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-   -   Z1 low light condition (https://www.dvinfo.net/forum/sony-hvr-z1-hdr-fx1/114013-z1-low-light-condition.html)

Marcelo Costa February 5th, 2008 08:45 AM

Z1 low light condition
 
Friends

I'm a wedding videographer and recently I purchased a Z1 and FX1... In a good light condition the image is great, but in low light condition... It is terrible...

Eg. when I shoot the guests dancing, using no light on the cam, and working only with DJ's lights (it changes very fast from dark to bright, one color to another...), I got a lot of squares on my video... I know that HDV, in this case Z1, works with mpeg compression, so, I believe that squares are a compression fail... So my question is, Is there any thing that I can do to solve this problem in very low light condition, specially in dance floor (fast light changes) ? Some setup on the cam or anything in the editor program (I worj Final Cut Pro 5) to minimize this fail?

Also, I can not use external light on the dance floor to fix it, I always say (or used to say) to my customers: "I do not bother the guests using external light in the dancing floor, I always try to use the environmental light, this way they do not see me when I'm shooting them, they will be more confortable"... When I worked with PD170 I did not have this problem... And I would not like to shoot my weddings using DV mode in a HDV cam... I payed more to get HDV and it is frustrating if I have to use it in DV mode to fix this problem...

In the worse situation, is that any price affordable HDV cam (like Z7 or Canon's cams) that does not have this problem ?

Thanks a lot for your attention and help.

Marcelo

Philippe Messier February 5th, 2008 08:58 AM

Hi there,

Just to clarify,...it won t change anything if you switch to DV mode on a FX1/Z1. You wont be getting a better low light performance at all. Simply, because there will be still a tons of pixel cram onto the 3 1/3 ccd... In DV mode, the camera still use those tiny pixel.

The only real option is to get a Z7 (supposedly better) or the EX1 (officially better).

Good luck

Phil

John M. McCloskey February 5th, 2008 09:13 AM

If you like having quick archiving capabilities where you can shoot and ingest and not have to dump to tape for archiving look at XDHD Cam. The time you will save is unbelievable. Just a suggestion

Tom Hardwick February 5th, 2008 10:27 AM

To say the Z1 is 'terrible' in low light is a bit much when it's just 1.5 stops behind your PD170. And you can use +18dB of gain up in the Z1 the amplifiers are so quiet - don't try doing that with a PD.

I use the little Sony 20-DW2 video light on top of my Z1 for the wedding dance. I diffuse it with a Lumiquest Mini Softbox and set the gain at something like +9dB, and the results are excellent. This is a lot cheaper than dumping the Z1 for an EX1.

Of course you have to lock the exposure (shutter, gain and iris) when shooting under disco lighting. But the 'squares' on your video? Never seen that either in HDV or DVCAM. Can you explain further?

tom.

Marcelo Costa February 5th, 2008 11:01 AM

Quote:

Originally Posted by Philippe Messier (Post 820598)
Hi there,

Just to clarify,...it won t change anything if you switch to DV mode on a FX1/Z1. You wont be getting a better low light performance at all. Simply, because there will be still a tons of pixel cram onto the 3 1/3 ccd... In DV mode, the camera still use those tiny pixel.

The only real option is to get a Z7 (supposedly better) or the EX1 (officially better).

Good luck

Phil

Ok, thanks for your help... I thought in DV mode the image should be better in dark environment, because it does not use mpeg compression, this way avoiding the squares... Thanks again.

Marcelo Costa February 5th, 2008 11:06 AM

Quote:

Originally Posted by John M. McCloskey (Post 820606)
If you like having quick archiving capabilities where you can shoot and ingest and not have to dump to tape for archiving look at XDHD Cam. The time you will save is unbelievable. Just a suggestion

thanks a lot, but XDHD is far way from Brazil's reality... :)

Marcelo Costa February 5th, 2008 11:56 AM

Quote:

Originally Posted by Tom Hardwick (Post 820643)
To say the Z1 is 'terrible' in low light is a bit much when it's just 1.5 stops behind your PD170. And you can use +18dB of gain up in the Z1 the amplifiers are so quiet - don't try doing that with a PD.

I use the little Sony 20-DW2 video light on top of my Z1 for the wedding dance. I diffuse it with a Lumiquest Mini Softbox and set the gain at something like +9dB, and the results are excellent. This is a lot cheaper than dumping the Z1 for an EX1.

Of course you have to lock the exposure (shutter, gain and iris) when shooting under disco lighting. But the 'squares' on your video? Never seen that either in HDV or DVCAM. Can you explain further?

tom.

Tom, thanks a lot for your help and tips...

I have some doubts, I would be glad if you could help me...

1-) The Lumiquest Mini Softbox that you mean, is this product at BH ?
http://www.bhphotovideo.com/c/produc...i_Softbox.html

2-) Does it really fit in the 20-DW2 ? I mean if it does not drop...

3-) I already have two 20-DW2 but I think it is too spot... Using the Lumiquest, the light will be more flood ?

4-) Under disco lighting I set up my Z1 as: Iris = Open; Gain = 9db or 12db and sometimes 15db, but never 18db; Shutter = 60. Is that Ok? What do you recommend?

5-) My english is not so good, so I uploaded 2 frames that were shot on a Sweet 15 (in Brazil we have Sweet 15, not 16). The first one is ok, no squares, the second one (it is just the next frame) has the squares that I said, it appears when I have a fast change of light, and in dance floor it happens a lot (light canons, strobes...), to me looks like a HDV MPEG Compression Problem... You can donwload both frames from my site:

Frame Ok:
http://www.mnproducoes.com/square/1st_frame_ok.jpg

Frame with a lot of squares:
http://www.mnproducoes.com/square/ne..._toosquare.jpg


Thanks a lot for your help.

Marcelo

Matt Davis February 5th, 2008 12:23 PM

Quote:

Originally Posted by Marcelo Costa (Post 820700)
4-) Under disco lighting I set up my Z1 as: Iris = Open; Gain = 9db or 12db and sometimes 15db, but never 18db; Shutter = 60. Is that Ok? What do you recommend?

5-) My english is not so good, so I uploaded 2 frames that were shot on a Sweet 15 (in Brazil we have Sweet 15, not 16). The first one is ok, no squares, the second one (it is just the next frame) has the squares that I said, it appears when I have a fast change of light, and in dance floor it happens a lot (light canons, strobes...), to me looks like a HDV MPEG Compression Problem

Disco lighting - drive in manual for everything, yes to open iris and gain (+9 dB tops). The square blocking is an HDV 'thing'.

The main cause of square blocking (very fine blocking, looking fuzzy) in Disco light is very strong colour - try desaturating the image slightly. But your images also show larger squares - 'macroblocks'. This is when too much is changing from one frame to another, and parts of the image are 'downrezzed' to make things work.

I shoot HDV, edit (in AIC, ProRez, whatever) at HD, then shrink the HD down to SD or web, so the blocks get very small and, for the most part, unnoticable.

You may want to look into holding off high gain, then using a colour correction filter (I use Colorista) to lift the brightness of the middle range of tone. I strongly recommend shooting with Black Stretch turned on (Z1 only, not FX-1).

So:
- Manual everthing
- Black stretch ON
- Shoot and edit HD, deliver SD
- De-saturate shots under strong coloured lighting
- Lift mids in post rather than pump more gain

PS: Something else you may wish to try (though I speak as a PAL user): instead of shooting 50th, I can shoot 25th and get an extra stop - the resolution is halved, but at HD downconverted, you're not going to miss much. If you must shoot by candle-light, it's a handy trick.

Robert M Wright February 5th, 2008 12:52 PM

You might try using the MSU Deblocking Filter:

http://compression.ru/video/deblocking/index_en.html

Tom Hardwick February 5th, 2008 01:35 PM

Now I see what you mean. This is a disco - a very unnatural happening in very unnatural light - they'll think you added those blocks as special effects.

Yes, that's the softbox I use. It comes with self-adhesive velcro and after a time the heat tends to make the velcro 'creep'. Not a problem in the slightest, and the diffuser remains in place and unmelted. It fits the lamp perfectly. With both filaments lit and the diffuser in place harsh shadows melt away.

It does rob you of some light, but the extra diffusion right in front of both lamps means it covers a much wider angle - useful as I use a super-wide to float with the b & g on their first dance. Best is that guests can look right into the light with no squinting - invaluable.

Follow Matt's advice re black stretch and manual everything, including the white balance. Don't worry about over or under exposure - this is an unnatural occurrence, and practically anything goes.

I don't advocate the 1/25th sec shutter speed though. You claw back a stop ok, but the stuttery look to the footage is not worth it in my view. Give it a go and decide for yourself.

For exteriors at night I often use 1/3rd sec so as to dial out the gain completely, but of course movement (camera and subject) can look odd.

tom.

Asaf Benatia February 5th, 2008 01:52 PM

and if you use Sony HVL-LBP
 
i know you said you can't use it, but can you test and see if you start using Sony HVL-LBP will you get a better pic on the dance floor?

Simon Denny February 5th, 2008 02:03 PM

I did a gig last night with the Z1 filming a couple of bands in a night club in Sydney, the only light was the stage lighting. The camera wanted about 12 - 18db of extra light but i only gave it 9db with the iris set to about 2.4.
When i got home and set this up through my widescreen the results looked great for the conditions.

I also use the Sony PD170 on this shoot and i gave this 3db of extra light and this also looked good.

The Z1 can handle low lighting but with all cameras grain will creep in. Get yourself a light and stick it on the camera for your wedding shoots but make sure it's a widescreen light, you will be very suprised at how good the results are from the Z1.

Regards
Simon

John M. McCloskey February 5th, 2008 02:14 PM

"- Shoot and edit HD, deliver SD"(Quote) Matt Daviss
I totally agree with Matt on this also, it is amazing the difference when edited in SD compaired to edited in HD. From what I have heard editing HDV in at DV25 you loose 60% of your raw HDV signal. Which is another question all in itself,"Why would anyone edit HDV in at DV25 for a finished project?" I have seen it and dont understand why someone would do that.

Marcelo Costa February 5th, 2008 02:28 PM

Quote:

Originally Posted by Matt Daviss (Post 820718)

I shoot HDV, edit (in AIC, ProRez, whatever) at HD, then shrink the HD down to SD or web, so the blocks get very small and, for the most part, unnoticable.

You may want to look into holding off high gain, then using a colour correction filter (I use Colorista) to lift the brightness of the middle range of tone. I strongly recommend shooting with Black Stretch turned on (Z1 only, not FX-1).


Matt, thanks a lot for your help, I really appreciate.

I'm new with HDV format and Final Cut (before I worked with PD and Premiere), so I have some doubts if you do not mind...

1-) What is AIC, ProRez ? Are these editor programs or codecs to use with Final Cut ?

Editing in Final Cut first I access Easy Setup... (under Final Cut Pro menu) and select HDV-1080i60 FireWire Basic, then I capture and edit... All my sequences has the compressor HDV 1080i60, Quality 100% and Field Dominance Upper (Odd), also Video Processing as Render in 8 bit YUV, process maximum white as white and motion filtering quality as normal.

Then to export it to SD, I export my sequence as a not self contained Quicktime movie and setting as Current Settings (it will use the settings of my sequence, as I described before), and in Compressor I use:

Video Format
File Format = MPEG-2
Video Format = NTSC
Aspect Ratio = 16:9
Field Dominance = Top First

Quality
Mode= Two pass VBR Best
Average Bit Rate= 5.5 MBPs
Maximum Bit Rate= 7.2 MBPs
Motion Estimation= Best

GOP
Gop Structure= IBBP
Closed
Gop Size = 15


Are my steps ok?


2-) Holding off High Gain, what do you mean? Work with gain as 0 or to use gain at 9db (tops) ?

Also, could you please send me the link of the plugin Colorista ? Actually to correct color and gain I use the filter Color Corrector 3 Ways (FCP default filter).

Thanks a lot for your attention, I really appreciate it.

Marcelo Costa February 5th, 2008 02:33 PM

Quote:

Originally Posted by Robert M Wright (Post 820739)
You might try using the MSU Deblocking Filter:

http://compression.ru/video/deblocking/index_en.html

Thanks for your tip... Should I use this program with my edited movie after compressed it to MPEG-2 (m2v) ?

Thanks again.


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