Bokeh-Focus-Object Shrinkage Effect? at DVinfo.net

Rob Johnson · September 26th, 2015, 08:43 AM

Ok, so OCD is acting up and trying to find this is driving me nuts. What is the specific name of the effect when the apparent size/outline of an object out-of-focus (blur, bokeh, blah) seems to appear larger than it really is when it actually comes into focus? The effect is subtle, and it isn't a much-covered subject. I learned about it years ago ... just can't remember the name of the effect. Anybody?

Jim Andrada · September 27th, 2015, 08:44 PM

Maybe you're thinking of Focus Breathing???? Google it and see if it's what you're thinking of. Basically image size changing as you focus.

Matt Sharp · September 28th, 2015, 01:02 AM

I think you're talking about bokeh. The way objects look in the out of focus areas. I have no idea if there's a specific term regarding the size. Just the correlation of iris, focus distance and lens length to how out-of-focus the background will be.

For example, (from Philip Bloom's speedbooster test.)

Large OOF objects:
http://philipbloom.net/blog/wp-conte...S-670x376.jpeg

Small OOF objects as focus goes closer to them:
http://philipbloom.net/blog/wp-conte...4-670x376.jpeg

Jack Zhang · September 28th, 2015, 02:44 PM

It does sound like lens breathing. Cheaper manual focus lens tend to breathe when rack focusing. It gives the illusion that the object is larger when in fact the entire frame is pushed in when the focus "breathes"

High end productions don't like lens breathing, which is why PL lenses in the higher price range rarely focus breathe. If you want focus breathing, any cheap Samyang Prime might do.

Rob Johnson · October 2nd, 2015, 12:39 PM

Quote:

Originally Posted by Jim Andrada

Maybe you're thinking of Focus Breathing?

Quote:

Originally Posted by Jack Zhang

It does sound like lens breathing.

Yes that's it exactly. Len/Focus breathing. Couldn't remember for the life of me! Thanks.

Jim Andrada · October 3rd, 2015, 10:46 PM

Glad we could fill in the mental blanks for you. I have more and more of them every year. Now just where did I leave my car keys???

September 26th, 2015, 08:43 AM	#1
Rob Johnson Regular Crew Join Date: Jul 2007 Location: Ft Myers, Florida Posts: 65	Bokeh-Focus-Object Shrinkage Effect? Ok, so OCD is acting up and trying to find this is driving me nuts. What is the specific name of the effect when the apparent size/outline of an object out-of-focus (blur, bokeh, blah) seems to appear larger than it really is when it actually comes into focus? The effect is subtle, and it isn't a much-covered subject. I learned about it years ago ... just can't remember the name of the effect. Anybody?

September 27th, 2015, 08:44 PM	#2
Jim Andrada Inner Circle Join Date: Feb 2007 Location: Tucson AZ Posts: 2,211	Re: Bokeh-Focus-Object Shrinkage Effect? Maybe you're thinking of Focus Breathing???? Google it and see if it's what you're thinking of. Basically image size changing as you focus.

September 28th, 2015, 01:02 AM	#3
Matt Sharp Major Player Join Date: Nov 2010 Location: Northridge, CA Posts: 280	Re: Bokeh-Focus-Object Shrinkage Effect? I think you're talking about bokeh. The way objects look in the out of focus areas. I have no idea if there's a specific term regarding the size. Just the correlation of iris, focus distance and lens length to how out-of-focus the background will be. For example, (from Philip Bloom's speedbooster test.) Large OOF objects: http://philipbloom.net/blog/wp-conte...S-670x376.jpeg Small OOF objects as focus goes closer to them: http://philipbloom.net/blog/wp-conte...4-670x376.jpeg

September 28th, 2015, 02:44 PM	#4
Jack Zhang Inner Circle Join Date: May 2005 Location: Burnaby, BC, Canada Posts: 3,053	Re: Bokeh-Focus-Object Shrinkage Effect? It does sound like lens breathing. Cheaper manual focus lens tend to breathe when rack focusing. It gives the illusion that the object is larger when in fact the entire frame is pushed in when the focus "breathes" High end productions don't like lens breathing, which is why PL lenses in the higher price range rarely focus breathe. If you want focus breathing, any cheap Samyang Prime might do.

October 3rd, 2015, 10:46 PM	#6
Jim Andrada Inner Circle Join Date: Feb 2007 Location: Tucson AZ Posts: 2,211	Re: Bokeh-Focus-Object Shrinkage Effect? Glad we could fill in the mental blanks for you. I have more and more of them every year. Now just where did I leave my car keys???