Canon 300hs and *HUGE* f-stop/aperture numbers

Started Apr 27, 2011 | Discussions thread
Jinwons Senior Member • Posts: 1,043
Re: Here is some more testing with both 300HS and ZS7 for bright scene

PaulRivers wrote:

Jinwons wrote:

As I expected my 300HS took telephoto shot with F/17! But my ZS7 took telephoto shot at F/6.3.

Well I think we both agree that that is messed up behavior. The Canon is doing something unwanted (and unusual for a Canon compact) by choosing such huge apertures when clearly it could raise the shutter speed.

It's unusual behavior for Canon and possibly Panasonic too as ZS7 is this way apparently. However, I have seen others like Samsung, Sony cams doing this before, shooting above F/10 under bright outdoors. I have those shots and can post here too. So it's a little less surprising to me than you. My gripe with 300HS was just that rate of it choosing high F/number seems a bit higher than normal with icontrast. Now that I keep iContrast off, chance of doing that is lower though it still does that for very bright objects as both you and I verified.

I read somewhere that Sony is using ND filter type of aperture to reduce the intensity on sensor to level of equivalent F/numbers. This way it reduces light intensity on sensor but doesn't actually reduce physical stop diameter to cause diffraction issue. My Sony WX9 does predominantly high F/number shots > F/10 under bright outdoors, but it goes below F/3.0 most of time indoors. Sony spec site says that it has hybrid stop consisting of physical iris and ND filters. So I guess that it might be using ND filters to reduce light intensity to effectively high F/numbers without causing severe diffraction. Since these new Canons (100HS, 300HS, 500HS) are employing the same type of CMOS 1/2.33" sensor, I think it's possible that Canon implemented similar kind of lens stop in them.

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