Circle of Confusion Calculations and A1 ccd at DVinfo.net

Go Back   DV Info Net > Canon EOS / MXF / AVCHD / HDV / DV Camera Systems > Canon HDV and DV Camera Systems > Canon XH Series HDV Camcorders

Canon XH Series HDV Camcorders
Canon XH G1S / G1 (with SDI), Canon XH A1S / A1 (without SDI).


Reply
 
Thread Tools Search this Thread
Old February 1st, 2008, 02:01 PM   #1
Regular Crew
 
Join Date: Jan 2007
Location: Austin, TX
Posts: 157
Circle of Confusion Calculations and A1 ccd

I'm trying to calculate a reasonable CoC to use in calculating hyperfocal distance, DOFmax, etc for the A1.

First- Does anyone know the actual ccd dimensions of the A1? I know traditional 1/3" chips are 4.8mmx3.6mm but I'm assuming that the A1 native 1440x1080 results in alternate dimensions.

Second- Am I correct in assuming that a very large CoC can be used for a 1/3" video chip relative to a 1/3" piece of film - as the video's limited resolution would become apparent much more readily than would any circles of confusion as the image is blown up?

If this is the case, how on earth can we decide on a reasonable diameter for CoC?
Cal Bickford is offline   Reply With Quote
Old February 1st, 2008, 02:39 PM   #2
Wrangler
 
Join Date: Sep 2001
Location: Northern VA
Posts: 4,294
You should be able to calculate the active portion chip size it from the field of view and focal length. Video pixels typically are not square. Keep in mind that film grain is random, CCD pixels have a fixed size and fixed location.

Last I knew, camcorders rate CCD size using the old tube convention (not actual physical size) to retain consistent lens performance expectation; i.e., a given focal length lens would produce the same FOV with a 1/3" tube- or 1/3" CCD-based camera.
__________________
dpalomaki@dspalomaki.com
Don Palomaki is offline   Reply With Quote
Old February 1st, 2008, 08:04 PM   #3
Regular Crew
 
Join Date: Jan 2007
Location: Austin, TX
Posts: 157
Ok so basically I'm assuming that the A1's vertical dimension will be identical to a traditional 1/3" chip and I'm assuming that the width of one pixel (vertically - as this is the shortest dimension anyways) would be the logical choice for max CoC.

Therefore: 3.6mm/1080 = 0.00013 INCHES

This is considerably less than the traditional CoCmax in film of .001 in. and even the more contemporary (due to refined technology) CoCmax of .0005 in.

In fact, a safe CoCmax would probably need to be even smaller than this to take into account the fact that each pixel is probably not actually .00013 in. across vertically due to chip space around the individual light sensitive bays and around the borders of the chip (I am only assuming this as I certainly have little knowledge of how an actual chip is engineered.)

So maybe a CoCmax of .00005 or .000075 in. is more appropriate.

Can anyone see anything wrong with my methodology here?
Cal Bickford is offline   Reply With Quote
Old February 1st, 2008, 08:22 PM   #4
Regular Crew
 
Join Date: Jan 2007
Location: Austin, TX
Posts: 157
ok so i crunched some quick #s and with a CoC of .000075in. and the A1 at full wide (4.5mm) and f4 the Hyperfocal distance would be 8.7 ft.

So if you wanted max DOF at this focal length and and fstop you would throw your critical focus at 8.7 ft and have everything in focus from about 4.35 ft to infinity.

This sounds like a pretty deep field even for video. Does this sound reasonable to you all? I'd go out and test it out myself right now if I wasn't crippled with the flu : (
Cal Bickford is offline   Reply
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

B&H Photo Video
(866) 521-7381
New York, NY

Z.G.C.
(973) 335-4460
Mountain Lakes, NJ

Abel Cine Tech
(888) 700-4416
N.Y. NY & L.A. 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 HDV and DV Camera Systems > Canon XH Series HDV Camcorders

Thread Tools Search this Thread
Search this Thread:

Advanced Search

 



Google
 

All times are GMT -6. The time now is 01:02 PM.


DV Info Net -- Real Names, Real People, Real Info!
1998-2017 The Digital Video Information Network