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You are here: Home / The Last Word / Comparing real and simulated defocus blur — Zeiss 135/2 Apo-Sonnar

Comparing real and simulated defocus blur — Zeiss 135/2 Apo-Sonnar

May 5, 2017 JimK Leave a Comment

This is the fifth in a series of posts about building a bokeh simulator. This series starts here.

In the last post, I compared simulated defocusing to the real thing with the Sony 135mm STF lens. Now I’m going to do the same thing with teh Zeiss 135mm f/2 Apo=Sonnar ZF.2. Here’s a sharp image with an a7RII at f/11:

Zeiss 135/2 Apo-Sonnar, sharp

Then I opened the lens up all the way and defocused by moving the focus point nearer to the camera:

Actual defocused image

Next I used the simulator with the actual 135/2 Apo-Sonnar OOF PSF, and told the simulation to make the blur circle 30 pixels in diameter on the 1500×2250 downsampled image I was using:

Actual Zeiss 135 OOF PSF — 30 px blur circle

Then I set the simulator for a perfect 30-pixel blur circle on the same 1500×2250 downsampled image. It also looks like there is an exposure difference.

Simulated defocusing, 30 px disk OOF PSF

Looks like the actual blur circle was a bit less than the sim.

I defocused a little more:

Actual defocusing #2

Then I used the real OOF PSF with a 40-pixel blur circle diameter;

Actual Zeiss 135 OOF PSF — 40 px blur circle

And a ideal 40-pixel blur circle:

Simulated defocusing, 40 px disk OOF PSF

Even more defocusing:

Actual defocused image

 

Simulated defocusing, 50 px disk OOF PSF

 

Simulated defocusing, 50 px disk OOF PSF

In this case, a 50 pixel blur circle wasn’t’ enough.

 

 

 

The Last Word

← Comparing real and simulated defocus blur — Sony 135 STF Adding off-axis imaging to the bokeh simulator →

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