good dslr that has a fast lens?

Started Dec 22, 2012 | Discussions thread
anniejohn
Regular MemberPosts: 127
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Re: good dslr that has a fast lens?
In reply to Deleted1929, Dec 22, 2012

Thanks. I do understand that the dslr should produce similar or better results in many conditions because of the sensor size, but someone had complained about subject blur and poor low light responsivity WITH the DSLR (the 3100) so I was hoping that someone would recommend one that didn't have that problem as that is exactly what I'm hoping to avoid by purchasing one.

AJ

sjgcit wrote:

The aperture number ( f-number ) of a lens is not absolute, but relative to the sensor size.

Hence a large sensor ( like a DSLR ) with a modest f-number lens like f3.5 is still a larger physical size aperture than a relatively small sensor camera like the XZ-1 with it's lower f-number.

When shooting this means :

* The wider aperture number can use a lower ISO at any given light level.

* But the smaller sensor has more noise at any given ISO than the large sensor. A modern DSLR sensor has a two or three stop advantage over a large sensor P&S.

* Depth of field is narrower on the DSLR when using a kit lens wide open compared to a compact camera with it's lens wide open, even an XZ-1.

So you don't really need a fast lens on the DSLR to get similar results ( or better ) than your XZ-1.

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StephenG

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