Why is APS-C vf small?

[bakubo]

This is a question I have been meaning to ask for awhile. Why is the vf in a camera such as the A700 smaller than for a FF SLR such as my old Minolta X-700, Maxxum 7, etc.? A couple of years ago I looked at an Olympus E-3 and my recollection is that the vf was pretty impressive. I didn't compare it immediately to an APS-C DSLR, but I think my impression was that it was bigger. David, sometime back, mentioned that adding a vf magnifier (Pentax?) made the A350 vf much bigger. I am sure there are several people here that can easily answer this question.

[Greg Beetham]

I agree with you there Henry, I don't know what the limitations are, maybe it just comes down to cost, one would think if they can design a borderless OVF once they can do it all the time...It's like in eyepieces for telescopes, you only have to look through a crappy kelner or even a vixen eyepiece and then through a Nagler or a Panoptic where there is no border to the field of view (by border I mean, like looking through a short piece of pipe with the walls of the pipe visible and the image at the bottom end of the pipe), and all you see is image right accross the field right in front of your eye.
Greg

ps. Naglers and Panoptics are about 6-10 times the cost though....

[01af]

Why is the viewfinder in a camera such as the A700 smaller than for a FF SLR such as my old Minolta X-700, Maxxum 7, etc.?

Because the image and consequently also the focusing screen are smaller.

Then why not compensating for the smaller screen by a larger optical magnification? Because a viewfinder showing the APS-C-sized screen at the same apparent size as a 35-mm screen would be HUGE ... and dim ... and expensive.

-- Olaf

[KevinBarrett]

Pentax's DSLRs, specifically the K20D and the K7 both have enormous optical viewfinders compared to the a700. Their sensor is also a 1.5x APS-C crop, but they achieve 98% coverage 0.95x magnification and 100% coverage with 0.92x magnification, respectively. Compare these figures to Sony's a700: 95% coverage with 0.9x magnification.

By further comparison, we see that the Pentax bodies are both smaller, lighter, and less expensive than the a700 (at introduction).

Oh well, I've ordered the new eyepiece magnifier as possibly my last investment in the Alpha system.

[bakubo]

Pentax's DSLRs, specifically the K20D and the K7 both have enormous optical viewfinders compared to the a700. Their sensor is also a 1.5x APS-C crop, but they achieve 98% coverage 0.95x magnification and 100% coverage with 0.92x magnification, respectively. Compare these figures to Sony's a700: 95% coverage with 0.9x magnification.

By further comparison, we see that the Pentax bodies are both smaller, lighter, and less expensive than the a700 (at introduction).

Where can you find this info about viewfinders? I am curious about the specs of the Olympus DSLRS too, such as the E-3 and E-30.

[01af]

Where can you find this info about viewfinders? I am curious about the specs of the Olympus DSLRS too, such as the E-3 and E-30.

Olympus' website?

Maybe you are already aware of it ... but don't forget to take the camera's format factor into consideration when comparing viewfinder sizes! For different formats, magnification and size are two different things. For example, a 35-mm full-frame camera's viewfinder with a magnification of 0,7× is 1.5 times as big as an APS-C camera's viewfinder with the same magnification. To match the 35-mm camera's viewfinder's size, in this example the APS-C camera's viewfinder magnification must be 0.7 * 1.5 = 1.05× ... which doesn't exist in the products currently available.

And the Four-Thirds format is even smaller than APS-C.

That doesn't mean I'm recommending against Four-Thirds. To the contrary, I believe the system is just great and has many favourable points ... among them the excellent (albeit expensive) lenses and the good AF performance (at least in the mid-level and high-level models). Many bash Four-Thirds for the small sensors ... but actually it's only slightly smaller than APS-C, and image quality is as good or better than many APS-C systems.

-- Olaf

[bakubo]

How does one compare the percent coverage figure and the magnification figure for different camera formats? For example:

Pentax K7: 100%/0.92x
Olympus E-3: 100%/1.15x
A850: 98%/0.74x

How does one determine which of these has the biggest view through the viewfinder? Sorry, this is probably a dumb question but I have always been a bit confused by this.

[bakubo]

Maybe you are already aware of it ... but don't forget to take the camera's format factor into consideration when comparing viewfinder sizes! For different formats, magnification and size are two different things. For example, a 35-mm full-frame camera's viewfinder with a magnification of 0,7× is 1.5 times as big as an APS-C camera's viewfinder with the same magnification. To match the 35-mm camera's viewfinder's size, in this example the APS-C camera's viewfinder magnification must be 0.7 * 1.5 = 1.05× ... which doesn't exist in the products currently available.

And the Four-Thirds format is even smaller than APS-C.

I was typing my post above at the same time you were typing this. Thanks!

[01af]

How does one compare the percent coverage figure and the magnification figure for different camera formats?

Just multiply them, then divide by the format factor.

Pentax K7: 100 %/0.92×

1.00 * 0.92 / 1.5 = 0.61

Olympus E-3: 100 %/1.15×

1.00 * 1.15 / 2 = 0.58

... or, when computing the format factor via the image height rather than the diagonal, which makes sense when you prefer a 4:3 aspect ratio over 3:2 in the final image:

1.00 * 1.15 / 1.8 = 0.64

Sony A850: 98 %/0.74×

0.98 * 0.74 / 1 = 0.73

-- Olaf

[bfitzgerald]

I can live with the APS viewfinders, but make no mistake..the film 7 murders them all (9 even more so), heck even the film 5 gives them a good doing over!

Lazy, is just one word I would use. Sony could increase the mag on the A3xx series finders, but want to sell another add on bit (for some extra cash)
The entry non LV models are usable, but not great, again..Sony have not attempted to improve them since the 5d was released some 4 years ago. Ok the VF on the 5d is ok, bit better than the equivalent Canikon models, Pentax have always been that bit nicer.
E3 has a good VF, but go down the range and it's far from great there as well. I remember how disgusted I was with the E500 VF when I tried one, that's why I got the Km5d, it was a lot better in that dept

[KevinBarrett]

Where can you find this info about viewfinders? I am curious about the specs of the Olympus DSLRS too, such as the E-3 and E-30.

I found those statistics over at DPReview. The figures work between systems where the crops are the same, but Canon (1.6x) is not comparable to Sony/Nikon/Pentax/Samsung (1.5x), and these aren't comparable to Four Thirds formats Olympus/Panasonic (2x)

The Sony a700's viewfinder is larger than the Canon 40D; both are 0.9x and 95% coverage, but the Sony is magnifying the same percentage of a larger image area than the Canon.