Exposure Issues with 50D Raw

[kyrobb]

Just put Magic Lantern's latest nightly build on my 50D. Exposing is not making any sense to me. Opening the aperture or increasing ISO is changing my shutter speed to let in more light, but after changing the shutter back to where I want it, I have to exact same exposure... It doesn't make any sense. How can I get shutter speed, aperture, and ISO to work properly?

[Walter Schulz]

Please put yourself in the position of a person reading your post without mental powers beyond common human reach.

You're giving almost no information what you have done and which options you are trying to use. Therefore: No info, no help.

[kyrobb]

Yes well increasing my ISO settings is not increasing my exposure. It simply isn't changing properly. The same goes with changing my aperture. It has no effect on my exposure. The only way I can increase or decrease my exposure is by changing the shutter speed. I'm wondering how I can fix this.

[kyrobb]

Problem somewhat understood now. With the latest build, the shutter speed values display wrong. Thinking my shutter speed was 1/48, it was actually something like 1/390. Had to switch to an earlier build to find correctly displayed shutter speeds. Hopefully this gets fixed at some point.

[ADJ]

This was driving me crazy last week. I still don't think I'm fully on top of it. I have two cards. I think I have the same version of Tragic Lantern on both - the most up-to-date version. On the Komputerbay 1000x 32GB card I couldn't get the exposure to work properly until I set Expo>Expo. Override to: ON. Then I can change the shutter and it displays in a different colour with Global Draw on.
The other card a Kingston 266x 16GB seemed to behave differently. I'm sure there will be an easy way to get each card to print out all the settings so I can compare them but it wasn't obvious to me.
http://www.magiclantern.fm/forum/index.php?topic=9852.0 The Kingston card seems to let me adjust the exposure differently. What's the best way to check which version is on the camera? It seems like a Noob question. On the canon menu the Firmware is "Firmware Ver. 1.0.9-ml-Tragic.An" which doesn't tell me.

I think my Komputerbay card has some setting with automatic exposure active but I can't track it down. It's not ETTR module which is off. Is it the same kind of problem you were experiencing?

[ayshih]

Problem somewhat understood now. With the latest build, the shutter speed values display wrong. Thinking my shutter speed was 1/48, it was actually something like 1/390. Had to switch to an earlier build to find correctly displayed shutter speeds. Hopefully this gets fixed at some point.

How much earlier of a build did you go back to to get the correct shutter speeds?  I fixed a bug with the shutter-speed display on January 7th, but it's entirely possible that there are still issues.  Can you provide more details about which exposure mode you're in and how you are changing your settings?

I'm sure there will be an easy way to get each card to print out all the settings so I can compare them but it wasn't obvious to me.

You can go to the "Modified" tab in the ML menu (all the way to the right).  All the settings that are different from their defaults should be listed here.

What's the best way to check which version is on the camera? It seems like a Noob question.

You can go the "Help" tab in the ML menu, and there should be lines at the bottom that will give you build information.

[ADJ]

You can go the "Help" tab in the ML menu, and there should be lines at the bottom that will give you build information.

I don't have ML installed at the moment. On TL the Headers are: Expo; Overlay; Movie; Shoot; Focus; Display; Prefs; Modules; Debug; Modified.

I don't see any help which shows the TL version.

I assumed there would be a way to write/print all the current camera setting to a log file for transfer to a computer. If it's not available at the moment would it be easy to introduce? It might save some time when people are looking for help on the forums. Maybe it's worth adding? I was going backwards and forwards between the two cards and I thought I'd like a paper print out and I could do a "spot the difference" and find the setting which was causing the problem.

I have a TV box which has native and extra firmware a bit like the ML canon cameras. They have software which can produce a readout of all the settings and it's very useful. http://forum.toppy.org.uk/forum/viewtopic.php?t=17888&postdays=0&postorder=asc&start=0

[ayshih]

I don't have ML installed at the moment. On TL the Headers are: Expo; Overlay; Movie; Shoot; Focus; Display; Prefs; Modules; Debug; Modified.

I don't see any help which shows the TL version.

Ah, yeah, I forgot that TL has the "Help" tab disabled.  You can look up the build information in the generated text file magic.cfg in the ML/settings folder on your card.

I assumed there would be a way to write/print all the current camera setting to a log file for transfer to a computer. If it's not available at the moment would it be easy to introduce? It might save some time when people are looking for help on the forums. Maybe it's worth adding? I was going backwards and forwards between the two cards and I thought I'd like a paper print out and I could do a "spot the difference" and find the setting which was causing the problem.

The settings can be found in the *.cfg text files in the ML/settings, which is very similar to what you are asking for.

Edit: revised method to find build info

[kyrobb]

I reverted to the October 22nd nightly for now. Shutter speed displays correctly below frame, but still incorrectly in the menu. Still, it's better than today's nightly, in which it displays wrong in both places. I may play with some other builds and see what works best.

[ayshih]

Okay, I think I understand what's causing the confusion.  The January 7th fix made sure that the LV overlay and the ML menu show the same shutter speed: the one that LV is actively using to simulate the exposure.  That is, if you have a certain shutter speed dialed in, but you stop down the aperture or increase the ISO from the lowest, LV uses a different shutter speed than the one you have dialed in to simulate the effect.  For example, with a maximum aperture of f/4:

• Exposure settings are ISO 100, f/4, and 1/500s => displayed shutter speed is 1/550s
• Exposure settings are ISO 400, f/4, and 1/500s => displayed shutter speed is 1/140s

That's because LV is using a shutter speed a factor of 4 slower than the dialed-in shutter speed to simulate the higher ISO.

Prior to the January 7th fix, the LV overlay would show the dialed-in shutter speed rather than the shutter speed being used by LV.  However, since RAW video is simply recording the LV feed, the dialed-in shutter speed is the incorrect one to display.  You can easily demonstrate this to yourself by trying to dial in a shutter speed longer than the frame cadence, such as 1 second.

Does this make sense?  If you still think that the displayed shutter speed is wrong, you can try to prove it by taking a video of a moving source and looking at the blur.  Note that you can't necessarily trust the metadata in the RAW video because I'm not sure it's being saved entirely correctly.

[ADJ]

The settings can be found in the *.cfg text files in the ML/settings, which is very similar to what you are asking for.

Thanks ayshih. That was very helpful

There were indeed different builds on the two cards. It's simple when you know where to look. The newest build was on the KB card which I can expose the way I want on TL.

[kyrobb]

Yes, I would still say displayed shutter values are incorrect. If you want to see the actual shutter speed with the latest build, just take a picture. Then you will see the real shutter speed, which could be vastly different from the one ML displays.

[kyrobb]

I suppose the top screen will likely display it correctly as well, but for some reason I didn't think to check.... Oops...

[a1ex]

ayshih is right, LiveView settings may not be the same as photo settings.

Try exposure override.

[1%]

Expo override will actually stop canon from adjusting shutter/iso/etc to simulate exposure. In photo mode its pretty simple, shutter displayed is how the shutter moves, etc.

in LV canon can adjust iso + digital, REAL electronic shutter and maybe other things to make it seem like the photographic exposure. The 50D is kind of aggressive here as there was no official video mode. Other cameras don't do this so much since they had to shoot H264.

If you want to see the actual shutter speed with the latest build, just take a picture
I suppose the top screen will likely display it correctly

For any video these are both incorrect. There is no mechanical shutter there, nor can we modify the top screen. Even with ADTG set shutter speed, if you add fps override some of what displayed on top is not even possible, else you get a corrupted LV image.

[kyrobb]

Oh ok. This all makes a lot of sense. Thank you for ending my confusion! Exposure override does the trick nicely!

[kyrobb]

I guess my final question would be: How do I ensure that I'm using a shutter speed as close as 1/48 as possible. With the latest nightly, and exposure override on, I can get 1/49, which is great. Do I just ignore that my top screen reads either 1/80 or 1/100?

[1%]

Yep, pretty much the only thing to do is to ignore it or reverse engineer a way to modify what is displayed up there.

Its still ok for photos