Understanding focus? at DVinfo.net

Go Back   DV Info Net > Canon EOS / MXF / AVCHD / HDV / DV Camera Systems > Canon EOS Crop Sensor for HD

Canon EOS Crop Sensor for HD
APS-C sensor cameras including the 80D, 70D, 7D Mk. II, 7D, EOS M and Rebel models for HD video recording.

Thread Tools Search this Thread
Old December 17th, 2009, 07:42 AM   #1
Major Player
Join Date: Jul 2009
Location: Japan
Posts: 295
Understanding focus?

When you set your lens at infinity, depending on the lens, will your shots all be in focus so long as the subject(s) are a certain distance from the camera? I wonder how that distance is measure?
3 lens: Sigma 30 1.4, Tokina 11-16 2.8 and Canon 17-55 2.8.

I want to setup my camera in small makeshift studio by myself (Not help from the wife wanted) to make some video Christmas cards.
Jason McDonald is offline   Reply With Quote
Old December 17th, 2009, 08:21 AM   #2
Major Player
Join Date: Feb 2005
Location: Thunder Bay, ON. Canada
Posts: 374
your markings are on the lens. If you look at the reading when you are zooming it will tell you how far the subject has to be from the lens. To be precise you can pull out the tape measure and be exact.
Jason Bowers is offline   Reply With Quote
Old December 17th, 2009, 08:37 AM   #3
Regular Crew
Join Date: Aug 2006
Location: Brussels, Belgium
Posts: 161
It sounds like you looking for the Hyperfocal Distance for your lenses. This is the focus setting that will provide good focus from infinity to half the selected fousing distance. The Hyperfocal Distance depends on three things: The focal length of the lens, the aperture (f-stop), and your definintion of "good" focus. Here is a chart that you can use to calculate this.

Hyperfocal Distance Chart - DOFMaster

You will see that for wide apertures (low f-numbers), the distances are rather long, so I don't think it will be relevant for your studio (unless you have a really big studio), but for short lenses and high f-stops,it may be useful for finding the greatest depth-of-field.

As you can see, and to answer your question directly, there is a distance where everything behing it will be in focus, but it's not infinity, it's one-half the hyperfocal distance for the particular lens and settings you are using.
Bill Engeler is offline   Reply

DV Info Net refers all where-to-buy and where-to-rent questions exclusively to these trusted full line dealers and rental houses...

Professional Video
(800) 833-4801
Portland, OR

Omega Broadcast
(512) 251-7778
Austin, TX

(973) 335-4460
Mountain Lakes, NJ

Abel Cine Tech
(888) 700-4416
N.Y. NY & L.A. CA

(800) 238-8480
Glendale, CA

Precision Camera
(800) 677-1023
Austin, TX

DV Info Net also encourages you to support local businesses and buy from an authorized dealer in your neighborhood.
  You are here: DV Info Net > Canon EOS / MXF / AVCHD / HDV / DV Camera Systems > Canon EOS Crop Sensor for HD

Thread Tools Search this Thread
Search this Thread:

Advanced Search



All times are GMT -6. The time now is 02:07 PM.

DV Info Net -- Real Names, Real People, Real Info!
1998-2015 The Digital Video Information Network