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Old Mar 15, 2010, 5:20 PM   #1
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Is there a huge difference from 2.8 to 3.4? Would that be a deal breaker if a camera started at 3.4 instead of 2.8? Thanks!
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Old Mar 15, 2010, 5:21 PM   #2
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well, it depends on if the aperture difference between the lenses is offset by the sensor of the 2 different camera models.

what specific cameras are you comparing? i think i have an idea, but want to be sure.
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Old Mar 15, 2010, 5:25 PM   #3
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Also depends if we are talking for depth of field or the amount of light into the sensor.
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Old Mar 15, 2010, 5:35 PM   #4
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I was looking at the Canon SX200 (3.4-5.3) versus something that would start at 2.8.
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Old Mar 15, 2010, 7:41 PM   #5
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That is less than a half a stop: it won't mean even a factor of two (one stop) difference in either shutter speed or ISO.

Every little bit helps, but if you can't find a more important difference than that between the cameras you are looking at - you ain't looking hard enough.
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Old Mar 15, 2010, 8:17 PM   #6
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yea, as I was alluding to, the differences between cameras in respect to their sensors and their processing algorythms will most likely have a bigger impact than that small of difference.

and as for DoF, small digicams have huge DoF anyways, it wouldnt be a factor either.

so, no it would not be the deal breaker.
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Old Mar 18, 2010, 12:24 AM   #7
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Quote:
small digicams have huge DoF
how can a small digicam with maximum 3.4 aperture can have a bigger dof? if i am wrong correct me but the aperture is the important part of dof and if it has smaller aperture like 9 it has bigger dof and small digicams doesn't have that kind of small aperture like 9, even my fz 38 has 8.
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Old Mar 18, 2010, 2:53 AM   #8
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The smaller (numerically larger) the aperture, the larger the depth of field. But the smaller the image sensor, the larger the depth of field. So a P&S digicam and a 'Full Frame' dSLR, at the same aperture and the same equivalent focal length, will have very different depths of field.
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Old Mar 18, 2010, 6:38 AM   #9
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Quote:
Originally Posted by imut View Post
how can a small digicam with maximum 3.4 aperture can have a bigger dof? if i am wrong correct me but the aperture is the important part of dof and if it has smaller aperture like 9 it has bigger dof and small digicams doesn't have that kind of small aperture like 9, even my fz 38 has 8.

I've posted this a few times so make no apologies for just copying it
There are 3 main areas to getting a shallow depth of field (dof).

Focal length - the longer the lens the shallower the dof.
Aperture - the wider the aperture (lower f number) the shallower the dof.
Distance from camera to subject - the closer to the camera the shallower the dof.

So ideal situations would be long lens, wide aperture and subject close to the camera.

There is another contributing factor, not to dof, but blurred background and that is getting the background as far from the subject as possible.

Talking about the SX200 specifically, f3.4 is only at the wide setting which is 5mm. So even with f3.4 at this focal length, if you are focusing on anything that is 5ft or further away, then the far limit of focus is going to be infinity. If it was had an aperture of f2.8, this still means that you only have an extra foot before you are again sharp to infinity.

So yes, a small f number does reduce dof, however as the lenses are so short due to the small sensors then dof is vast anyway.
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