Go Back   Steve's Digicams Forums > Digital Cameras (Point and Shoot) > Sanyo

Reply
 
Thread Tools Search this Thread
Old Jan 19, 2006, 6:21 PM   #11
fdf
Junior Member
 
Join Date: Jan 2006
Posts: 9
Default

gusher1--
I'll see if I can get any exposure info out of the movies or by taking
"0.3M" stills. Something should be labeled as ISO 3600, I would think.
The only suggestion that comes to mind is to do the "reset" option in
the setup menu, and then don't change much of anything, because I
didn't--except I do need to use the manual white balance for good results.
The manual said somewhere that "automatic" would make good choices
for ISO settings, and for me, it does seem to. There was no obvious
benefit to the elsewhere-mentioned "fireworks" setting, that I could tell.

As a very rough benchmark for light sensitivity, one of the first video clips
I tested was of a white cat walking away and into a dark room. I glanced
at the cat and at the screen, and my eyes could see the cat a little longer
than on the LCD, as she passed into the darkness, but only barely.
--Fred
fdf is offline   Reply With Quote
Old Jan 19, 2006, 8:17 PM   #12
Junior Member
 
Join Date: Jan 2006
Posts: 12
Default

gusher1 wrote:
Quote:
fdf wrote:
Quote:
I just got my c6 from warehouse123, and so far I'm pretty impressed.
I'll try to attach a cut down frame of video from my c6 and my Minolta z3.
I like lots about my z3, but low light video is not good. If I turn on every light
in the room, and maybe bring in an extra lamp, it's just barely usable. The c6
is lots better. The only thing I have to do is set the white balance--no "fireworks."
I don't know if my expectations are different from other people's, or maybe since
I just got my VPC-C6, it has a new program, firmware revision. Does anyone
know how to check what level of firmware a c6 has?

--Fred

Quote:

Fred, my C6 videos in medium to low light look more like your video frame from the Minolta. I would not get anything as bright or clear as your C6 video frame in anything but a very well-lit room.

I'd like to know the answer to your firmware question. I'd also like to know whether one can get an exif reading from a video frame. I'm starting to seriously wonder whether there is something wrong with my C6, and I'm wondering whether my camera is getting the same results, and whether I could find out by comparing exif statistics?
Quote:
I used Image-ExifTool-5.93 to look exif info. But sanyo VPC C6 does not supply the ISO for video, only for stills! I also may be would not trust it becuase for example the VPC-C1 records the video resolution to 320x240 maximum resolution if this is true I should take legal action. So how to prove that video use iso 3600! I still suspect that most of the low light examples are using stills in candle light mode.
deal2live is offline   Reply With Quote
Old Jan 19, 2006, 9:05 PM   #13
Member
 
Join Date: Dec 2005
Posts: 43
Default

fdf wrote:
Quote:
gusher1--
I'll see if I can get any exposure info out of the movies or by taking
"0.3M" stills. Something should be labeled as ISO 3600, I would think.
The only suggestion that comes to mind is to do the "reset" option in
the setup menu, and then don't change much of anything, because I
didn't--except I do need to use the manual white balance for good results.
The manual said somewhere that "automatic" would make good choices
for ISO settings, and for me, it does seem to. There was no obvious
benefit to the elsewhere-mentioned "fireworks" setting, that I could tell.

As a very rough benchmark for light sensitivity, one of the first video clips
I tested was of a white cat walking away and into a dark room. I glanced
at the cat and at the screen, and my eyes could see the cat a little longer
than on the LCD, as she passed into the darkness, but only barely.
--Fred
Fred, I'm not using any custom settings to try to improve low-light video because I haven't seen them make any difference. When you use manual white balance, are you using one of the preset settings (i.e., not the automatic setting), or are you using the "one push" option that requires you to point the camera at a piece of paper to set the white balance>
gusher1 is offline   Reply With Quote
Old Jan 20, 2006, 1:52 AM   #14
fdf
Junior Member
 
Join Date: Jan 2006
Posts: 9
Default

I've found better results with the "one push," since if have a mix
of tungstun and florescent lighting. By the way, I've tried holding down
each of the buttons while powering up, to see if that might display
an informational screen with a firmware revision number--no luck.

fdf is offline   Reply With Quote
Old Jan 25, 2006, 3:25 PM   #15
Member
 
Join Date: Dec 2005
Posts: 43
Default

Well this is interesting. I recently bought a Samsung A900 cellphone, which also has a camera with the ability to take videos. I noticed when looking through the LCD viewfinder of the camera phone in video mode, in a low-light situation, that the image on the LCD seemed much brighter than the same image would appear on my C6 viewfinder. So I compared them side by side today in low light and the image on the camera phone viewfinder is MUCH brighter than the image on the C6 viewfinder.

I'm not going to try to take a video with cameraphone to compare to the C6 because I plan on returning the phone, but I assume if the image on the LCD is much brighter, the actual video that is captured would also be much brighter.

I'm no expert on cameras, but I always thought the reason for the poor performance of small hybrid cameras in low-light situations is the small lens and CCD. Well the lense of the camera phone is much smaller than that of the C6, and I can't imagine they put a better CCD in a camera phone than in the C6.

Can anybody who understands this stuff better than I offer up an explanation for why a little camera phone can achieve brighter video in low-light than the C6???
gusher1 is offline   Reply With Quote
Old Jun 17, 2006, 7:33 PM   #16
Junior Member
 
para7's Avatar
 
Join Date: Jan 2006
Posts: 9
Default

It may be similar to adding some GAMMA or brightness to an image in image software. A boost but with noise resulting.
para7 is offline   Reply With Quote
Old Jun 17, 2006, 8:36 PM   #17
Administrator
 
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378
Default

gusher1 wrote:
Quote:
I think what you may be referring to here is that the still pictures (in lamp mode at ISO 900) come out MUCH brighter than videos which are supposed to be at ISO 3600. That is definitely the case for me.
I don't know a thing about the video performance of the C6. For that matter, I don't know much about video period. ;-)

Even when I've had cameras with video modes, I never used them at all (other than a quick test to see if they worked or not).

But, I had to chuckle reading the comments about the comparisons between the ISO 900 still images and the ISO 3600 videos.

Proper Exposure is reliant on three things:

* Light Levels (commonly measured as EV for Exposure Value in Photography)

* Aperture (this is the iris opening in the lens, and it works like the pupiils in your eyes, opening up wider in lower light). As expressed in f/stop, it's a ratio between the focal length of the lens and the area of the aperture diameter. Larger Apertures are represented by smaller f/stop numbers. The larger the aperture, the more light that gets through to the film or sensor, so the "faster" you can expose an image for any given lighting.

* Shutter Speed (and a CCD uses an electronic shutter in most non-DSLR models).

* ISO speed (how sensitive the film or sensor is to light).

The camera must keep the shutter open long enough for proper exposure. Otherwise, you'll get a dark (underxposed image). In low light, that can take a while.

The lens on the C6 has a largest available aperture of f/3.5 on the wide end of the lens, dropping down to f/4.7 on the long end (you lose light as focal lengths get longer with most zoom lenses).

Average home lighting at night as an EV of around 5.

In EV 5 lighting at ISO 800 and f/3.5 (the largest available aperture for this model's lens), you'd need to keep the shutter open for approximately 1/20 second for proper exposure. If you were on the long end of the lens (more magnification), you'd need to keep it open for around 1/12 second).

In order to capture video at 30 frames per second (including on the long end of the zoom), you'd need to have at around ISO 2000 available for proper exposure in average home lighting.

If lighting was one stop lower than average (EV 4 lighting), then it may need ISO 3600 (and may even be slightly underexposed at ISO 3600).

I've got one local restaurant here with light so low I need to underexpose ISO 3200 1/3 stop just to get shutter speeds up to 1/10 second shooting at f/2 with a KM Maxxum 5D wearing a Minolta 100mm f/2. f/2 is more than 5 times as bright as f/4.7 (where you'd be at on the long end of the lens with the C6).

So, in that lighting, you'd need shutter speeds of 1/2 second to expose an image at ISO 3200 with a C6 if you zoomed in much. That would make for very dark (black) images trying to shoot video at 30 frames per second (1/30 second exposure time), even if you had ISO 3600. ;-)

Again, I know nothing about video. But, it sounds like it's quite possible it's using ISO 3600. You have to take exposure time into consideration. With video, there is not enough time to expose each frame properly in low light. So, they have to amplify the signal quite a bit to shoot indoors at all.

As light hits the photosites in a sensor, a charge starts building up. After it's been long enough for proper exposure, the signal level from each photosite is read and zeroed out again to start all over. With video, you don't have the luxury of waiting long enough for proper exposure. So, they've got to amplify the signal a lot to get it to work at all (and amplifcation how you increase the effective ISO speed with an electronic sensor).


JimC is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 4:20 AM.