Hot Dog

[kezmal]

Its quite a warm day here in sunny Queensland, and my old dog Brinkley is feeling it. I dont think he's moved much today. I have been playing with the depth of field, and not succeeding. Am after a blurred background, however I just think its my camera. F2.8 1/250 - my husband set his at the same on his Nikon D7000 and got the intended effect of a blurred background.

[Donald]

Kerry

With such wide angle lens as you have on that camera, even at f2.8 your going to get a deep depth-of-field.

[Dave Humphries]

I have been playing with the depth of field, and not succeeding. Am after a blurred background, however I just think its my camera. F2.8 1/250 - my husband set his at the same on his Nikon D7000 and got the intended effect of a blurred background.

Hi Kerry,

It is the small physical size of the sensor in your Panasonic DMC-FZ35 that causes this effect, you'll be able to match the D7000 DoF on Christmas day (hope that's not giving too much away).

The Depth of Field (DoF) any of us experience is directly related to the focal length and aperture, unfortunately, there are two ways of thinking about this when the sensor size differs between cameras;

1) You may know that your lens has a 'crop factor' - a figure which you multiply the focal length by to get the equivalent focal length of an old film 35mm camera, this figure will be about 5 for that camera. You shot this at 4.8mm (according to EXIF), so 5 x 5 (rounding up), is about 25mm, that's quite a wide angle and wide angle lenses have less DoF, but that's not all; the crop factor also applies to the aperture, so f/2.8 x 5 (or 3 x 5) is about f/15, which gives too much DoF, hence the wall is sharp too.

2) A simpler way to think of it (especially for ex-35mm film shooters) is not to apply the crop factor at all; so how much DoF does a 4.8mm lens (on a 35mm film camera) give at f/2.8, well it'll be 'a heck of a lot'.

The answer is; to get less DoF, you need a bigger sensor, hence the popularity of DSLRs over P&S when you want narrower DoF and a preference for 'full frame' (FX) cameras for wide angle shooters.

I have over simplified the above example, because the D7000 isn't a full frame sensor either, so in whole stop terms, I suspect that the DoF of the D7000 at f/11 (and 18mm) on the lens, will be closest to what you get at f/2.8 and 27mm.

You could probably get less DoF by moving further away from 'hot dog' and zooming in - but leaving aperture as wide as you can, however, that'll change the perspective too, so the nose will not appear so large.

Cheers,

[kezmal]

Thanks so much Donald and Dave. This information will sink in eventually and I think that during Christmas I'll be reading the Photography Tutorials on this site to get a better understanding. I am also doing a 2 day photography course in the New Year, so am hoping that will be of great benefit to. I'm sure Mal is hoping it sinks in soon, all my silly questions are surely bugging him.