Interesting focal length example

[Everette]

Don't forget to factor in fstop. That first shot taken with a 60mm lens would probably have had clear detail throughout at f8, where as the second with the 120 would show much less of a change at f8. Isn't that correct?
Everette

Hi Folks,

I generally haven't thought too much about how focal length affects
a photograph. Well, I think about how it will affect the DOF, but
not so much the sense of distance/closeness of objects.

So, I was working on some photos tonight and couldn't quite place
why two photos looked so different. I had a little "aha" moment
and checked the focal length, and sure enough, one was at 60mm and
the other at 112mm (of a 28-135 lens on a 10D, but camera doesn't
matter, this is about photography).

Here is the 60mm shot wide open (4.5). Take note of the hedge at
the end of the block.



And here is a similarly composed shot, but at 112mm wide open.
Again, take note of the hedge



I've read that focal length will affect the distance two objects
appear, but I've never really noticed it in any of my photographs.
So, I thought I'd share and hopefully it is a little educational.

Have a nice night.

Jim
--
Jim Fuglestad
http://www.fuglestadphotography.com
http://www.pbase.com/jfuglestad/galleries
http://www.pbase.com/jfuglestad/366

• You're not in third grade anymore. Take as many recesses as you

want!

• Why simply live and let live? Live and help live.

 

[willemd]

My sister showed me some interesting examples from her photography class as well.

They had to fill the frame with the same subject but at different focal lengths. Very interesting how this can affect the view of a subject, either with its surroundings, at full wide, or isolated, at full zoom.

I analysed how I use my zoom here :
http://forums.dpreview.com/forums/read.asp?forum=1009&message=8178939

and realise I probably use zoom more as a cropping tools then a tool to change prespective. Must learn to be more conscious about it.

Willem

 

[Florindo Gallicchio]

Jim:

Good post! I don't know if this has been mentioned in one of the responses (I didn't read them all), but I believe this focal length issue is what used to give my wife a big nose. She didn't like that at all. It was something that happened with my 707, and it especially happens now with my dSLR lenses, especially in the 70mm to 100mm range.

Thanks!

Florindo

 

[Everette]

Referring to my previous post. Remember how on the lenses for film cameras the area in focus could be found on the lens next to the fstops. I believe it was on the focussing ring.
Everette

Hi Folks,

I generally haven't thought too much about how focal length affects
a photograph. Well, I think about how it will affect the DOF, but
not so much the sense of distance/closeness of objects.

So, I was working on some photos tonight and couldn't quite place
why two photos looked so different. I had a little "aha" moment
and checked the focal length, and sure enough, one was at 60mm and
the other at 112mm (of a 28-135 lens on a 10D, but camera doesn't
matter, this is about photography).

Here is the 60mm shot wide open (4.5). Take note of the hedge at
the end of the block.



And here is a similarly composed shot, but at 112mm wide open.
Again, take note of the hedge



I've read that focal length will affect the distance two objects
appear, but I've never really noticed it in any of my photographs.
So, I thought I'd share and hopefully it is a little educational.

Have a nice night.

Jim
--
Jim Fuglestad
http://www.fuglestadphotography.com
http://www.pbase.com/jfuglestad/galleries
http://www.pbase.com/jfuglestad/366

• You're not in third grade anymore. Take as many recesses as you

want!

• Why simply live and let live? Live and help live.

 

[Brian G.]

Hi Shutter (Jim),

I am sure your example here will be helpful to many. I just wanted to clarify something that many people seem to get confused with. I will say upfront that I am trying to do this in the spirit of being helpful, and am not trying to start any arguments.

I've read that focal length will affect the distance two objects
appear, but I've never really noticed it in any of my photographs.
So, I thought I'd share and hopefully it is a little educational.

People often speak of how focal length changes will change perspective, speaking, for example of "telephoto compression", or "wide-angle expansion". However, this is not quite correct. Changing focal length will increase or decrease scene elements equally. There is no change in perspective, only a change in rendition size.

Changes in perspective are effected by changes in camera position, not focal length . Moving closer will expand apparent distance between objects, emphasizing near-far relationships, while moving farther away decreases apparent distance between scene elements.

The reason people often talk of such things as telephoto compression and wide-angle expansion is not due to the focal length, it is due to the fact that telephoto shots are often taken from farther way- that is, there is a change in camera-to-subject distance.

To prove this for your self, one can perform the following demonstration:

Pick a subject, and take a shot with the wide angle of a zoom lens. Now, without moving, zoom in and take the same shot (obviously, you'll have a smaller field of view, but that's ok). You will notice everything is enlarged equally in the zoom shot (including your main subject). There is no change in perspective at all. Things are just bigger.

Now take a shot with the wide angle of your zoom lens again. Then, go to max zoom, and back up until you've got your subject rendered in approximately the same size in your viewfinder as it was in the wide-angle shot. Take that shot. Now if you compare these two shots, you will find that even though your subject looks the same, the background will differ considerably. The zoomed shot will look flatter with the background looking much larger than in the wide-angle shot. The perpective has changed, because the camera-to-subject distance has changed.

So...the take home message is that focal length does not alter perspective, camera-to-subject distance does.

For those who might think I am making all of this up,

The exercise I suggested above can be found in many good photography books as a way to illustrate the point I was making. I hope this has been helpful to some.

Kind Regards,
Brian

--
Brian



Digital Image Gallery:

http://mywebpages.comcast.net/spiritmist/Brian_Geldziler_Digital_Image_Gallery/index.htm

 

[Chris R-UK]

Brian G. wrote:
[snip]

To prove this for your self, one can perform the following
demonstration:

Pick a subject, and take a shot with the wide angle of a zoom lens.
Now, without moving, zoom in and take the same shot (obviously,
you'll have a smaller field of view, but that's ok). You will
notice everything is enlarged equally in the zoom shot (including
your main subject). There is no change in perspective at all.
Things are just bigger.

Now take a shot with the wide angle of your zoom lens again. Then,
go to max zoom, and back up until you've got your subject rendered
in approximately the same size in your viewfinder as it was in the
wide-angle shot. Take that shot. Now if you compare these two
shots, you will find that even though your subject looks the same,
the background will differ considerably. The zoomed shot will look
flatter with the background looking much larger than in the
wide-angle shot. The perpective has changed, because the
camera-to-subject distance has changed.

So...the take home message is that focal length does not alter
perspective, camera-to-subject distance does.

For those who might think I am making all of this up,
The exercise I suggested above can be found in many good
photography books as a way to illustrate the point I was making. I
hope this has been helpful to some.

Kind Regards,
Brian

The following link, first posted by Johannes earlier in this thread, demostrates this point very clearly:
http://www.reasonableexpectations.com/myths/perspective.htm
--
Chris R

 

[Shutter.]

Everette, it's the same lens, just at different focal lengths. With the 10D f8 isn't enough to get it all in focus for this shot, but I'm not really concerned with f-stop in this example. I could have had the f-stop at f22 for the 112mm shot and the bushes wouild still appear much closer, only they'd also be in focus.

Jim

Hi Folks,

I generally haven't thought too much about how focal length affects
a photograph. Well, I think about how it will affect the DOF, but
not so much the sense of distance/closeness of objects.

So, I was working on some photos tonight and couldn't quite place
why two photos looked so different. I had a little "aha" moment
and checked the focal length, and sure enough, one was at 60mm and
the other at 112mm (of a 28-135 lens on a 10D, but camera doesn't
matter, this is about photography).

Here is the 60mm shot wide open (4.5). Take note of the hedge at
the end of the block.



And here is a similarly composed shot, but at 112mm wide open.
Again, take note of the hedge



I've read that focal length will affect the distance two objects
appear, but I've never really noticed it in any of my photographs.
So, I thought I'd share and hopefully it is a little educational.

Have a nice night.

Jim
--
Jim Fuglestad
http://www.fuglestadphotography.com
http://www.pbase.com/jfuglestad/galleries
http://www.pbase.com/jfuglestad/366

• You're not in third grade anymore. Take as many recesses as you

want!

• Why simply live and let live? Live and help live.

--
Jim Fuglestad
http://www.fuglestadphotography.com
http://www.pbase.com/jfuglestad/galleries
http://www.pbase.com/jfuglestad/366

• You're not in third grade anymore. Take as many recesses as you want!
• Why simply live and let live? Live and help live.

 

[Shutter.]

Hey Brian, you should know by now I'm not a technical guy! haha The point is the same that background objects appear closer to the subject.

And don't you think it's odd? The farther you are from the objects the closer they appear together.

You know, this is also why the recent Perry/Fonda photo raised such a hoot. They appeared to be sitting almost next to each other, but the original photographer maintains that they were 15 feet apart as he shot it with a 300mm lens.

Thanks for the clarification!

Jim

I am sure your example here will be helpful to many. I just wanted
to clarify something that many people seem to get confused with. I
will say upfront that I am trying to do this in the spirit of being
helpful, and am not trying to start any arguments.

I've read that focal length will affect the distance two objects
appear, but I've never really noticed it in any of my photographs.
So, I thought I'd share and hopefully it is a little educational.

People often speak of how focal length changes will change
perspective, speaking, for example of "telephoto compression", or
"wide-angle expansion". However, this is not quite correct.
Changing focal length will increase or decrease scene elements
equally. There is no change in perspective, only a change in
rendition size.

Changes in perspective are effected by changes in camera position,
not focal length . Moving closer will expand apparent distance
between objects, emphasizing near-far relationships, while moving
farther away decreases apparent distance between scene elements.

The reason people often talk of such things as telephoto
compression and wide-angle expansion is not due to the focal
length, it is due to the fact that telephoto shots are often taken
from farther way- that is, there is a change in camera-to-subject
distance.

To prove this for your self, one can perform the following
demonstration:

Pick a subject, and take a shot with the wide angle of a zoom lens.
Now, without moving, zoom in and take the same shot (obviously,
you'll have a smaller field of view, but that's ok). You will
notice everything is enlarged equally in the zoom shot (including
your main subject). There is no change in perspective at all.
Things are just bigger.

Now take a shot with the wide angle of your zoom lens again. Then,
go to max zoom, and back up until you've got your subject rendered
in approximately the same size in your viewfinder as it was in the
wide-angle shot. Take that shot. Now if you compare these two
shots, you will find that even though your subject looks the same,
the background will differ considerably. The zoomed shot will look
flatter with the background looking much larger than in the
wide-angle shot. The perpective has changed, because the
camera-to-subject distance has changed.

So...the take home message is that focal length does not alter
perspective, camera-to-subject distance does.

For those who might think I am making all of this up,
The exercise I suggested above can be found in many good
photography books as a way to illustrate the point I was making. I
hope this has been helpful to some.

Kind Regards,
Brian

--
Brian



Digital Image Gallery:

http://mywebpages.comcast.net/spiritmist/Brian_Geldziler_Digital_Image_Gallery/index.htm

--
Jim Fuglestad
http://www.fuglestadphotography.com
http://www.pbase.com/jfuglestad/galleries
http://www.pbase.com/jfuglestad/366

• You're not in third grade anymore. Take as many recesses as you want!
• Why simply live and let live? Live and help live.

 

[John Forish]

Hey Brian, you should know by now I'm not a technical guy! haha
The point is the same that background objects appear closer to the
subject.

Here's why:

If, in your wide angle shot, the main subject is 10 feet away and a background object is 30 feet away that's a ratio of 3:1.

Move backward 20 feet and zoom in so that your main subject is the same apparent size as in the wide angle shot. Now the main subject is 30 feet away and the background object is 50 feet away, a ratio of 5:3, or 1.67:1.

If you move another 100 feet away the ratio is even less: 150:130 or 1.15:1.

Telephoto lenses "compress" distance.

---John

 

[Shutter.]

Hey Brian, you should know by now I'm not a technical guy! haha
The point is the same that background objects appear closer to the
subject.

Here's why:

If, in your wide angle shot, the main subject is 10 feet away and a
background object is 30 feet away that's a ratio of 3:1.

Move backward 20 feet and zoom in so that your main subject is the
same apparent size as in the wide angle shot. Now the main subject
is 30 feet away and the background object is 50 feet away, a ratio
of 5:3, or 1.67:1.

If you move another 100 feet away the ratio is even less: 150:130
or 1.15:1.

Telephoto lenses "compress" distance.

---John

--
Jim Fuglestad
http://www.fuglestadphotography.com
http://www.pbase.com/jfuglestad/galleries
http://www.pbase.com/jfuglestad/366

• You're not in third grade anymore. Take as many recesses as you want!
• Why simply live and let live? Live and help live.

 

[jrdu]

thank you for the short course in optics.

If I want to take a portrait, using a 105 mm focal length lens, should the distance I stand from my model be 1/.105 or around ten metres?

 

[jrdu]

I think I learned something. I hope I don't forget it too quickly.

 

[Ulysses]

This is all about how changing focal length also affects your perspective. And yours is a very cool demo of it. Nice job, Jim!

For anyone who wants more on it (if it hasn't been mentioned already):
http://photozone.de/3Technology/demos/focalCompress.htm

Hi Folks,

I generally haven't thought too much about how focal length affects
a photograph. Well, I think about how it will affect the DOF, but
not so much the sense of distance/closeness of objects.

--

Ulysses
http://www.ulyssesphotography.com

 

[Ulysses]

So...the take home message is that focal length does not alter
perspective, camera-to-subject distance does.

Your point would hold true if you stood in exactly the same place, and nothing else changed other than the focal length.

If you're changing your focal length, and then you change your POSITION relative to the subject, then your perspective does change. And that's exactly what Jim did in his original samples. He changed his perspective because his physical position changed along with the focal length.

--

Ulysses
http://www.ulyssesphotography.com

 

[Brian G.]

Hi Ulysses,

So...the take home message is that focal length does not alter
perspective, camera-to-subject distance does.

Your point would hold true if you stood in exactly the same place,
and nothing else changed other than the focal length.

If you're changing your focal length, and then you change your
POSITION relative to the subject, then your perspective does
change. And that's exactly what Jim did in his original samples. He
changed his perspective because his physical position changed along
with the focal length.

Yes, exactly. That was my point. Perspective changes only with changes in camera-to-subject distance. In shutter's example, the change he sees is the result of him stepping back to take to longer focal-length shot. It's not the focal length that changes perspective, it's the change in distance. Focal length changes only increase or decrease the size of rendition- everything will either apear larger or smaller, but perspective betwen any two image elements will not change unless distance changes.

But if I remember correctly, i shutter's original example, he had mentioned the change was the result of a change in focal length.

Anyway, it appears we are on the same page.

Kind Regards,
Brian

--

Ulysses
http://www.ulyssesphotography.com

--
Brian



Digital Image Gallery:

http://mywebpages.comcast.net/spiritmist/Brian_Geldziler_Digital_Image_Gallery/index.htm

 

[Shutter.]

Brian, you're splitting hairs. You can't have a change in subject to lens distance without chainging the focal lenght if you want to maintain the same compositional aspects.

So...the take home message is that focal length does not alter
perspective, camera-to-subject distance does.

Your point would hold true if you stood in exactly the same place,
and nothing else changed other than the focal length.

If you're changing your focal length, and then you change your
POSITION relative to the subject, then your perspective does
change. And that's exactly what Jim did in his original samples. He
changed his perspective because his physical position changed along
with the focal length.

Yes, exactly. That was my point. Perspective changes only with
changes in camera-to-subject distance. In shutter's example, the
change he sees is the result of him stepping back to take to longer
focal-length shot. It's not the focal length that changes
perspective, it's the change in distance. Focal length changes
only increase or decrease the size of rendition- everything will
either apear larger or smaller, but perspective betwen any two
image elements will not change unless distance changes.

But if I remember correctly, i shutter's original example, he had
mentioned the change was the result of a change in focal length.

Anyway, it appears we are on the same page.

Kind Regards,
Brian

--

Ulysses
http://www.ulyssesphotography.com

--
Brian



Digital Image Gallery:

http://mywebpages.comcast.net/spiritmist/Brian_Geldziler_Digital_Image_Gallery/index.htm

--
Jim Fuglestad
http://www.fuglestadphotography.com
http://www.pbase.com/jfuglestad/galleries
http://www.pbase.com/jfuglestad/366

• You're not in third grade anymore. Take as many recesses as you want!
• Why simply live and let live? Live and help live.

 

[EmnmE]

http://hyperphysics.phy-astr.gsu.edu/hbase/geoopt/foclen.html
all about focal length it's a length inside the camera
Hope this helped!
--

• Michiel de Brieder -

Enjoying V 1, Exploring D 3 0
http://www.pbase.com/giel
Be aware of the optics of life!

--
Cheers!

:: EmnmE ::

http://www.LostFocus.com
http://www.EmnmE.com

'if that can be done, heck I can do it myself too (all I need is a camera)' - lostFocus

 

[EmnmE]

Thanks for posting this pair of shots - you reminded me of some
optical phenomena that I myself had for a long time had
difficulties to understand.

There are, BTW, a few people who have bothered to run some extended
series of test shots on these things and then were kind enough to
post the results on the net. Have a look at these two links:

http://www.reasonableexpectations.com/myths/perspective.htm

http://www.ctlow.ca/Photo/FocalLength.html#persp1

... but plan to spend some time there as both happen to be just one
small part each of a couple of very comprehensive and higly
interesting sites!

And I just remembered Michael Reichmann of Luminous Landscape too
has an interesting page on this theme - see here:

http://www.luminous-landscape.com/tutorials/dof2.shtml

Regards,

Johannes

haha... yep, duh. I thought about that after I sent it too. lol
But, the focal length distance thing is still interesting.

Jim

--
Cheers!

:: EmnmE ::

http://www.LostFocus.com
http://www.EmnmE.com

'if that can be done, heck I can do it myself too (all I need is a camera)' - lostFocus

 

[1ofUs!]

An interesting exercise is to take a framing card (window cut in a card at the same aspect ratio as the camera) and hold it up and move forward and backward towards a scene while at the same time shifting the card closer or further away from the eye to keep the same framing. It really hits home watching the objects separate as the distance to the scene changes.

This is one reason it is such a bad habit to get into composing on the computer monitor with a wide shot vs. composing in camera with a combination of focal length and focus distance. Aside from the obvious crop of pixels the artistic interpretation becomes extremely limited. Good topic, Cindy

Hi Folks,

I generally haven't thought too much about how focal length affects
a photograph. Well, I think about how it will affect the DOF, but
not so much the sense of distance/closeness of objects.

--
CindyD or SarahD
If one of us is laughing, and the other one isn't, one of us must be wrong...

 

[Ulysses]

Hi there, Brian.

It's not the focal length that changes
perspective, it's the change in distance.

Funny thought came to mind. Another forum member likes to describe it as: "The thing that changed was where your feet are." For some odd reason the image that came into my mind was a photographer who is pigeon-toed versus one who has feet splayed outward. I couldn't for the life of me figure out how that would change anything. Heheh... oh well.

But if I remember correctly, i shutter's original example, he had
mentioned the change was the result of a change in focal length.

I don't know if he said it specifically (maybe he did later in the thread), but upon seeing the images, I know that he had to have changed his physical position to around 2x his starting distance. Like you and I have each been saying, it wouldn't have worked any other way.

Anyway, it appears we are on the same page.

Yes indeedy!

--

Ulysses
http://www.ulyssesphotography.com