Why is 100% viewfinder coverage so important?

In the days when slide film was dominant, I can see why 100% could be important. The "excuse" for narrower

coverage was that the slide mount would cover it anyway. But now in the age of digital when a large number of

photos are manipulated, why is 100% considered valuable? This question was stimulated by a comment in another

thread where a person stated he would prefer the D300 over the D700 because of the 100% viewfinder coverage of

the D300 compared to 95% for the D700.

You may find this post by Thom Hogan in DPReview very informative:

http://forums.dpreview.com/forums/read.asp?forum=1021&message=28576261

Basically, when I shoot I don't plan on cropping later, and I don't like surprises in the form of stuff in my compositions that I didn't see and didn't plan for. It was much more important when I was shooting things like slides for artists, but now it's a habit. It's not an important issue, but many photographers take a bit of pride in getting things right when they push the button, rather than having to make them right later.

I'd back up Michael's comments (above) - when I shoot for instance a landscape I want to get as much correct in camera as possible - this includes the framing of the scene without unwanted elements overlapping into view. Of course there is much more to getting it 'right' in camera but 100% viewfinder coverage is a good start - It takes the 'guesstimation' out of the process.

100% coverage is not important. Sorry guys, I have no patience for the "I must have uber-control" excuse.

 

95% coverage is an area measurement. Each linear dimension crops the square root of that: sqrt(0.95) = 0.975.

 

So you lose 2.5% of each linear dimension. That's 1.25% symmetrically off each edge, one part in a hundred. On a FF

35mm capture, that''s cropping the outer 0.46 mm (0.018 in.) out of 36 mm horizontally and 0.30 mm (0.012 in.) out of

23.9 mm vertically.

 

Do you really think your eye is that good? Get over yourself. The N80 Galen Rowell used had 92% coverage (which is

trumped by the lowly D40's 95% coverage.)

Kerry.... I like a 100% viewfinder, but I wouldn't call it a must-have. As Michael and Matthew pointed out, it's nice to know you are capturing what you see. At the same time, a 1% or so loss around the edges will not cause the decline of western civilization.

For me as a glasses wearer I find eyepoint, brightness and magnification actually more important.

 

I like to use MF lenses like the 28mm f2 ais, 45mm P, 50mm f1.2 and so focusing is important. I want to get the framing right but frankly I am trying to get leveled, rules of composition and subject in exact moment to catch the action I see in my minds eye.

 

Thanks Brad for explaining your view on VF view coverage. You convinced me that its not that important, my F3 has 100% but my F100 has 95% I like both because they are both HP type bright VF and I never noticed I got more garbage that I didn't want at the screen's edge on the F100.

 

These days we are more concerned with vignetting and edge softness that would make us want to crop off the edges that are technically not as bright and clear as they should be than unwanted elements we didn't see.

Just in case anyone is curious, as I was, I checked the coverage for all other current Nikon models. Turns out that the pattern is that the top FX (D3) and top DX (D300) are both at 100% and all others are at 95%. I wonder whether this is a conscious decision and therefore a trend that will continue? The only evidence against is that D200 is at 95% despite until recently having been the top DX model.

 

That said, even as a humble D80 user, there are times when 100% would be nice. When shooting through fences for example, or around other tricky obstacles, there have been times when I've thought my shot was clear but in fact the object I was trying to avoid popped up in a corner of the end image.

It's not. However, you'll find that cameras with 100% frame coverage have more generous eye relief and brighter viewfinders, and that is why it's so nice.

Actually, I'd love to have more than 100% coverage (assuming the lenses have the coverage necessary). Rangefinder users will know what I mean.

I do like bright viewfinders and eye relief.

 

I have been making an effort to find eyepieces that have diopter correction, and have found a few.

 

It makes it so nice not to have to use glasses for focus and framing.

 

The Nikon f4e has an excellent built in variable diopter correction.

Back in the day having full frame coverage was a luxury when printing full frame negatives in a filed out neg carrier. It wasn't the end of the world but when you had unseen intrusions to an otherwise perfect composition it was a little annoying. It may sound minuscule to have a 5% disparity in your viewfinder but that is assuming that the unseen image is evenly spaced around the viewfinder. this may not hold true at all. I've seen cameras that were lopsided with their coverage.

It's important to me because I don't like things poking into the image that weren't there in the finder when I was composing the photo. All Nikon pro-level cameras have a 100% viewfinder and there is a reason for it. Pros like to know what they are getting on film, period.

 

I've found the D300 is not 100%, rather it's about 99%. Still I appreciate the coverage over what the D70 and D80 offered.

The viewfinder on the D700 seems to be 1.2x larger than on the D300 but has only 90% frame coverage (0.95 x 0.95).

 

D700:

36.0 x 23.9 mm sensor, viewfinder 95% horizontal and 95% vertical, 0.72x

 

Viewfinder area = (36.0 x 0.72) x (23.9 x 0.72) x (0.95 x 0.95) = 401.47 sq mm

 

D300:

23.6 x 15.8 mm sensor, viewfinder 100% (vertical/horizontal), 0.94x

 

Viewfinder area = (23.6 x 0.94) x (15.8 x 0.94) = 329.37 sq mm

With my F3, if I use the accurate viewfinder to the full and compose to the edges, I can be sure that lab scans of my negs will not include everything I saw in the viewfinder and my Kodachrome's will be even more cropped. Even a 93% viewfinder has more coverage than a standard slide mount!

 

However with digital, the edges of the frame are as easy to access as the middle, so I feel that good viewfinder coverage should be a must. Even on my Fuji F30 the rear composing screen shows 100% and I make full use of the available pixels. Heck, even my 1997 Olympus C-1000 bridge camera (digital) has a 100% optical viewfinder so it cannot be that hard to impliment (for the smaller sensors at least).

 

As a side note, and I am not sure about digital here, but the size of the recorded image varies with the lens used and distance focussed. Therefore an exact 100% view may never be possible. Let me explain. With film cameras, there is a square mask in front of the film. There is an airgap between the mask and the film, and as the rear element of the lens gets nearer to the film plane (wide angle prime lens), the image gets just a touch larger (I measure 24.11mm x 36.12mm on a shadowgraph) and with the 180mm lens with a massively recessed back element the image on the film measures just under the 24mm x 36mm norm. Think of a square hole cut in a piece of card and then bringing a light source nearer toward it - the light exiting on the other side will get larger or smaller depending on distance of the lamp from the card. The viewfinder optics having no airspace behind the mask (focussing screen and associated baffle) can never show EXACTLY what you get on your negative. Only live view can be a true 100%.

 

Ian

Finder coverage is typically specified for a 50 mm lens focused to infinity.

I'm pretty sure that the effect depends on the exit pupil position.

 

Two lenses of the same focal length can have different exit pupil positions and it's also possible for two lenses of different focal length to have the same exit pupil position.

 

Photographic Optics by Arthur Cox is good but it's pretty old now, I think.

 

Ian's point is a good one though, isn't it, since a 100% finder could actually show more than is on the film under certain circumstances - not good at all!

"a 100% finder could actually show more than is on the film...."

 

Richard, from my studies, the "100%" viewfinders are actually a little under most of the time (99.5% I would say) so you may get a smidgeon more image on your negative in certain circumstances, but you will never get less. Nikon say "approx 100%" to be on the safe side. As Bjorn says, the viewfinder accuracy is tested with one lens at one distance only.

 

If you study the edge of a negative under magnifacation, you will find bright areas actually travel beyond the frame - onto an adjacent image sometimes. And don't forget those old lenses that protrude into the mirror box - they must make images that extend almost to the film perforations!

 

Ian

How about an almost-exactly-100%-with 50mm-lens-at infinity-accurate finder ;-)

 

Hey - I just remembered where I first read about this effect. It's in my 1966 Ashai Pentax Way by a not-so-old looking Herbert Keppler. He actually says that the rays from a wide angle lens creep under the picture frame at an acute angle.

Bit O.T., but back when I used to enter slides into photo competitions, I did a rather naughty trick.

 

I used a Kodak Retina IIIc rangefinder, and with a file I opened up the film gate a goodly amount - it reduced the frame spacing down to under 1mm! When I got my slides back I filed the opening to show all the image. Bigger image = more impact. Not sure if it was worth the effort, but I used to grin to myself in the hall where the entries were shown when my 'jumbo' sized photos came around!

 

Ian

Sneaky - but your folding Retina was then no longer so collectible.

.... And anyway you should have used a Kodak 828 Colorsnap which at 28 x 40 would have really wowed them ;-)

I actually like a viewfinder showing a bit less than 100%. When I am struggling to not cut off the fingers or the toes or whatever I am shooting, I have been happily surprised a few times that I didn't cut off that detail when I thought I had. Saved by the 95% viewfinder, d200 in my case.

 

I know you can use a filed out neg holder to get full frame prints, but how often do you do this? I think I have done it once. In the dark room you usually need to crop a bit just to hold the neg so your photo needs to have a bit extra. And with digital, we all know how to crop.

 

So it is not a big issue for me.

 

I read one comment on PN saying that he was not going to buy the d700 just because of the 95%. Hmm, I say don't sweat the small stuff.

As long as the viewfinder is 92% or above I'm fine. As my eyes grow older I do appreciate larger and brighter viewfinders.

When I was shooting and printing my own black and white 35mm negs, I liked the 100% viewfinder because I would mostly print the entire image with a black border. I liked the F3HP viewfinder very much as I wear glasses, but after I sold it last year and bought a cheap FM, I find I can still enjoy using it as well.