Originally posted by kamwai
I have seen those Med/Large format camera before, but why some pple prefer that over 35mm??
higher resolution? sharper image?
In what occasion when pple need to use LF/MF?
There is something call Range Finder too rite? what so good abt it and how does it work?
Hmm... this is really one of those times when I wish I had a URL to link to.
Medium format generally starts at a film size which is 6cm x 4.5cm, upwards to include, commonly, 6x6, 6x7, 6x8, 6x9, 6x12 and 6x17. A 645 negative or tranny is 2.7 times larger than a 35mm negative (2.4 x 3.6cm). That means that, barring for small differences in lens optical performance, using the same film, a 645 image has 2.7 times the detail that a 35mm neg/tranny possesses. It also means that for any given enlargement size, a MF original needs to be enlarged at least 2.7 times less than a 35mm neg/tranny. This means that the grain is smaller, and the tonal scale is better.
With large format, your originals are 5x4 inches, 5x7, 8x10 and upwards (there are still a few 20x24s floating around, 3 if I'm not wrong). So you take those advantages of medium format and multiply it several fold. One sheet of 8x10 film is approximately equivalent to an entire 35mm 36 exposure roll!
In addition, MF users generally have the advantage of interchangeable film backs, which mean you can switch easily between different types of film (high speed, low speed, colour and black and white, negs and trannies), and also change film much faster than 35mm users (particularly if they have an assistant).
A number of MF and most LF camera also have camera movements, which by altering the position between lens and film plane, can achieve different objectives such as control or distort perspective, limit or maximise DOF etc. The Fuji 68 system is the only commonly available MF slr system that has camera movements, but there are a range of MF monorails from manufacturers like Arca-Swiss that function exactly like LF cameras but with the economy and speed of use of MF film.
LF cameras also have the advantage of sheet film, which allow for the application of the Zone system which helps to achieve consistent, good exposures by guiding the photographer in exposing, processing and printing their B&W negs. It is difficult to fully apply to roll film as it requires individual processing.
Rangefinders are cameras like the legendary Leica M6. The do not utilise a reflex mirror and require a separate viewfinder to look through the lens. It's benefits are silent operation as there is no mirror to slap out of the way, and this also allows slower shutter speeds to be handheld without the jarring of the mirror flipping out of the way. Their silence allows them to be used unobtrusively without drawing attention to the photographer. Because there is no mirror to get in the way, it is easier to design better wide angle lenses for rangefinders (as otherwise the rear element of the lens would impede the mirror), hence the presence of comparatively good and cheap superwides like 13mm lenses.
The drawbacks are the need to match the viewfinder to the lens in use, as you are not actually looking through the lens unlike in a single lens reflex cameras. At short distances, there will also be parallex error as there is a small difference between looking out of a viewfinder and the lens a few centimetres away. It also makes telephoto lenses slightly more difficult to use.
(Actually, after typing all that I've realised CK's linked to Rob Monaghan's excellent website)
Hope all that helps. Chances are I've missed some things out, but I've just written that off the top of my head.