F stops, distance and baby portraits

[sufran]

I was taking some newborn shots recently and make a point of using primes at the lowest "f stop". Many shots were taken with the 100mm/2.8. I was seeking to get some low DOF and focus on particular features of the baby. I didn't merely do close-ups, so the DOF was varied. However, it made me wonder what f stops people most commonly used when taking pictures of babies.?

[swifty]

Hi sufran,
The f-stop used for baby portraiture is no different to any other forms of photography.
As well as being an important part of exposure, as you've noted you can control DOF with aperture settings. But don't forget that aperture is not the only criteria in determining DOF.
Shallow DOF can be desirable in obliterating unwanted backgrounds or isolating interesting areas of focus.
Lenses perform differently at different apertures and selecting an optimal aperture can improve sharpness and contrast.

Indoors where I'm often fighting for adequate light, I typically shoot wide open. But I typically like very selective focus anyways even without exposure constraints.

[sufran]

Thanks for the reply. I researched this a bit further on the net after posting and it seems there's a number of people recommending in the range of 3.5 to 5.6. What prompted my interest, and makes it a little different photographic experience for me, is that many newborn shots are taken in close physical proximity to the baby, focusing on one aspect of the baby (e.g. his or her mouth). So I was finding that even with f2.8 which I am normally quite comfortable with taking images of a couple (from a somewhat greater distance of course) and provides a clear image of the couple, was yielding images where a reasonable proportion of infant was out of focus. While this was something I deliberately wanted to play with, the contrast was a bit more than I was expecting, so I was curious as to what f stop other photographers might generally use in similar circumstances (i.e. the closer distance which often seems needed for a number of baby photos) - whether there was a preference for playing the out of focus DOF in close-ups, or whether there was generally a preference to have a greater depth of field. The following is an example: I wanted the focus to be on the baby's tiny fingers, but do photographers generally aim for a greater depth of field in these circumstances so that more details of the baby's face would be apparent in the image?

[arthurking83]

Two points come to mind re this thread(question)

1. it's quite impossible a task to advise on an appropriate aperture value for just about any type of photography, let alone a specific genre.
The needs wants and gear involved all make it so variable, that to advise on an aperture range that is so limited seems quite funny actually!

That is, to give the advise that f/3.5 to f/5.6 is an ideal range for baby shots, is not really looking at it from the point of view of the photographer.. the person actually taking the shot.

You may as well just use stock photography and cut and paste the face of the baby in question onto the base stock photo of a single baby and be done with it.

Apologies if this sounds harsh, it's not meant too, it's more about the point that there really is no best setting to use.

ie. try using f/3.5 in the typical studio environment where strobes are the norm, and a specific shutter speed may be required, and so on and so forth.

Again the question about whether others tend to try for more or less DOF .. while it may be relevant to those other photographers, to you it should really be of no consequence what aperture values, and hence DOF rendering they choose.
If everyone shot at the same aperture value and tried to get the same DOF rendering, you basically end up with the same shot, on a different day with a different looking face(which on the whole tend to look similar anyhow!!)

2. You say that you were surprised by the extra contrast within an image when shot at f/3.5 to f/5.6.. but you haven't referenced that with what your usual aperture setting is, and it's hard to guess at what this may be, other than a quick reference to f/2.8 and a feeling of comfort.
Is that the max aperture value your fastest lens has? is this the usual aperture value you prefer to use.

On an f/1.4 lens, the difference between f/2.8 and f/3.5 in terms of contrast may go completely unnoticed to most observers.
So for this instance, I guess it's safe to assume that your lens is f/2.8, as 2/3 to 1 stop down on most fast yield such an observation.

And again, this is dependent on the lens too, some lenses are well known for their softer less contrasty rendering overall, where other lenses of similar type/focal length can be more contrasty.

Of course DOF rendering amount is not only a factor of the aperture you select.
Focal length and distance to the subject is an important consideration you need to allow for as well.

Do you have any prime lenses .. even an f/1.8 lens?
many f/1.8 lenses can be had quite cheaply and can give some remarkable results, so look into them as another option too.

[swifty]

I basically agree with everything AK said. Although I think your reference of the word contrast was to the degree of difference between the in and out of focus area whereas I (and maybe AK) was referring to contrast from a luminosity point of view, where contrast improves with a little stopping down from max aperture.

Your example of f2.8 shot from a greater distance yielding acceptable focus brings up two issues. Firstly, AK has referenced the subject to camera distance and this is probably the most important factor in DOF. You should also consider your focal length, in addition to aperture. Too often ppl consider just the aperture for DOF. So your working distance with adults usually give you more DOF leeway.
Secondly, the plane of focus is important. If a couple are both facing the camera such that both faces are essentially equal distance to the camera, it won't matter too much what the aperture is and both faces will be acceptably sharp because they're located on the same plane. Move in closer, zoom in, shoot at max aperture and both faces'll probably still be acceptably sharp as long as they're on the same plane. Now add in 2,3,4 more faces and the situation changes as it'd be difficult to position all the faces equi-distance to the camera. Some will be a little more forward and some further back. Now you will need to increase your DOF to try and get everyone in acceptable focus which might mean using a wider focal length, moving back and/or stopping down.
Now, applying that to your baby shot. You're at close shooting distances so DOF is shallow. Shooting wide open further narrows your DOF but if you have room to maneuver, you can place both the baby's hand and eyes on the same plane of focus, or at least closer to the plane of focus such that the baby's face is less blurred.
I won't go into it but there are also ways to shift the plane of focus with specific lenses (tilt- shift in Canon speak or Perspective control in Nikon speak) and specific cameras (technical cameras) but that's beyond what you're likely interested in.

- - - Updated - - -

Btw I'm at wide open most of the time which for me is at 1.4 or 1.8 on my primes and 2.8 on my zoom and use plane of focus to control what I want in focus but with a quick drop off in DOF due to the large apertures used. But that's just my preference.
In your shot, you could simply stop down, use a wider focal length or move back to increase your DOF.

[sufran]

Thank you both for the time taken in constructing these detailed responses! I do have faster primes (than the 100mm/2.8 used in the photo), but found that close-up to the infant, even f2 was just a little too open for what I was trying to achieve (for my taste). I was curious about others' apertures of preference for baby portraits in particular (rather than portraiture in general) just because it is accepted that for baby portraits some will be extremely close and focus in on a particular feature. Swifty,I was using the term "contrast" more generally, rather than specific to a photographic context.

The point you make about the focal plane is a good one Swifty. I have tended to consider wide open apertures and images showing greater detail (better dof) as an outcome of distance from the subject. And, hence, I hadn't really consciously applied the concept of focal plane and dof to baby portraiture i.e. combining close-ups, wide open aperture and the same focal plance to take advantage of the low dof and subject appearing in focus.

So in a sense, my question was misleading (in light of the provided information). I was focusing on aperture because I considered that the primary cause of the dof outcome in the photo, whereas it is really a combo of aperture and focal plane most importantly (in this situation). Thanks again both of you for your time.