Hvr Z7 & S270 Pan & Tilt Problem

[Arlen Sahakian]

well i have the both cameras Z7 and the S270 and i noticed that when u make a pan shot or a tilt the picture flickers or its blury, this is when im shooting 1080i ...i know that ur gonna tell me that this is what interlace makes but this didn't appear when i was using DV

can anyone help me please ....I dont know if the problem is in the Camcorders or in HDV

[Shaun Roemich]

Sounds like artifacts introduced by the CMOS imagers (your previous DV experience would have been with CCD imagers).

[Chris Soucy]

Welcome to the world of compression/ limited bandwidth.

When the camera is stationary, the change, frame to frame is miniscule, if any at all, therefore the data in the I frames is minimal and well within the tape bandwidth.

When the camera is moving, the change, frame to frame increases linearly with the speed of movement, until it reaches a point where it exceeds the available storage medium bandwidth.

At that point the compression algorithm starts "dumping" data to maintain the data stream at it's given maximum.

The more it "dumps", the worse the blurring/ yuck factor.

HDV is not alone, any system which is constrained by a maximum bandwidth must dump data if the incoming exceeds the rate of output.

Hence the push to yet higher and higher storage medium bandwidths.

Unfortunately, climbing this food chain is an exceedingly expensive business.

The only solution with HDV is to move slow and/ or keep the centre of attention as large in the frame as possible.

To explain that last bit - imagine shooting a moving car. The car itself, if held centre frame, will not change (much) frame to frame, so of itself is not adding greatly to the bandwidth. The background will be wizzing by at a great rate and chewing up bandwidth likewise.

The more of the former and the less of the latter, the better the overall picture will be.

Make sense?


CS

[Arlen Sahakian]

Originally Posted by Chris Soucy

Welcome to the world of compression/ limited bandwidth.

When the camera is stationary, the change, frame to frame is miniscule, if any at all, therefore the data in the I frames is minimal and well within the tape bandwidth.

When the camera is moving, the change, frame to frame increases linearly with the speed of movement, until it reaches a point where it exceeds the available storage medium bandwidth.

At that point the compression algorithm starts "dumping" data to maintain the data stream at it's given maximum.

The more it "dumps", the worse the blurring/ yuck factor.

HDV is not alone, any system which is constrained by a maximum bandwidth must dump data if the incoming exceeds the rate of output.

Hence the push to yet higher and higher storage medium bandwidths.

Unfortunately, climbing this food chain is an exceedingly expensive business.

The only solution with HDV is to move slow and/ or keep the centre of attention as large in the frame as possible.

To explain that last bit - imagine shooting a moving car. The car itself, if held centre frame, will not change (much) frame to frame, so of itself is not adding greatly to the bandwidth. The background will be wizzing by at a great rate and chewing up bandwidth likewise.

The more of the former and the less of the latter, the better the overall picture will be.

Make sense?


CS

Thx Chris .. the only thing that makes sense is that there is no solution ))
but the problem is cause of CMOS ? or cause of HDV codec which is like mpeg2 ?
what i want to know is when i shoot DV on the Z7 will it still make the same problem

thank you again

[Chris Soucy]

If the symptoms I described are actually what you're seeing, then no, I can't see it having anything to do with the sensor type.

That CMOS sensors have "issues" cannot be denied, but the above symptoms are not on the list.

As I said, the symptoms you describe are fully explained by the HDV codec and it's inherrant limitations.

Shooting in DV should show none of the above symptoms, tho' the massive loss of detail going from HD to SD will make the SD look pretty avarage by comparison.

Once you've got used to the detail in HD, SD always looks a bit "second hand" (to me, anyway).


CS

[Arlen Sahakian]

hi there

i was trying to fix this problem about pan and tilt and i even tried working SD cause some advised that it will be less blury... it was less but still bad.

anyway i did some tests on the EX3 cause this camera doesnt work on tapes i thought the results will be different but its the same problem on tilt and pan and moves, can anyone advice me which camera will fix this problem but with normal budget of course.

Arlen Sahakian

[Chris Soucy]

"which camera will fix this problem but with normal budget of course."

There you have the root of the problem.

Any camera system that eliminates or at least reduces compression to the extent that overloaded data streams cease turning the picture into mush will be beyond any budget you're likely to have in mind.

A "bolt on" like this:Convergent Design, experts in HDMI, SD, HD, and HDV

that goes a pretty long way to solving the problem isn't for the financialy feint of heart either.

Any way you do the math, bumping up the data rate/ reducing the compression costs big time.

If you're a pro shooter making pro money that can support the investment, it's a no brainer.

If you're an amateur shooting for fun, it's only for those with very, very deep pockets.


CS

[Zach Love]

Just to be clear: CMOS does NOT create any artifacts. Motion / color artifacts are created when the image is too complex for what the codec can handle. If you're seeing artifacts in HDV & not DV, then CMOS has nothing to do with what you're seeing. It would be the codec.

CMOS will create skew, jello or flash banding depending on what you are shooting & the quality of the CMOS chips in your camera.

The biggest advantage of CMOS over CCD, is that they are much cheaper to produce, & for the price they have more pixels & better sensitivity. (There are no 1080x1920 full raster 3CCD cameras that cost less than $20k. While both the EX1 & HPX300 have full raster 3CMOS & cost well below $10k.)

There is NO best camera out there, just the best camera for you. I think my Z7 has served me very well. Being able to shoot interlaced / progressive, tape / tapeless, HD / SD, has made me not regret purchasing my Z7U.

Panasonic's P2 line of cameras has 4:2:2 & intraframe recording options, but your media cost is much higher than a Z7 / S270. P2 is a "better" format than HDV when you look at pure image specs, but when you work in workflow, cost, backup & storage space the Z7 can fit the needs of a lot of people that a HVX200 would not be a good option.

The best option at $0 cost to you, is to learn to shoot around the problem's you're seeing. Maybe a slower pan might take care of the issues you're seeing. Any camera will have quirks & things you'll have to work around. The great thing is learning something on your own, doesn't cost you much out of pocket.

[Arlen Sahakian]

Originally Posted by Chris Soucy

"which camera will fix this problem but with normal budget of course."

There you have the root of the problem.

Any camera system that eliminates or at least reduces compression to the extent that overloaded data streams cease turning the picture into mush will be beyond any budget you're likely to have in mind.

A "bolt on" like this:Convergent Design, experts in HDMI, SD, HD, and HDV

that goes a pretty long way to solving the problem isn't for the financialy feint of heart either.

Any way you do the math, bumping up the data rate/ reducing the compression costs big time.

If you're a pro shooter making pro money that can support the investment, it's a no brainer.

If you're an amateur shooting for fun, it's only for those with very, very deep pockets.


CS

what if i was a pro and making pro money but of course not as much as the film makers )) which camera u advise me ??

[Chris Soucy]

If you really want to put a permanent (and expensive) dent in this problem you need to be looking at:

Sony XDCAM/ HD CineAlta ranges

Panasonic P2HD Series

JVC GY - HM Series

As a guide you really need to be looking at a minimum of 50 - 55 Mbs data rate (twice the data rate of HDV) for full HD, IMHO.


CS