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Showcasing Magic Lantern => Share Your Videos => Topic started by: daveesl77 on July 11, 2012, 06:37:45 PM

Title: FPS Override test RC1 on 550d
Post by: daveesl77 on July 11, 2012, 06:37:45 PM


Camera:  550d;  Canon Firmware: 1.0.9;  16GB SanDisk Extreme SD HCI  30MB/s; Canon 50mm f1.8 lens; Ambient Temp  32c

In this test I wanted to see how dialing down the FPS in movie mode, using FPS Override, worked.  Shot was done in a covered porch, each shot starting immediately after the previous ended.  All camera controls set to Manual.  Shoots were done to create approx. 10 seconds of finished video for each test.

Tests #1-#4: Aperture, Shutter speed and ISO all same (f18; 1250; 100)
FPS Override as follows:
Test #1:  3 FPS, 100 second shoot
Test #2:  2 FPS, 150 second shoot
Test #3:  1 FPS, 300 second shoot
Test #4:  0.5 FPS, 600 second shoot

During the test shoots, it is obvious that exposure becomes more and more over exposed as fps rate drops. 

Test #5 changed exposure parameters from #4, but almost to a reverse view as it seemed that where it should have gotten darker, the shot got even lighter.

Test #5 :  Aperture f22,  Shutter 4000,  ISO 100
Camera overheated at about 4 minutes shooting time (4 seconds movie time) and required shut down.  This may be only due to high outside temp, even though shooting in shade.

Main concern is that when using slow fps, trying to focus, set exposures are very difficult due to view delay in Live View.  Not certain why over-exposed.
Title: Re: FPS Override test RC1 on 550d
Post by: Francis on July 11, 2012, 06:50:33 PM
thanks for sharing. It is difficult to adjust focus and composition while in FPS override mode due to the lag in changes but changing shutter speed is not that bad at least on my 550d.


Main concern is that when using slow fps, trying to focus, set exposures are very difficult due to view delay in Live View.  Not certain why over-exposed.

So what you are experiencing is your set shutter speed being overridden by the FPS setting. Under FPS Override submenu change the 'Optimize for' setting to increase your range of available shutter speeds. The default setting 'Low light' locks the shutter speed to the FPS setting. So at 3 FPS the shutter speed is actually 1/3, not 1/1250. If set to 'Hi-jello' your range of available shutter speeds should be 1/3 to 1/396 (at least on my 550d). You can then change the speed just like normal back in Liveview. The lag for changing shutter speed should not be that debilitating.

Also I split this topic from the RC1 announcement so it would be easier to find for other users interested in FPS override.
Title: Re: FPS Override test RC1 on 550d
Post by: a1ex on July 11, 2012, 07:01:01 PM
For changing settings, it's probably best to turn off FPS override temporarily, adjust things, then turn it back on. Not very fast, but when setting up a timelapse you usually have the time to setup the shot.
Title: Re: FPS Override test RC1 on 550d
Post by: daveesl77 on July 11, 2012, 07:56:20 PM
Tried it again, using the suggested things above, but no luck.

If I turn fps override off, set the A and S to pegged limits (4000 and 22), in Live View image is black.  Turn fps override on and start recording at 0.2 fps.  Initial image (1 second) is perfect. image at "Second 2" immediately jumps to extreme over-exposed.   Tried this multiple ways:

1) set parameters for fps override, then set ap and shutter while fps override is on, then start movie
2) set params, set ap and sh while fps off, turn fps on and start movie
3) turn fps on, start movie, set params, set ap and sh
4) start movie, darken ap and sh, set params, turn on fps

all give the same result.  1st frame is perfect, 2nd frame goes to over exposed, 3rd frame goes to blown out.

but  I did just notice that for some reason the "Optimize..." control will initially show a range, then it will only show 1:1.  I will remove RC1, reformat and reload to try again.  Will also try on a different card.  Info to follow.

I LOVE MAGIC LANTERN!!!  If I can get this part working it will be absolutely AWESOME!!!!

 :)dave
Title: Re: FPS Override test RC1 on 550d
Post by: a1ex on July 11, 2012, 08:09:13 PM
Fast exposures at low FPS are only possible on 60D and 600D (optimize for something different than low light).

You can try the high jello mode, that one also allows fast exposures (but with side effect).
Title: Re: FPS Override test RC1 on 550d
Post by: daveesl77 on July 11, 2012, 08:37:09 PM
Thanks Alex.  Yeah just figured that one out too, limitation of the camera model.  I then assume this would be the same on the 500d, but looks like it does drop on the 60 and 600D, is that correct?

For future reference, did a new card, replaced lens with an old Tamron pure manual, got the same result.  What I was able to see once I went below 2fps was that the "movie" would consist of the first frame at the set exposures, next frame would ratchet up and 3rd frame would go massive over exposed.  Since my aperture control with the Tamron lens is pure manual, and I set the Canon max ISO to 400, I am assuming that ML doing fps override then ratchets down the shutter speed dramatically.  I don't know how I missed it before, but in reviewing the video I saw the motion blur on the images, where shutter speed was shown to be set to 1/4000 or 1/2000 or 1/1250, but in reality I guess it was way down from there.

Having fun!

dave

Title: Re: FPS Override test RC1 on 550d
Post by: daveesl77 on July 11, 2012, 08:57:52 PM
Got around the over exposure part by putting on 2 polarizing filters (circular and linear), then cranking them down to essentially black.  Can now set light and color exposure to whatever I want, operating at 0.2fps.  Still have the extreme motion blur from the slow shutter speed.  So you can force the slow frame rate on the t2i, but you have to use filters and will get motion blur.

Which brings up the point, why would the camera automatically reduce shutter speed if everything is set to manual and I guess it doesn't do it on the "6x..." series camera?  Haven't tested it yet on those, but will soon.

dave
Title: Re: FPS Override test RC1 on 550d
Post by: a1ex on July 11, 2012, 09:10:25 PM
See the user guide: http://wiki.magiclantern.fm/userguide#fps_override
Title: Re: FPS Override test RC1 on 550d
Post by: daveesl77 on July 11, 2012, 10:28:56 PM
Alex, where is the fun in reading directions?  :)

Sure, this made sense and negates my entire thread, but it least it gave me something to do for a few hours.  I'm old and bored.  Anyway, the feature seems to be working well so far.  Starting it up on the 600d now.

Has anyone tried using this with a "long shoot"? Seems like it should work, as the file size I got on a 10 minute shoot was about 75MB doing 0.2fps at 1920 x 1080, and with that thinking, then a 4GB limit might hit somewhere around the 9-10 hour mark if the camera doesn't overheat.

 I'll give it a shot and let you know how it goes.

dave

dave
Title: Re: FPS Override test RC1 on 550d
Post by: wagger on April 26, 2014, 09:09:47 AM
daveesl77 - how did you solve this issue?

I have the exact same problem, and the link to the User Guide does not help at all. I put the settings on "High Jello", but the effect is the same as you described: First image fine, the rest super-overexposed.

I am using a Canon 60D in this case.

Thanks =)