Mamiya 7 view finder angle of view

J

jcm0

Guest
Hi everybody !


I own since very recently a M7+65mm. That's my first rangefinder camera. I am getting use of focusing.
In order to appreciate what I see in the viewfinder versus what I will get on my print I was wondering if what can be seen is the viewfinder match the angle of view of a 65mm or a 80mm or any other lens.
The M7 specifications gives values for the 65mm lens angle of view (69°) and the viewfinder magnification ration (0.58 if I recall), but I don't know how to convert these values to make a comparison.
Alternatively, does somebody conduct some test to evaluate the rendering of the M7 viewfinder ?

Thanks in advance for your answer !

JCM
 
the veiw finder frames adjust according to your lens. so if you put a 65mm lens on the camera, the fram in your view finder will move out towards the edges and what you see is what you will capture. if you use an 80mm the frame gets smaller. so, just stay withing the frame lines to know what your coverage is. When you get to a 50mm or smaller, then you need to use the optional view finder because the frame lines of the camera view finder do not go out far enough for the smaller lens.
 
wrong question

wrong question

Hi Jorge,

Thank you for your answer.

I just realised how wrong was my question. In fact I have used the wrong word "field of view". Your answer is correct regarding my question.

My exact question was about the perspective compression rather than field of view: tele lens produce a perspective compression; wide angles produce the opposite effect. So my question is: what lens will be closer to the m7 viewfinder compression of perspective.

I am asking this question to try to previsualize the image I will get (maybe a SLR user mind distortion :p )


Thanks,

JCM0
 
JCMO, there's still a problem of perception, if you'll pardon the humor. Strictly speaking, perspective compression/expansion is not at all dependent or even related to the lens, but only to your position relative to the objects in the scene before you.

You could equally well ask, "what lens most closely represents the perspective of the human eye?" And again there can be no real answer, as perspective is distance related.

It's common and useful to think of a long focal length lens as compressing distance perspective, but that's only because we need to be farther from the objects to fit them in the narrow angle of view. The reverse for wide-angle lenses of course.

The answerable question is your earlier one about field of view. Changing the focal length with a given size of film will change the field of view. The Mamiya or Leica or Bronica rangefinder camera's viewfinder will change its frames automatically to match the lens attached, and if the lens is out of the range of viewfinder framing adjustment then a separate accessory viewfinder will be needed.

So the camera framelines can change to match the field of view of the lens, and (like your eye) it has no inherent perspective compression effects.

You can study this yourself by placing two objects at difffent distances from you. Move closer to the closest one and it will seem to get larger faster than the farther object. If you move farther away then the closer object seems to shrink more than the one farther away. There's your perspective change... :)
 
sure but...

sure but...

Hi Doug,

Thanks for your answer. I think I have understood what you said.

However, imagine you have one SLR with 2 lens: a tele lens, a wide angle.

Mount the tele lens on the SLR. Then, choose a small object in from of you, and walk toward the object while looking at it through the SLR viewfinder until you manage to make it fill 50% of your viewfinder. Now take a picture. Finally change the lens and do the same thing.

If you compare the two pictures, the object will look similar (approximatively) on both picture. But if you look at what is before the object and after the object: you will notice a big difference: this is the compression/ expansion effect.

So, regarding my question: what lens focal is equivalent to the M7 viewfinder (regarding compression/expansion effect not angle of view) ?

Thanks !!
 
In your example of the two pictures... They have exactly the same "compression/expansion effect" for items closer and further away. That's because they were both take from the same location. The only difference is what's included; the field of view.

If you take your normal-lens picture and crop it so that it has the same framing as the tele picture, then the pictures will be virtually identical. Two lenses, same subject from the same location = the same perspective. Without the cropping, only the field of view is different. (And the cropped one might be less sharp and more grainy)

Your question now comes back to field of view. The viewfinder has the same compression/expansion effect as any lens you put on the camera, since that effect depends only on camera position.

As you change lenses on the RF camera, its viewfinder framelines are changed by a mechanical link to match the field of view of the lens. Like "cropping" the viewfinder. :)

With a bit of walking back and forth, taking a couple pictures, and a pair of scissors, you'll see what I mean.
 
true

true

Yes that's true ... if you don't change your location between the two shots.

But to answer my question, you have to compare what you get when you want to take a picture of the same subject filling the same area of the picture (for example: 50%) using 2 different lens. This is because when you want to take a picture you select a subject; then front and rear item rendering (size) is dictated by the lens.

If you want to achieves this when you take the 2 pictures, you will have to move. In this case, front an rear item are very different if you use a tele or a wide angle lens.

The M7 viewfinder as fas as I have seen behaves as a wide angle. But I still don't know if it's rather a 80mm or 65mm or xx mm. If you know that the viewfinder behave as a 65mm for example, that means that when you use a 80mm, what you see in the viewfinder suffer for spatial compression. So in the real picture (compared to viewfinder), front item will be closer to you and rear item will be farer to you.

Do you agree ?
 
Hi -- Yes, you're right; if you move, then the perspective will change, and the relative spacial relationships among the objects at different distances will be different.

But the perspective change occurs whether you use a wide angle lens or a telephoto lens, and only the field of view is different with the different lenses.

So, yes, if you use a wide angle lens in close, and then back away with a telephoto lens so that the center object is the same size on the negative, the perspective relative to the other objects changes. But the perspective change is due to the different position, not the different lens.

Now that we know perspective is solely an effect of relative positions, and has nothing at all to do with the lens focal length, you can see how the question about perspective compression discrepancies in the M7 viewfinder is not meaningful. The effect you describe does not occur. The viewfinder does not act like any particular focal length, and then introduce viewing errors when smaller framelines are chosen. The apparent distances to objects in the viewfinder don't change as the framelines change; they cannot and should not. The framelines simply mark out the approximate field of view of the lens mounted, and have no effect on perspective.... which is simply a matter of relative distances to objects in the field.

The bottom line here is that you can relax and enjoy your M7 while being assured that there are no discrepancies in perspective introduced by the viewfinder. :)
 
Hi Doug,

I still cannot realize that. I think I will be better with some trials. This sounds like a very good news. Thanks a lot for your answers.

Regards,

JCM0
 
You're very welcome! Yes, nothing quite like doing a few field tests... :)

If you have a few empty picture frames of different sizes, say 4x5 through 11x14 or so, you could carry them out into some open area. Sit on a bench or a rock and hold up the biggest frame in front of you and observe the scene within the frame.

Mentally label this as a wide-angle view of the scene. Now hold up a medium-size one at the same distance from your face and again note what's in the frame. Less stuff is in the frame, though the perspective hasn't changed. Now try the smallest frame, and think of this as a telephoto view... note again the perspective has not changed; things in that frame that are nearer have the same relationship to farther objects as with the previous frames, or even with no frame.

The frames delineate different angles of view of the scene before you just as the various framelines in the Mamiya 7 do. Would one be concerned about the lens focal length corresponding to your eyesight? I don't think so, and likewise for the camera viewfinder.

I will add, though, that the question of what is the most "natural" camera lens field of view has come up many times. The question assumes that there is some angle of view that corresponds to the human eye and which records the scene in the most natural realistic way.

Research has even gone back to paintings done well before photography was invented, and surmised the angles of view of the paintings as if they were photos. This gets muddied by the discovery that painters "cheated" with the "camera obscura" long before. The camera obscura ("dark room") is simply a room-sized pinhole camera, and the painter used the image projected on the wall opposite the pinhole to trace the locations and proportions of objects in their painting-to-be.

The problem in trying to match some lens focal length to the eye is that the eye's field of view is not sharply delinieated. We have peripheral vision, and the sharply-seen area fades gradually off to some indefinite region perhaps 90 degrees off to the side. Yet the 180 degree angle of a fisheye lens looks grotesque ... maybe if we curved the fisheye print around our face toward the limits of peripheral vision it might look more normal?

Photographers who use different lens focal lengths develop the ability to mentally "tune" their vision to concentrate on different angles of view.

For instance, you could exercise a bit of deliberate tunnel vision to see the world around you in terms of the 150mm Mamiya lens's angle, and "see" photo possibilities occur before you in those terms. Or you might shift your attention to a wider view of the world like the Mamiya 50mm lens and then you'd be seeing wide-angle pictures. :)

For what it's worth, there's some sentiment that a lens giving somewhere around 50-65 degrees in angle produces a rather more "natural" looking picture than outside that range. This would about correspond to a lens between 90mm and 70mm on the Mamiya 7II.

Have fun!
 
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