My World: I do not want a physics degree..

Focal Length and Aperture in the Field

I want to take photographs. In everyday life. Of everyday life.

In the field: Focal length, DOF, Perspective

The way I use my lenses and aperture in the field. In Practice. In far way lands or at home.
On mountain tops, On the street, Temples. Hotels. Rice fields.


Aperture: I use aperture primarily to control depth of field ( DOF ). Very rarely to
control the amount of light falling on my sensor or film

Wide Angle lenses: To give a perspective to the viewer of my photograph a sense of spatial distance between objects and/or between the foreground and background.

Indeed on mountain trails at 3-4k meters high, taking 2 steps back would be my death. There is often no space to take steps backwards.

Tele lenses: To give a perspective to the viewer of my photograph a sense of spatial compression between objects.

I am basically lazy. I do not want to go forward or back.
I take a photo from where I have decided to take it.

Some examples:


Sitting across the table from the gentleman. Notice the slightly out of focus background.
Notice also the apparent closeness of the background to the gentleman. We are sitting quite far away from the Cathedral in the back.

I used a 75mm lens ( I had that and the 28mm ) with an aperture between 2.8-4.0. Less aperture would have blurred the background more. Even less aperture would have put one ear oof.


I am crouching at the edge of the rice field. I want to enhance the feeling of vastness of the rice field and the houses at the far end. I also want to emphasize the clouds.

I only had my 35mm. Set it at f=8.00 for depth of field.
I used a 35mm from where I stood.


Let me illustrate with another example; this from Scotland!
I too am on the sidewalk. A little in front of the gentleman.

Notice how the cabs appear closer than they should be to the man with the coffee cup. Notice too
the slightly out of focus cabs on the main street.

I used a 75mm ( was on the camera ), an aperture of f=4.0 to make sure I got the man sharp.
I know by experience the aperture to use for certain distances on MY lenses for the effect/s I desire.


Yes, and this one. I am in line with the tyre ( almost ). Behind me is a wall. The girl wants me to do it quickly. Take a photograph that is. I want everything you see here in focus. I also want the perspective you see here. I whip out my 35mm, screw it on the camera. Set the aperture to f=8.0; aperture priority mode. Measure the girl ( yea! ) with the light falling on her. Focus. And click.

I was where I was. I have the small 35mm or the bigger 100mm.
I chose the 35mm. Just as a side note..I could have selected f = 11.0 and not focussed. The photo would have been sharp too! A f/11 would put a great deal in front and behind the lens in focus.

Learning theory is very good. Learning to do it in practice and fast is equally good.

Knowing both is the best. It shall allow you to make informed choices.

But for me, I like to do things. Practically. In the field.

Regards.

The last example of Focal length, DOF and Perspective and use of Aperture.


This is the ZF 100mm on a D700 at an aperture of f=2.8.

Notice the sharp and oof areas. Notice the almost out of focus background. Notice the gradual transition of
in-focus and out-of-focus areas.

Could one do it with a wide angle lens? Of course! Easy? Not really!

Regards.

And since it is my world, here is one with a STANDARD lens.


Here I am using an aperture of f=5.6, because of strong light. I have also cropped this photo.
I have given it some pp treatment.

Notice the background. There is a formula that relates camera to subject distance, aperture and the
distance in-front and at the back of the plane of focus ( WOW! plane of focus..the subject I say ).

What is that formula? Asking me? Wrong person friends.

I just take photographs.

Hi, Mohammed,

fahim mohammed said:

Tele lenses: To give a perspective to the viewer of my photograph a sense of spatial compression between objects. Generally, I do not find myself having the luxury of moving forward with a WA lens and/or cropping it to give a similar perspective to that which I could just by using a tele lens.

Click to expand...

Some here may benefit from realizing that it is not the long focal length here that produces this "spatial compression" result but rather the fact that we are shooting from a greater distance (usually, of course, fitting in with the choice of a long focal length lens).

As an experienced photographer, you intuitively know this (you would hardly use a long focal length lens to shoot a certain scene from close up, if that happened to be where you were). But you denigrate my articulating it!

Among other things, this knowledge lets the photographer know that, if no long focal length lens is at hand, the identical perspective effects can be had (from the appropriate shooting position) with a short lens through cropping - even though as you aptly point out, that is not a desirable alternative.

The fact that we need not know that the circumference of a tree is pi times its diameter when we lean against it for shade makes that no less so.

À chacun son égout (excuse the Quebecois typography - À vs. A).

The other day in a social gathering, I was asked what motivates me in my incessant tutorial efforts. I said that perhaps I had a horror that someone would miss an opportunity for some benefit, or would be injured, or die, because he didn't know something I could have told him.

The other person said, "Well, you need have no worry!"

Its duality of meaning was well in line with my own practice.

Thanks for the nice examples of various techniques related to this and nearby areas.

Now if only I could figure out what focal length would make Ayesha smile more!

Best regards,

Doug

Doug Kerr said:

À chacun son égout (excuse the Quebecois typography - À vs. A).

Click to expand...

Actually, even if many French people will deny it, the correct typography is À, not A.

And, if I may...

1: it is Québécois, with 2 accents.
2: it is goût ("taste"). Égout is a sewer.

Doug Kerr said:

Hi, Mohammed,

.....

Best regards,

Doug

Click to expand...

Hello Doug.

Important ( to me ) things first..

My friends call me Fahim. On the Net, I have been called various unmentionable names!!

Now Doug, what would you prefer to address me as.

Kindest regards.

fahim mohammed said:

I want to take photographs. In everyday life. Of everyday life.

In the field: Focal length, DOF, Perspective

How I use my lenses and aperture in the field. In Practice. In far way lands or at home.

Click to expand...

(...)


There is nothing wrong with your approach and nobody criticized you for it. Indeed, as a photographer, the basic rules you listed are more convenient to use in the field. And if some people like me like to understand why this or that action will produce this or that result, and go back to the laws of optics to find out, it won't make them take better pictures. Actually, it will usually make them (me) take worse pictures, because the time spent understanding the technical details would be better invested understanding feelings and art theory.

But it is a hobby, and I am allowed to enjoy myself with the laws of optics if I so please. I do not have to take pictures as good as yours, I am not selling them.

Hi, Fahim,

fahim mohammed said:

Hello Doug.

Important ( to me ) things first..

My friends call me Fahim. On the Net, I have been called various unmentionable names!!

Click to expand...

Well, I have no idea why I did that right there. Must have been a senior moment. My apologies.

Best regards,

Doug

I am having problems with the internet.
Shall get back on the mobile.

Regards.

Hi, Fahim,

fahim mohammed said:

I am crouching at the edge of the rice field. I want to enhance the feeling of vastness of the rice field and the houses at the far end. I also want to emphasize the clouds.

I only had my 35mm. Set it at f=8.00 for depth of field. I could have gone back to my hotel, got my 100mm on the camera, waded across paddy fields or driven in a jeep to the other side of town to get the same perspective of this rice field with the 100mm. I did not. I used a 35mm from where I stood.

Click to expand...

Not so, if I correctly understand that you are speaking of the alternative of a shooting position farther back from the present one.

The perspective of the scene would be different. For example, the little shack on the left would now not appear to be nearly so far back from the irrigation tower (or whatever it is). There would be other differences between the relative positions of various scene objects.

In fact you did not want that - you say, "I want to enhance the feeling of vastness of the rice field and the houses at the far end." Had you shot from father back (with whatever focal length lens), you would not have had that result. So your choice of a shooting position was good.

But we cannot properly say that if you had shot from father back, that would have captured "the same perspective". You would not have, and that is exactly the reason that your shooting position was a good one - the "feeling of vastness" it portrays is in fact an aspect of the perspective at the current position - and would not be nearly so prominent in the perspective of the image taken from farther back.

Best regards,

Doug

Hi, Fahim,

fahim mohammed said:

Yes, and this one. I am in line with the tyre ( almost ). Behind me is a wall. The girl wants me to do it quickly. Take a photograph that is. No time to jump in a jeep or for calculations. I want everything you see here in focus. I also want the perspective you see here.

Click to expand...

Then no Jeep work would be indicated, or even allowable. Why would you mention it? If the perspective you want is obtained where you are, then you must shoot from right there. That's how perspective works.

Best regards,

Doug

Hi, Fahim,

fahim mohammed said:

This is the ZF 100mm on a D700 at an aperture of f=2.8.

Notice the sharp and oof areas. Notice the almost out of focus background. Notice the gradual transition of in-focus and out-of-focus areas.

Could one do it with a wide angle lens?

Click to expand...

Well:

• With a wide-angle lens, shooting from the same position, the perspective would be the same. The objects would be smaller on the sensor than in this case.

• With a wide-angle lens, shooting from a closer position, the perspective would not be the same. I'm not sure in this scene how to describe how that would look (I work best with telephone poles and noses).

If the two distances were such that some "middle-of-the-scene" object had the same size on the sensor in each shot, then if the f-number was the same, the depth of field would be nearly the same.

I do not mean to suggest that the OOF transitions would appear the same.

Best regards,

Doug

Hi, Fahim,

fahim mohammed said:

Notice how the cabs appear closer than they should be to the man with the coffee cup.

Click to expand...

I'm not sure I agree that they appear "too close", but the degree to which they "look close" results from the fact that you were a substantial distance from the subject. And of course you used a focal length that worked well at that distance.

Now you might have chosen the lens first and then moved until the framing was what you wanted. But that does not change the reality of "what causes what".

If you had shot from that same spot with a "shorter" lens, the "distance compression" would have been identical. But you would have had to use a more aggressive crop to produce the same presented image.

Had you shot from farther back yet, with any focal length, the "distance compression" would have been even more pronounced. Of course in that case, you might have wished to have a greater focal length available. But it would have no affect on the distance compression effect.

Best regards,

Doug

Doug, Jerome..

Thanks for the comments that both of you have provided. Much appreciated.

Doug you have mentioned that I seemed to have denigrated you articulating your point/s of view.
My apologies if you have that impression.
You would be the last person on OPF that I would disrespect.

Disagreement and sarcasm ( you too seem to have your share of it ) might be encountered in my
posts. But never intentional disrespect.

I really would not be interested to know the formula for calculating the circumference of a tree trunk.
Unfortunately, I had to learn it long time ago. But similar formulae..I am not interested. Formulae do not give me the kick that actual photography provides. YMMV.

I shall let you know what FL lens would make Ayesha smile, once I acquire it when funds permit.

Best regards.

Fahim,

I love the picture here! When I look in a gallery I just enjoy the picture. Later on I might wonder how it was done but that would be a very, very rare occasion. however, here you have explained. For this forum that's always appreciated!

fahim mohammed said:

I

I am crouching at the edge of the rice field. I want to enhance the feeling of vastness of the rice field and the houses at the far end. I also want to emphasize the clouds.

I only had my 35mm. Set it at f=8.00 for depth of field. I could have gone back to my hotel, got my 100mm on the camera, waded across paddy fields or driven in a jeep to the other side of town to get the same perspective of this rice field with the 100mm. I did not. I used a 35mm from where I stood.

You could calculate and do it with a 70-200mm zoom and a jeep or your legs.

Click to expand...

"I could have gone back to my hotel, got my 100mm on the camera, waded across paddy fields or driven in a jeep to the other side of town to get the same perspective of this rice field with the 100mm. I did not. I used a 35mm from where I stood."

I doubt it! Perspective only depends on where you stand! The image size of objects in the center just gets smaller with a wide angle lens. The relationships would have changed as you moved backwards, compressing the distance between foreground and background. That's just the nature of things, call it physics or not! Going backwards and using a longer lens cannot ever reproduce this perspective! Perspective has zero to do with focal length and even moving back 1 cm will change the perspective.

All we care about, in the pictures we share, is whether or not the experience is meaningful. We want to be moved! Many of your pictures do this! You bring us the field of green with plants stretching to the horizon and voluminous soft gradients in the transient clouds balancing the sharp geometric linear repeated features of the thriving plants. If we're enjoying a song, we've no interest in what the muscles of the larynx. Likewise here: the geometry and other specifics of a shot are only important when explaining, avoiding or exploiting some effect.

The bottom line is are we moved? That's it and if not I move on!

Asher

Hi, Fahim,

fahim mohammed said:

Doug you have mentioned that I seemed to have denigrated you articulating your point/s of view.
My apologies if you have that impression.
You would be the last person on OPF that I would disrespect.

Click to expand...

No problems, my friend.

Thank you for your confidence.

Best regards,

Doug

Doug, Asher..

I have done some reading!

I stand corrected. Indeed the ' perspective ' depends on where I stand.

I am wiser man now.

But, and I cannot escape this nagging question , am I/ shall I be a better photographer now.

I guess I have to take some photographs to ' see '.

My thanks and regards to all ( specially Doug ) for their typing and driving!!