Jon Fordham's HD10 complete review, Parts 1 & 2

[Craig Jones]

Originally posted by Jeff Donald :

Until you print it, project it or transmit it to a TV. Then differences in CoC, as a variable of film size, chip size etc., will have an effect on DOF.

Since this is a video forum and people's work will be viewed on a TV or projection screen (magnified), it is misleading to ignore CoC and it's impact.

Assuming an identical projected size, the CoC on the imager will be smaller on the smaller imager in proportion to its reduced size. That reduction means that DOF is reduced, but that reduction is offset by the reduced magnification required of the optics to achieve the same perspective. The reduced sensor size means that diffraction effects must be similarly reduced. Since DOF is inversely proportional to the square of magnification and CoC and allowable diffraction are proportional to sensor size, the end result is a wash (except at high mags where effective aperture is different from physical). At low mags and identical physical apertures, the smaller sensor will have larger DOF in proportion to the ratio of sizes.

[Jeff Donald]

Craig, we're in agreement except I've never been to a theatre that projects 35mm film to a 32 inch diagonal. The Inverse Square Law does play a role, as you point out. If you see factor D in my article, the viewing distance (or size of screen, print etc.) has an apparent effect on DOF.

At low mags and identical physical apertures, the smaller sensor will have better DOF in proportion to the ratio of sizes.

If by better you mean a larger DOF, we're in agreement.

[Craig Jones]

I suppose a target viewing size could be unreasonable for one format and not another, but you wouldn't need to compare their DOF performance then. If you wish to compare DOF characteristics of different formats, you must choose a common final viewing standard or the comparison won't make sense. You are correct, viewing angle/distance effects DOF but it does so equally on both formats in the comparison.

I changed "better" to "larger".

[Don Berube]

Hi Craig,

I notice that you own a JVC HD1 in addition to your Sony VX2000?

Do you ever shoot 16:9 on your VX2000? How are you incorporating the HD1 into your work? Will you be considering taking the HD1 underwater with you? Also, would you possibly have any spare time to produce a few side-by-side comparison images between the VX2000 and the HD1? They don't have to be swan song images or such, just a few side-by-sdie examples of any type of subject will do. I thought it would be helpful to get a tangible report of your experiences with the HD1 so far.

I understand if your schedule does not allow for this, but would certainly love to hear your feedback.

- don

[Jeff Donald]

you must choose a common final viewing standard or the comparison won't make sense.

And therein lies the problem with discussions of DOF and personal observations collected in an unscientific manner.

No standards were established at the beginning of the comparisons of the DVX100 and HD10. We must rely on Jon's experience and professionalism to convey his impressions of the cameras performance.

[Les Dit]

So... back to the DOF differing pics that Jon posted: Can the HD10 come close to the short DOF the DVX got in that shot?
I wonder if ND could shorten it that much?

For the academic types: A picture is worth 10^3 words. It's fun to chat about images, but posts of images and viewing them are where it's at.
"Where's the beef?" comes to mind.

-Les

[Jeff Donald]

The two cameras in question, if operated identically and are focused on the same subject, and the subject is of similar proportion, will produce identical DOF.

[Les Dit]

Define "operated identically".

The JVC has no readout of it's aperture setting, that complicates matters. I suppose you could ND the JVC until you see a drop in viewfinder exposure seen, and then assume it is at the widest f stop it can do. Then you have to assume that aperture is what JVC states as the minimum aperture. Too many assumptions for me.
In Jons sample pics, the JVC obviously had enough light to stop down. Says something about LUX ratings, but I don't want to open than can of worms either!
-Les


<<<-- Originally posted by Jeff Donald : The two cameras in question, if operated identically and are focused on the same subject, and the subject is of similar proportion, will produce identical DOF. -->>>

[Jeff Donald]

Les, operated identically is self explanatory.. If the operation of the camera requires too many assumptions for you to be comfortable, then the JVC is probably not the camera for you, at this time.

Ergonomics and features are just as important as picture quality in determining the suitability of a camera to an individual operator. Let alone suitability towards specific projects. If you have a project that requires the limits of shallow DOF then the HD10 may be a less desirable camera. Not because it cannot deliver the limits if it's range of DOF. But, because it is obviously more difficult to accurately reduce the cameras aperture setting. Combine this with the inability to reproduce exact settings i.e. no manual controls, and you have a camera that won't be suitable for everyones needs.

[Heath McKnight]

Whew, I'm sorry I opened a can of worms on this subject! My apologies to all, and thanks to Chris H. for stepping in!

heath

[Les Dit]

Jeff, please explain how the DOF can be held constant on both cameras , even if you operate them identically, if the effective ISO speed of the cameras CCD's are different. You must mean using ND's to control the f-stop , that's all I wanted to clarify.
Are you sure the lowest F number of the two cams in question is the same?
If not, you may not get the same DOF, ( no matter what ND ) I hope you know that!
For most casual users, fumbling with ND's is a hassle, but we do it to coax the consumer grade cams to do what we want.
I own the HD10. I know it's limitations, but it is the camera for me at this time, because it resolves closer to movie film, which I am used to working with digitally at 2 to 3K res starting in 1988.
I always wished for more resolution, and when I saw that in this JVC , I was sold.
No more 'web cam' DV res for me. Hallelujah!
-Les

[Les Dit]

Did some digging.
The Panasonic lens is f1.6
The JVC lens is f1.8.
The JVC's lowest possible DOF is higher than the DVX.

[Jeff Donald]

Les, the problem with most discussions of DOF is the theoretical aspects measured by formulas vs. the observed aspects of viewers. Using standard DOF calculators, the difference between F1.6 and F1.8 is pretty small at most distances and focal lengths. A subject distance of 15 feet and focal length of 10mm, the difference in DOF is just over 2 feet. Because of the subjective nature of individual viewing, the difference in DOF may not be visually apparent to most viewers.

I agree that multiple ND filters is not ideal. There are several operational features that are either missing or inconvenient in their use. This will lead many potential users to wait for the next generation. I can understand pioneers, like yourself, purchasing the HD10. It is a unique camera that offers many great features, but will challenge many, in it's more complicated operation.

[Craig Jones]

Originally posted by Don Berube :

Hi Craig,

I notice that you own a JVC HD1 in addition to your Sony VX2000?

Do you ever shoot 16:9 on your VX2000? How are you incorporating the HD1 into your work? Will you be considering taking the HD1 underwater with you? Also, would you possibly have any spare time to produce a few side-by-side comparison images between the VX2000 and the HD1? They don't have to be swan song images or such, just a few side-by-sdie examples of any type of subject will do. I thought it would be helpful to get a tangible report of your experiences with the HD1 so far.

I understand if your schedule does not allow for this, but would certainly love to hear your feedback.

- don

I have not used the VX-2000 in 16:9 mode nor tried to combine footage from the two cameras.

I've worked with Gates to develop the JVC housing (which is now in early production). I haven't received my housing, though. I intend to use it mainly underwater but my first real underwater test won't be until February. Until then it will be pool tests only.

[Heath McKnight]

Don't use the VX2000 (or XL-1s) in 16:9 mode, the chips aren't powerful enough.

heath