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 First test with eMotimo TB3 - is this Aperture flicker? 
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Joined: Wed Apr 03, 2013 7:20 pm
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Post First test with eMotimo TB3 - is this Aperture flicker?
Just got my TB3 delivered today and went out to give it a test before heading away for a long weekend.

Setting up was relatively straight forward, but on compiling the timelapse sequence I find there's some fairly noticeable flicker through the clip. I've done some quick reading through the forum and I'm guessing that it's a case of aperture flicker?

I shot full manual (ISO 1000, f4, 1/5 second shutter), no de-flicker applied in AE. I usually shoot astro/night timelapse and have never encountered this problem before.

Anyone have any suggestions? I'll read some tomorrow before heading away. The other thing I think I've done is to move too much too quickly and introduced an amount of jerkyness - I used a ramp so it seems to be progressively worse a few seconds in. I shot a second sequence in less light that didn't seem to exhibit as much flicker.

Shot with Canon 5D3, Canon 24-105 and CPL filter.

Any ideas appreciated!

http://www.youtube.com/watch?v=KTkUbOcT_hE&feature=youtu.be

Karl.

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Tue Sep 24, 2013 1:51 am
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Location: Sydney - Australia
Post Re: First test with eMotimo TB3 - is this Aperture flicker?
Congrats on the new TB3!

The flickering is aperture flicker caused by the iris blades of your lens coming back together in very slightly different places for each exposure. There are two solutions - do the lens twist trick (search for it on this forum) or use a manual de-coupled lens so the aperture blades are not moved.

The jerkiness is caused by your ratio of exposures to move time of the TB3 ie: your move is too fast for the number of exposures. I'd suggest you start out shooting something well known (such as clouds) and try a range of ratios so you can understand what works best. It took me several shoots to fully understand how to pick the right ratios for different scenarios. The rules of thumb for non motion timelapse do apply but it gets trickier when you add movement. I've found that using slow shutter speeds can help a lot as it introduces motion blur. For daytime work you'll need to use ND filters to get a proper exposure.


Tue Sep 24, 2013 2:48 am
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Post Re: First test with eMotimo TB3 - is this Aperture flicker?
Thanks for the fast reply.

I've seen the lense twist trick mentioned a few times so I'll have a sneaky read tomorrow at work - I'm heading away the day after so don't get as much time to test it all out as I would have liked.

I'll stay in the 'safe zone' of movement and not push it too far until I've had decent time to learn the ranges of motion for available light and subject. Hopefully I'll get the chance to shoot a few sunsets and maybe stars over the ship wrecks (Moreton Island for those in Aus) over the long weekend. I have a Hoya NDx400 that I'll be taking for day shoots, but only one battery for the TB3 so will have to choose the shots carefully to save the battery.

The second sequence I shot had a similar range of motion but was 2 seconds longer so exhibited a lot less stutter, but was shot on a 14mm wide angle which would have helped minimise that horrible effect.

Anyway, looking forward to getting used to the TB3 and shooting a lot more day-lapse!

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Tue Sep 24, 2013 4:26 am
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Post Re: First test with eMotimo TB3 - is this Aperture flicker?
are we looking at the same video? the swampwater?

i dont see any flicker. im not sure what you guys are looking at, maybe im just crazy but i watched it 10 times and dont see any flicker. I see jumping in the video, which at times almost made it feel as if there was flicker, but I just dont see any aperture flicker.

I am not familiar with that lens, is it any good? The reason i ask is i routinely stop down to 5.6 or 6.3 on my old Tokina 12-24 f/4 and never saw any flicker, i wouldnt start seeing it untill f/7 or smaller. That is a zoom lens, i would assume 3.5 is the widest, sitting at f/4 should not introduce any flicker unless the lens is just real cheap. In fact just about any lens i have ever used i dont think i have ever seen any flicker unless it was at least 2-3 stops down from wide open.


As for the motion, i do not have an emotimo but i have built pan heads before, what i see there looks more like either missing frames or the camera is not triggering. It is not consistent jerkiness, if it was an issue with the improper frame rate it would have a less than smooth look, but that should be uniform throughout the motion. This jerkiness is not, i suppose that COULD be the video host, but i would suspect missing frames.

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Tue Sep 24, 2013 6:56 am
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Location: St Gallen, Switzerland
Post Re: First test with eMotimo TB3 - is this Aperture flicker?
Hi Karl,

Funnily enough (from my end), this is an issue for me too today, processing a clip shot with a Merlin head in my local mountains this weekend.

First off, I`d go with the lens twist technique in any case. You have a Canon, why not avail yourself of that clever trick?

However I doubt your clip shows aperture flicker. My clip exhibits the same "flicker" as you call it, but I had a manual Nikon lens with adaptor on a Canon camera, so aperture flicker was impossible.
I think I turned my Merlin head a little too fast - 0.12° per shot with a 24mm lens on a 6D. Next time I`ll slow it down, maybe 0.09° per turn.

Just my 2 cents. I`m not definitely right, but certainly could be!


Tue Sep 24, 2013 8:40 am
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Location: St Gallen, Switzerland
Post Re: First test with eMotimo TB3 - is this Aperture flicker?
By jove, what am I talking about? I`ve just redone the same sequence at 60 fps and it`s buttery smooth! The juddery one was 24 fps.


Tue Sep 24, 2013 8:50 am
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Post Re: First test with eMotimo TB3 - is this Aperture flicker?
I am with Jack on this. Missing frames or something moving.

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Tue Sep 24, 2013 10:24 am
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Post Re: First test with eMotimo TB3 - is this Aperture flicker?
Thanks for all the responses guys. Jack - the lense is one from Canon's L series so it's not a cheapy, it's f4 through the full zoom range.

I had to switch the youtube player to 1080HD to see the flicker - it doesn't appear in the standard/low quality. It's quite noticeable at home as well. It's interesting you mention missing frames as I did notice the camera buffer filling between moves which would probably have caused missed frames, and be a cause for the jerkyness.

Thanks for the info Ian - I'll try another couple of tests after work today and try one without the lense twist and one with, plus not push the motion too far for the shoot time. Hopefully I'll find a nice balance in there. The eMotimo doesn't give you 'degree per shot', I guess you could work it out though. I think it will come with experience using the device.

Off to read up on the lense twist trick just incase!

Thanks all.

Karl.

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Tue Sep 24, 2013 2:32 pm
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Post Re: First test with eMotimo TB3 - is this Aperture flicker?
Well I could see the flicker, maybe you have to be in Australia :lol:

If you think you are getting missed frames I'd suggest having a look at the TB3 FAQ page. In 'The TB3 is moving during my exposure' topic is a handy graphic that shows how the timing works. For shorter moves you may also want to have the motors not power down as this can cause slippage. How you set this depends on the TB3 you have. On my 'orange' one it requires loading in specific firmware. I think the 'black' has the option to toggle it on and off.

http://emotimo.com/learn/tb3-faqs/


Tue Sep 24, 2013 3:20 pm
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Post Re: First test with eMotimo TB3 - is this Aperture flicker?
Yeah I have the black - I've read about powering down the motors between moves which is probably something I'll figure out for the longer 4-5 hour astro shoots to save battery life. I went with the larger / heavier lead acid battery over the li-ion ones purely for battery life shooting astro.

I think the missing frames was probably my fault. I'd set the interval times etc but then gone backwards and edited something and perhaps not checked it hadn't reverted back to a default setting. I'm pretty positive the buffer was filling and missing shots, but I also think I was moving too much over too short a time.

All a learning experience with a new piece of kit, but once I've got that down I'm looking forward to shoots that aren't 5 hours of sitting in the dark, alone, in the middle of nowhere, fun as those can be!

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Tue Sep 24, 2013 3:33 pm
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Post Re: First test with eMotimo TB3 - is this Aperture flicker?
Make sure you post some footage of the sunsets over shipwrecks!

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Tue Sep 24, 2013 6:46 pm
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Post Re: First test with eMotimo TB3 - is this Aperture flicker?
Just posted a youtube link in the Showcase forum.

The 2nd clip in the sequence was shot using the TB3 although you wouldn't know it from the clip. I lost the little allen screw that attaches the Fotomate plate to the TB3 that night on the beach so couldn't use the TB again the whole trip. Now trying to source a replacement. Also gave the lense-twist trick a go and seemed to work perfectly!

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Wed Oct 02, 2013 12:05 am
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