Help With Depth of Field on GL2... at DVinfo.net

Ash Varma · February 21st, 2008, 07:45 AM

Hi All,

I have recently purchased a GL2 and having trouble getting a proper DOF shot. I have a talent at the front and a talent in the background. I'd like to move focus from the subject in the background to the subject in the front and vice versa.

This vid has acheived it nicely without any other equipment:

http://www.youtube.com/watch?v=UXbTo6b_bxs

Can someone please guide me step by step on how I can acheive this effect?

Thanks so much in advance.

Todd Clark · February 21st, 2008, 09:18 AM

It is tough with video but the best thing you can do is move the camera back as far as possible and zoom in all the way. Open the iris up as far as it will go. You might need to use the ND filter to keep the shutter speed at 1/60.

Use Manual Focus to change the focus from front to back. It takes practice.

Don Palomaki · February 21st, 2008, 03:36 PM

Also you may have to "over focus" a bit; i.e., focus a bit past the far subject and in front of the near subject so each is just barely within the DOF range for their distance and the other is out of it.

Mike Barber · February 22nd, 2008, 01:02 AM

Quote:

Originally Posted by Todd Clark

the best thing you can do is move the camera back as far as possible and zoom in all the way.

One issue with zooming "all the way" is the spatial compression that occurs. Be sure to look at your blocking through the camera. You may need to cheat a bit and have the actors farther away on the Z axis in order to maintain a realistic looking distance between them.

Sadly, the G2 does not have witness marks on the lense -- but then, why would it? That abomination servo focus defeats the possibility of using them. However, get yourself a roll of white paper tape (aka, artist tape... NOT masking tape!) and wrap some around the focus ring and the lens barrel in order to give you a place to add some reference markers for whoever will do the focus pulling.

Chris Coulson · February 22nd, 2008, 02:49 AM

the technical answers above are all correct, I believe, but just for the dummies (like me) reading this, here's the non-technical answer... (I think)

Low F numbers - F1.8, F2
Maximum zoom

will produce the smallest depth of field. Anything different will make the DOF larger, but you still might find it's good enough for you.

good luck!

Don Palomaki · February 22nd, 2008, 07:40 AM

If you want to spend some more money (~$1000), consider the LETUS product as a way to obtain 35mm film-like DOF with a video camera using 35mm still lenses. see: http://www.letusdirect.com/

Search the forums for "LETUS" for comments by others on this product. And there ares some instructions around on the web for do-it-yourself versions that will cost as little as $15 in materials if you have a reasonable amount of spare/junk stuff around the house and are handy.

Mike Barber · February 23rd, 2008, 12:40 PM

Quote:

Originally Posted by Chris Coulson

Low F numbers - F1.8, F2
Maximum zoom

will produce the smallest depth of field. Anything different will make the DOF larger

That is correct. The two factors involved in DOF are 1)iris diameter and 2) focal length. The issue with automatically jumping to maximum zoom is the spatial compression along the Z-axis that comes with it. You have to balance depth of field with depth perception, so to speak. It's one of those subtle details that tends to get missed.

February 21st, 2008, 07:45 AM	#1
Ash Varma Regular Crew Join Date: Aug 2007 Location: Oakville Posts: 33	Help With Depth of Field on GL2... Hi All, I have recently purchased a GL2 and having trouble getting a proper DOF shot. I have a talent at the front and a talent in the background. I'd like to move focus from the subject in the background to the subject in the front and vice versa. This vid has acheived it nicely without any other equipment: http://www.youtube.com/watch?v=UXbTo6b_bxs Can someone please guide me step by step on how I can acheive this effect? Thanks so much in advance.

February 21st, 2008, 03:36 PM	#3
Don Palomaki Wrangler Join Date: Sep 2001 Location: Northern VA Posts: 4,488	Also you may have to "over focus" a bit; i.e., focus a bit past the far subject and in front of the near subject so each is just barely within the DOF range for their distance and the other is out of it. __________________ dpalomaki@dspalomaki.com

February 22nd, 2008, 07:40 AM	#6
Don Palomaki Wrangler Join Date: Sep 2001 Location: Northern VA Posts: 4,488	If you want to spend some more money (~$1000), consider the LETUS product as a way to obtain 35mm film-like DOF with a video camera using 35mm still lenses. see: http://www.letusdirect.com/ Search the forums for "LETUS" for comments by others on this product. And there ares some instructions around on the web for do-it-yourself versions that will cost as little as $15 in materials if you have a reasonable amount of spare/junk stuff around the house and are handy. __________________ dpalomaki@dspalomaki.com

February 21st, 2008, 09:18 AM	#2
Todd Clark Regular Crew Join Date: Feb 2007 Location: Parma, Oh Posts: 172	It is tough with video but the best thing you can do is move the camera back as far as possible and zoom in all the way. Open the iris up as far as it will go. You might need to use the ND filter to keep the shutter speed at 1/60. Use Manual Focus to change the focus from front to back. It takes practice.

February 22nd, 2008, 02:49 AM	#5
Chris Coulson Regular Crew Join Date: Feb 2008 Location: Kent, UK Posts: 101	the technical answers above are all correct, I believe, but just for the dummies (like me) reading this, here's the non-technical answer... (I think) Low F numbers - F1.8, F2 Maximum zoom will produce the smallest depth of field. Anything different will make the DOF larger, but you still might find it's good enough for you. good luck!