Depth of Field and Zoom at DVinfo.net

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

Canon XL and GL Series DV Camcorders
Canon XL2 / XL1S / XL1 and GL2 / XM2 / GL1 / XM1.


Reply
 
Thread Tools Search this Thread
Old July 13th, 2004, 09:59 AM   #1
Major Player
 
Join Date: Aug 2003
Location: Los Angeles, CA
Posts: 817
Depth of Field and Zoom

I read the article on how they are generating native 6x9 from a 4x3 CCD here (thanks Chris) :

http://www.dvinfo.net/canonxl2/articles/article06.php

If I read this correctly, and understand my physics correctly, the use of a smaller portion of the CCD and the resulting 1.35x magnification factor will mean that we have an even wider depth of field than we do now, is that correct? Does have a sense of how bad that will be? The depth of field is definitley my least favorite part of dealing with the 1/3 CCDs anyway.... not helping with the film look there...

BTW, if the 3x4 image has a magnification factor of 1.35x, and you put an existing 16x lens on that camera, does that mean it will act as a 21.6x lens? Does the math work that way? Does that also mean if you put the new 20x lens on an XL1s that it will be a 14.8x lens?

What do you think?
__________________
Barry Gribble
Integral Arts, IMDB
Barry Gribble is offline   Reply With Quote
Old July 13th, 2004, 10:23 AM   #2
Trustee
 
Join Date: Sep 2003
Location: Saguenay, Québec, Canada
Posts: 1,051
If I understand the way lenses work correctly, the number of x represent the number of time the field of view is in telephoto, compared with the one in wide angle. so 20x is 20x, 16x is 16x, but if you put one of these on the Xl1, the lens will be a little bit more wide.
__________________
Jean-Philippe Archibald
http://www.jparchibald.com - http://www.vimeo.com/jparchib
Jean-Philippe Archibald is offline   Reply With Quote
Old July 13th, 2004, 11:18 AM   #3
Trustee
 
Join Date: May 2003
Location: Atlanta GA
Posts: 1,427
My understanding was similar except that the 16x lens (since it was originally made for the xl1) will be a little longer on the xl2 and the 20x lens (since it was made for the xl2) will be a little wider.
Nick Hiltgen is offline   Reply With Quote
Old July 13th, 2004, 11:46 AM   #4
Wrangler
 
Join Date: Dec 2002
Location: Mays Landing, NJ
Posts: 11,543
Re: Depth of Field and Zoom

<<<-- Originally posted by Barry Gribble : What do you think? -->>>

I think the DOF in 16:9 mode should match the XL-1s since the full chip width is used, and that appears to be what Canon designed this camera for. Aside from that, you might expect it to behave more like a 1/4" camcorder such as the GL-2 in 4:3 mode. I think someone mentioned in another thread that the XL-2 is rated at 5 lux which is evidently less than the XL-1s and probably the result of the higher pixel count chips. (sorry if that's not correct, the info is pouring in faster than I can absorb it!)
Boyd Ostroff is offline   Reply With Quote
Old July 13th, 2004, 01:23 PM   #5
Regular Crew
 
Join Date: Apr 2004
Location: Huntsville, Alabama
Posts: 44
As I just posted in the thread on CCDs, the image size of the 4:3 section on the XL2 should measure exactly 1/4", for what it's worth (I ran some simple math to calculate it).

The low light rating is almost certainly a result of this (not the pixel count) because with a smaller area you can't absorb as much light.
__________________
Russell Newquist
http://www.russellnewquist.net/
Russell Newquist is offline   Reply With Quote
Old July 13th, 2004, 01:39 PM   #6
Trustee
 
Join Date: Oct 2001
Location: San Luis Obispo CA
Posts: 1,189
I checked into the lux ratings between the xl1s and xl2, and at least by my reading of it, the xl2 does appear to be an improvement in this area. The 5 lux rating refers to 1/60 sec at f1.6 on the xl2, whereas the 2 lux rating of the xl1s is at 1/8 sec. Now all things being above board here, I think that means the xl1s lux rating is actually 16. Of course your mileage may vary. Both Camera's still carry the 100 lux recommended illumination.

The pixel pitch looks slightly better than the gl2, 345k vs 410k in 1/4inch chip...so I think, given canons claim of new noise free image processing, the low light sensitivity should be pretty good. We'll all know soon.

Regarding depth of field.. I think we might see a slight increase in DOF in 4:3 mode, and possibly a slight decrease in 16:9 mode( compared to the xl1s 4:3) due to the chips higher native resolution.

Barry
Barry Goyette is offline   Reply With Quote
Old July 13th, 2004, 03:01 PM   #7
Warden
 
Join Date: Mar 2002
Location: Clearwater, FL
Posts: 8,267
If the image size of the subject needs to be a specific size (models head) then the DOF will increase on the smaller cop of the chips. As it stands now with smaller chips the head will be too large and to get a smaller head a wider angle lens will need to be used or the camera position will need to be moved back from the subject. Either or both will result in an increase of DOF.

Lux ratings are misleading because you don't have enough information to know how Canon measured the lux ratings. Lux ratings are at best a rough guide or estimation of low light performance.
__________________
Jeff Donald
Carpe Diem




Search DVinfo.net for quick answers | Where to Buy? From the best in the business: DVinfo.net sponsors
Jeff Donald is offline   Reply With Quote
Old July 13th, 2004, 07:10 PM   #8
Major Player
 
Join Date: Aug 2002
Location: Eugene, Oregon
Posts: 366
As I mentioned on another thread, my measurements of the XL2 CCD sensing areas in 4:3 mode are .238-inch or a bit less than 1/4 inch. The 35% upshift in magnification with the smaller sensing area of the XL2, would give 21.6X when using the older 16X lens from the XL1.

If you used the 1.6X Canon telextender
accessory, mounted under the lens, you'd get 34.56X with the older lens and 32X with the new one. Adding the Century Precision Optics 1.6X telextender on the ends of these lenses, together with the Canon 1.6X extender, would produce
53.29X with the old lens and 51.2X with the new one.

Steve McDonald
Steve McDonald is offline   Reply With Quote
Old July 13th, 2004, 07:14 PM   #9
Trustee
 
Join Date: Sep 2003
Location: Saguenay, Québec, Canada
Posts: 1,051
Steve, a 16x lens remain a 16x lens on any camera. The number of X is not a magnification factor. See my first comment on this thread.
__________________
Jean-Philippe Archibald
http://www.jparchibald.com - http://www.vimeo.com/jparchib
Jean-Philippe Archibald is offline   Reply With Quote
Old July 13th, 2004, 07:50 PM   #10
Trustee
 
Join Date: Apr 2002
Location: Auckland, New Zealand
Posts: 1,727
Jean-Phillipe, it is still a "relative" magnification factor right? If you look through the lens at fill wide, and then zoom in on something to full tele, a 16x lens will make that object look 16x bigger? Now I know that lenses all start at different magnifications and the CCD affects that starting magnification but the relative magnification is what the XXXx means correct?

Aaron
__________________
My Website
Meat Free Media
Aaron Koolen is offline   Reply With Quote
Old July 13th, 2004, 07:58 PM   #11
Trustee
 
Join Date: Sep 2003
Location: Saguenay, Québec, Canada
Posts: 1,051
Yes, you are right Aaron, but the 16x lens (or the 20x for that matter) will be a 16x lens (16 times the field of view in full telephoto) on the both the XL1 or XL2. But the value of the focal lengh in terms of 35 mm equivalent will change depending of the camera due to the change of CCD size used. But I am not an expert and I can be wrong on that, in that case, correct me.
__________________
Jean-Philippe Archibald
http://www.jparchibald.com - http://www.vimeo.com/jparchib
Jean-Philippe Archibald is offline   Reply With Quote
Old July 13th, 2004, 07:59 PM   #12
Major Player
 
Join Date: Aug 2002
Location: Eugene, Oregon
Posts: 366
Jean-Phillippe, as you say, the 16X and 20X zoom ranges of the two lenses stay the same, regardless of the cameras on which they are used. However, since the CCD sensing area of the XL2 is smaller than that of the XL1, the magnification effect with any lens is greater when it's used on the XL2.

The zoom range and the amount of magnification a lens gives on a certain camera, are indeed two separate specifications. But, there's a positive correlation between the two figures, with any lens on amy camera.

Some persons are speaking of the zoom range and the magnification effect of a lens, as though it were like comparing apples and oranges. It seems to me more like comparing size ranges of two varieties of apples.

Steve McDonald
Steve McDonald is offline   Reply With Quote
Old July 13th, 2004, 08:12 PM   #13
Warden
 
Join Date: Mar 2002
Location: Clearwater, FL
Posts: 8,267
The zoom ratio (10X, 16X, 20X etc.) has no relationship to magnification (focal length of lens). A 4mm to 80mm lens (20X zoom ratio) would have less magnification than a 10mm to 100mm lens (10X zoom ratio). The smaller the chip the greater the magnification if subject size is to remain the same.
__________________
Jeff Donald
Carpe Diem




Search DVinfo.net for quick answers | Where to Buy? From the best in the business: DVinfo.net sponsors
Jeff Donald is offline   Reply With Quote
Old July 13th, 2004, 08:37 PM   #14
Trustee
 
Join Date: Apr 2002
Location: Auckland, New Zealand
Posts: 1,727
OK, I think we're getting confused here - and it's quite possible it's me!

Magnification is a relative comparison is it not? It's not absolute. So if I magnify something 2 times, it's twice the size. If I'm right then the "magnification" of a 4-80 *IS* more than a 10-100 because the 4-80 will magnify something that you're looking at by 20 times from full wide to full tele, but the 10-100 will only magnify it 10 times from wide to tele. Am I not right here?

Aaron
__________________
My Website
Meat Free Media
Aaron Koolen is offline   Reply With Quote
Old July 13th, 2004, 08:49 PM   #15
Trustee
 
Join Date: Oct 2001
Location: San Luis Obispo CA
Posts: 1,189
Aaron....magnification is a bad term...we all use it, but it actually refers to things like microscopes...things with a ratio of 1:1 or greater. That said magnification is not really a relative term in the sense you are talking about, a 20x microscope would magnify its subject by a specific amount relative to the viewer. A video lens that is a 20x has no such specificity to it. Its simply a term to describe the RANGE of the zoom, or the relationship between its widest setting and its longest setting. I think you are using the word magnification to refer to this relationship, and that's where you're going wrong.

If we were to apply the word magnification to a video camera lense (we'd be incorrect, but in the same sense as we would a microscope) then the longer the maximum setting, then the greater the "magnification".

Am I getting somewhere?

Barry
Barry Goyette 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 XL and GL Series DV Camcorders

Thread Tools Search this Thread
Search this Thread:

Advanced Search

 



Google
 

All times are GMT -6. The time now is 09:22 PM.


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