This is kind of stupid but..I just "Got it"!

[Leigh]

You have just described something that has a name, a term; cropping.

No, I'm not talking about cropping. I'm talking about how one lens works with different film formats.

What term do you use for this difference, Leigh?
It's the same camera, ..., same field of view, same angle of view. But the image is different, what is this called?

You're asking for something that does not exist, because your analysis is wrong.

The field of view and angle of view are different for the two formats.
Those are determined by the size of the medium (8x10, 4x5, or whatever).

This is basic optical design and trigonometry.
The distance from the film to the rear node of the lens = the lens focal length when focused at infinity.
The angle of view is between that line and a line drawn from the rear node to one corner of the film, times two.
Obviously that angle changes with the size of the film.

- Leigh

[RichardSperry]

There is a noticeable difference, IT exists. It is a thing.

Your word or terminology may not exist.

A system of science would have a system for naming things, describing things within it. Why doesn't photography, Leigh? You called photography a science; where's the word?

Any noob or layperson can see the difference between these two images, why isn't there a word for it? There is no analysis required, it is observational. The images obviously look different.

[RichardSperry]

The field of view and angle of view are different for the two formats.

How can it? It's the same camera and lens. That's no different than saying the focal length changes.

On the 4x5 back, the same image is projected. Half of it hits the back adapter and not the film. The field of view or angle of view does not change within
the camera(behind the same lens).

[RichardSperry]

What's the word or term then, Leigh?

You're getting close with "angle of view", I suppose. You're probably using the 8x10 ground glass to compose even for the the 4x5 sheet. Are you saying the angle of view of the camera and lens changes as soon as you slide the 4x5 holder in?

Is that the term you use?

Do your caretakers let you surf the Internet without supervision, I hope they have some kind of Alzheimer's LoJack on you in case you leave the house in the middle of the night. Safety suggestion, tattoo your name and address on your arm, that way when you wander off people will be able to get you back home. I've seen people like you do that.

[RichardSperry]

Obviously that angle changes with the size of the film.

It's not obvious to me.

I can't see how the angle changes, it's the same lens. How does it know what film or sensor is behind it?

Is there a switch, or does it use telepathy to make this miraculous change of physics?

http://en.m.wikipedia.org/wiki/Angle_of_view

This makes no mention of this change that you say happens with the lens. Can you post a link to a source that states how it occurs?

[Leigh]

OK. Let me try this with a diagram.



The rectangle on the right represents the subject (a building or whatever).

There are two dimensions on the left, 8" representing an image on 8x10 and 4" representing an image on 4x5.

The red lines delimit the angle of view obtained with 8x10 film.
The blue lines delimit the angle of view obtained with 4x5 film.

As you can seel, the only parameter that changes is the Angle of View, being the angle between lines of the same color.

The camera position and lens position have not changed.

- Leigh

[rince]

To me it is still cropping. If all stays the same but the size of film, I am just cropping the image circle more with a 4x5 the image the lens produces is still the same, I only decide to record less of it. If you lay the 4x5 neg on top of the 8x10 , the information on the 4x5 and the corresponding section of the 8x10 are the same. So to me a 300mm stays a 300mm regardless of the format.

[Leigh]

If you lay the 4x5 neg on top of the 8x10 , the information on the 4x5 and the corresponding section of the 8x10 are the same.
So to me a 300mm stays a 300mm regardless of the format.

Exactly. That's what I said in post #28.

I think of cropping as an operation that's done on the negative image when printing,
but perhaps the term can be applied in-camera.

- Leigh

[Mark Barendt]

It's the same camera, same aspect ratio, same lens, same distance, same DoF, same image circle, same field of view, same angle of view. But the image is different, what is this called?

I don't know there is another proper term but for all intents and purposes I can think of, it's cropping.

In an enlarger the scene is the negative, from the scene the light passes through the lens and an image circle is projected on the baseboard or floor, many times both. Changing the size of the film or paper you might use is simply cropping.

The conceptual difference for most non or new large formaters is that they come from a world where the size of the film is fixed for the camera in their hand.

Effective focal length is non-sense as far as I'm concerned, it's only use was to sell cameras. It isn't a principle of optical science. Half frame and APS size cameras are simply cropping more than full frame 35mm film cameras.

It is a fresh thought for most people to think that the limit to the camera system's angle of view may be the lens and that the film size in play is just one possible arbitrary crop.

[RichardSperry]

Saying a 50mm "becomes" a 75mm will take you down the wrong road.

Isn't what Leigh is NOW saying is that the 50mm has the same 'angle of view' as the 75mm?

Now what is so hard about that?

Instead of resorting to intentional obfuscation, 5th grade insults, and condescension, why don't you just acknowledge the difference and just explain the terminology?