How long has canon, Pentax and Nikon been making slr cameras?

I'm making my own website for my web design class about slr cameras and i need to find out this information.

Since you are making a website, you should be familiar with the internet. I did a quick google search on "history of ___"(insert manufacturer name), and amazingly… The details you want AND MORE are easy to find.

http://www.canon.com/about/history/01.html
http://en.wikipedia.org/...iki/Pentax
http://en.wikipedia.org/...on#History

I think your real question should be: When did they stop making SLR's that used film and when did they start making digital. The first one was made in 1994 and the film model was invented in 1935. Which type do you wish information on?

Another good searchword is 'timeline'. 10 minutes on Google will give you more than you need.

Pentax: Since 1952
Canon: Since 1959
Nikon: Since 1959

Pentax single-handedly popularized the previously little-known 35mm SLR, back when Nikon and Canon were still making Leica rangefinder clones. The Canons, in particular, were shameless copies, differing mainly in the name badge.

In 1952, Pentax was called "Asahi Optical Company". Their 1957 "Pentax" model, which popularized the pentaprism (previously you had to look down into the SLR, viewing a reversed image), was so popular they changed their brand name to Pentax, and eventually changed the company name to Pentax too.

Pentax was once hugely popular, but some big mistakes eventually let Nikon and Canon eat their lunch:

1) Pentax was popular with amateurs and enthusiasts, but Nikon was much better at offering accessories that working professional photographers wanted. Pentax's efforts to court pros were too little, too late.

2) Pentax was slow to move from screwmount to bayonet mount. Bayonet mount is quicker to mount and unmount, and allows more automation.

3) Although Pentax popularized innovations in the 1950s, by the 1970s they were slow to add important features found on other brands, especially auto-focus.

4) In the 1990s, Pentax (and Minolta) wasted time with Power Zoom, which almost no one wanted, while Canon brought out in-lens silent auto-focus motors. Many of Pentax's best lenses from that era are as big and heavy as Nikon lenses, due to the power zoom, which no DSLR uses nor will ever use.

5) It wasn't really Pentax's fault, but their first DSLR effort was abandoned while still in prototype phase in 2001, due to high sensor noise (anything above ASA 100 was quite noisy). As a full-frame sensor, it would have competed with the 2002 Canon EOS-1Ds, which went to ASA 1250. The sensor in that Pentax prototype was only ever released in the Contax N, which was not a market success, due to high sensor noise. So Pentax started over with a new (smaller) sensor, but by the time the *ist D was released in 2003, Nikon and Canon were already on their next generation of DSLRs.

6) Bad marketing. Since at least the 1990s, Pentax's marketing has ranged from bad to nonexistant. The only really good Pentax marketing I've seen are vintage ads from the 1950s & 1960s.

7) Some say that the new Q is a big mistake. They may be right. The most interesting thing I see about the Q is that the lens mount is big enough for a much bigger sensor. A bigger sensor may be necessary for the Q to be successful.