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I want to buy and do a photos+video interview with Sigma F/1.8 24mm Fixed Prime.

I did profile photos/interviews with my Sigma 85mm F/1.4 on My Sony A77 APS-C camera. I used to use F/1.7-F/2 as a perfect range for me as nice bokeh blur.

But the I also want to shoot some pictures/interviews in a big house balcony with nice view of cathedral square. The problem with 85mm F/1.4 (used at F/1.7), that the background is also zoomed a lot and camera stays far from interviewee.

I want to use 24mm and show the same 'user profile sitting on a chair' and FRAME IT from top head till mid legs (knees). What I also want, is to see much more cathedral (not just a fountain of it), so I know I should use a lens like 24mm, 28mm or 35mm. 35mm might be not enough space to put camera in a balcony and get a sitting guy view, but 24mm or 28mm (on my Sony A77 aps-c it: 36mm or 42mm).

My questions is - will 24mm will not distort the humans face (sitting in left 1/3) so that in videos or photos it will look bad? And 2nd questions, which is the best 24mm lens for nice looking bokeh, and king a sharp human face in a picture.

I want to use it in ~F/1.8 range when shooting videos/pictures.

Or should I go with 35mm F/1.8 Sony SAL prime lens, because of face distortion.

Imagine that that photo video would go on TV.

Thanks for any advices, because I got lost between choices.

==== EDIT:

As per request I'm putting the past attempt, when I used 85mm at F/1.7 on A77 APS-C. Camera was around 10-12meters away probably. And there is a palace in background, but I was not able to capture it This is a screenshot from a video file (it does not allows me to attach images):

http://img441.imageshack.us/img441/2918/yulp.jpg

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  • \$\begingroup\$ What camera body, will you still be using the A77? What distance is the subject from the camera? Do you have any example photos of your past attempts you could share links to here? \$\endgroup\$
    – dpollitt
    Jul 31, 2013 at 3:27
  • \$\begingroup\$ I will still use A77. On 85mm the distance was around 10-12 meters to person. Now I want to put camera around 2-3 meters. I will probably get a bit less of persons view putting that close, but I probably will get way more of view in background. \$\endgroup\$
    – KestutisIT
    Jul 31, 2013 at 8:00
  • \$\begingroup\$ I think the perspective won't be the most flattering but still won't look like a deformed clown if you don't take close ups. \$\endgroup\$
    – fortran
    Jul 31, 2013 at 9:03

4 Answers 4

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My questions is - will 24mm will not distort the humans face (sitting in left 1/3) so that in videos or photos it will look bad?

As you noted, on a crop-sensor camera a 24mm lens will effectively be about 36mm. 35mm is a very common focal length for "environmental portraits" -- not "head and shoulders," but showing some of the surroundings, too. So, if you use a 24mm lens on a crop-sensor body to take environmental portraits, I'm sure you won't have any distortion concern. If, on the other hand, you want to do "head and shoulders" portraits you will see less flattering results with the 24mm lens. It won't look bad and it won't really appear distorted, but it will be less flattering to the subject.

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The depth of field, which determines how much background blur you get and how quickly the person goes out of focus, is determined by the focal length and aperture of the lens as well as the focal distance. It is going to be the same from lens to lens.

You need to use an appropriate aperture for your shooting distance and focal length such that you can get the depth of field you need to keep your subject in focus and still get the amount of background blur you desire. Many online depth of field calculators are available to help you with determining what distances, focal lengths and apertures will work for your needs.

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  • \$\begingroup\$ Can you write a some best calculators for that purpose because what I really would like to have is some 'visual' calculator, which would show how much of 'background' I would see, and how big is the person will be. I know that I like F/1.7 on 85mm and at focus distance I was showing ~5ft in height (~150cm). So now I want to see the same size of person, with in a focus area, just I want to put camera way more close, and I want to have blur background (so it should be ~ f/2), but I want to more of the object (a catedral) in behind the person. On 85mm it was getting only fountain in the back. \$\endgroup\$
    – KestutisIT
    Jul 31, 2013 at 5:19
  • \$\begingroup\$ @KestutisITDev - weird, I didn't get a notification about your comment for some reason, but I see you found a DoF calculator you like from your own answer. But yeah, there are lots of good ones out there, I personally normally just use one on my phone or whatever comes up first in Google. :) \$\endgroup\$
    – AJ Henderson ♦
    Jul 31, 2013 at 14:00
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So I ended up with this calculator: http://www.dofmaster.com/dofjs.html

And I accidentally found a lens which I really liked - it had very best reviews about the Image quality, very beautiful Bokeh, and had lowest possible distortion in this range.

So I bought Sigma 30mm F/1.4 EX DC for Sony Alpha (from Amazon):

http://www.sigmaphoto.com/product/30mm-f14-dc-hsm-a

  1. It has autofocus,
  2. It has a perfect F/1.4 aperture
  3. It is only costs $400 now (on Sale)
  4. I also have a Sigma 18-250mm Zoom lens and I have filters for it, and these filters are 62mm, so I can reuse all my filters :)
  5. It will give me much wider background view than I got from Sigma 85mm F/1.4
  6. I will be able to go again to F/1.7
  7. And the Auto-focus works well, better than in Sigma's 24mm F/1.8 and 28 F/1.8 models

I believe I will be happy with It, because when I found that this lens is supported by Sony, I felt 'oh, I was searching for this lens, and I finally felt that "I found it" feeling'

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    \$\begingroup\$ If you have the 18-250mm, why don't you give a try to the framing with that focal length? The perspective will be the same (although with more DOF and less sharp). \$\endgroup\$
    – fortran
    Jul 31, 2013 at 9:05
  • \$\begingroup\$ I did had a time to play at that moment with my zoom lens. So it is post-poned to online search. \$\endgroup\$
    – KestutisIT
    Jul 31, 2013 at 9:26
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You were saying that the background is blurred. When you're shooting around f/1.7-f/3, you're going to get a blurred background. The wider the aperture is, the shallower the depth of field. As you stop down to say maybe f/5.6-f/8, more will be in focus due to there being a deeper depth of field. I'd recommend shooting f/5.6-f/8. Anything above f/10 is closing the aperture too much. In order to compensate, adjust the ISO, exposure, or shutter speed. I think you said you're taking video, so don't increase the shutter speed too much, or else it will give audiences headaches due to the lack of motion blur. Of course, you can add in motion blur later, but you're making yourself do more work in post.

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  • \$\begingroup\$ Dude, I want that background would be blured. I don't want to go over F/2 in that case when interviewee is sitting. It is beautiful for me, and easy to understand what I'm shooting there. \$\endgroup\$
    – KestutisIT
    Aug 1, 2013 at 1:32

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