1/3 v 1/4 inch chips... whats the difference
 

hi,

i just wondered if someone could explain to me what the benefits would be by having 3x1/3 inch chips over 3x1/4 inch ones.

cheers

tony

3 things I can think of, given the chips have the same resolution and specs.

1. the 1/3 in chip will be more sensitive...ie need less light to achieve exposure (the pixels are larger, and less densely packed, and thus gather more light)

2. The 1/3 inch chip will probably have less noise (for the same reason as #1).

3. the 1/3 inch chip will have somewhat less depth of field, which is typically preferred as it lets the user isolate focus...difficult with most dv cameras.

However, the differences between the two sizes is not great, so differences will be subtle rather than glaring.


Barry

Barry, because of #1, can #3 be equalled out? What I mean is because 1/4 chips are less sensitive, you might have to open the iris more, and hence reduce the depth of field to get the same exposure. Is this correct thinking? Assuming I am on the right track here, will the amount required to get equal exposure make the DoF's about the same? Take for example with the Xl1s and the Gl2, will exposing them the same with increased aperture on the Gl2 give them similar DoF? I'd really like to see some tests done of this sort!

Regarding depth of field, facter in the lens differences as well, and how much zoom (or no zoom) the cameras are set with.

Aaron

Yes, in fact, I did note in my review and comparison of the gl2, pd150 and xl1s, that the gl2's lower sensitivity ended up having the effect of the same or slightly less depth of field in a close up shot with identical lighting... (you can see it in the still life comparison stills link in the review)

However the PD 150 and xl1 are still capable of less (better) depth of field (through the addition of ND, increased shutter speed, or lowered light level) than the 1/4 inch gl2 is capable of....ie. lens wide open the image on the 1/3 inch chip would have less DoF than the image on a 1/4 chip. (if we get too far into this, someone's gonna start yelling that depth of field has nothing to do with chip size, but rather the focal length and angle of view of the lens required to produce the image on the chip....but the result is the same.)

In Practice, I know that there is a distinct difference between my xl1s and gl2 in terms of depth of field...the xl1s has significantly less.

Additionally, there are a multitude of reasons you might want a chip with more sensitivity, as it extends the range of your lighting options (you can always add ND to lower the exposure, but you can't always add more light).

Barry

****Regarding frank's point, lets assume the cameras are positioned at the exact same point, with the lenses zoomed to produce identical images on their respective chips.

Barry

So Barry would you say if you were going for a (And here is that horrible phrase again) "film look" i.e. Nice tones, in a well lit scene with nice DoF for a close up or something, would something like the XM2 (GL2) be better overall than the old Xl1? Even though the Xl1 can give less DoF, the XM2 is superior in it's image adjustments and resolution. I can see myself wanting to use a nice low DoF in some shots and can't afford the xl1s so it'd be the old XL1 as an alternative to getting the XM2. Any opinions?

Cheers
Aaron

Aaron

I've only touched an old xl1 for about 5 minutes. It was at b&H in NY, and I felt the image was pretty bad...(although this opinion is also swayed by the fact that the image was displayed on an 800 line monitor, sitting next to another 800 line monitor hooked up to a $16,000 sony). It was soft, and harsh (two things you don't want at the same time).

The gl2 is about 5 years ahead of the old xl1, and the image is sharp, yet delicate, and there's room to soften it in camera if you like that sort of look. Additionally, the gl2 has most of the feature set of the newer xl1s. I'm not sure why anyone would invest now in older, non-upgradable technology.

With the gl2, you don't get a manual zoom, or an auto zoom that is as accurate as the xl1, but you get a lens that is arguably sharper throughout its entire range, and an autofocus system that is a bit slower, but is otherwise superior.

As to doing DoF shots...it will be a struggle with the gl2, but its possible. The gl2's lens is very sharp even wide open, so as long as you zoom in a bit, and keep your subject framed tightly, you should be able to throw the background out, albeit less than with the xl1.

As far as "film-like". The gl2 with it's lower contrast and higher resolution, delivers the most film like image I've seen from a camera in this class.

Barry

Thanks for that Barry. It looks like what I really want is an Xl1s ;) haha, but I'm not forking out that much dosh for one. I think I'll stick with getting a XM2 unless something like an old Xl1 comes up ridiculously cheap.

Cheers
Aaron

No one has mentioned that a 1/4-inch CCD camera will give more zoom power than one with 1/3-inch CDDs, if they both have the same lens.

Zoom will be the same: 12X = 12X, etc.

The zoom range will stay the same (10mm to 100mm zoom is 10x). But take a lens from a 1/3 in chip and put it on a 1/4 inch cip and the image size will increase by 1.3X. So, for example, a 50mm lens on a 35mm camera is considered normal (1X) because it approximates the angle of view of the human eye. The same 50mm lens on a 1/3 inch chip increases the image size 7.2X and on a 1/4 inch chip by 9.5X.

Jeff

If the question was the difference between the two in size and not gains in technology, the answer would be resolution wouldn't it? The larger the CCD the more information can be gathered. But to compare the technological gains of the GL2 to the older XL1 you would have to speak of years worth of research that allow more and more pixels in a smaller area. I have read the new GL2 has 480,000 pixels per CCD. I believe an XL1S is 270,000. If a 1/3 inch CCD were built today with GL2 technology it would have much better resolution than the 1/4". Smaller CCD's as far as I can see were used because of the expense of building larger ones. I think we are talking apples vs oranges.

" i just wondered if someone could explain to me what the benefits would be by having 3x1/3 inch chips over 3x1/4 inch ones."

Is there truly any benefits of a 1/3 inch CCD over 1/4, given the same technology used to build the two, I would say resolution, it is just the GL2 has newer technology in it's 1/4 CCD's.

One question to ask is, is the newer technology perfected, are the new pixels as good as the older ones? sensitivity, artifacts, etc.

Actually, increased resolution is not necessarily a given, as the gl1 and xl1s have the same resolution on different size chips (270k). One of the benefits of larger chips has been to increase the size without changing resolution, thus giving higher sensitivity, and lower noise characteristics. (this has also been the trend in higher end digital still camera's). Note that the new panasonic ag-dvx100 has 1/3 inch chips at the same resolution (410k) as the gl2 (panasonic makes the gl2's chips), and these 1/3 inch chips would be a likely candidate for inclusion in an XL2.

Conversely, sony's new cameras are putting more resolution on 1/5 inch chips than the pd150 has on a 1/3inch.

Barry

We are back to a question just being asked before the great server crash, can the XL1S be retrofitted with new chips or is the component that recieves the data from the CCD's incompatible with larger amounts of info.

It is not possible to retrofit a camera with newer CCD's at any place or time other than the manufacturer's initial point of assembly. In other words, the XL1S itself is already retrofitted with CCD's newer than the original XL1. But will it be done on an individual basis at a service facility, no. There's much more involved than just replacing the chips, and the cost would exceed the value of the camera.

Let's look at it this way. In the beginning, miniDV cams had larger CCDs and less CCD pixels, for the most part. The cam's lux requirements were lower than today's cams and the resolution was lower. Now (for the most part) CCDs have shrunk, and their pixel counts have increased. The result? Higher resolution but higher lux requirements. Just take for example Panasonic's EZ1: 1/3" CCDs, low CCD pixels count = lower resolution but a lower lux requirement---and this cam was small! Now look at today's EZ50U: 1/6" CCDs and mega-pixeled. The result? Higher resolution but the lux sucks! It's just another one of those give and take situations. Okay, I'm off to bed---.

Speaking of depth of field
 

OK, I'm way out of my league, but the size of the CCD has to have something to do with Depth of Field, right? One of the huge headaches (for me) with video is getting those wonderful soft backgrounds with the razor sharp foreground that is so easy to do with film. I thought that the size of the image figured into the equation. That is, it's easier to get narrow DoF with 35mm than with 16mm, and the reason that video has such huge DoFs has to do with the little tiny chip sizes. Am I way confused here?

Ralph

Every thing you said is correct (although there are a few DoF junkies around here that will quibble with true root cause of limited depth of field). Welcome to the league.

Barry

Barry' correct (and by the way I'm a Dof junky, but I'm working my steps) . a very easy way to look at Dof is as follows:

Depth of Field (DOF) is dependent upon the following variations:
a. The focal length of the lens.

b. The diaphragm opening (effective aperture, not F-number).

c. The distance from the lens to the object that is focused on.

d. The distance from which the image is viewed.

e. The viewer's personal standard of the permissible degree of sharpness (or unsharpness).

Other variables remaining constant, it follows that:

a. The shorter the focal length of the lens, the greater the DOF.

b. The smaller the diaphragm opening, the greater the DOF.

c. The greater the distance to the object being focused on, the greater DOF.

d. The greater the distance from which the image is viewed, the great the "apparent" DOF.

The smaller chip size forces you to either change the focal length of you lens or change the distance to the object to keep the subject the same image size. The smaller chip has the effect of making the subject larger. You can make the subject smaller by using shorter focal lengths (increasing DoF) or increasing distance to the subject (increasing DoF). Like Barry says it all works out the same.

Jeff

In response to Ralph's post, as a Betacam SP, DIGI &SX, DVCam (D30, DSR200, & PD150), & DV shooter (VX1000, XL1 (eeech! sorry folks)...

you are absolutely correct when it come to your analogy of the ease with which you can achieve a very shallow depth of field with 35mm compared to 16mm film... it is VERY much the same with 1/3" chips vs. 2/3" chips... even with neutral density (internal & external) distance to subject, and every other trick the previous posters have brought up, there are sometimes that I just cannot under any circumstance get the background as out of focus as I would like when I am using a camera with 1/3" chips... I'm in the process of trying to educate my clients of this as well but a goodly number of them just don't understand...

In a perfectly controlled environment which is lit well and with a great amount of space at your disposal (which almost never happens in the real world), it would be somewhat easier, but I maintain that imaging device target size is one of the most crucial (if not THE most crucial) variable in the DoF debate/struggle...

Please understand as well that sometimes the benefits of a large DoF outweigh the drawbacks (I NEVER comeback with footage that the clients says "well... that looks a LITTLE soft on my broadcast monitor")

Good shooting!!!