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Time Lapse sunset exposure


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#1 Steve Larsen

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Posted 13 August 2006 - 10:06 PM

Hi everyone, I recently purchased a Konvas 2m / 35mm camera from russia and have it set up with a Tobin time lapse motor. I am looking for advise on how to expose a time lapse shot that starts an hour before the sun goes down to an hour after the sun has gone down with the sun in the picture. I am shooting at a 10 sec interval, trying to get 30 sec @ 24fps.

If your interested in the Konvas camera I have pictures of mine online @ www.konvas.info

Steve Larsen
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#2 Stephen Williams

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Posted 15 August 2006 - 06:39 AM

Hi everyone, I recently purchased a Konvas 2m / 35mm camera from russia and have it set up with a Tobin time lapse motor. I am looking for advise on how to expose a time lapse shot that starts an hour before the sun goes down to an hour after the sun has gone down with the sun in the picture. I am shooting at a 10 sec interval, trying to get 30 sec @ 24fps.

If your interested in the Konvas camera I have pictures of mine online @ www.konvas.info

Steve Larsen



Hi,

My usual starting point for time lapse is 50 asa /6 seconds exposure/ND 3.0 (10 stops) T5.6, giving 1 stop over exposure to the sunny F16 Rule. You may want to open another stop as you are starting 1 hour before sunset.

Stephen
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#3 Steve Larsen

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Posted 15 August 2006 - 09:00 PM

Hi,

My usual starting point for time lapse is 50 asa /6 seconds exposure/ND 3.0 (10 stops) T5.6, giving 1 stop over exposure to the sunny F16 Rule. You may want to open another stop as you are starting 1 hour before sunset.

Stephen


Hi Stephen and thanks for the advise.
I am wondering the reason you expose for 6 sec ? ( I thought my Min expousre of a 1/2 sec might be a problem, I guess not... )
Do you ever pull the stop and/or pull ND as the suns going down ?

Thanks in advance,

Steve Larsen
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#4 David Venhaus

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Posted 16 August 2006 - 07:26 AM

You might try shooting some test rolls with a still camera, bracketing the exposures, of course and writing down all the info. while doing that, then figuring out the correct exposure(s) for the time lapse.
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#5 Stephen Williams

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Posted 16 August 2006 - 10:01 AM

Hi Stephen and thanks for the advise.
I am wondering the reason you expose for 6 sec ? ( I thought my Min expousre of a 1/2 sec might be a problem, I guess not... )
Do you ever pull the stop and/or pull ND as the suns going down ?

Thanks in advance,

Steve Larsen


Hi,

I was assuming you would use a constant speed motor so 6 sec open 6 sec closed, you were talking about a shot every 10 seconds, the maths works better for 12! You want the trees etc to be blured as they move in the wind so a long exposure is good.
With an animation motor offset the shutter by 180 degrees, then the camera stops open. The 1/2 sec 'exposure' is just the film advance, and any delay is the exposure.

I don't pull the ND as the sun goes, but time to play in telecine is useful. I do know people who change the T stops with motion control when shooting 24 hour day & night timelapse.

Stephen
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#6 Steve Larsen

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Posted 16 August 2006 - 11:40 AM

You might try shooting some test rolls with a still camera, bracketing the exposures, of course and writing down all the info. while doing that, then figuring out the correct exposure(s) for the time lapse.


Hi David, I have shot some test rolls on my K3 and I have kept very good records of what I took the exposure from (ie: a spot reading and/or an incident reading) and tracked those readings on a graph Taking an exposure reading every 10 min's. When I started shooting with the Konvas I made myself a template table/details page to fill in as I shoot a Time-lapse shot. I have posted it online it might be usefull to someone else:
http://www.vancouver.....pse Table.htm
http://www.vancouver.../shotreport.htm

Steve Larsen
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#7 Steve Larsen

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Posted 16 August 2006 - 12:03 PM

Hi,

I was assuming you would use a constant speed motor so 6 sec open 6 sec closed, you were talking about a shot every 10 seconds, the maths works better for 12! You want the trees etc to be blured as they move in the wind so a long exposure is good.
With an animation motor offset the shutter by 180 degrees, then the camera stops open. The 1/2 sec 'exposure' is just the film advance, and any delay is the exposure.

I don't pull the ND as the sun goes, but time to play in telecine is useful. I do know people who change the T stops with motion control when shooting 24 hour day & night timelapse.

Stephen


Hi Stephen, and thanks again. I have a Tobin time-lapse motor for a Bolex adapted to my Konvas 2m. It has 2 modes; regular @ .75 fps exposure at any interval and long exposure (your interval - 1 sec (2 sec-100hr) )

The way I've calculated my shutter speed is: Tobin specs for regular speed = .75 fps = 1.3 spf x Konvas 2m shutter = 150 deg. = 150/360 = .416
1.3 x .416 = .541 sec = 1/2 s.

I think I am starting to get my exposure close now, but there is a huge difference in stops between 10 min before sunset and 10 min's after. I have asked quite a few DP's I work with how to expose/shoot a sunset and I don't seem to get the same answer twice. One of my best tests on the K3 I pulled 2 stops as the sun went down (approx 10-15min) watching with the spot meter to make sure I was pulling the stop slower than exposure's drop, so even though I'm opening the stop the picture is still getting darker. I have another 6 sunsets in the can now (on 35mm) and a few of them I've pulled 4 stops. They should be in the lab soon.

I created this table to calculate shooting time at various intervals and footage for play back at 24fps:

http://www.vancouver... Calculator.htm

Steve Larsen
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#8 Stephen Williams

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Posted 16 August 2006 - 01:11 PM

Hi Stephen, and thanks again. I have a Tobin time-lapse motor for a Bolex adapted to my Konvas 2m. It has 2 modes; regular @ .75 fps exposure at any interval and long exposure (your interval - 1 sec (2 sec-100hr) )


Hi,

The only time I tried to pull the stop by hand I screwed up the shot! I am interested in seeing your results.

Stephen
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#9 Steve Larsen

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Posted 16 August 2006 - 07:36 PM

Hi,

The only time I tried to pull the stop by hand I screwed up the shot! I am interested in seeing your results.

Stephen


Hi Stephen, here's a link to download the test I did with the K3, I looked over my notes and I pulled the stop from f11-3.5 with a pola filter / 1/30 s. / 50asa as the sun was going down. I had to give up doing time-lapse with the K3 because of the fogging problems and some strobe effect i was getting...

Steve.

http://www.konvas.in...test_a.mov.html
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#10 Steve Larsen

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Posted 06 September 2006 - 09:32 PM

Hi,

The only time I tried to pull the stop by hand I screwed up the shot! I am interested in seeing your results.

Stephen



Hi again Stephen and anyone else intereted. I just got my first Time-lapse footage transferred to HD, all shot with the Konvas 2m & Russian glass. For the most part I am very happy with the results, no fogging on a 10 sec interval with the sun in the shot. I pulled 4 stop manually on every sunset shot, trying to open slower than it's getting darker. I'm posting my results as we speak on http://www.konvas.info in my album.

Steve Larsen
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