Night Interval Shooting

W

Wayazo

Member
I've had some fun doing single night shots of the sky using Nikon still camera equipment, 30+-second exposures at f/2.8 with a wide angle lens. I'm wondering if anyone has used the HMC40 in interval shooting mode to do capture movement of the stars over time? Is it even possible with this camera? I know that low light is not this camera's forte but I'm wondering if long interval recordings might work. Night interval shots of, say, light trails from car lights on an illuminated highway shouldn't be a problem. What about the night sky above a distant mountain landscape, or a shot of the rising moon over mountains?

Anyone had any success with this?
 
Using an exposure of 1/2 a second with around +17dB --> +30dB of gain I was able to get some great timelapse night shots and yes, you could see the stars. The longest exposure is 1/2 a second in timelapse mode.

http://vimeo.com/9817217

http://vimeo.com/9096330

A 1/2 a second exposure was way too much for getting just the moon, even if I set the F-Stop to F-11. I haven't played around to see what the ideal exposure is to see the moon clearly.



Bob Diaz
 
Took a look at both videos. Pretty cool stuff. How did you establish the 1/2 second exposure time? I'm still learning the cam settings so when you speak of a +17 to +30db gain, are you adjusting while using the WFM. Was the aperture at 2.8 + the gain? Also, at a 1-sec interval, are each of you master clips 30-60 minutes? I am waiting patiently for Barry's HMC40 book to come out so I can bone up and understand all the settings.
 
As a general rule of thumb, I'd love to have the shutter speed to be about 50% of the frame rate. So 1 frame per second should have a 1/2 a second exposure; that way any movement in the timelapse will blur slightly. I can't do that in full sunlight unless I put some major ND filter in place, but at night it's easy. Also, given how dark things are, the longest shutter speed, 1/2 a second seems like the logical choice.

The lens was wide open, at F-1.8 (about 1 and 1/3 stops more light than F-2.8).

The WFM (Wave Form Monitor) told me that I had to crank the gain up to at least +17dB --> +30dB. This is where I was just trying things. In HD, I don't like to go over +18dB, because the grain becomes excessive; however, the higher gain did brighten the night shots. In looking at the video, +30dB was over kill, but +24dB seemed about right. It's still a lot of grain at +24dB, but when reduced to SD resolution, it's OK. I like the slightly darker look to the stuff I shot at +24dB and +17dB seemed a bit too dark.

With a 1/2 a second exposure, the moon is just too bright, even at F-11.

With timelapse:

Interval = 1 second, 1 hour becomes 150 seconds (2.5 minutes)
Interval = 10 seconds, 1 hour becomes 15 seconds
Interval = 30 seconds, 1 hour becomes 5 seconds
Interval = 1 minute, 1 hour becomes 2.5 seconds
Interval = 2 minutes, 1 hour becomes 1.25 seconds

In my case I would shoot for 12 minutes to 24 minutes to get around 30 seconds to 60 seconds of footage using 1 frame per second.

On the nights where I'm NOT working, we've had nothing but overcast, so I haven't tried any shots at 10 or 30 seconds per frame. I believe that star movement show appear clearly in those modes.


Bob Diaz
 
Thanks. I understand the settings. Can you tell me the formula for determining the time change? By the way, if I haven't already said so, I appreciate you sharing this information. It's helping to reduce the learning curve.
 
how's battery life affcted by this?
on the stock battery, would you be limited to 3hrs? or time lapse allows for longer batteyr life with the lcd closed.
 
On playback, each frame is on screen for 1/24 of a second (24p). I like to use, "1 hour will appear as this time on playback"

IF shooting at 1 second per frame: 1 second / (1/24 of a second) = 1 x 24 = 24x speed increase. Thus 60 minutes / 24 x = 2.5 minutes.

IF shooting at 10 seconds per frame: 10 seconds / (1/24 of a second) = 10 x 24 = 240x speed increase. Thus 60 minutes / 240x = 0.25 minutes or 15 seconds.

IF shooting at 30 seconds per frame: 30 seconds / (1/24 of a second) = 30 x 24 = 720x speed increase. Thus 60 minutes / 720x = 0.0.83333 minutes or 5 seconds.

IF shooting at 1 minute (60 seconds) per frame: 60 seconds / (1/24 of a second) = 60 x 24 = 1,440x speed increase. Thus 60 minutes / 1,440x = 0.041666 minutes or 2.5 seconds.

IF shooting at 2 minutes (120 seconds) per frame: 120 seconds / (1/24 of a second) = 120 x 24 = 2,880x speed increase. Thus 60 minutes /2,880x = 0.0208333 minutes or 1.25 seconds.

==================================================

To look at it another way, you want 15 seconds of finished footage...

IF shooting at 1 second per frame: 15 seconds x 24x = 360 seconds (6 minutes).

IF shooting at 10 seconds per frame: 15 seconds x 240x = 3,600 seconds (60 minutes or 1 hour).

IF shooting at 30 seconds per frame: 15 seconds x 720x = 10,800 seconds (180 minutes or 3 hours).

IF shooting at 1 minute (60 seconds) per frame: 15 seconds x 1,440x = 21,600 seconds (360 minutes or 6 hours).

IF shooting at 2 minutes (120 seconds) per frame: 15 seconds x 2,880x = 33,200 seconds (720 minutes or 12 hours).



I hope that helps...


Bob Diaz
 
Alejo_NIN said:
how's battery life affcted by this?
on the stock battery, would you be limited to 3hrs? or time lapse allows for longer batteyr life with the lcd closed.
Click to expand...

I really have not tested this, I think it's about the same, BUT that's untested.
If you use the AC Adapter, you can go the full 12 hours...



Bob Diaz
 
Just as a side note, I've noticed that my timelapse math is either different, or just a more roundabout way of getting the same answer. My brain thinks:

1frame per second=60frames per minute=3600 frames per hour divided by your output frame rate.

1/2 fps=30fpM=1800fpH

For example 1 hour at 1FPS:
3600 frames/24p= 150 seconds of footage, divided by 60 to get 2.5 minutes of footage
3600 frames/30p= 120 seconds of footage, divided by 60 to get 2.0 minutes of footage

I think i should program this into my ti-83 calculator next time I'm in a math class :)
 
I've taken a number of photos of the moon with my Nikon equipment. I nice bright full moon using a 400mm telephoto, ISO 200, f/11 @ 1/500th turns out pretty good. You get detail in the disk and a nice black background, no stars.
 
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