Size of viewfinder image?

I have used:

angle of view = 2 * arctan ( 0.5 * 43.2 / f )

where f is the focal length for FF,
and 43.2 is the length of the diagonal of a FF sensor

Here is a diagram from Wikimedia (alpha is the angle of view, and d is the length of the diagonal, i.e. the diameter of the sensor)

Got it. I learned early to use both eyes when using a camera. This was a tip from a former war correspondent. Keep both eyes open to see what is going on while you take the shot. However, I can't do it with an EVF. The slight delay between the real world at least for me is noticeable. Also shooting continuous - the blackout drove me crazy.

My brain had little problem correlating a different fields of view using an OVF between a 35 mm to 75 mm (35 mm equivalent). I might try shooting two eye with my Z8 - faster refresh rate and no black out.

When I look into my viewfinder, I'm only concerned with what will be captured on the film (or sensor). Never had reason to consider this.

Thank you, Tom.

Why not consider it now?

For what reason?
Neither composition nor perpective do change with viewfinder image size.

Because I see no practical reason to do so.

Well, that is debatable: it depends on how you define perspective; but let's not get into that argument here.

On a different point, I would imagine I am not alone in preferring the wider viewfinders over the narrower ones. However, I think both have their merits.

It would probably be far too expensive and bulky, but a zoom viewfinder would seem ideal to me, covering a range of different angles of view.

Does anyone know if there has ever been a camera with a zoom viewfinder?

If viewfinder covers 100% of the sensor, FOV is determined by lens. What zoom viewfinder will do?

Normally, the viewfinder covers a fixed angle of view, but the angle of view of the lens varies with its focal length. A zoom viewfinder would vary its angle of view.

If the AoV is the same for the viewfinder and the lens, then you see a life-size image in the VF. If the AoV of the lens is greater, then the VF shows a smaller than life-size image. If the AoV of the lens is less than the AoV of the VF, then the VF shows a larger than life-size image.

This is the first time I hear that viewfinder covers a fixed AoV, unless you are talking about rangefinder camera. In SLR, DSLR or MILC cameras what you see in VF is determined by FoV of the lens.

Some prefer detail vison on the whole VF image.
For me VF magnification of ~0.8x is preferrable.
Panasonic G9 is 0.83x, already a tad on the large side.
You might try Sony A1 or A7R V which get 0.90x VF.

These are weird terms. A viewfinder is typically expected to show what the sensor or film will capture with whatever lens is attached, not something wider or narrower - although there can be some exceptions in both cases.

But among viewfinders that do the typically expected thing, what normally varies among them is the degree of magnification. So, which is the 'wider' type of viewfinder you prefer ... one with less magnification or more?

If you're saying you prefer one whose image 'matches' what your other eye sees when a wider lens is attached, that would be a viewfinder with less magnification.

If you're saying you prefer one whose image occupies a larger area within your eye's field of view, that would be a viewfinder with more magnification.

Is that provocative comment really necessary?

I own a camera with a pentaprism viewfinder which shows a much larger view than will be captured by the sensor. The captured part is indicated by a clear view against a slightly gray surround. It is called a "Sportsfinder" and some like it, some do not.

I don't think my comment was provocative in the context of the thread and the quoted text. Sorry if you think it is.

Regarding your reply, was that necessary? I did say there are exceptions, and you have one of the exceptions.

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.