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Depth of Field in renders

John SimsJohn Sims Posts: 360
edited July 2019 in The Commons

We all like a bit of DoF in our renders to help focus the eye and make the render look more photographic ....and here is the crux. With no disrespect to the providers, there seems to be a proliferation of HDRis with DoF. Many of these are scenes with bright sunlight, and this is where I tend to question the inclusion of significant DoF.

In real photography limited DoF is a result of wide apertures and/or a long focal length lens.  In bright sunlight it can be difficult to create the boken of DoF as the aperture needs to be closed down due to the bright sunlight. You can use a longer lens and neutral density filters but, without post processing, you need to try hard and have some pretty advanced kit. Just using a longer lens also has its issues as the foreshortening effect of the lens can also impact on the image. You can ramp down the iso and increase the shutter speed but, as noted above, you have to be trying hard.

My point is, in bright sunlight, full figure posed shots are unlikely to have significant limited DoF, in real life. As such including same can tip that ballance between what looks real and what looks like a 3D render. Alternately, if you are going for a paparazzi type candid spy shot taken from extreme distance, with a massive lens, then minimum DoF (lots of boken/blur) is the way to go.

Just my thoughts but one of those things when you look at a render and think "Why doesn't that look real?", it might be inappropriate DoF. 

Post edited by John Sims on

Comments

  • Richard HaseltineRichard Haseltine Posts: 108,000

    Sorry to go off on a tangent, but I'm puzzled by the comment about focal length. The more zoom I have the higher the minimum f-stop, and DoF effects are usually exaggerated by low f-stop. I don't dispute the end result, you obviously have far more knowledge than me, but I find it puzzling.

  • John SimsJohn Sims Posts: 360
    Richard Haseltine said:

    Sorry to go off on a tangent, but I'm puzzled by the comment about focal length. The more zoom I have the higher the minimum f-stop, and DoF effects are usually exaggerated by low f-stop. I don't dispute the end result, you obviously have far more knowledge than me, but I find it puzzling.

     

    Longer lenses do tend to be slower (smaller maximum apperture), unless you are spending big money, just due to the physics of the lens. None the less if you read the relative specifications you will find that DoF diminishes as the focal length increases. Older zoom lenses (Tamron SP for example) would have scales on the side of the lens barrel which indicate this quite well.

  • Richard HaseltineRichard Haseltine Posts: 108,000
    John Sims said:
    Richard Haseltine said:

    Sorry to go off on a tangent, but I'm puzzled by the comment about focal length. The more zoom I have the higher the minimum f-stop, and DoF effects are usually exaggerated by low f-stop. I don't dispute the end result, you obviously have far more knowledge than me, but I find it puzzling.

     

    Longer lenses do tend to be slower (smaller maximum apperture), unless you are spending big money, just due to the physics of the lens. None the less if you read the relative specifications you will find that DoF diminishes as the focal length increases. Older zoom lenses (Tamron SP for example) would have scales on the side of the lens barrel which indicate this quite well.

    Thank you.

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