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Messages - andycivil

#1
Right, I'm getting there. I see that Tb is coerced to be at least Tb0, which means that you can never get a faster shutter speed than is set in the Canon menu. In fact, the best you can get (by choosing "High Jello") is that you slow it entirely with Ta, which would in principle keep the exposure angle constant. However, I notice that if I choose 1/4000 before I start, I can get down to 2 FPS quite nicely with a roughly 1/150 shutter, but if it was strictly proportional, it would be more like 1/250. What started as 2.7° crept up to 4.8°. I want to look at the code: I found it at bitbucket because you quoted it and I googled, but how can I be sure that I'm looking at the source of the version I have in my camera? I don't know how bitbucket handles versioning.
#2
Thank you A1ex, that's certainly getting to the information I wanted; I'm on my way to understanding it, if you happen to read this message, could you tell me what "FT" is in the display? Is it Ta0 or Tb0 depending on whether it appears under Timer A or Timer B? (i.e. "Factory Timer-value")

Also, when a value of exactly 8192  occurs, which would also be by implication "FT + 0" the display changes to "x15.00" - why?

#3
Quote from: Francis on September 11, 2012, 06:31:34 AM
... it is more of a 'how does this work' than a 'how do I do this' question?
Really, my question is "how do I get the FPS override to work more like a conventional time-lapse, taking a normal exposure frame a few times a second?". I had a feeling that question was likely to be answered with "lmgtfy" or "that depends..." and I'd end up needing to understand what the (camera specific) constraints are - so I thought I'd cut straight to the chase and ask how it worked. Should I ask somewhere else?
#4
I'm sorry, I passed over that program because I thought it was mac or smartphone or something! It's a start, because now I've played with it, I can see that the timers are chained dividers from the main clock (in my case it's 2,880,000Hz) so the frame rate is
FPS = 2,880,000 / (timer A * timer B)
Apart from giving me that information, the program seems to be focused on getting an exact frame rate, which doesn't seem important to me at the moment, since no one's going to know if your timelapse movie is shot at 3x speed or 3.1x speed... but I digress.

Remaining questions are:
What is the difference between timer A and timer B, if any?
What controls the shutter speed?
What controls the jello effect? (I know what causes it, what controls it?)
When you increment the timer values, sometimes they show "(FT + nnn)" where 'nnn' increases and decreases with the value, implying that "FT" is a constant. What is "FT"?
From the program, it appears that Timer A goes up to 8192, and Timer B goes up to 16384, is that right?
The program gives values for Timer B that are always bigger than Timer A. Why?

Thanks
#5
Quote from: nanomad on September 10, 2012, 11:28:36 PM
http://wiki.magiclantern.fm/userguide#fps_override
Yes, thank you that was what I meant by "I read the FAQ". It doesn't really explain much; like, it says "Timer A: displays the value of timer A and lets you fine-tune it." Well yeah... but what does Timer A actually do? And I understand that the jello effect and shutter speed are related, but I'm none the wiser why, and without an understanding of the constraints the feature works under, I can't calculate what's possible. Like, if I want a fast shutter of less than 10° for example, what's the slowest fps I can get? There's no explanataion, and no calculations. Even what looks like a formula "the current FPS, computed as TG_FREQ / timerA / timerB" which looks like the most useful part of the guide, I think is only illustrative - not mathematically accurate.

What do Timer A and Timer B actually do? I don't even know if they're two separate timers - they could be the numerator and denominator of one single timer for all the explanation there is. And what are their valid ranges, are they 16-bit signed numbers, or what?
#6
Hi, I installed ML so that I could use FPS override, and of course, I've now discovered the limitations of the timer A and timer B and why I can't get the shutter speed I wanted.

I know there's a brief description of the "jello" modes in the FAQ, but where's the best description of what these timers do, and what my choices are (and why) for these timers?