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Author Topic: Time Lapse Photography  (Read 3243 times)
BenGreaves
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« on: July 04, 2010, 05:01:21 AM »
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Ok so I've recently started trying to get my head around time lapse photos.  I understand the maths behind it, eg a 30sec "video" at 24 fps = 720 frames.  I also understand how to figure out roughly how to gauge how many shots to take based on knowing roughly how long the event will go for.  Eg, 4 hour event = 14,440 seconds divided by 720 frames would = 20 second intervals between frames.

This much makes sense.

What I intend on shooting is a lot of sunset or sunset to night sequences.  Given that these are two very very different levels of light and naturally shooting in the lower conditions you would have to drag your shutter more. This longer shutter would mean those sunset photos would have a much higher chance of being blown out. Right??

After racking my brain for a few days trying to get my head around this, what are peoples thoughts? Is there anything I'm missing or is there something particular to pay attention to while doing this for good all round exposures.

Would setting to aperature priority help on a "zero" exposure bias and let the camera determine shutter speed?

HELP!?!?!

Thanks

Ben
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BobFisher
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« Reply #1 on: July 04, 2010, 06:36:30 AM »
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The only way, really, to do that kind of light/dark transition is in Av.  Shooting in manual you will, as you noted, have problems with the varying light conditions.

Some will say that shooting anything but manual is almost sacrosanct.  They feel that shooting in Av introduces flicker as a result of the varying shutter speeds and that in camera exposure meters aren't accurate enough so you'll get a combination of properly exposed, underexposed and overexposed shots.  I've come to the conclusion that's pretty much a pantload.  It'll happen rarely but not regularly.  I've determined that most of the flicker in timelapse clips; mine anyway, is a result of naturally varying light levels that would appear as slow changes over time but appear as flicker when sped up in timelapse.

If you're really concerned about it, there are deflicker filters for Virtualdub; which is a free (Windows only) video editing software, and those filters do a really nice job of reducing or eliminating flicker.  Some other video editing apps. have similar filters built in.  I use Sony Vegas and it doesn't so I added Vdub to my workflow.  

The other thing you may get is wind shake.  Even with the camera locked down on a good tripod and even if you put some ballast on the 'pod, if the wind is strong enough, you can get shake from the wind buffeting the tripod.  This is far more bothersome, to me, than flicker.  Vdub has a deshake filter that also does a really nice job.

In terms of timing, if you only want a 30 second clip from that 4 hour event then your timing is right.  A long interval, like 20 seconds, is going to make your 'action' very choppy.  You might consider making a longer end product and using intervals in the 5 to 10 second range.  When I shoot HDR timelapse, I typically use a 12 second interval and when shooting single shot timelapse it's typically a 6 second interval.  The shorter the interval between shots, the smoother the movement in the final video will be.  

There are some good timelapse groups at Vimeo where you get a look at some good clips.  In some cases, the creators have included the relevant shooting information.

http://vimeo.com/channels/timelapseinhd
http://vimeo.com/groups/hdrtimelapse
http://vimeo.com/groups/timelapse

I curate the HDR timelapse group.
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BenGreaves
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« Reply #2 on: July 04, 2010, 08:40:47 AM »
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Awesome. Comforting to know that I wasnt too far off with this line of thinking.  The last thing I wanted to be doing is playing with settings super quickly without moving the camera and making sure I get it right before the next shot.

"The other thing you may get is wind shake."

True. Theres not too much you can do to stop the wind but hey, at least now I know there is a way to help minimise it in post. Something I never would have really thought possible. So thanks.

I agree if I were to shoot a 4 hour scene into a 30 second clip it 24fps would be pretty choppy. Thanks for the tip on the 5-10 second range though. I'll keep that in mind when I shoot a few and see how it goes.

Im quite a fan of hdr and its what I mainly shoot but holy crap that seems like a TRUCK load of processing to get the end product. Im also not well versed enough in photoshop (cs4 extended) to be able to create an action and run everything through a batch process.  Although, I guess I could play around in Photomatix and do it there. I'd be silly to rule it out considering its what I know.

Ive watched a few hdr time lapse clips and I have to say they're pretty neat so I'll head over to Vimeo and check those links out.

Is it also true that its best to set white balance manually and shoot jpg? Or could I get away with shooting raw and set the balance later?  I know it will most likely change from scene to scene but also is it safe to say that shooting with the lowest iso possible would be best due to low noise factor??

I hate sounding like such a noob and I know the best way is to go shoot and learn from mistakes but a headstart never hurts :-)
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BobFisher
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« Reply #3 on: July 04, 2010, 09:37:25 PM »
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HDR for timelapse isn't too bad.  You can batch everything in PM.  Writing a script for PS to do batch HDR is something I'm working on but not nearly there yet.  It'd have to be a script.  An action wouldn't do it.

Most cameras WB well on Auto for outdoor shooting.  Using a manual WB will be difficult, particularly if you're going from light to dark or vice versa.  You could end up with some pretty funky colour shifts due to colour temperature changes.  

As far as JPEG vs. RAW, I shoot JPEG for timelapse for a couple reasons.  First, in the case of HDR, I don't have cards large enough to shoot RAW and have enough card space.  Second, since I only need 1080 as a max. resolution, shooting RAW doesn't make a lot of sense.  Since the end product is 'moving' and you're not looking at a still shot for any period of time, you can actually get away with a bit lower quality than if you were making a print.  If my camera had the ability to shoot a small RAW file I might use that, but it doesn't

Lowest ISO you can get away with, yep.  Same as for anything else.  Keep in mind that if you're going from light to dark your shutter speeds will get longer as it gets darker.  You can set a higher ISO at the start or, do like I did in a recent clip and use the change of ISO - which necessitates touching the camera and will lead to some pretty big shake - to change the focal length to add a bit of a different viewpoint to the clip.  Did it twice then integrated them with a crossfade in editing.
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BenGreaves
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« Reply #4 on: July 05, 2010, 08:22:53 AM »
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One of the joys of PM. Makes life easy.  If only I learned about the "exposure fusion" tab earlier though lol.

Speaking of manual WB. Ive never done it before and was looking at these two options

http://www.digitalcamerawarehouse.com.au/prod6247.htm
http://www.digitalcamerawarehouse.com.au/prod3675.htm

Which would be better? Im thinking the micnova cards would be a bit more versitile.  But what benefit would there be to the grey and black cards??

Im really due for a camera upgrade, the lowest I can shoot for now is ISO200! But I know my way around it well so quickly changing ISO wouldnt be too hard. Oh what I would give to go back and start again knowing what I know now.  In saying that, a D3s is mighty tempting lately.

Seems like I'm really trying to jump in to the deep end as im basically headed straight for trying to achieve the illustrious holy grail.  I spent a bit of time on vimeo today and found some very good reads and a whole world of camera technical nerdiness that I dont even want to think about right now.  Waaaayyyy to involved at this moment in time.

Now if only my intervalometer would hurry up and arrive so I can shoot!!!
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BobFisher
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« Reply #5 on: July 05, 2010, 08:50:50 AM »
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You can WB off anything neutral, so grey and black work as well.  If I were going to get something like this, I'd probably go for the cap that fits over the lens.  Looks similar to the Expodisc.

Want an even cheaper way to do it?  Use the coffee filter trick.  Put a white coffee filter (two if they're really thin) over the lens and use that.  Works well.  They have to be the white filters though, not the yellowish ones.  And unused, of course.  
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