LX7 - does its IQ compete with e.g. Sony RX100?

Started Apr 6, 2013 | Discussions thread
ultimitsu
Veteran MemberPosts: 5,673
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Re: LX7 DOES have a have a faster lens. ƒ1.4 is faster than ƒ1.8, sorry.
In reply to Erik Ohlson, Apr 8, 2013

Erik Ohlson wrote:

ultimitsu wrote:

kkardster wrote:

The sensor specs favor the RX100 but the brighter and sharper LX7 lens often makes up for its lesser sensor.

This is a common misconception.

LX7 does not have a faster lens.

LX7's lens is 4.7mm F1.4, aperture is 3.6mm in diameter, actual opening is 10.2mm2

RX100's lens is 10mm F1.8, aperture is 5.6mm in diameter, actual opening is 24.6mm2

RX100's lens lets in 150% more light. it is much much brighter.

If the figures you give, above are the correct figures:

LX7 - ƒ1.4

RX100 - ƒ1.8

ƒ1.4 is bigger than ƒ1,8 just as ƒ2 is bigger than ƒ4.5, sorry.

You need to be sorry indeed, because you could not be more wrong.

Don't get hung up on the diameter of the hole ƒ-numbers are RATIO of opening to focal length, it doesn't matter a hoot how big the 'hole' is,

It precisely the opposite, all that matters is the size of the hole.

the aperture is a mathematical RATIO,

No, Aperture is the size of the hole.

"in optics, an aperture is a hole or an opening through which light travels."

and the bigger that number the less light is projected at that focal length.

it is only so if FL is constant.

For instance, the 6-inch diameter telescope I built from scratch (ground and polished the mirror) some 60 years ago was - yes - 6 inches in diameter ("the 'hole') but over 36 inches focal length and it worked out to about F11 "wide open".

The 200-inch diameter telescope on Mt. Wilson, 200 inches in diameter, has a prime focal length of 55.5 feet & that works out to ƒ3.3 - (same as my ZS19 ) - with that 200 inch "hole".

your examples have no relevance to your theory, they neither support or detract it. I do not understand why you bother typing it up.

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