Author Topic: 550D: Stacking HDR, LCD trigger, Electronic shutter, Mirror Lock, Etc...  (Read 9715 times)

Boboche

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Hello everyone,

I've been following the CHDK and Magic Lantern development for some time, and I must say, what you guys did with the 550D (T2i) is amazing.... so amazing in fact that it might be the perfect solution for a project I am working on. 

I need to shoot anywhere between 5,000 and 100,000 images per "cycle", which is something I usually do with framegrabbers.  This would obviously kill any DSLR in less than a day. 

My need is to shoot at various exposures (HDR) with external triggerting without killing the camera. 

So essentially, I would like to use HDR bracketing, LCD sensor, mirror lock up,  AND electronic shutter altogether.

I've managed to get the HDR bracketing triggered with the LCD Sensor (love it!), so I can put some electronics there to automate the acquisition, I tried the silent picture and mirror lock up, but I can't seem to find the way to take pictures without triggering any mechanics (maybe its the liveview? automatic setting in HDR?). 

The setup would be static (no need to refocus or do anything else other than taking pictures)  Lighting could vary but be compensated by various EV stops in the HDR bracketing and fixed in post.

Also I was reading on the main page that the silent mode is limited to 2 megapixels, but in the menus I see more resolution when doing 2x2, 5x5, etc.. is it a lack of update in the features list or am I missing something?

Thanks all!


Francis

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Re: 550D: Stacking HDR, LCD trigger, Electronic shutter, Mirror Lock, Etc...
« Reply #1 on: February 20, 2013, 01:04:08 AM »
Silent picture writes the liveview buffer to a file, so you are limited by that buffer size. Needless to say, image quality is limited as well. The hi-res mode works on some models, like the 550D. There is no other way to take images without using the shutter. Mirror lockup is not intended to hold the mirror up between exposures.

Boboche

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Re: 550D: Stacking HDR, LCD trigger, Electronic shutter, Mirror Lock, Etc...
« Reply #2 on: February 20, 2013, 05:51:16 AM »
Ok, 2 questions for you based on what you just wrote:

- What's the Liveview raw buffer data structure? uncompressed? Raw? Jpeg? What do you mean by "image quality is limited" other than resolution? I'm using a 550D.  Now that I think of it, I guess it doesn't use the ISO setting I've set the camera to right?

- Is there a way to keep the mirror up between exposure? Worst case scenario I could always detach it from the camera once it dies if that's the only show stopper...
 

Francis

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Re: 550D: Stacking HDR, LCD trigger, Electronic shutter, Mirror Lock, Etc...
« Reply #3 on: February 20, 2013, 06:59:03 AM »
Format is YUV422. Resolution is the big limiting factor and noise from digital gain. Silent pictures are faking exposure by using digital gain and the aperture. There is no real shutter speed/exposure length involved.

Boboche

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Re: 550D: Stacking HDR, LCD trigger, Electronic shutter, Mirror Lock, Etc...
« Reply #4 on: February 20, 2013, 01:27:00 PM »
Ok then lets approach this from another angle...

1. Can the camera and known firmware and limitation support the building of a video with frames assembled from external trigger and varying ISO exposures? i.e. HDR Video with external (i.e. LCD sensor) trigger?

2. What happends if I remove the shutter mechanism altogether and shoot, is canon using the electronic shutter on standard picture taking or sorely relying on the mechanics?

wolf

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Re: 550D: Stacking HDR, LCD trigger, Electronic shutter, Mirror Lock, Etc...
« Reply #5 on: February 20, 2013, 04:57:29 PM »
I just wonder what is the shortest movie-clip that could be recorded. With fast pressing 1 second is achievable.
Is it technically possible to record a shorter clip?


Francis

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Re: 550D: Stacking HDR, LCD trigger, Electronic shutter, Mirror Lock, Etc...
« Reply #6 on: February 20, 2013, 05:51:47 PM »
1) Not sure what you are asking here. Can an external trigger stop and start video recording? Yes.

2) In stills mode, you camera is using the physical shutter always. Your camera would probably not work at all if you removed it. You would get ERR2s or whatever the shutter failure message is. There is no such thing as an electronic shutter on a CMOS-sensor cameras. Here is a good post on another forum talking about the differences and rationale of CCDs/electronic shutters vs CMOS/physical shutter. They are talking about flash sync speeds but the info still applies.

The shortest clip possible is 1 sec. That's why FPS override records videos of 1s at regular framerate, then switches fps so you can stop at anytime. Otherwise it will not let you stop the recording until 1s of video is recorded.

What is your end goal here? HDR timelapse with no shutter actuations?

Boboche

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Re: 550D: Stacking HDR, LCD trigger, Electronic shutter, Mirror Lock, Etc...
« Reply #7 on: February 20, 2013, 06:46:18 PM »
Quote
1) Not sure what you are asking here. Can an external trigger stop and start video recording? Yes.

I meant being in HDR video mode, and use triggering to record a single frame (well multiple frames at different iso exposures).  So essentially build the equivalent of a timelapse VIDEO where each frame would be captured at different intervals (i.e. triggered by LCD sensor). 

Example: Video HDR bracketing iso 400 and 3200.  LCD trigger, Frame 1 and 2 recorded.  Wait for another LCD trigger then add Frame 3 and 4...

About the 1s recording, that is not an issue, we can put garbage data or do this process until reaching 1s... whatever... that doesn't matter I can correct/extract in post.

Quote
2) Your camera would probably not work at all if you removed it. You would get ERR2s or whatever the shutter failure message is.

That can be bypassed electronically, its a sensor, a resistance value or a cherry switch somewhere that requires shorting, so not an issue for me. 

Quote
There is no such thing as an electronic shutter on a CMOS-sensor cameras. Here is a good post on another forum talking about the differences and rationale of CCDs/electronic shutters vs CMOS/physical shutter. They are talking about flash sync speeds but the info still applies.

Ok so what I could do to work around this is put everything in the dark, remove the shutter and sync the light source like if it was a shutter, put the proper lumen output to balance everything out... hmm.. complicated but still better than paying for an overpriced framegrabber that will output less quality...

Quote
What is your end goal here? HDR timelapse with no shutter actuations?

HDR with no actuations, replacing Timelapse with external trigger.

Boboche

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Bump... Anyone? :)

Francis

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What you need as last described is there already. Intervalometer-movie record. Set to 1 sec record time, HDR video, combine frames in post. No need to rip the shutter off or use FPS override or any of that. I would save some frustration and get an AC adapter for a project like this. Also, it sounded like you had it under control ;)

Boboche

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Hello Francis,

No problems :), I know I'm throwing a lot of variables and brainstorming at the same time, and I might get confusing a little.

I don't have it under control because I cannot use the intervalometer, like I stated above, this is not a regular event/flow.  It requires external triggering (i.e. LCDsensor) else I will miss or double expose shots or shoot moving parts, etc... can't start scrubbing this in post-prod manually (over 100,000s frames... , and also I will have missed some, which I can't). 

The external triggering makes 100% sure I won't get any garbage content NOR miss anything.

The other thing is HDRvideo limits me to 1080p with already compressed content... Ideally I would want more than 1080p resolution so static shots, if possible.   

If there's a way to do frame-by-frame HDR video shooting with LCDsensor I completely missed that.

Thanks for your patience ;)

Francis

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Sounds like you could write a script of some sorts. Not familiar with the API, but it sure looks not that bad. If external shutter releases create the same event as a full shutter push, you could script it so with every "shutter push," push shutter button, wait 1 sec, push it again to stop. If you don't want to use the shutter, you're not going to get your full senser res, period.

Boboche

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The functionality is there, the problem is the incompatible event flow...

I'm wondering if I get my hands on a Code ninja, I'd assume the hardware is exposed enough to compile a firmware where we could LCDsensor trigger  + HDR video Timelapse (timelapse being triggered by LCDsensor not by timer).

Since it would be a slow process, codec could be set near uncompressed.  That would actually be the best approach other than removing the actuation hardware...

I'll check the scripts to see what's exposed but I would assume that what I need requires a code ninja....


Francis

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Instead of waiting for some code monkey, look at the scripting API and figure it out. That's why it's open source and recently a lot of effort has been put into making it very user-friendly programming. People with specialized needs have to tools to use. Look for CHDK scripts that do what you are looking for and translate it.

What is triggering the LCD sensor? If you can make it start and stop the recording, then everything is there that you need. Mess around with it and try to piece it together.

Also the codec could not be set to uncompressed because that is not possible at this time.

Boboche

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That's why I said Near uncompressed (i.e. use much higher bitrates than what's possible with standard 30-60FPS recording since it's going to be capturing much more slower).

I'll put a shutter mechanism (i.e. toggling actuator) to trip the LCD sensor.   I'm good with electronics, but C++ is really not my thing. 

Thanks a million for your help!

jbuy41

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I would really like to know what you are doing with that amount of exposures?

cihub

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It's probably won't work for your Canon, but so that you know it seems that Panasonic's G5/GH3 has such thing as electronic shutter, so it is possible to do it. For more info you can read this: http://m43photo.blogspot.com/2012/12/gh3-electronic-shutter.html and http://www.mu-43.com/f43/panasonic-g5-electronic-shutter-review-36669/ Though, at the latter URL G5 user says exactly what have been said here.