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gmitchel
3rd of July 2004 (Sat), 13:22
I really like the Lens Blur filter in PS CS. It does a much better job of blurring backgrounds than a simple Gaussian Blur.

I've added two images to this post. The first is a simple JPG directly from the RAW file. It is an image of a white iris from Leu Botanical Garden in Orlando, FL. I used a Canon 10D camera, a Kirk Dual Macro Flash Bracket, 2 Canon 550EX flashes, and a Canon 180mm "L" macro lens.

As you can see, I pretty well nailed the exposure. I used f/32 for maximum DOF because I wanted to get the iris sharp from petal tip to petal tip. Unfortunately, f/32 also allows a lot of background detail.

I cropped the image to 4:5 aspect ratio. Duplicated the background layer. Converted the image to 8-bits, since the Lens Blur filter is 8-bits only.

For the reduced DOF, I started with a mask of the white flower. I used the red channel to make the mask. It took all of two minutes to generate the mask, save it as an alpha channel, and clean it up with the brush tool. Then I inverted the mask and applied a 1 pixel Gaussian Blur to soften the edges of the mask.

The settings for the Lens Blur filter were:
(1) use the alpha channel as the depth map source
(2) 240 as the Blur Focal Distance
(3) "Invert" check box checked
(4) Hexagon iris shape with 75 for radius and 0 for curvature and rotation
(5) Brightness 20 and threshold 255 for specular highlights
(6) Noise 5, Gaussian distribution
(7) "Monochromatic" checkbox not checked.

The second image shows the final result. You can also see it temporarily on my home page (http://www.thelightsrightstudio.com). I added my new gallery print edge effect to the image. I'm in the process of renovating my galleries, and one of the changes is to use this new gallery print look to my Web images.

The background is much less distracting. I get the benefit of maiximizing DOF for the white iris while narrowing the DOF behind the iris in a way that looks very similar to the bokah I expect with my 180mm "L" macro lens.

Comments are welcome!

Cheers,

Mitch

http://www.thelightsrightstudio.com/samples/leugardens_0028_rawtojpg.jpg

http://www.thelightsrightstudio.com/LeuGardens_0028_Cropped_Framed_Web550.jpg

Meerkat17
3rd of July 2004 (Sat), 16:55
Great effect Mitch,
Just a shame I can't use it on my background as I don't have CS and PS7 doesn't have the Lens Blur filter :cry:

However, love the flower and the sharpness of the final output, reall nice whites too.

Regards
David

gmitchel
5th of July 2004 (Mon), 06:54
Thanks, David.

I nailed the exposure. I did not need to adjust the exposure at all in PS. I applied a +2/3 stop exposure compensation on the camera to keep those whites white and not burn them out in the direct sunlight.

The only change I made in ACR II was to adjust the shadow tint. It was a -15 change to shift it a touch more green.

It is true that you need PS CS for the lens blur effect. It's one of the things that makes PS CS worth the price of admission: 16-bits for layers and most tools, ACR II, lens blur filter, etc.

Cheers,

Mitch

gmitchel
1st of August 2004 (Sun), 20:15
I added a tutorial to my site today that explains how to use the Lens Blur filter to reduce the DOF in your images.

http://www.thelightsright.com

Cheers,

Mitch