What aperture for couples/groups

Discussion in 'Portraits and Fashion' started by kylebybee, Nov 21, 2016.

  1. Shooting crop sensor I have had some difficulty getting more than one face in focus while still trying to achieve a shallow depth of field. Is
    this asking too much from a crop sensor, should I look at going full frame, or keep practicing? I was using Nikon D7000 with old version
    of Sigma 50-150 f/2.8 shooting at f/2.8.
     
  2. SCL

    SCL

    Are the faces equidistant from the camera? If not, you may need to stop down your lens a little. I sincerely doubt that your lens' sweet spot is wide open, especially at all points of the zoom range, so you should probably expect some softness when shooting at 2.8, IMHO
     
  3. With a full frame camera, the depth of field will be even shallower.
     
    david_olsen|6 likes this.
  4. William Michael

    William Michael Moderator Staff Member

    Are you sure that you specifically want a "Shallow(er) Depth of Field"?
    If that is what you want, then, if you move to "Full Frame" and you continue to use F/2.8, the for the same Framing of any Shot you will attain a Shallower Depth of Field using the FF Camera.
    But from the way you pose the question, if you do that then you will have MORE difficulty in having two faces in focus, so I don't think buying a FF Camera and another F/2.8 lens for it will solve that problem.
    I think what you might be asking is "For PORTRAITURE how do I best select my APERTURE to achieve a nice SUBJECT SEPARATION from the BACKGROUND and still have both Subjects in acceptable focus?"
    That is achieved using an appropriate DoF for the Subjects (i.e. choosing an APERTURE to have BOTH subjects in acceptable focus) and then ensuring that the Subjects are at a suitable distance from the BACKGROUND. That might mean on occasion you will choose to use F/8 (for example to get the necessary DoF to accommodate two people one behind the other for a tight shot.)


    A good rule of thumb for your APS-C Format Camera and that lens is to have the Subject to Background Distance about three times the Camera to Subject Distance, when using F/5.6.

    So we would state that as Ratio of Camera to Subject Distance to Subject to Background Distance = 1:3

    To be technically correct, the Camera to Subject Distance (i,e. the FRAMING of the SHOT) and the APERTURE used and the CAMERA FORMAT are also all relevant to assessing the minimum ratio for this Rule of Thumb: but if you typically use a 50 to 150mm lens on an APS-C camera and only close to about F/5.6, then a 1:3 or greater ratio should be adequate nearly all the time to give reasonable Subject Separation. If there were to be any difficulty, it would be where you get to FULL LENGTH shots - you'll need a greater ratio.
    Sometimes for Groups you just cannot get bthe background really "out of focus".

    WW
     
    stuart_pratt likes this.
  5. Kyle, you may want to determine your regular camera to subject distances and plug them into this dof calculator: http://www.dofmaster.com/dofjs.html But you still need to learn your lens. Get that camera to subj distance and shoot a series of shots at progressively smaller apertures starting wide open. Label and compare them in bridge. Then do the same with a second subject slightly behind the first subject. Take a shot,move it back, record the distance, and continue back to 5-6 feet. Label and compare in bridge as well. Also try the subject at different distances from the bg. Again label and compare. Find what you like. Try going out and achieving it with a subject. When you can get what you want nearly every time, you own it.
     
  6. This is a problem with today's lenses. There is no DoF indicator on the lens, so DoF becomes more difficult to figure out. DoF was easy when I could see it right on the lens.
     
  7. William Michael

    William Michael Moderator Staff Member

    If your Photography is generally “couples and groups” that implies tasks similar to Weddings and Social Functions.

    Regarding calculating/estimating/knowing DoF:

    For mostly all of this type of work I have not found Dof Charts or Tables; quantifying the Subject Distance; nor referring to the DoF calibrations on the lens of very much benefit, especially when working under the pressure of time.

    On the other hand, it was not difficult for me to memorize a set of approximate Depth of Fields for three APERURES based upon three typical FRAMINGS for Portraiture.

    The point is, for typical SUBJECT DISTANCES that we encounter in “portraiture” generally: provided the FRAMING; APERTURE and CAMERA format remains the same, the Depth of Field will be constant. This is the Axiom of DoF and we can use this to make simple cheat sheets or to memorize typical DoF for typical framings. I leaned this axiom in the first year of my College Diploma and I think it is probably the most valuable and useful bit of Photographic Theory I have been taught – I have been amazed how many Photographers are not aware of its simplicity and its usefulness and valuable application in the field.

    This knowledge can also be used for other genres, such as Street Photography.

    Here is a copy of one of my DoF Cheat Sheets for 135 Format Cameras:
    [​IMG]



    Similarly for Vertical Orientation:
    [​IMG]

    Those DoF figures in my (now very old) Cheat Sheets have been rounded to the conservative (safe) side. Note how there is a pattern - easy to memorize. After time it became second nature. I have the same rote memory of DoF for APC-C and 645/6x6/6x7 format Cameras. If one shoots enough Photos it just becomes second nature, like not thinking about what is ‘alphabetical order’ when referring a phone book or a dictionary and like just ‘knowing’ that ‘six eights are forty –eight’ because it has been repeated so many times.

    Add to this rote learning the general observations that generally person’s ‘thickness’ (i.e. ‘depth’) is 12” and a person’s width is 24” and a man’s height is 6’ then, when packaging couples or groups, if done often enough it becomes second nature to simply ‘know’ how much wiggle room that there will be for the DoF for any given aperture.

    BTW The same knowledge of the Photographic Theory taught to me over four years of study those many years ago and then (importantly) following up with much practice, is why I just 'knew' that 1:3 ratio would be a reasonably safe starting point for you to get an acceptable Subject Separation using an APS-C camera and the lens at F/5.6. (It is probably a pity that there are not very many regimented/registered/job pre-requisite Theory Courses and job credentialed Exams anymore, but that's another topic).

    I still carry a tape measure and a set of DoF dial calculators in my bag, but I rarely use them.

    WW
     
  8. You have received many good responses. Most of the group portraits I have taken have subject placement depth requiring something in the f/11 range for facial focus. I usually make a PS gaussian blur layer from the original and paint a mask where I want the subjects to pop.
     
  9. I have never been good at on-the-spot calculations of DoF (or many other things). If I don't have time to set up properly or it's outside of a very few basic setups that I can keep in my head then I'm in trouble. And this is why I very often shoot aperture brackets manually and wish there was a built-in capability for it.
    Actually I wouldn't mind being able to shoot a bracket (aperture) of brackets (exposure). Press the shutter, fire of 9 shots, choose the best later when I'm relaxed.
     
  10. No, it will be not. DOF is only correlated to the focal lenght.
     
  11. New to this forum. Your use of uppercase is hilariously 18th-century.
     
    William Michael likes this.
  12. Having done about a million of these I can tell you that if you are 2-4 rows deep you need at least 5.6 and more than 4 rows you'll need 8 or more. You also run into problems with light fall off if you use more than about 4 rows and are using some sort of strobe setup.

    Rick H.
     
  13. In some important ways, the 21st century has nothing on the 18th.

    In any century, however, any one of us could take a lesson from William in clear and informative writing on the subject of both photography and Photography! :)
     
    William Michael and stuart_pratt like this.
  14. The style of the post reminded me of Thomas Pynchon's playful mimickry of the Writing of that Era, replete with capitalized Nouns, in Mason & Dixon.
     
  15. a more important component of controlling depth of field is by the distance from lens to subject which effect the size of your subject. Closer bigger subjects and less DOF and farther smaller subject and more DOF. When using a telephoto lens, if you are having problems with DOF take a few steps back and make the head size shrink a bit. You can always crop in later on your computer back to 200mm angle of view and you will benefit with the added DOF from your further shooting distance. This is why I no longer shoot with a 200mm but rather an 85mm. I still at times step too close which makes a bigger head size and thus the DOF gets very shallow.
     
    William Michael likes this.
  16. William Michael

    William Michael Moderator Staff Member

    We're kind of talking amongst ourselves now, as the OP appears to not have visited the site since Nov 2016 . . .

    Yet, it is probably time to get the conversation back to the topic of DoF and Group Portraits:

    I think that Michael's point bears reiterating as very good practical advice for all who read this thread

    "if you are having problems with DOF take a few steps back . . . you can always crop in later on your computer . . . and you will benefit with the added DOF from your further shooting distance."

    WW
     
    michaelmowery likes this.

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