Overexposed DNG's

[raphaeloo]

Hi there,

I am trying to set-up a timelapse with the Silent picture mode activated and the DNG's are overexposed with at least 3-4EV. While in LiveWiew the Histogram meters correctly and the auto ETTR works just fine.

Example:

1. Take photo with AutoEttr default settings & silentpic off + 15s Interval> photos get exposed correctly & saved
2. Take photo with AutoEttr default settings & silentpic off + 15s Interval> photos get overexposed

I can read that Autoettr says next photo will be 1/100 then next 1/200 so it is trying to change shutter speed with no luck. Ultimately it says: ETTR and Expo limits reached.

I do understand that by showing the message the limits were reached, but if I use the same settings 1/500 f2.8 iso100 i get a very dark image, so it seems like it is not changing the shutter speed. By changing the aperture to F22 I was able to lower down the DNG to -1/-2 EV, but this is not a solution.

Camera model: EOS 6D with ML 2015May03.6D113

Any ideas of what it could be?

Many thanks!

[garry23]

Don't use silent picture, as you will not have full control over exposure: at least not yet.

Silent is a work in progress.

Use A-ETTR for timelapse and normal shutter action.

OR experiment with Silent and an ND to narrow the shutter time range.

[dmilligan]

There are limitations in the full-res silent picture mode. Please read:
http://www.magiclantern.fm/forum/index.php?topic=12523.msg143510#msg143510 http://www.magiclantern.fm/forum/index.php?topic=12523.msg120497#msg120497

When there is no mechanical shutter controlling exposure, pixels collect light the entire time they are "on" even when they are being readout. This is where the exposure increase comes from. Normally, the mechanical shutter blocks light from getting to the pixels during readout to provide short exposure times.

[raphaeloo]

I do understand,

@dmilligan I think I've read this article 5 times today but did not occur that this might be the issue. Yesterday I had OK results (some flicker appeared) with DNG's but used an ND and probably this is why today was not working without it.

Another question: When using A-ETTR is there any way to increase the slow shutter to something bigger than 32" ?

Why I am asking this? Well, if I use an ND with silent picture to get -1EV trough the day, I will need more than 32" through the night (after Bramp). What is the solution?


@garry23 Seems like Slient is for day timelapses and if you want some BRAMPING then A-ETTR alone is the key am I right?

Many thanks guys!

[dmilligan]

When using A-ETTR is there any way to increase the slow shutter to something bigger than 32" ?

Not currently, but it's theoretically possible to implement such a feature for normal photos, but if your using FRSP, you're actually limited to 15" (see links).

[Levas]

Fastest shutter time for 'full resolution silent pictures' on 6d is about 0.3 seconds.
So if you're doing night time timelapses or use strong ND filters, you could try to use silent pictures.

Only one thing, real exposure time differs a little bit by use of silent pictures, so don't expect ETTR to be spot on...
Trial and error

[garry23]

@raphaeloo

Unless your BRAMPing is in the Full Silent 'sweet spot', you will have exposure control issues.

IMHO, I wouldn't use Full Silent when the exposure need is greater than, say, 15s or less than 0.3s; and 'unpredictable' in terms of DR deltas.

In other words, if it is an important TL, use the shutter.

A-ETTR is a way of not doing 'BRAMPing', ie consider it as auto-BRAMPing.

I use LRTimelapse as well: BTW there are some good videos tutorials on the LRT website.

Cheers

Garry