Viewfinder Specifications

[KyleSTL]

I know the typical ratings for an optical viewfinder (maginification, accuracy and sensor format) are readily available for most cameras, and often, if you dig deep enough you can even find the eye relief rating for a viewfinder. Does anyone know why there isn't any rating for any camera (that I can think of) for apparent field of view (similar to telescopes, binoculars or microscopes)? Anyone who has looked through the eyepiece for a high-quality microscope or telescope knows what I'm talking about. Does anyone know what the AFOV would be for your average camera VF?

Primer on binocular FOV:
http://www.nikon.com/products/sportoptics/how_to/guide/binoculars/basic/basic_08.htm

 

[brad-man]

The field of view will be determined by the lens mounted to your camera. It is not a constant as it is with telescopes, etc.

 

[rs]

The field of view will be determined by the lens mounted to your camera. It is not a constant as it is with telescopes, etc.

+1

It's basically the AoV of the mounted lens, with two additional calculations: if its an EF lens mounted to an EF-S body, it sees 1/1.6 of the view, and the accuracy is then also a further reduction of the angle of view - eg 95%, 98% etc. .

Unlike a rangefinder, an SLR viewfinder will rarely be capable of showing a wider angle of view than is captured in the photo. Something is misaligned if it does do that.

 

[KyleSTL]

I see what you are saying, maybe I'm using the wrong term. Let me try to explain what I'm attempting to figure out. When I look through the VF of my 5D, the focusing screen is fairly large, but it in no way fills my entire field of view (i.e. I can still see the black frame around the focusing screen and the eyepiece without moving my eye). With a very high quality microscope, telescope or binoculars when you put your eye up to the eyepiece it seems to fill your entire field of view (very little preceived black area around the projected image).

Now, this morning I measured the actual opening through which you look on my 5D, and the opening is approximately 15mm x 10mm. On an XSi (had one sitting on my desk) the viewfinder opening is much smaller, about 11mm x 8mm (and has rounded corners).

One other observation I had is that if you place the viewfinder to your eye and focus on the center AF point and slowly move the camera away, the AF point appears the same size, regardless of the distance between your eye and the VF. So, in essence I guess what I'm asking would be the product of eye relief and magnification. I have no experience with MF cameras, does anyone with experience with MF cameras know how format effects how much of your perceived field of view is filled with the viewfinder?

Does anyone know what is preventing camera manufacturers from producing VF with magnification as large as the manual focus cameras of yesteryear (other than probably R&D development costs and non-existent ROI)? Example:

Pentax MX - 0.97x / 95 % / 1.0x crop = 0.92 (best 35mm format MF viewfinder I know of)
Nikkormat EL2/FT3 - 0.90x / 92% / 1.0x crop = 0.83 (entry-level Nikon circa 1977)
Canon AE-1 - 0.86x / 96% / 1.0x crop = 0.83
Olympus OM-4T - 0.84x / 97% / 1.0x crop = 0.81
Nikon F/F2/F3 - 0.80x / 100% / 1.0x crop = 0.80

Also, it appears that a larger eye relief could be acheived by using slightly larger lenses in the VF and a larger opening (say, a 18mm x 12mm or 21mm x 14mm eyepiece). Anyone know the opening size for the higher eye relief cameras (and/or higher magnification)?
Canon 1D X - 0.76x / 100% / 1.0x crop = 0.76 (best 35mm format AF viewfinder ever)

 

[Loswr]

I see what you are saying, maybe I'm using the wrong term. Let me try to explain what I'm attempting to figure out. When I look through the VF of my 5D, the focusing screen is fairly large, but it in no way fills my entire field of view (i.e. I can still see the black frame around the focusing screen and the eyepiece without moving my eye). With a very high quality microscope, telescope or binoculars when you put your eye up to the eyepiece it seems to fill your entire field of view (very little preceived black area around the projected image).

You mean that black area where useful stuff like exposure information is displayed?

 

[KyleSTL]

I see what you are saying, maybe I'm using the wrong term. Let me try to explain what I'm attempting to figure out. When I look through the VF of my 5D, the focusing screen is fairly large, but it in no way fills my entire field of view (i.e. I can still see the black frame around the focusing screen and the eyepiece without moving my eye). With a very high quality microscope, telescope or binoculars when you put your eye up to the eyepiece it seems to fill your entire field of view (very little preceived black area around the projected image).

You mean that black area where useful stuff like exposure information is displayed?

Oh, neuro, your sarcasm is always entertaining. But seriously, you of all people (as a scientist) must know what looking through a good Nikon or Leica microscope and how the image fills your entire field of vision. I obviously know that the shooting information needs to be displayed, but I'm sure when you look through the viewfinder of your full frame cameras you can easily see the frame of the eyepiece as well. I'm not in any way complaining about the viewfinder of my 5D, but just wondering if there in any way an SLR could replicate the 'immersive' experience of a high quality eyepiece from a telescope, microscope or binoculars.

 

[Loswr]

...but just wondering if there in any way an SLR could replicate the 'immersive' experience of a high quality eyepiece from a telescope, microscope or binoculars.

What's one key difference between a dSLR viewfinder and the ocular lenses of a telescope, microscope (my good ones are Zeiss, BTW - we have less good Nikon scopes for tissue culture and a single 'beater' Leica on a lab bench ), or binoculars?

Shape.

The FoV for binoculars and 'scopes is circular, whereas the dSLR viewfinder is rectangular to match the image sensor. I suspect that accounts for a fair bit of the lack of an 'immersive' view through a dSLR VF.

 

[jrista]

...but just wondering if there in any way an SLR could replicate the 'immersive' experience of a high quality eyepiece from a telescope, microscope or binoculars.

What's one key difference between a dSLR viewfinder and the ocular lenses of a telescope, microscope (my good ones are Zeiss, BTW - we have less good Nikon scopes for tissue culture and a single 'beater' Leica on a lab bench ), or binoculars?

Shape.

The FoV for binoculars and 'scopes is circular, whereas the dSLR viewfinder is rectangular to match the image sensor. I suspect that accounts for a fair bit of the lack of an 'immersive' view through a dSLR VF.

Great point. Additionally, when looking through a telescope of microscope, the image is projected directly into your eye, with little eye relief. When looking through a DSLR viewfinder, the image you see is a superimposed projection of a reflection off a rectangular mirror. Usually it is paired with a fairly significant eye relief (around 20-25mm for DSLRs)...so there is little chance you could get that vision-filling wide angle of view anyway (even if the projection was circular and not cropped to the sensor frame.)