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DPChallenge Forums >> Tips, Tricks, and Q&A >> Apature specs
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05/02/2006 03:03:34 PM · #1
Pentax Optio 33L claims to have an apature range from f2.5 to f5, but sometimes it claims to have shot at f6 or f8. How is this possible? (Yes I know its a toy camera Auto everythhing but I have to buy a new computer BEFORE I upgrade my camera. I'm still Win98)
05/02/2006 03:17:42 PM · #2
generally the aperture specifications are for minimum f-stop across the range. so a canon lens ef 18-55mm f/3.5-5.6 means that it'll be 3.5 minimum at 18mm and 5.6 minimum at 55mm.
it can usually go much higher, up to like 20 or so.
05/02/2006 03:24:40 PM · #3
Sounds good, except f/3.5 is bigger than f/8, so actually f/3.5-5.6 is the MAXimum aperture of the Canon kit lens.

The pentax Optio it seems to me is a P&S camera. With only a few exceptions, these cameras have an absolute minimum aperture of f/8. There are a couple that go to f/11.

Remember, f-stops are a ratio or a fraction (same thing), so just as 1/2 is a bigger peice of pie than 1/8, f/2 is a bigger aperture than f/8.

These numbers apply only as a ratio, and as the lens gets bigger, a bigger hole is required to keep that fraction balanced.
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