Size of viewfinder image?

I did my best to explain why in the original post, and you can see that I clearly asked what the poster meant by his comment. That took me five editing attempts to get to the point where I thought my words would be well understood! It's not going to get any better, believe me.

Why don't we just see if TomAxford responds? After all, he's the person I asked.

I referred to the angle of view in my OP and in the statement above, "wider" meant a "wider angle of view". I am sorry if that was not entirely clear.

If you find magnification easier to understand, then a wider angle of view corresponds to more magnification. They are two different ways of measuring the same thing.

A viewfinder with a magnification of 1.0 shows a life-size image for a 50mm lens by definition. The angle of view is 47 degrees on a FF camera.

A viewfinder with a magnification of 0.5 shows a half life-size image for a 50mm lens and a life-size image for a 100mm lens. The angle of view is 24 degrees on a FF camera.

A wider lens (shorter focal length) gives a wider angle of view which requires more (not less) magnification in the viewfinder to achieve a life-size view. These things can be a bit confusing at first.

That is correct.

The advantage with using the angle of view rather than the magnification is that angle of view is format independent.

The definition of viewfinder magnification refers to a 50mm lens which immediately suggest that it is format dependent, which raises all sorts of uncertainties, e.g. do you have to apply a crop factor to it when changing sensor size?

I find angle of view is easier to understand.

Added note:

The definition of "magnification" seems to vary when applied to viewfinders. Here is an excerpt from the specifications for the E-M1.3 from the official Instruction Manual supplied by Olympus. When they say that the viewfinder magnification is 100%, I presume they mean that 100% of the image is visible in the viewfinder and nothing more.

60 to 70mm on my a7iv

Now I know you prefer one with more magnification. Thanks.

Yes, that's a little weird. The thing in question is equalizing direct eye magnification and through-the-EVF magnification, and should not be influenced at all by aspect ratio.

The question is: how much magnification is required in the viewfinder to see the image at life-size?

In other words, how much magnification is needed to see the image with the same angle of view as the camera captured. A wide-angle image needs to be magnified more that a telephoto image because it needs to fill a larger angle of view than a telephoto image (which captures only a narrow angle of view).

Take the particular example of an optical viewfinder in an SLR or DSLR in which the image is 36 x 24mm on the ground glass. If you view it from 250mm away with the naked eye, you see the image at life-size if it was taken with a 250mm lens. If you want to see it at life-size when the taking lens is 50mm, then you need to use a magnifier lens in the viewfinder that magnifies 5 times, i.e. creates the appearance that you are looking at a 180 x 120mm image from 250mm away. The latter image fills a much larger angle of view than the former.

If you wanted to see a life-size image from a 25mm lens, the viewfinder must magnify the image by 10 times and the image will occupy an even larger angle of view.

HAND.

Thanks, it's useful to know that it's simply an error.

Thanks Alan, that does make sense.

We have been talking at cross purposes. You are talking about the angle of view seen by the camera lens - how much of the view in front of you it captures in the image.

I was talking about a completely different angle of view, that seen by the person viewing the image, ignoring the content of the image. Imagine that you are looking at a pure white image that doesn't represent anything. It still makes sense to talk about the angle of view with which a viewer sees that image. Suppose that the image is 36x24mm. If you view it from 25cm (10") away, you see it with a very small angle of view. If you enlarge the image ten times to 360x240mm and view it from 25cm, you see it with a much larger angle of view.

I am distinguishing the angle of view seen when viewing the image in the viewfinder (even when looking at a blank image) from the angle of view seen by the camera lens and captured in the image.

The image appears life-size when the angle of view seen by the viewer equals the angle of view seen by the camera. In other words, it appears life-size when the viewing angle of view equals the taking angle of view.

HAND.

I do not think that is relevant to viewfinders. The image in the viewfinder is flat: all of it is at the same distance from the eye.

It's probably best to start another thread if you wish to discuss human perception of photographic images, which is a huge subject.

HAND.

It depends on how good your eyesight is. My eyes are far from perfect and I find it quite difficult to accurately compare the image I see in one eye with that in the other. I think I would have found it much easier when I was younger and my eyesight was better.

Canon R5 FF camera in full sensor mode: EXIF reports 62mm from my RF24-240 when my two eyes experience the same magnification with my personal diopter adjustment.

The easiest way for me was to rotate the camera counterclockwise to portrait orientation (EVF on the left of the camera) and put the EVF up to my right eye, and then choose a target that has clear repeating horizontal lines.

I am not at all sure why you are talking about angle of view. What does angle of view have directly to do with angular subject magnification?
You could conceivably use AOV in some intermediate math as long as you adjust for other factors,, but the fact is, you can have the same subject magnification with different angles of view. If my FF camera did crop mode by matting 61% of the sensor area instead of magnifying an extra 1.6x, the angle of view would be different, when the magnification would be the same. The optics of the viewfinder also play a role; the same angle of view with a sensor size and focal length

We have an angle of view windowed in the used sensor area (based on focal length and sensor size), and we also have an angle that the EVF appears to exist at (independent of focal length), but neither defines magnification alone without other factors.