Sony SR11 and "Twilight mode" at DVinfo.net
DV Info Net

Go Back   DV Info Net > High Definition Video Acquisition > AVCHD Format Discussion

AVCHD Format Discussion
Inexpensive High Definition H.264 encoding to DVD, Hard Disc or SD Card.

Reply
 
Thread Tools Search this Thread
Old August 21st, 2008, 07:32 AM   #1
Regular Crew
 
Join Date: Jun 2005
Location: Stockholm Sweden
Posts: 184
Sony SR11 and "Twilight mode"

Hi

At the moment I am learning to work with my Sony SR11, it is the first Sony I ever had.

I am using the cam in manual mode all the time and use either AE shift or manual exposure and I will soon start using spot focus.

I have started to follow a project about rebulding some old houses. That means that it will sometimes be not so much ligth.

I understand that Sony adds gain when it needs to and the only way to stop the cam from going up to +12/18 dB is to put the cam in "Twilight mode" that way the cam goes no futher than 9dB and if I understand everything correct the picture will have little if any noise in 9DB

What i donīt know is if I put the cam in Twilight mode does that mean it overides anything else when Iīm in manual mode?

Can I have the cam always in "Twilight mode"?

I hope someone knows.

Cheers

Hans
__________________
Remember, that English is my second language.
Hans Ledel is offline   Reply With Quote
Old August 21st, 2008, 03:49 PM   #2
Regular Crew
 
Join Date: Jul 2008
Location: Fort Wayne, IN
Posts: 60
One limitation I have found with twilight mode is that AE shift has no effect in low light. In good light I can do + or - AE shift with autoexposure and twilight mode set to on, and the exposure changes accordingly as I change the amount of shift using the dial on the front.

In low light such as dark night scenes, I would not expect that it could do a + shift, given that the iris is already at 1.8 and the gain is at the +9 limit of twilight mode. (Well I guess it could slow the shutter speed to 1/30 but doesn't - it keeps it at 1/60.)

But in low light I would think it should be able to do a negative AE shift. I was shooting some night scenes of a city street that had points of bright lights (signs and traffic lights) along with dark areas such as the night sky. I had the SR11 set to autoexposure and twilight scene mode. (I used autoexposure because I was panning and the light level was changing as I panned, so manual exposure wasn't practical.)

The bright lights were overexposed and burning out, so I enabled AE shift and set it to -1 to try to underexpose a little and reduce the over-exposure of the lights. But it didn't change the exposure I saw on the LCD. So I tried -4 and again it did not change the exposure I saw on the LCD. When playing the video back, I saw that the exposure was 1/60, 1.8, and +9 regardless of whether the AE shift was on 0 or -4.

It seems to me it should be able to accomplish the negative AE shift by reducing the gain below +9 or closing the iris down. For some reason it doesn't. Maybe autoexposure won't let the exposure level go below a certain point and ignores AE shift if that point is reached??
Dale McClelland is offline   Reply With Quote
Old August 22nd, 2008, 05:24 AM   #3
Regular Crew
 
Join Date: Jun 2005
Location: Stockholm Sweden
Posts: 184
Thank you very much.

Really good to know..

Cheers

Hans
__________________
Remember, that English is my second language.
Hans Ledel is offline   Reply With Quote
Old August 22nd, 2008, 07:23 PM   #4
HDV Cinema
 
Join Date: Feb 2003
Location: Las Vegas
Posts: 4,007
Quote:
Originally Posted by Hans Ledel View Post
I am using the cam in manual mode all the time and use either AE shift or manual exposure and I will soon start using spot focus.
When you use Twilight, you are forced into AWB. Because exposure can fluctuate in AE Shift, I do not recommend using it. Use Manual Exposure. Then use AF or Spot Focus.
__________________
Switcher's Quick Guide to the Avid Media Composer >>> http://home.mindspring.com/~d-v-c
Steve Mullen is offline   Reply With Quote
Old August 23rd, 2008, 08:01 AM   #5
Regular Crew
 
Join Date: Jun 2005
Location: Stockholm Sweden
Posts: 184
Thank you Steve.

That was really important to know.

You are right about manual exposure and Spot focus, I actually was thinking about going that way instead of Twilight mode.

I found out that 6 "clicks" from the right (+) on the exposure scale was 9dB so I will be using that insted

Cheers

Hans
__________________
Remember, that English is my second language.
Hans Ledel is offline   Reply With Quote
Old August 23rd, 2008, 12:18 PM   #6
Regular Crew
 
Join Date: Jul 2008
Location: Targu Jiu, Romania
Posts: 29
Well, two thigs I saw today in twilight mode.
1. Spot focus is not active
2. Autofocus is very bad at 8x zoom. I switch to manual and correct, back to auto/fuzz, switch from twilight and autofocus is sharp again!
Hans, so manual exposure=limited autogain? I put in daylight 6 clicks left and the image become too dark... autoexposure is ok in daylight, in the night it's best to manual adjust.

I think to a method to do a comprehensive test for various manual setting (like scenery, etc). It involves a table with multiple sheets in which we put all variables (so it will be easy to determine which other settings are available and best to use. We must setup the same scene (camera on tripod, manual/auto focus on a moving scene like sprinkler) and on different time (day, night, etc). Each file will be indexed and played directly to HDTV; result put in table...
However, the table will be the most easy part. Actual recording/setting/playing will take a long time... from what I see nobody did such a comprehensive test for a single camera, except probably Steve...

LE: another setting inactive in twilight mode is autoslow shutter. So that's why shutter didn't go to 1/30...

Last edited by Mircea Voinea; August 23rd, 2008 at 01:06 PM. Reason: New added
Mircea Voinea is offline   Reply With Quote
Old August 23rd, 2008, 06:18 PM   #7
HDV Cinema
 
Join Date: Feb 2003
Location: Las Vegas
Posts: 4,007
The Sony manual and my eBook tells you the modes that are locked-out when you set cetain modes. Basically, Programmed Settings lock out other settings.

When you limit gain, AF will be less effective because of less image to focus on.
__________________
Switcher's Quick Guide to the Avid Media Composer >>> http://home.mindspring.com/~d-v-c
Steve Mullen 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...

B&H Photo Video
(866) 521-7381
New York, NY USA

Scan Computers Int. Ltd.
+44 0871-472-4747
Bolton, Lancashire UK


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 > High Definition Video Acquisition > AVCHD Format Discussion

Thread Tools Search this Thread
Search this Thread:

Advanced Search

 



All times are GMT -6. The time now is 01:12 PM.


DV Info Net -- Real Names, Real People, Real Info!
1998-2024 The Digital Video Information Network