Why do they make viewfinders with only limited coverage?

[dogbert]

I aware that some cameras have viewfinders with 100 per cent

coverage while others have only around 90 per cent or even less. On

a recent trip to the south west is was using my Sigma 12-24 a lot on

an EOS 300 (Rebel 2000 for americans). Quite a few of my photos had

shadows of my arms, feet or railings in the botton of the frame,

though I am pretty sure these weren't in the viewfinder when I took

the shots. I am fairly careful when it comes to framing things. So

my question is, why not make all cameras with 100 per cent or near

100 per cent viewfinder coverage? Surely it can't cost that much to

make a viewfinder that very closly resembles what is being recorded

on film - at least better than 97 per cent. After all, isn't the

reason we have SLRs so we can actually see what the film/sensor will

see?

[pok_hon_wally_yu]

Search the archive for more details...

 

To make it simple, it's about cost and size. A 100% pentaprism is considerably bigger than what you have in your EOS 300. Certainly it's more expansive. Compactness is one selling point of EOS 300 and something needs sacrifice in the design.

[EricBoehm]

Have a look at the following article by Mike Johnston. I think you'll find it very interesting and topical.

 

http://www.photo.net/mjohnston/column6/

 

It's a combination of factors to be sure. Cost is a biggie.

 

Eric

[awindsor]

Expense. You need a larger mirror (which requires a larger mirror box), a larger glass screen (not a big deal), and a larger pentaprism (which is a heavy and expensive hunk of optical glass). Finally larger coverage normally means lower magnification.

 

Your Rebel 2000 is a cheap camera and gets only 81% coverage by area. Terrible isn't it. It has the same viewfinder stats as the EOS 300V but seems to have a pentaprism (is it true ?). The good news is that it won't be a huge shock when you transition to digital.

[dogbert]

Thanks. I figured it must have something to do with cost or a conspiracy against entry levl camera use. But I am still surprised that it costs a lot to make a viewfinder with greater than 95 per cent coverage than say 80 per cent. Afterall its only an extra 15 per cent. BTW, I think the rebel has a pentamirror. Also I shoot mostly digital already - drebel xt. I think it has about 88 per cent coverage, and with its crop factor has been enought to keep feet and shadow out of the frame.

[affen_kot]

it has a lot to do with consumer greed. canon (and the other manufacturers) know that most consumers will - en masse - race out and fight each other to buy a camera with a 50-percent-coverage finder, just to save 20 bucks over the model that has an 80-percent finder. slight exaggeration, but you get my drift. the major manufacturers have to cut corners where they can to maintain their market share in the "budget imaging" arena.

 

we have low-quality products/services because there is a huge market for them, and i would venture a guess that there always will be.

[bobatkins]

Pentamirrors are cheaper and lighter, but dimmer. Yet another cost saving measure.

 

The origin of sub-100% viewfinders is also said to be that they better show what you get on a print, since photo finishers don't print the full negative size and slide mounts cover up the edges of the frame. Certainly true for film, but the argument holds less well for digital.

 

Camera companies assume consumers are too dumb to account for this and so are happier with viewfinders that show what ends up on the print. Pros are assumed to be smart enough to mentally compensate for loss of image due to printing or masking.

 

Smaller viewfinders are also brighter. Pros use f2.8 lenses and so a large viewfinder isn't a big deal. Consumers use f5.6 lenses and so already take a 2 stop brightness hit.

[mawz]

Another issue is that 100% viewfinders are inherently lower magnification, which is how lower-coverage viewfinders initially evolved. However the ultra-low coverage and dark viewfinders in something like an EOS 300 is all about cost.

 

I certainly don't miss the 8% difference between my F90x's 92% viewfinder and an F5's 100%, but the F90x has a huge, high-magnification and bright finder.

[dogbert]

....."slide mounts cover up the edges of the frame. Certainly true for film, but the argument holds less well for digital."

 

We not even in my case with an appalling 80 per cent viewfinder - the slide mounts do not go close to masking to match the view the the view finder.

 

Actually I had been implicitly accounting for this with the drebel XT as I was aware that the viewfinder gave less coverage and would deliberately frame more tightly to compensate. I guess I was caught by suprise going back to the EOS 300 as I don't use this camera very often any more and hadn't used it that much in the past with slides.

 

Thanks everyone for your repsosnes this has been quite educational. The article by Michael Johnston is very scary. Do photofinishers really print from only a near-APS sized piece of the film. Good grief!

[jon_austin]

This whole issue of images being cropped during photo processing highlights just one more of the reasons why I love digital imaging. Once the image file is in my photo editor, *I* have total control over the cropping, and I can adjust it precisely to my liking, and as fits the aspect ratio of the print size I choose. With my 13x19 printer and the availability of custom framing components, I can choose from an unlimited number of aspect ratio and print size choices.

[Troll]

Geoff, if it's any consolation, the latest $3000 M-7 Leicas also have viewfinders which cover only 80% of the actual field of view.

[john_jovic]

I wouldn't be surprised if there is an element of superiority and seperation being applied by the manufacturers to force the purchase of the most expensive pro bodies over the next model down. In other words, the semi pro camera often has 1/200th flash sync, whilst the pro model always has the highest sync speed possible. Surely 100% coverage is the same and only applied to the most expensive models drawing the pro's to buy them rather then the next model down, and usually much cheaper too.

 

100% coverage is absolutely necessary for me, that's why I bought 2 Canon 1v's for my work, but in reality it is not that big a difference between say 95-98% for the average user.

 

JJ

[majid]

Bill, the M7 may have a 0.72x or 0.85x magnification, but it actually has greater than 100% frame coverage, i.e. you see bright-lines for what goes in the frame, as well as a portion of what lies outside the frame. This allows you to optimize framing and maintain situational awareness better than with a SLR. See <a href="http://www.leica-camera.com/imperia/md/images/leica/produkte/msystem/kamera/54.jpg">this link</a> for an illustration.