Why not all VF with 100% ?

[table1349]

$$$. That's why.

 

[Orrin]

Okay, I have a newbie question I cant find an answer to.

Why are there viewfinders that do not show you 100% of the picture you're going to shoot ? For example my D5100 doesnt.

It just makes the viewfinder massively less useful and makes no sense to me. Why would anyone do this in the first place ? It makes it impossible to carefully "compose" your picture in the viewfinder. For snapshots, its good enough, of course.

Historically, it was done so that the print you received from your developed film was about the same coverage as you saw in the viewfinder.
Prints were never made from the entire negative. This allowed the operator to merely center each negative without getting a black border on one side of a print, causing a re-do!

 

[Garbz]

Is 95% instead of 100% really such a huge saving ?

This is optics. 5% difference in apparent field of view does not equate to 5% change in focal length. Remember it's not only height but also width that comes in to play. Add to that different viewfinder designs will have a different eye-relief range and thus may be harder / easier to use while wearing glasses.