Tag Archives: small aperture

Depth of Field

Posted by enmanscamera on
I have included a few examples that show the technique.

I have included a few examples that show control over the technique.

D of F 2

hoodo and fence 3

Plowing the field

Shoot'n the sunrise 1

A smaller aperture for more depth of field.

Shoot'n the sunrise 2

A wider aperture for less depth of field.

Heron

Blue Freighter Frog

Brewster copy 2

Truck in the meadow copy

River Sandon BC

 

A topic that I recently discussed in my classes, that I repeatedly explain to photographers that come to my shop complaining about what they believe are lens focusing problems, and have written more than once about is “depth-of-field”, but it still seems to be an elusive concept for many. However, it is really important and photographers should make the effort to grasp it even though it appears difficult.

I pondered this last Thursday when a local photographer showed me an image she had made during a wedding. She showed it to me proudly and commented that she has chosen that lens because it let in more light when photographing in low light, but complained that the expensive lens she had didn’t seem all that sharp.

The image showed a view of the central aisle of the church with pews left and right, leading up to the bride in the distant centre, approximately 20 feet from where the photographer was standing. The overall exposure shot at an aperture of f/2.8 was fairly good. However, what that photographer saw was the lack of sharpness everywhere, except for the bride standing in the aisle.

The definition of depth-of-field is “that area around the main subject, in front of, and behind it, that is in acceptably sharp focus”. In application the wider the lens’ aperture is set the less will be the depth of field, or that area of sharp focus, around the main subject will be.

Wide aperture lenses are very popular these days and using a lens at a wide aperture like f/2.8 when making a portrait isolates the main subject and produces a soft, out-of-focus background referred to as bokeh by reducing the depth of field. Bokeh is a pleasing soft blur produced by a wide aperture lens in the out-of-focus area directly behind the subject.

In this instance the photographer was relying on the wide aperture to increase the exposure in limited lighting conditions. That additional light allowed a faster shutterspeed for handholding, but along with the benefit of additional light reaching the camera’s sensor the resulting effect was to reduce depth of field.

Using that wide aperture created a field of focus in front of the subject of a couple feet and only a bit more behind that would be fine in a portrait, however in that photograph of the church aisle with pews on both sides, that included lots in the foreground and much of the background, looked out-of-focus.

Many photographers unwittingly rely too much on their photography equipment to (magically?) make good images, and blame faults in their photographs on that same equipment. Understanding the basic concept of depth-of-field would have made that photograph more to the photographer’s liking.

The smaller the lens aperture number is the less the depth-of-field. I prefer using a small aperture (larger number) for scenic photography and, as in this instance, interiors. The answer to that photographer’s low light problem would be to increase the ISO and use a smaller aperture. (I would be surprised to find a modern DSLR that wouldn’t shoot noise free at ISO1600 or even more)

Assuming the lens isn’t sharp when the real problem is with photographic technique is expensive if the photographer goes so far as to replacing a lens. My recommendation is to spend time learning the basics of depth of field instead of blaming equipment when problems occur.

 

I appreciate reader’s comments. Thanks, John

My website is at www.enmanscamera.com

The Importance of Depth of Field

Posted by enmanscamera on

Depth of field is defined as, “that area around the subject that is in acceptably clear focus”.   

I chanced upon a copy of a local magazine and took the time to look through its pages. I always go through magazines by first glancing at all the pictures then go back and review select articles. This particular magazine interested me because some articles were accompanied by photographs that were not in focus.  At first, I put it to poor printing, but this particular issue had a cover and several photographs in it by a friend of mine and they were sharp.

So why were some images “soft” and others as good as those we regularly get from the lab when we take our memory cards in for printing?  Modern cameras do the focusing for us and it is fairly difficult to get several images of stationary subjects that aren’t sharp.

Now I’ll go back to why I opened this column with the definition of depth of field; and why I think there are lots of photographers that are either spending time adding sharpness using PhotoShop or printing images that lack that overall sharpness. 

The problem I see happening all too much is that many photographers forget that basic concept of how depth of field works with a given lens and think “a wider aperture gives me more light therefore I can shoot with a faster shutter speed” and therefore, “I don’t need a flash or a tripod”.  Well, they are right to a point and (I’m not going to discuss at this time why I think most photos of people benefit from camera flash.) I think that photographers need to be reminded that limited depth of field comes with problems.

When I looked at those images in the magazine I thought about depth of field and how, although the lens may have been very capable of producing sharp images at F2.8, it couldn’t overcome the basic rules of depth of field.  I found there were sharp elements in the pictures, but so much was just out of the “limited area of focus” around the subject that the “softness” affected how the entire image was viewed. 

If one reads the internet forums or asks photographers what lens would be their favourite, of course they would come up with many different choices of focal length, but more often than not they would also indicate they wanted an aperture of F2.8.  The reasons given for that small aperture are either so that the photographer can “shoot in low light or so they can soften the background”.  That’s good, however, one of the purposes of the aperture is to control depth of field. The smaller the aperture the wider is that in-focus area around the subject, and the larger the aperture the narrower that in-focus area around the subject is.  Remember that means that a smaller aperture has a higher number like F16, and a larger aperture has a lower number like F4.   

I think it is a good idea for photographers to have equipment that allows different perspective. I own lenses that have apertures of F2.8 and larger, but I do not take them for granted. I select lenses and use their different apertures to create the effect on my subjects that I want. My advice? One should think about the picture about to be taken and select an aperture that works for and not against the subject.

http://www.enmanscamera.com