as well. I was not very happy with the lens that came with the camera at all for portraits. I shoot weddings and needed a better lens so I bought a Tamron 28-75mm f2.8 lens. this lens is incredible and while I agree that a fixed lens is ideal this lens serves as a good all around lens...Dean

[mwinog2777]

i agree with the 50mm, f1.8. Very fast, very sharp; same as an 80mm.

When a fast lens isn't critical I also use a Tamron, 28-200, 3-8-5.6. It is extremely sharp at ~80-100mm.

[KennyG]

The best portrait lens that does not cost a fortune is the Canon 85mm 1.8 This is one of the most highly regarded portrait lenses made.

Forget using a zoom unless it is as good as the 70-200L 2.8 or the 24-70L. Do not go cheap and nasty on your lenses, you really do get what you pay for.

[CyberDyneSystems]

I agree with Kenny that the 85mm is a better choice.

Althought the 50mm will give a "crop factor" of an 80mm.. it willnot givv you the same perspevtive that a short telephoto like the 85mm does. It is in some ways this aspect that makes the 85mm so highly recomended as THE focal length for portraits.

[rdenney]

CyberDyneSystems wrote:
I agree with Kenny that the 85mm is a better choice.

Althought the 50mm will give a "crop factor" of an 80mm.. it willnot givv you the same perspevtive that a short telephoto like the 85mm does. It is in some ways this aspect that makes the 85mm so highly recomended as THE focal length for portraits.

CDS, you have driven me temporarily out of lurkdom! It is not a crop factor. There is no crop factor. The 10D (and the Digital Rebel) is a smaller-format camera, just as a 35mm camera is a smaller format than a Hasselblad. 28mm is a normal lens on a 15x23 camera like the 10D, just as 43mm is normal on an Elan II, 80mm is normal on a Hasselblad and 150mm is a normal lens on a Speed Graphic. Thus, the 50mm provides you exactly the same perspective on the 10D as any lens that is just under twice the focal length of the normal lens, no matter what camera format.

Perspective is controlled solely by camera position. A 10D with a 50 will have to be in the same location relative to the subject as an 80 on an Elan II, in order to cover the same subject with the same field of view. Thus, it has the exact same perspective.

It doesn't, however, have the same depth of field, depending on how you compare degree of enlargement. If you want razor-thin depth of field and you have the itch to spend more than the cost of the 1.8, get the 50/1.4.

Just to put the final nail in the notion of an 85mm lens as a universal focal length for portraits, try putting it on a view camera. An 85 with a wide enough illumination circle is a pretty wide lens on 4x5, and if you moved in close enough to keep your subject as a head-and-shoulders portrait, that nose would get mighty big.

Rick "with too little time lately for forums" Denney

[MediaMagic]

rdenney wrote:
CyberDyneSystems wrote:
I agree with Kenny that the 85mm is a better choice.

Althought the 50mm will give a "crop factor" of an 80mm.. it willnot givv you the same perspevtive that a short telephoto like the 85mm does. It is in some ways this aspect that makes the 85mm so highly recomended as THE focal length for portraits.


Just to put the final nail in the notion of an 85mm lens as a universal focal length for portraits, try putting it on a view camera.


I don't recall reading a post anywhere that touts the 85mm as the "universal focal length for portraits using any and all formats". Quite the contrary. Most say they love the 85 on a 35mm camera, but don't necessarily care for it on the 10D.

[ChrisNardone]

rizla wrote:
As i'm a very keen angler,Most of my photography is head and shoulders shots,holding a carp up to my chest, sometimes in bad light.


Based on your needs, I recommend either the 50 f/1.8 or f/1.4. If you fish from a boat the picture taker will be close to the subject. So the 85mm might be too much focal length. Also those focal ratios will help if you are shooting in low light.
The 50 f/1.8 is a great lens that is cheap. So you won't worry as much about smearing worm slime on it.

[CyberDyneSystems]

Hay Rick! Nice to see you!

O-kay, I am ready for more schooling!

Although I am clearly still misunderstanding the effect of the smaller film plane/image sensor in relation to the lens focal length... I am also not sure that I have made my own opinion clear either..

First let me make sure I have the 1.6X "thing" (since we can't seem to agree on a name for "it" ) :D :D

Many people will say that a 500mm lens on a 10D is = to an 800mm lens on a 10D.

But this is not true,. it is a 500mm lens and will only provide the lens magnification of a 500mm lens.

The fact that the image sensor is smaller means that the "extra 300mm" effect only exists when the image is printed on a given media size (or displayed on a given screen)

The "enlargement" from 500mm to "800mm effective" occurs outside of the camera. Inside the camera all you have is a film plane that is smaller than a 35mm film plane ... thus a crop of the 35mm film plane.

Is the image sensor any closer or farther from the rear element of the lens in comparison to 35mm film?

So when we view the image on our screens or print it, we are in effect veiwing what is EXACTLY the same iamge as if we had a full frame sensor but used photoshop to crop off the outside edges of the full frame sensor and used only the image info that reamined in the center.

O-kay that part aside,.

What I was refering to as "perspective" was perhaps the wrong word. I am really not sure what the word for it is. But if you take an image shot with a 50mm lens and crop out 9/10ths of the image and enlarge the remaining 1/10th at the center of the image to a full size print "equivelent" to the image size a 500mm lens would give you, the image will NOT look exactly like the image that a 500mm lens will give you (even if we disregard the obvious quality loss)

the tiny crop will not have the same visaul effect (I used the word perspective) as a 500mm lens.

We know this just as we know that taking a photo of a a lion form 2 feet away with a 17mm lens will not look anything like taking a photo from 100 feet away with a 200mm lens (o-kay so I have no idea what the math should be here to get the two images the same size on the film using the different focal lenghts,. so sue me)

It is the inherent difrence in the image qualities of the different focal lenghts that I was trying to refer too.

So,. Rick and Mediamagic, please return and tell me where I have gone wrong in my understanding of all this. :)

[MediaMagic]

CyberDyneSystems wrote:
So,. Rick and Mediamagic, please return and tell me where I have gone wrong in my understanding of all this.

Hey! don't drag me into this one! lol, I understand what Rick is trying to get across, but I don't understand all the math involved. I'd have to get out my calculator and lens charts to calculate the apertures for DOF on each lens to really match perspectives of say a 50mm and an 85mm. Since the picture is flat, but gives the illusion of 3d, matching both the perspective and illusion of depth exactly between two lenses is mathematically possible, but I'm not sure how practical it is. I think we just *know* what looks right and what doesn't without the need for mathematical proof. I'd like to see a more in depth analysis of this just because it's interesting.

My comment though was not directed at your recommendation of the 85, but rather at Rick's assertion that the 85mm lens it touted as *the* portrait solution for all formats (medium, 35mm, small frame digital). This assertion simply isn't true. I've read people talking about loving this lens for 35mm portraits, and some for the 10D, but not one has made the blanket statement that this is some magical focal length that is the portrait solution for all situations and formats. If there is such an animal, sign me up now.

I personally love my 85mm f1.8. It's just tighter with the 1.6x CROP FACTOR (perspective, visual charasteristic, whatever the hell it's really called) than I'm used to working with. So on the 10D, I use the 24-70 and set it at about 52mm. That gives me the "perspective" I'm used to seeing for my portable studio work. But, as others have stated, the bokeh of the 85 lens is superior, it's very sharp, and if you can back up far enough (a few good steps usually), it is still quite excellent for portraits. If I'm taking candids where there is plenty of room, I don't hesitate to whip out the 85 and *love* using it.

Take care,
David

[CyberDyneSystems]

.... and then of course there is "bokeh"

aaaargh!

Thanks MediaMagic,... that can't even be measured! :D :D

[jjguest]

my ideal portrait lens is sigma 50mm2.8 macroex

http://www.pbase.com/image/22179219.jpg

[rizla]

Thanks all for the input,

One other question is i have a canon eos 300 (film not digital) with a 35-80mm 1:4-5:6 ii,will this lens be any good for portraits and will it be o.k. to use on the digital camera.

What a fantastic forum, unbelievable amount of information to absorb.

regards
rizla

[DaveG]

CyberDyneSystems wrote:
I agree with Kenny that the 85mm is a better choice.

Althought the 50mm will give a "crop factor" of an 80mm.. it willnot givv you the same perspevtive that a short telephoto like the 85mm does. It is in some ways this aspect that makes the 85mm so highly recomended as THE focal length for portraits.

The 50 will give you EXACTLY the same perspective as a 80 if you use it on a 10D.

Imagine that you used a 20 mm lens and a 100mm lens and stood at the same place and took two pictures. You enlarge the 20's crop so it is the same as the 100's. You will have two images exactly the same, except that the 20's will of course suck.

[CyberDyneSystems]

Imagine that you used a 20 mm lens and a 100mm lens and stood at the same place and took two pictures. You enlarge the 20's crop so it is the same as the 100's. You will have two images exactly the same, except that the 20's will of course suck.


But this assumes that the lenses and the magnification have zero effect on the image taken,. and that is not true,.

Wide angle lenses impart a distortion on the image,. as do telephoto which distorts the image in excatly the opposite way,. telephoto lenses flatten an image,. they distort depth perception,.. so things in the far distance may look like they are immediately behind something when in fact the distance may be hunddreds or thousands of feet. You can not say the two images are identical.

These differences in the image are the differences to which I am refferring,. not differences in scale.

[photography By Evangelos]

The 85 1.8 is the best lens for portrait work I use it for all my portrait work. And best of all it will not break the bank $$$.

[Butzl]

CyberDyneSystems wrote:
Imagine that you used a 20 mm lens and a 100mm lens and stood at the same place and took two pictures. You enlarge the 20's crop so it is the same as the 100's. You will have two images exactly the same, except that the 20's will of course suck.


But this assumes that the lenses and the magnification have zero effect on the image taken,. and that is not true,.

Wide angle lenses impart a distortion on the image,. as do telephoto which distorts the image in excatly the opposite way,. telephoto lenses flatten an image,. they distort depth perception,.. so things in the far distance may look like they are immediately behind something when in fact the distance may be hunddreds or thousands of feet. You can not say the two images are identical.

A telephoto lens does NOT flatten an image at all. Humans only get this impression because they have a natural view like a 50mm lens (which is difficult to prove but experience shows it).
Hard to believe but true: Perspective is ONLY a matter of the distance of the object to the camera, and nothing else.
And indeed, a 10% crop of a picture taken with a 50mm lens looks exactly the same as a 500mm full frame picture, even the DOF is the same at identical apertures.

Interesting discussion, though!
--Jens--

[CyberDyneSystems]

:D

I am afraid I don't think you will be able to convince me otherwise...

There is a trick that cinemaphotogrphers have been using for decades which consists of a combined dolly shot and active zoom.

The shot begins with the camera (motion picture camera) on a dolly for example 10' away from the subject... on the cue,. the grips dolly the camera back slowly,. while at the same time the Cinematographer zooms the lens in and focuses maintaining the same aspect ratio of the scene,. however as the camera depth of feild changes (usually with a look of horror on the face of the actor :D and usually with a corridor in the backgound seemingly stretching out behind the actor..) the radical difference between the image that a wide angle Vs. a telephot lens protrays is CLEARLY illustrated.

We studied this trick in basic Film class in College, it was used in many of of Hitchcocks films... ( I can't remeber if it was pioneered then)

The trick takes example of what I am calling a persective change perhaps incorrectly. But the trick exists and the difference in image from a wide ange to a telephoto despite constant aspect ratio is not only known to Cinematographers,. it is a tool they use all the time.

Some Film shooters are perfectly aware of this as well... I am alittle taken aback that it seems such a mystery to many here.

[slejhamer]

You say crop factor, I say format difference, you say oysters, I say ersters ...

To respond to the original poster, both the 85 and 50mm lenses will be great for portraits taken with a 10D. One will be better for tight headshots than the other. This does not take into account any stylistic preferences you may have. I've seen some very interesting contemporary portraits done with much shorter lenses...

[slejhamer]

CyberDyneSystems wrote:

There is a trick that cinemaphotogrphers have been using for decades

That is a great, classic effect! And you raise an interesting point.

My guess is that the camera is being physically moved back more than the lens is physically lengthening. For example, to keep your frame filled in the same way with a subject (same aspect ratio as you called it), you have to move the camera back a lot more than 50mm when you zoom the lens from 30mm to 80mm.

Thus, consistent with the above comments, it is the distance from lens to camera that changes the perception of perspective, not the focal length of the lens.

[CyberDyneSystems]

Went back to my old books,. It was Vertigo (1958 ).

A lot of hitchcock's are great, but here we have the introduction of the zoom lens (at least after this it was widely used)

Here you can see the famous dolly out-zoom in effect, since copied a zillion times.

The camera moves backward while the focus puller zooms in and keeps the framing the same, you can see the background move which gives a very alienating effect. Hithcock was great with strange camera angles.

Uncredited second-unit cameraman Irmin Roberts invented the famous "forward zoom and reverse tracking" shot (now sometimes called "contra-zoom" or "trombone shot") to convey the sense of vertigo to the audience.

This and similar effects using zoom and camera motion are common parlor tricks among the cinematogrphers.

[CyberDyneSystems]

Rizla,..

I am sorry we have gone so far off on this tangeant,. If I had the ability to move part of this discussion elsewhere I would :) Both lenses 50mm and 85mm will serve you well! :)


BUT!!!!!!! On to business!!! :D


slejhamer wrote:
CyberDyneSystems wrote:

There is a trick that cinemaphotogrphers have been using for decades

That is a great, classic effect! And you raise an interesting point.

My guess is that the camera is being physically moved back more than the lens is physically lengthening.

Of course you are right,. each 10millimeters would be equivelent to feet... I do not know the math however :(

Thus, consistent with the above comments, it is the distance from lens to camera that changes the perception of perspective, not the focal length of the lens.


I it is irrellevant if it is the distance or the optics..the point is that by using an 85mm lens instead of a 50mm we need to increase the distance we stand back (of course no argument here) than what I am arguing is that by backing up as a result of the telephoto lens to keep the framing the same,. we have altered the image "perspective" and this perspective is more intriguing that the one that the 50mm allows which is in some opinions boring by comparison. Likewise using a wider lens and getting closer to maintain the same framing results in an odd image sometimes percieved as more humorous in apperance.

From a Cinematography text book (this confirms your statement Slejhammer)

DOLLY.— Dollying is moving the camera toward or away from the subject. You can dolly in to increase gradually the size of an object on the screen, or dolly out to produce an opposite effect. Likewise, dollying decreases or increases the field of view.

ZOOM.— A zoom is made with a zoom lens. It looks like a dolly and is used for the same purpose. During a zoom the camera does not move; therefore, perspective does not change as it does during a dolly

So it is the longer telephoto lens FORCING us to "dolly out" that results in the change in perspective...

hmmmm.

Seems we were all correct in one way or another,. the effect is cleary there. It is the length of the telephoto that causes us the photographers to alter our distance and thus our the images perspective.

[MediaMagic]

CyberDyneSystems wrote:
:D

I am afraid I don't think you will be able to convince me otherwise...

There is a trick that cinemaphotogrphers have been using for decades which consists of a combined dolly shot and active zoom.



I agree about the frame/zoom trick. On this zoom trick, I believe the aperture of the camera is remaining consistant (correct me if I'm mistaken). Changing the distance/zoom around a common aperture is what is creating the effect. I know modern video cameras, at least consumer models, automatically control the aperture so keeping a constant aperture is not possible for recreating the trick as a test.

My point about the math is, I think it is possible to create the same image frame and illusion of depth between the two lenses by changing the aperture values along with the distance from the subject. Maybe I'm not saying this correctly. Let me try it this way...

50mm is dX distance from subject with aperture value A. For the 85 to have the same frame, the 85 would be dX + dY = dN (new distance away). If no changes to the A value are made (both are using the same aperture value), the appearance or illusion of depth will be different (thus creating that cinematographer's trick). So, to create an identical image, the aperture value would have to change in proportion (aperture ratio or aR) to the value of the change in distance distance (dY).

So the equation for the cinematographer's trick would be something like

A[(dX + dY) = dN] = change in illusion of depth because value A remains constant

(this is not a correct numeric equation for working the numbers, the aperture change ratio would have to be a mathematical function of the change in distance. It is merely to illustrate the constants vs the variables, if we were to plug in numeric values, we'd get meaningless results with these illustrative equations, I'd have to spend a little time working out the actual numeric equations rather than popping them off the top of my head).

And to create an identical image with the same illusion of depth (avoiding the cinematographer's trick) would be something like:

A(aR)(dY)[(dX + dY) = dN] = no change in illusion of depth because value A is changing along with the distance and zoom


So, to sum up this wild tangent, if the aperture changes along with the the distance and the zoom(from 50mm to 85mm for the lens discussion) then the actual frames should theoretically appear identical with the same illusion of depth (not accounting for bokeh of course). Have I made a mistake with this? If I have made some incorrect assumptions, then let me know. Things are seldom as simple as first thought.

Again though, I think we just *know* when it looks right without all the calculations, but I'm enjoying the discussion.


Take care,
David

[DaveG]

CyberDyneSystems wrote:
Imagine that you used a 20 mm lens and a 100mm lens and stood at the same place and took two pictures. You enlarge the 20's crop so it is the same as the 100's. You will have two images exactly the same, except that the 20's will of course suck.


But this assumes that the lenses and the magnification have zero effect on the image taken,. and that is not true,.

Wide angle lenses impart a distortion on the image,. as do telephoto which distorts the image in excatly the opposite way,. telephoto lenses flatten an image,. they distort depth perception,.. so things in the far distance may look like they are immediately behind something when in fact the distance may be hunddreds or thousands of feet. You can not say the two images are identical.

These differences in the image are the differences to which I am refferring,. not differences in scale.

In the centre of a 20 mm lens there will be no distortion. Blow the thing up and look.

[CyberDyneSystems]

aargh... :D

...if it didn't look any different than the dolly-out zoom trick would result in no perceptable effect at all for the audience....

We have all seen this effect,. and so we MUST all know that (scale aside) the image that the wide end of a zoom gives differs from the image the tele end of the zoom provides.

[Butzl]

CyberDyneSystems wrote:
aargh... :D

...if it didn't look any different than the dolly-out zoom trick would result in no perceptable effect at all for the audience....

We have all seen this effect,. and so we MUST all know that (scale aside) the image that the wide end of a zoom gives differs from the image the tele end of the zoom provides.

Check this link for "Perspective":
http://www.sweethaven.com/academic/lessons/021500/110/default.asp?unNum=1&lesNum=4
Here you find a pretty good explanation of the principle and in the last chapter a definition of "perspective".

--Jens--

[MiG82]

DaveG is correct. His statement of "perspective is determined by the subject distance" stands alone without other assumptions.
Saying that telephotos give different perspective assumes that the subject size is constant due to a varying subject distance.
It might be much of a muchness to some of you, but these are very important differences.

[MarkH]

CyberDyneSystems wrote:
aargh... :D

...if it didn't look any different than the dolly-out zoom trick would result in no perceptable effect at all for the audience....

We have all seen this effect,. and so we MUST all know that (scale aside) the image that the wide end of a zoom gives differs from the image the tele end of the zoom provides.

Aargh yourself.

The dolly out zoom trick works because the DISTANCE is changing, which changes the perspective. Zooming just keeps the size of the subject the same (which cropping would also do).

If you use a 50mm on a 10D and frame a subject as normal, you get the same shot as an 80mm on a 1Ds when framing the subject the same way. Either way you are the same distance from the subject and the shot looks identical (except for the 11MPix vs 6MPix).

Distance is the key to perspective, not zoom.

The forshortening effect of long zooms is caused by making it look like you are close to the subject, when you are not. The perspective compared to apparent closeness is the effect you are talking about, it happens because of the distance not the zoom (cropping can replicate the increased magnification).

So a close crop from a 50 is equal to a 500 if both shots are taken from the same spot, but the crop will only have 1% of the pixels. That's why we use the 500.

[Dans_D60]

It truly is a matter of personal preference. Even super wides can get that “look” you may want. Below are a few examples of different lens configurations:
Dan
http://www.pettusphoto.com


70-200 2.8 L OUTDOORS

http://www.pettusphoto.com/plens/1.jpg


28-70 2.8 L STUDIO

http://www.pettusphoto.com/plens/2.jpg


50 1.4 STUDIO

http://www.pettusphoto.com/plens/3.jpg


28-70 2.8 L OUTDOORS

http://www.pettusphoto.com/plens/4.jpg

[Andy_T]

Dans,

that's a great demonstration!

When comparing picture #1 and #2, it's clearly visible that the 28-70 lens (picture 2) shows the girl as she is, whereas in the 70-200 lens (picture 1) there clearly is distortion making her face appear wider :)

Regards,
Andy

:)Just kidding, though!

[Andy_T]

Rizla,

if you still have a 35-80 4.5-6 lens from your film Canon EOS, then you should just try out whether the results with this lens are up to your expectations!

It certainly covers the zoom range necessary (56-128 with the 1.6 CROP FACTOR), it might only be a little slow under bad lighting conditions. But then, the DRebel should have very little noise at ISO 800. Also, it might not be as sharp as 'L' lenses or as very good prime lenses like the 50 or 85.

Another issue is Bokeh. To get a nicely blurred background to set your angler apart from the background, you can either
- use a fast aperture (lower DOF)
- use a long focal length (lower DOF)
- have enough distance between the object and the background (background is out of DOF area)

If you can't use all of these dimensions, you must experiment. (Or catch more spectacular fish, so that the viewers won't give much consideration to the background :))

Basically, it's up to YOUR expectations and test...

Have fun,
Andy

PS: Although this thread might not be exactly what the original author expected, I find it highly interesting and entertaining.

[CyberDyneSystems]

andythaler wrote:


PS: Although this thread might not be exactly what the original author expected, I find it highly interesting and entertaining.

Me too :D

And again, Sorry Rizla for this wild tangeant,. but who can predict?

[Mashuri]

So here is what I could gleen from this discussion of the 300D's "crop factor." With a 50mm lens I will get the "focal equivalent" of 80mm (50x1.6) but my DOF will still behave like a 50mm lens and must be taken into consideration when setting my aperture. Is this correct?

[rdenney]

(Forgetting that one needs to quote to avoid losing the connections in the thread...this is a response to CDS's first response to me)

The 1.6 factor is an equivalency factor so that people who know what focal lengths mean in practical terms on 35mm cameras will know which focal lengths for the 10D will have the same practical uses. So, if I know that 28mm is a useful wide-angle lens for the sort of images I make on my Elan II, then the equivalency factor tells me that a 17 will meet the same need on the 10D.

Only those who are steeped in the meaning of focal lengths for 35mm use and are confused by the equivalency factor. They know that 35 is moderately wide, 28 wider, 24 really wide, 20 extremely wide, and 14 monstrously wide. They know that 50 is normal, 80 is a good short portrait lens, 135 is a good long portrait lens, 200 is too short for sports, 400 is okay for sports but too short for wildlife, and so on (or whatever they mean to you). They have a sense of the what the numbers mean in terms of their practical application.

Thus, they want to know what a given lens on the 10D is "like". Is a 14 on the 10D like a 28 on my old camera? No. Well, then, what about a 17? Yes.

It started with the point-n-shoot digicams, all of which have a very small sensor. Many of them don't even print the actual focal length on the lens, but rather the equivalant focal length so that 35mm photographers will know what they mean. Hence "5.6 to 15mm (38mm to 100mm equivalent)".

For those of us who are used to shooting in many formats, this is just too much arithmetic, and we tend to think in terms of how a lens relates to the normal for that format (aka the diagonal dimension of the film).

For example, I have a 180mm Sonnar for my medium-format camera. Is that a long lens or a short lens? How would I know? It is 2.25 times the normal focal length lens for that camera, and thus it is equivalent to any lens on any camera that is 2.25 times the normal focal length on any other camera (i.e., it takes the same picture as a 100 on a 35mm camera and a 63 on a 10D). Thus, it's a medium-length portrait lens. But it would be only slightly longer than normal on my 4x5 camera.

If we think of lenses as factors of the normal focal length, then we can end the confusion.

Perspective is controlled solely by how far you are from the subject. Now, how can I explain that better? Let me try it this way:

What is the focal length of a pinhole in a pinhole camera? It doesn't matter. Why? Because the pinhole has an arbitrarily small aperture and "focuses" on film placed any distance from it. If you put the film close the pinhole, you sweep up a lot of scene, and it's a wide-angle lens. If you put it far from the pinhole, it captures only a small part of the scene and it's a telephoto. But if you cut out the same frame from the wide-angle shot as you got with the telephoto shot, you'd have the same image, because the relative size of objects in the frame is controlled solely by how far the camera is from it.

Let's say you are standing before a scene with a tree and a mountain. The tree is close and the mountain is far. If you stand six inches from the tree, all you will see is bark and the mountain will be behind the tree. If you stand 500 feet from the tree, the mountain will loom large and the tree will be a detail. Unless it's a pretty small mountain, the 500 feet will have negligible effect on the size of the mountain on the film (if only the tree weren't in the way). The tree is bigger than the mountain only when you are really close to the tree. That is perspective.

Now, if you use a 14mm lens from six inches in front of the tree, and a 1000mm lens from 500 feet away (or whever focal length is required to cover the same patch of bark), you'll still just get the same patch of bark. But if you took away the tree, the mountain would seem small with the 14 and so vast that you could only see a bit of it with the 1000. What is changing? The big change between these two is magnification. The perspective is still controlled by the location of the camera. The perspective works on the details, too. The tree taken in closeup with a 14 would look round, while the same tree from 500 feet away using a 1000 would look flat. Here's the important point: From 500 feet away, the tree would look just as flat with the 14, if you could enlarge the image enough.

We have exactly this problem on a forum devoted to medium format on which I'm active. 35mm photographers coming to medium format for the first time want to think of focal lengths in their 35mm equivalents, but this causes more confusion that it relieves.

So, to your second question: A 500mm lens is a 500mm lens is a 500mm lens. But on a 10D, it is the 35mm equivalent of an 800mm lens, just as on a 4x5 camera it is the 35mm equivalent of a 135.

Rick "hoping this is clear" Denney

[rdenney]

(responding to CDS's description of the zooming trick in cine)

The trick to which you refer works because the perspective is changing while the magnification of the subject is not. Perspective is the relationship between the subject and the background, while magnification is the size of the subject on the film.

As the subject at the camera move, the zoom is operated to maintain a constant magnification of the subject. For this magnification to stay the same, the distance from the subject has to change--that's why you have the dolly. As the distance from the subject changes, the perspective changes, and the background gets small or large with respect to the constant subject. It's a freaky effect, to be sure, but it is absolutely consistent with what we've been saying.

Everyone is right when they say a 500 provides the same perspective as a 50 from the same spot. The problem is that we don't like taking a picture of one eyelash, so we move. The reason wide-angle lenses make the nose look big is that we have to move in close for it to be a portrait of a person and not a picture of a room with a person on the other side of it. The nose looks smaller with the longer lens not because the lens projects any differently (it doesn't except for the magnification), but because we have to back up to get more in the image than just the nose. It's when we move our feet that the perspective changes.

Rick "seeing an approaching slap on the forehead" Denney

[rdenney]

(responding to Mashuri)

Right, depending on how much you intend to enlarge the image. When using large format, I have to stop the lens down much farther to get the same depth of field as with shorter lenses on a smaller format (that would otherwise take the same picture). It's one of the reasons why portraits taken 80 years ago by Paul Strand on 8x10 cameras have such narrow depth of field, even though his lenses were no faster than about f/8 or f/11.

Rick "not ready for a more detailed discussion of depth of field at this time" Denney

[CyberDyneSystems]

ROFL,

Thank you Rick,.

I will go back and but the BOLD PHP tags around my new signature "tagline" :D