Author Topic: Full resolution liveview vs. Crop Record  (Read 2345 times)

Ballinger

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Full resolution liveview vs. Crop Record
« on: August 31, 2018, 02:53:57 AM »
Hello,

I'm currently using a Magic Lantern Crop 4k build for the EOS Rebel T5i/700D that includes options for 2K+ resolutions in 5X crop mode.  I'm trying to gain a better understanding of what full resolution liveview recording is versus crop recording?  Does full resolution liveview recording facilitate 2k+ resolutions in a full frame rather than a cropped frame liveview?   My current understanding is that for the T5i/700D, one must always be in 5x crop view mode to record in 2K+ resolution and that full frame recording in high resolution is not possible due to hardware limitations. 

I'm wondering if I misunderstanding the concepts here and that I'm not fully grasping what full resolution liveview recording is.   I would greatly appreciate any insight that could be provided, thank you!   

bakersdozen

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Re: Full resolution liveview vs. Crop Record
« Reply #1 on: August 31, 2018, 08:02:23 AM »
I was also pondering on this, as I have tried to search for an explanation before and couldn't come up with anything that would fully explain it. Would love to know. And how this also relates to FRSP with the Full Res and Full Res LV differences.
EOS M + 5D3

a1ex

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Re: Full resolution liveview vs. Crop Record
« Reply #2 on: August 31, 2018, 08:38:32 AM »
FRSP: exposure starts on all rows at the same time, but end up at different times (rolling shutter). This gives a gradient (timing analysis) and limits the shutter speed at short exposures. Long exposures are fine (15 seconds out of the box, patches available for 15 minutes or more). Implementation uses Canon's still photo capture routines, but without actuating the shutter. Code not optimized for speed (not pipelined). Available on all models.

Full-res LiveView: this is simply LiveView with resolution changed to maximum values (the ones used for still photos). Obviously, that limits the frame rate (7.4 on 5D3, 6.1 on 700D). Higher frame rates require lower resolutions. There will be rolling shutter (128ms on 5D3) at both start and end of the exposure, but there's no gradient and exposure time can be very small (1/15000 on 5D3). Long exposures (longer than 1-2 seconds) probably won't work well; not tested. Continuous recording at ~ 5 FPS (5D3). Preview is broken and hard to fix, but some progress was made. Shutter lag is high (switching LiveView resolution takes time). Currently available on 5D3 (crop_rec_4k builds) and 700D (only as a PoC), but doable on all other models (except maybe for the classic 5D). On models other than 5D3 and 700D, you can get it right now with adtg_gui and some trial and error; if you do, please report back and write down what registers you have changed.

bakersdozen

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Re: Full resolution liveview vs. Crop Record
« Reply #3 on: August 31, 2018, 01:43:09 PM »
Thank you for the explanation @A1ex.

Would there technically be any output difference in shooting FRSP FullResLV  (.MLV output) with intervalometer set to 4 seconds VERSUS recording RAW Video FullResLV with FPSOverride set to 0.25?

On paper it should yield the same results. Is my logic right?
EOS M + 5D3

a1ex

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Re: Full resolution liveview vs. Crop Record
« Reply #4 on: August 31, 2018, 02:16:42 PM »
On paper, yes. In practice, there might be some differences; I have not tested this scenario, but that's roughly where the two methods can overlap. For example, on DIGIC 5, FPS override at very low frame rates have some issues with vertical stripes; the defect is likely there with full-res LiveView, too.

For timelapse, I have in mind some sort of semi-automatic exposure mode with 180-degree exposure time (intervalometer time / 2), that would select one of these two methods (or maybe both) as appropriate for the scene (either long exposure with the "classic" FRSP, or stacked full-res LiveView exposures, possibly at different exposure times and/or ISO), but that's likely not going to happen very soon.

bakersdozen

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Re: Full resolution liveview vs. Crop Record
« Reply #5 on: August 31, 2018, 02:27:30 PM »
Thanks for the logic check. And that idea sounds really cool!
EOS M + 5D3