Author Topic: Fireworks - Dual ISO low-light videography at 14 fps with the EOS-M  (Read 1248 times)

IDA_ML

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Hello all,

At New Year's eve, I had the opportunity to play around with the EOS-M and the Viltrox speedbooster (VSB).  So, I decided to push this camera to its limits by filming the fireworks in the first few minutes of the 2020.  Several hours ealier, just a few minutes before it became completely dark, I captured the last sun light of 2019 that was producing a beautifil sunset.  These shots, filmed out of my window at Dual ISO 100/800, worked out quite nicely, without problems at all. The fireworks, however, turned out to be a real chalenge.  It was so dark outside that I could barely frame the shots.

I used my favorite EF 35/F2 IS lens which the VSB turns into a 24/F1,4.  This large apperture was very welcome in the darkness, so I filmed wide open.  My Dual ISO setting was pushed to the limit (200/3200) to get the exposure right but still, the fireworks clips were underexposed by two to three stops.  To have enough vertical resolution for the Dual ISO, I decided to use the maximum 1736x2928 anamorphic resolution available on the EOS-M for 16:9 aspect ratio.  This resolution allows continuous recording at 14 fps and 12-bit lossless if the shot is slightly underexposed.  I had plenty of underexposure, so I could film as long as I wanted and never had an early stop. As an additional bonus, this resolution almost completely eliminates aliasing and moire which can be a big problem with sharp lenses.

I know, many people fear low frame rates but I use them all the time for wide angle videography with no issues at all.  When moving objects in the frame are small, which is true in most cases with this type of videography, then their angle velocity with respect to the optical axis is small enough to eliminate visible interruptions in the motion.  Adhering to the 180 deg. rule provides very smooth filmic motion as you can see in the video. EOS-M has a very useful feature which allows the shutter speed to be fine tuned to the desired shutter speed, so I adjusted it to 1/29 s. - close enough to the 180 deg. shutter. 

As always, I did the Dual ISO conversion with a few basic adjusrments in MLVApp and the conversion to 24 fps, video editing and adding music - in DaVinci Resolve 16 Lite.

The final result is not perfect but in my opinion, usable.  For some reason, Vimeo reduced the contrast which is not nice but ... see for yourself:


Your comments will be greatly appreciated.

ZEEK

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Re: Fireworks - Dual ISO low-light videography at 14 fps with the EOS-M
« Reply #1 on: January 18, 2020, 11:13:45 PM »
Hey Ivan, great work on this capture! It actually looks really nice even with the reduced fps. Love the colours, location and good sound track.

Pretty good low light performance, although I personally wouldn't go near iso 3200. Still looked great though 👍

One thing I notice with dual iso, is that you get this  "green cast" flickering e.g. @0:37-0:40. I find it sometimes leaves when you "unitck" highlight re-construction. Not sure if there are any other ways of eliminating the dual iso cast flickering.

Anyway, apart from this, really great work, it looks really good! 📽👌
EOS M - EOS M2 - 5D2

IDA_ML

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Re: Fireworks - Dual ISO low-light videography at 14 fps with the EOS-M
« Reply #2 on: January 19, 2020, 10:34:06 AM »
Thanks a lot, Zeek.  It's nice to hear kind and encouraging words from such an experienced person like you.  Much appreciated!

The reason why I set the upper ISO to 3200 was that I really wanted to push the EOS-M to its limit to see if it still is capable of providing usable results.  The other reason was that it was really very dark and the image was severely underexposed even with these settings.  Instead of using Dual ISO 200/3200 and 1/29 s shutter speed I could have set 100/1600 and 1/14 s shutter which would have gained me one more stop of light and maybe a little less noise in the darks but in that case I would have had 360 deg shutter which would affect motion smoothness at 14 fps - something that I wanted to avoid.   In future, I plan to test this option too to see how motion smoothness is affected at 360 deg. shutter.

As far as the "green cast flickering" is concerned there are two effects here.  One is the greenish cast coming from the lights illuminating the street.  These bulbs provide an ugly cold greenish cast.  This can be corrected to some extent using the Hue vs. Hue option.  The observed flickering will be harder to correct.  It comes from the 50Hz power line frequency which differs substantially from the 1/29 s shutter frequency.  1/50 s shutter speed may be the only remedy here.  Needs further testing though.  I also tried unchecking Highlight reconstruction on this file as you suggested.  This did not make any difference.  In my experience, Highlight reconstruction makes a difference only if the highlights are close to overexposure which is not the case here. 

Thanks for your comments.  I also think that the EOS-M is a very capable low-light video camera, especially with the speed booster.  I am quite amazed to see that even at F1,4 this little toy barely degrades image quality.  You can notice some immage degradation only when pixel peeping the extreme frame corners at 100% magnification.  The fact that it allows EOS-M shooters to use all their EF lenses, making them by 41% wider and by one stop brighter, is absolutely fantastic!

ZEEK

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Re: Fireworks - Dual ISO low-light videography at 14 fps with the EOS-M
« Reply #3 on: January 19, 2020, 12:42:55 PM »
I used to shoot a lot of Dual ISO, even with x3 Crop Mode & 2.5K Mode. Even with 1/50 shutter I sometimes get the green cast flickering on brick walls or on concrete footpaths. It is definitely a capable low-light camera at it's price-point and when paired with a speed booster it's a different camera. Anyway, good test and the results came out nice, especially in such conditions. I could imagine how good it would look in bright daylight. Cheers!
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IDA_ML

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Re: Fireworks - Dual ISO low-light videography at 14 fps with the EOS-M
« Reply #4 on: January 19, 2020, 12:55:29 PM »
I used to shoot a lot of Dual ISO, even with x3 Crop Mode & 2.5K Mode. Even with 1/50 shutter I sometimes get the green cast flickering on brick walls or on concrete footpaths.

That's really strange.  Are you sure you are not seeing some kind of ugly aliasing artefact?  What happens if you change the shooting angle and/or reduce exposure?  Is it still there?  What happens if you change the lens?

ZEEK

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Re: Fireworks - Dual ISO low-light videography at 14 fps with the EOS-M
« Reply #5 on: January 19, 2020, 02:08:14 PM »
It is strange. I need to do more tests. No aliasing especially with the x3 crop mode. But in some instances, there will appear a green cast of the flickering. I'll play around with a few things. But really do love the Dual ISO stuff!
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ngemu

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Re: Fireworks - Dual ISO low-light videography at 14 fps with the EOS-M
« Reply #6 on: January 23, 2020, 09:18:54 AM »
I don't think the 35mm is 24mm with a speed booster.

The actual focal length is 35x1.6x.71 which is around 39.71mm.

I also have a 35mm f/2 and i think it looks very nice with the eos-m. It behaves more like a 50mm on our aps-c sized cameras.

DeafEyeJedi

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Re: Fireworks - Dual ISO low-light videography at 14 fps with the EOS-M
« Reply #7 on: January 23, 2020, 09:29:57 AM »
Fantastic test and thanks for sharing @IDA_ML!
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IDA_ML

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Re: Fireworks - Dual ISO low-light videography at 14 fps with the EOS-M
« Reply #8 on: January 23, 2020, 01:22:34 PM »
I don't think the 35mm is 24mm with a speed booster.
The actual focal length is 35x1.6x.71 which is around 39.71mm.

Yes, you are right but I meant 24 mm w.r.t. the crop sensor and not to full frame.  So, in my calculation, the 1.6x factor is missing.