Mt first lightning... :D

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Offline ursamajor

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Mt first lightning... :D
« on: 20 / June / 2016, 13:14:56 »
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Using script called MDFB 2013 v 1.1a I managed to capture my first lightning with my little SX510HS. I still have difficulties with script setup, because it takes more than a picture (3, 4 even 5 more pictures) after each trigger (lightning, in this case) without no reason.
Is there another script, better/easier to setup than MDFB?

Other problem is the sound/beep of focusing each time camera take a picture, though I use manual focus to infinite...  :blink:

« Last Edit: 20 / June / 2016, 13:20:07 by ursamajor »
SX150IS (retired) :D, SX510HS

Re: Mt first lightning... :D
« Reply #1 on: 20 / June / 2016, 17:20:12 »
Is there another script, better/easier to setup than MDFB?
Every CHDK motion detection script calls the same function for motion detection.  So you will have the same setup issues with each of them.

Perhaps this will help  : Motion Detection : Performance Tuning
Ported :   A1200    SD940   G10    Powershot N    G16

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Online reyalp

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Re: Mt first lightning... :D
« Reply #2 on: 20 / June / 2016, 17:45:37 »
If it triggers after the shot, the "Burst/Review/Video time" option might be helpful.
Edit: Oops. Looking at the code, this probably wouldn't help, since it keeps the button down.

It could checking too early and picking up changes in the buffer related to shooting rather than actual motion.

If you have "review" turned on in the canon settings menu, turning that off might also help.

edit:
also, nice shot :)
« Last Edit: 20 / June / 2016, 17:50:38 by reyalp »
Don't forget what the H stands for.

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Offline ursamajor

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Re: Mt first lightning... :D
« Reply #3 on: 21 / June / 2016, 11:03:24 »
Reviewing is inactive on all my cameras. :D Always had it so.
The challenge for me is to fine tuning the script. Not so easy because there are positions/settings that I don't understand so good. Maybe I better start by using a simplier script to understand basic functions, then "migrate" to other more complex.
SX150IS (retired) :D, SX510HS


Re: Mt first lightning... :D
« Reply #4 on: 21 / June / 2016, 11:23:00 »
The standard CHDK distribution includes a really simple motion detection script called motion.bas  There is an identical script called motion.lua - written in Lua rather than uBASIC.  It does not get any simpler than that.
Ported :   A1200    SD940   G10    Powershot N    G16

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Offline ursamajor

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Re: Mt first lightning... :D
« Reply #5 on: 21 / June / 2016, 13:11:17 »
Indeed there is that simple script. Should I understand that it makes basically same things as the complicated one?
SX150IS (retired) :D, SX510HS

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Online reyalp

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Re: Mt first lightning... :D
« Reply #6 on: 21 / June / 2016, 13:20:31 »
The challenge for me is to fine tuning the script. Not so easy because there are positions/settings that I don't understand so good. Maybe I better start by using a simplier script to understand basic functions, then "migrate" to other more complex.
Starting with the defaults, the main setting that should make a difference to triggering is the "Trigger threshold". You really shouldn't have to "tune" most of they other parameters much in normal use.

The "trigger delay" setting might help if the camera is picking up viewport changes caused by the camera getting ready to shoot. This seems like a likely cause of triggering more than once on a single motion.

I'd suggest trying to narrow down what is actually happening first. For example, run the the script with the camera point at completely unchanging scene.
Does MD trigger by itself? If so, your threshold might be too low, or there might be a bug in your port.
If not, quickly pass you hand in front of the camera once. Does MD trigger just once, or multiple times? If it triggers multiple times, then trigger delay might be the issue.
Don't forget what the H stands for.

Re: Mt first lightning... :D
« Reply #7 on: 21 / June / 2016, 14:07:46 »
Setting the "g" parameter to 3 is a really handy way to see what is happening relative to the sensitivity level you have set.
Ported :   A1200    SD940   G10    Powershot N    G16


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Offline ursamajor

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Re: Mt first lightning... :D
« Reply #8 on: 21 / June / 2016, 14:19:42 »
Good to know what you both said. I'll test it tomorrow. Right now I prepare myself for a visit to my cardiologist in Bucarest. :) Thanks guys! I appreciate it!
SX150IS (retired) :D, SX510HS

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Offline Anaglyphic

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Re: Mt first lightning... :D
« Reply #9 on: 21 / June / 2016, 19:15:42 »
ursa. dude. Another vet.  :P This post is kinda deja vu. More like deja deja vu. lol.

As you may or may not remember, I am a huge lightning photography geek, and have been a bolt hunter for ~40 years. (sheesh who is that old person?)

I love MD, and fudgey's script is very useful, but not for what you want to use it for. If you go through the archives, you will find me saying it is useful back in the day, but nowadays I know better. It was hubris; I really really wanted CHDK MD to be the driving force of my lightning shots. I mean, how cool is that?!

But reality is not poetic nor passionate. It's just fact. And the fact is, you will very rarely catch lightning bolts with MD on CHDK. Just do it like we've always done, back when we had to pay for developing dozens of rolls of film with no lightning on them.

Here's the deal. Lightning "fires" in pulses. There is a pre-flash, then the main bolt, then depending on the potential of that cloud, the resistance of air, the pollution, rain, humidity, pressure, blah blah blah.... additional pulses. The timing from the pre-flash to the main bolt is ~30ms. And CHDK capable cameras simply cannot detect and react in that time. Consider yourself lucky if your camera can reliably do 130ms.

So what are we catching when using MDFB? Either catching those bolts that have huge potential and pulse 5+ times, that it's still discharging and ionizing the air when the shutter trips, or more likely, it's luck - a different bolt (that is done and gone) triggered the detection and another bolt just happens to be discharging when the shutter fires.

So Instead?

Set camera for base ISO all NR disabled (that you can anyway), maybe shoot a new badpixel, set aperture to sharpest and focus to manual @ hyperfocal point, and try for an exposure that's 2 - 10 secs depending on frequency of strikes. Then turn the intervalometer loose. Shoot til the battery dies or the storm ends. If it's pitch black you can shoot much longer, but you will get multiple strikes/flashes and it can cause the foreground to look surreal with multisource lighting... it can be a cool effect, but make sure you want it.

ProTip: Don't delete those shots that don't have lightning in them, you can imagestack these to make a near-noiseless scene, looking like it was shot with a much bigger/better sensor.

If you like daytime lightning shots, I highly recommend a variable ND filter. You can use regular ND8s and such, but because during a storm the lighting conditions can change so fast, +/- many stops, having to unscrew or add another filter vs. just adjusting rotation with a fingertip...

DIY is fun. I would tell you to grab a pair of Real3D glasses next movie you go see ("Finding Dory" is a Real3D release here)... you can re-purpose the lenses into a DIY holder for the 510. Real3D lenses are circularly polarized and of not-too-shabby sharpness. There will be degredation, but it's not severe. Google is your friend here, many DIY sites will cover this including ideas of what to make the holders out of (I like pill bottle tops, they are knurled and incredibly uniform... another option is to mount a proper filter-sized tube to your 510, so that you can thread actual photography filters on; again, Google, lots of options.

I really wish I could tell you MD is the way to go for lightning, but it's not. I have done some really cool artistic things, and once I showed a presentation to an NYPD surveillance team how to monitor people entering/exiting a store (but not just passing by) 1500m away, wearing only pink shirts, with a ~$300 20x superzoom Canon w/CHDK & fudgey's MDFB. (they were spending $$$$ on some schyster's proprietary stuff, but ultimately I think they went with a different facial recognition spy setup - made by? Canon!

Good luck at the doctor!
Since we cannot know all that there is to be known about anything,
 we ought to know a little about everything.
-- Blaise Pascal

 

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