Buying a New Lens..confused about DOF

Joined: 03 Aug 2006 Posts: 254

Hey Everyone...

I own a Nikon D50 with an 18-55 lens. I've been really happy with it so far. I've been using it for portraits mainly and thats where I feel the lens performs best.

The problem is though when I am shooting full body shoots or family photos...for some reason I can't get all the subject in focus. I find it's too soft or I have 1 person in focus and not another.

I know this has to do with the F-Stop....I used the online calculator to see what my focus points are for different F-Stops with my lens and it seems that the focus area is very small...

What kind of lens would I buy to get a larger DOF for stronger family photos? or lifestyle shots?

THANKS SO MUCH FOR ANY AND ALL RESPONSES!!!

Joined: 18 Nov 2006 Posts: 288

Depth of field is controlled by aperture, suject to camera distance and focal length. Shallow depth of field is generated by wider aperture, closer subject distance and longer focal length. To get deeper depth of field, then, you need smaller aperture, more subject to camera distance and/or a shorter focal length. It is all under your control. You don't need a new lens to get deeper depth of field.

Posted: Mon Apr 16, 2007 11:13 am

Here are some links

http://www.mir.com.my/rb/photography/fototech/htmls/depth.html

http://www.photodo.com/topic_122.html

As was said, larger dof, comes from a smaller aperture so something like f8 or f11 instead of f4. This setting lets in less light, and therefore you will need a faster film or ISO or a brighter flash.

Posted: Thu May 24, 2007 4:24 pm

realworld28 wrote:

Hey Everyone...

I own a Nikon D50 with an 18-55 lens. I've been really happy with it so far. I've been using it for portraits mainly and thats where I feel the lens performs best.

The problem is though when I am shooting full body shoots or family photos...for some reason I can't get all the subject in focus. I find it's too soft or I have 1 person in focus and not another.

I know this has to do with the F-Stop....I used the online calculator to see what my focus points are for different F-Stops with my lens and it seems that the focus area is very small...

What kind of lens would I buy to get a larger DOF for stronger family photos? or lifestyle shots?

I have a spreadsheet that works out the depth-of-field (which you are welcome to have). But they general rule of thumb is the smaller the aperture the greater the depth-of-field. Also at the same distance and f-stop, shorter focal lengths will have a greater depth of field.

From what I understand, focal lengths around 50mm are preferred for portraits, but it depends what kind of shot you're after.

Give us a bit more detail about what settings you had the lens set to (i.e. focal length, f-stop, approx distance to subject [could be tricky]) and we'll try to provide some advice. :-)

Mark

Joined: 31 Jul 2005 Posts: 131 Location: Boulder, Colorado

50mm is ok for portraits and quick candids....but most folks move to an 80mm or 120mm (sometimes greater) to really "blow out" the back grounds and Isolate their subject. The longer the lens, further "out of focus" the back grounds can be rendered.....also, with a longer lens, the DOF you can use for keeping your subject in focus is wider....meaning you can keep their nose and ears in sharper focus at the same time...or keep several folks in focus. (as in one behind the other, etc.)