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210 AF IF or 300 APO AF IF for beauty work

Jack

Sr. Administrator
Staff member
You are correct but we not only chose a lens for focal length but maybe the correct word here is perspective or distortion. Maybe better said a longer lens flattens more given the same framing. Maybe the word I am looking for is distortion
Unfortunately it's not semantics, the lens' focal length does not matter one iota for compression or any other aspect of perspective. It's the longer shooting position that achieve's perspective compression, period.

I would agree that secondarily, a longer lens provides us with a more desirable framing at -- and actually forces us to use -- that longer shooting distance, so the result from using it is more compression.

But I want to make sure folks understand perspective is not a property of the lens chosen, rather only a function of shooting position regardless of lens mounted, that determines all aspects of "perspective".

Cheers,
 

Mike M

New member
Left-brainers think analytically in terms of exact science. Right-brainers think intuitively about the application of the science.

A left-brainer will use his analytical mind to deduce that there is no difference between focal lengths and it's the camera position alone that alters perspective. But a right-brainer thinks in terms of application and a change in focal length coincides with a change in camera position in order to maintain the same framing of the subject. Both are basically saying the same thing in different ways.

Perspective is about more than just the science behind the hardware because it's also about the psychology of the viewer that is interpreting the visual information. Right-brainers are more apt to understand the psychological effect that focal length and camera position has on the viewer because there isn't much science available and so it's still an intuitive process. However, the science is catching up and there are studies and books written which try to scientifically explain perspective in art.

Our eyes and minds play tricks on us. A good example might be how the light from a flouerescent source appears relatively neutral to our eye but render green when captured at a daylight color balance. The light really is green, but our eyes and minds turn it neutral. Another example is that most people are utilizing two eyes to view a photograph yet they're only really perceiving one image. The single image is sometimes referred to as the "ego center." The lens axis plane can be thought of as the equivalent to a human's line of site while the film/sensor could be considered the ego center of the camera. The basic point I'm trying to make is that there are psychological factors with how the viewer will perceive perspective that might not yet be easily explained analytically through current science. Yet, many right-brainers already understand them intuitively and that's why they will associate a change in focal length with a change in perspective and the ability to manipulate perceptions of the viewer.
 

David K

Workshop Member
Seems like I'm not the only one who is a bit confused on this issue. I understand exactly what Jack is saying but thought that despite this there would still be some facial compression, i.e. a different look to the image. i will try this myself when I have some time. Having said that I do like the look of portraits taken with longer lenses. Some of my personal best head shots were taken with a 400 2.8 when I was shooting Canon.
 

fotografz

Well-known member
I'll jump in here and offer an opinion. I use two Quadra packs with 4 heads ... one head stays mounted to a light stick with a Beauty dish ... the other three heads are used to light people with one pack as a background source. I got this kit knowing the limitations of the Quadra system. I only use it for lighter duty as a much better alternative to using multiple speed-lights ... mostly people shooting on location. It would not even enter my mind to use it for any major commercial product job.

If you are getting into an area requiring 3 battery packs or 2 packs and a mono head ... I'd seriously look at the new Hensel Porty L Lithium 1200 pack and 3 or 4 Mini P heads. It offers radio control with either Hensel Strobe Wizard or Profoto Air ... both of which provide full channeled control from the camera (the Profoto Air works over greater distances than the Skyport or Strobe Wizard). Hensel has a very robust modifier mount second only to Profoto, and a full array of modifiers including one of the best Beauty Dishes I've ever used.

The Quadra mount is limited, and the EL adapter is is not robust enough to safely support any major modifier ... and the modeling lights are anemic. I'd especially recommend looking at the Hensel route if you are doing product work where you may need more DOF from a key light. If additional mono lights are needed later you can choose from either Hensel or Profoto since the Porty responds to both radio systems. An AC insert is available to turn the Porty into a studio pack.

My 2¢

-Marc
 
K

krb

Guest
Yet, many right-brainers already understand them intuitively and that's why they will associate a change in focal length with a change in perspective and the ability to manipulate perceptions of the viewer.
I don't think this has any direct relationship to right brain or left brain. A person either understands how this is working or they don't. People who misunderstand the relationship between focal length and perspective are likely to be confused once the camera behind the lens becomes a factor. Given the same framing of the subject, a 100mm lens will give very different perspective on a 645 vs on 35mm vs on a digital crop camera. People who do not understand that the perspective changed because of the distance are likely to attribute the difference to some sort of "magic" in the size of the sensor.

There's a fine line between intuition and superstition.
 

Mike M

New member
I don't think this has any direct relationship to right brain or left brain. A person either understands how this is working or they don't. People who misunderstand the relationship between focal length and perspective are likely to be confused once the camera behind the lens becomes a factor. Given the same framing of the subject, a 100mm lens will give very different perspective on a 645 vs on 35mm vs on a digital crop camera. People who do not understand that the perspective changed because of the distance are likely to attribute the difference to some sort of "magic" in the size of the sensor.
A left-brain type of person would probably say that the distance from the subject is what effects perspective rather than focal length. This is true in terms of science.

A change in focal length will usually coincide with a change in distance from the subject in order to fill the frame. This leads a right-brain person to conclude that a change in focal length is the same as a change in perspective. This is true in terms of the the application of the science.

Both of them are basically correct at the same time, but just describing things differently.

Intuition is not the same as superstition because it is a way of thinking that allows right-brain people to solve a problem backwards. They will often know the correct answer to a question but not know how they came to the conclusion. Then they will have to backtrack to find out how they came up with the correct answer.
 

Jack

Sr. Administrator
Staff member
Mike M, no offense, but your intuition on this is incorrect and you are adding confusion instead of helping -- 3D > 2D perspective mapping is a product of physical science and nothing else.

You can prove this to yourself by shooting the same subject from the same position with two different focals and crop the wider one to match the longer one -- the two resulting images will have IDENTICAL perspective, end of story.
 

Mike M

New member
Mike M, no offense, but your intuition on this is incorrect and you are adding confusion instead of helping -- 3D > 2D perspective mapping is a product of physical science and nothing else.

You can prove this to yourself by shooting the same subject from the same position with two different focals and crop the wider one to match the longer one -- the two resulting images will have IDENTICAL perspective, end of story.
Yes, you're 1000% right in terms of the science. I've already said that is correct in my previous posts. It's kindergarten type of science.

But photographers don't usually change focal lengths and remain in the same position in application. They usually change their position in relationship to the subject in order to fill the frame. Right brained people "think" in terms of application, so this leads them to conclude that a change in focal length is the same as a change in perspective. They are CORRECT in terms of how the science applies to technique in photography because whenever they change focal lengths they also change the distance to the subject. The two go hand-in-hand.
 
H

Hikari

Guest
Actually, the science is clear, changing focal length or cropping will change perspective--you can even look that up in the Focal Encyclopedia of Photography. Changing subject distance also changes perspective, or to be more exact, linear perspective. Perspective is simply the appearance of depth in an image.
 

Mike M

New member
Actually, the science is clear, changing focal length or cropping will change perspective--you can even look that up in the Focal Encyclopedia of Photography. Changing subject distance also changes perspective, or to be more exact, linear perspective. Perspective is simply the appearance of depth in an image.
Perspective is a big thing...there are a lot of elements involved in it. But what Jack is saying is correct for the type of perspective he is talking about.

BTW - the appearance of depth within in image is how draftsman relate to perspective. But photographers use the same word to describe different things than what a draftsman might associate with the word. For example, a painter might use bluish/cooler tones to paint objects that are supposed to appear at far distances in a painting and he might say his choice of color is related to perspective. This is because cool tones in the background of a painting increase the sense of depth that a viewer perceives in a painting. But most photographers aren't even familiar with that concept because perspective in terms of photographic application generally revolves around other elements related to perspective that don't just have to do with a sense of depth.
 
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Hikari

Guest
Perspective is a big thing...there are a lot of elements involved in it. But what Jack is saying is correct for the type of perspective he is talking about.

BTW - the appearance of depth within in image is how draftsman relate to perspective. But photographers use the word to describe other things too. For example, a painter might use a bluish tones to paint objects that are supposed to be at far distances and will say that his choice of color is related to perspective. But most photographers aren't even familiar with that concept because perspective in terms of photographic application involves different ideas.
Perspective is our perception of space and it is how photography relates to it--there is not absolute physical reality of perspective. The red/blue shift is also in the definition of perspective in photography.
 

Mike M

New member
Yes, warm/cool shifts have an effect on the illusion of 3dimensional depth in a still photo but that's not what most photographers are referring to when they're discussing perspective as it relates to photography. Most photographers think of perspective as a way of controlling horizontal and vertical lines and they also think of it in terms of how it effects the sense of proportion in subject matter. The latter part is what we seem to mostly be alluding to in this thread.

For example, if a beauty photographer were to choose a particular low vantage point and use a wide angle lens for a headshot of a model then the shoulder of the model could appear as large as her head in terms of proportion in the final image. But if the same photographer were to use a telephoto lens from the same vantage point while placing more distance between the camera and the model then the subject's shoulder might appear to have a more natural relationship with her head in terms of proportion in the final image. This is an example of the type of phenomenon we seem to mostly be discussing in this thread in relation to elements of perspective. I think Jack is arguing that it isn't effected by focal length as much as it is effected by distance between the subject matter and the camera lens. He's right.
 

dick

New member
I have found that I need f16 to get a whole head in focus with MF... see:

http://www.rags-int-inc.com/PhotoTechStuff/DoF_Calculator/DoF_Calculator.html

But there can never be a really sharp head shot, as 35MM has not got the res, and with MF there is the trade off between DOF and diffraction... unless you immobilize the model and use DOF merge!

In the days of film and split-image range-finders I focused on the ears... this made the picture look sharp as the hair was sharp, but the face was slightly OOF, and flatteringly softened.

With an AF MFDSLR you can focus lock on the neck and re-compose.
 
H

Hikari

Guest
Yes, warm/cool shifts have an effect on the illusion of 3dimensional depth in a still photo but that's not what most photographers are referring to when they're discussing perspective as it relates to photography. Most photographers think of perspective as a way of controlling horizontal and vertical lines and they also think of it in terms of how it effects the sense of proportion in subject matter. The latter part is what we seem to mostly be alluding to in this thread.

For example, if a beauty photographer were to choose a particular low vantage point and use a wide angle lens for a headshot of a model then the shoulder of the model could appear as large as her head in terms of proportion in the final image. But if the same photographer were to use a telephoto lens from the same vantage point while placing more distance between the camera and the model then the subject's shoulder might appear to have a more natural relationship with her head in terms of proportion in the final image. This is an example of the type of phenomenon we seem to mostly be discussing in this thread in relation to elements of perspective. I think Jack is arguing that it isn't effected by focal length as much as it is effected by distance between the subject matter and the camera lens. He's right.
That is fine. The relationship between the image size ratio of two objects is proportional to the object distance ratios--and you notice the object distance, in an absolution sense, does not have to be the same. Two bottles with one shot from ten feet and the other at twenty feet will have the same image size ratio as two bottles with one shot at one foot and the other at two feet (ratio of 1:2). Unfortunately, many people have twisted this to a simplistic answer that the only thing that defines perspective is a specific object distance, that is clearly false.

However, with your situation of shooting at a low or high angle at the model, the perspective will change with focal length. Not because the shoulder to head image ratio changes, but because the foreground to background ratio changes--the two images are not going to have the same foreground and background.

An interesting thing is that a change in focal length will still impact pespective when shooting a model straight on. If you understand two-point perspective where you use two vanishing points on a horizon to determine perspective, then you know that displacing those two points closer or further from each other will change the perspective. When you change focal length, you change magnification. The affect of the change in magnification displaces those vanishing points. So while I can use the knowledge that my object distance is going to affect the nose/ear ratio of a portrait, I can also apply my knowledge of focal length to affect the perspective.

The ideas and relationships in photography are easy. The vast interconnected number of them make it complex--and really, really interesting.
 
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