Shutterless stack shooting with Magic Lantern

pontop · Post by **pontop** » Thu Apr 09, 2015 3:56 pm

Finally the "Full resolution silent pictures" module has made it to the nightly build version of Magic Lantern (for those who don't know: Magic Lantern is a set of add-on functionality for Canon DSLRs). Silent pictures allows saving pictures from live view without tripping the shutter. Previously only the low resolution preview picture could be saved, but now the full resolution is available.
Below is a quick test combining full resolution silent pictures with another useful Magic Lantern function: Focus stack. It lets the user set start and end point of the stack and number of autofocus motor steps between frames.
94 frames on EOS 6D with smallest step the Canon 100mm Macro 2.8 USM (non-L) can take and starting almost at closest focus (1:1). 1 second exposure at full aperture. Available light (lamp in the ceiling of my livingroom). Stacked with Zerene Pmax. No further processing.

I doubt flash will work with this method since normal shooting from live view does not trigger the flash. I am going to try a setup for my DIY "stackshot" with separate triggers to the flash and to the camera (with suitably long exposure time and darkness in the room). Unfortunately that requires changes to the remote cable since the silent picture readout is triggered by shutter half-press. Something to do in the weekend

/Bo

banania · Post by **banania** » Fri Apr 10, 2015 12:18 am

Hello pontop

Do you know about the details of the sequence of shutter operations on the Magic lantern version?

In an another discussion rjlittlefield wrote (about Canon) that:

"In normal mode the shutter action is

•long pause while framing and focusing
•mechanical first curtain
•exposure delay
•mechanical second curtain
•reset both curtains

In EFSC mode it is

•mechanical first curtain
•long pause while Live View
•EFSC clears sensor
•exposure delay
• mechanical second curtain
• reset both curtains "

Do you know if the Magic Lantern version of "shutterless stack shooting" is identical to shooting stack with mirror locked and EFSC ON? Would there be any advantage in using Magic Lantern "shutterless shooting" as compared to using Canon LiveView + EFSC?

Real "shutterless shooting" with simulated clearing and resetting of shutters, or even only first shutter curtain, would be possible in principle (I think) and that would be a very interesting development. It would open up all sorts of possibilities, like fast stacking with minimum camera induced vibrations and it could also solve the problem of shutter wear.

Henri

Charles Krebs · Post by **Charles Krebs** » Fri Apr 10, 2015 1:07 am

In EFSC mode it is

•mechanical first curtain
•long pause while Live View
•EFSC clears sensor
•exposure delay
• mechanical second curtain
• reset both curtains "

Not exactly. In Canon bodies, when EFSC is used (with continuous light, with no Canon flash attached), there is no mechanical first shutter curtain when an exposure is started. The sensor is cleared electronically (no significant delay) and the exposure starts. At the end of the exposure the mechanical second shutter curtain closes. Then the shutter re-cycles for the next exposure.

pontop · Post by **pontop** » Fri Apr 10, 2015 3:40 am

This is real shutterless. In the Magic Lantern silent shooting mode there is no shutter operation at all (apart from first entering live view). It uses EFSC same as Canons silent mode, but also electronic second shutter. I have not tested shorter exposure times yet - I read previously that there was some exposure gradient because of different timing of the first and second electronic shutter. EFSC clears the sensor in a sweap to simulate the moving shutter curtain and there was some issue with reading out the sensor at the same speed. With my quick test yesterday I could not see any such gradient with the 1 second exposure. So either the clever guys at Magic Lantern figured it out or my exposures were too long for it to show. I have still to read through all the threads discussing this in the Magic Lantern forum....

/Bo

Bill Eldridge · Post by **Bill Eldridge** » Fri Apr 10, 2015 7:55 am

Good news -- thanks for sharing.

The announcement and 28-page Magic Lantern Full-Resolution Silent Pictures forum thread can be found here.
Magic Lantern nightly builds are here.

One interesting thing to note is that you can shoot even if you've worn out your shutter!

Limitations (from the hack's author):

- The fastest shutter speed I've got is around 1/10 seconds (very rough estimation by comparing brightness from a regular picture).
- Long exposures are fine up to 15 seconds (longer exposures will crash the camera). Longest exposure for 550D is 0.8 seconds.
- Fastest capture speed: 220ms on 5D3, 320ms on 5D2.
-- Saves DNG or MLV only, not CR2 or JPG.
- If you use the intervalometer, I recommend taking a picture every 10 or 15 seconds (not faster). Saving DNGs from the camera is slow.
- In photo mode, aperture will be most likely wide open, regardless of the setting, because of exposure simulation (enable Expo Override to fix it).

rjlittlefield · Post by **rjlittlefield** » Fri Apr 10, 2015 8:46 am

Charles Krebs wrote:
In EFSC mode it is

•mechanical first curtain
•long pause while Live View
•EFSC clears sensor
•exposure delay
• mechanical second curtain
• reset both curtains
Not exactly. In Canon bodies, when EFSC is used (with continuous light, with no Canon flash attached), there is no mechanical first shutter curtain when an exposure is started. The sensor is cleared electronically (no significant delay) and the exposure starts. At the end of the exposure the mechanical second shutter curtain closes. Then the shutter re-cycles for the next exposure.

Both descriptions are correct. In this context, my bulleted list would be more clear with one more entry in it:

In EFSC mode it is

•mechanical first curtain
•long pause while Live View
• "shutter release"
•EFSC clears sensor
•exposure delay
• mechanical second curtain
• reset both curtains

--Rik

pontop · Post by **pontop** » Fri Apr 10, 2015 12:09 pm

Made a few further test shots. The following two pictures are taken with the same settings ISO 100, 0.5 s, f 8.0. The first one is a "normal picture" the second is Magic Lantern shutterless:

No settings were changed between the pictures.
It is quite clear that the white balance is different. And the exposure too.
Here are two shots of a white piece of cloth. Same exposure settings 1/4s f 4.0, normal shot first and shutterless second:

White balance clearly off and exposure a couple of steps higher using shutterless. Here there is also some gradient showing in the second picture.
The gradient shows more clearly when the pictures are converted to b&w and the curve is stretched:

Another issue is that the EXIF info is wrong. Whatever setting is used it shows 1 s at f / 1.0

Despite these shortcomings I think the shutterless function is usefull. In my first test I did notice the white balance problem (fixed that in lightroom before stacking) but I did not notice the exposure gradient.

/Bo

rjlittlefield · Post by **rjlittlefield** » Fri Apr 10, 2015 12:30 pm

pontop wrote:...but I did not notice the exposure gradient.

I notice that your orchid was at 1 second, while this latter test showing the gradient is at 1/4 second. I strongly suspect that the gradient results from having a different speed of clearing the sensor row by row to begin the exposure, versus reading it out to end the exposure. If this is correct then the gradient should be worse with shorter exposure times.

--Rik

pontop · Post by **pontop** » Fri Apr 10, 2015 1:19 pm

That is also my interpretation. So the shutterless function seems to be usefull at long exposure times only. And you have to adjust white balance afterwards. And keep track of the EXIF info manually.

/Bo

JW · Post by JW » Tue Apr 21, 2015 2:36 pm

Cool, will this work on my old 50D? I have a 12-month old or so build of ML on it now, wondering if I should upgrade, as it works fine as is.

pontop · Post by **pontop** » Wed Apr 22, 2015 1:19 am

Not sure, but I think it should work. Why don't you give it at try and report back?

I am sketching on a circuit that would give a delayed flash triggering. That should allow using flash combined with shutterless operation - given that the room is resonably dark. Something like this:

1. Trigger signal (manual or from whatever controller you like) starts electronic clearing of the sensor and a timer circuit for the flash
2. Wait for the sensor clearing to finish
3. Flash
4. Readout of sensor. (Exposure time needs to be set long enough to accomodate the wait in 2.)
5. Refocus, wait for recharge of flash and vibration damping, go back to 1.

/Bo

ChrisR · Post by **ChrisR** » Wed Apr 22, 2015 3:47 am

When we were considering the delay before, the question of the "little red light" came up. I don't know if a 6D has such a thing, which flashes about when the shutter is open, but it's (just) possible that it could be detected and used to reduce the "wasted" open-shutter time in the sequence.

rjlittlefield · Post by **rjlittlefield** » Wed Apr 22, 2015 6:27 am

Bo, see Canon T1i: EFSC has large variation in shutter delay. The "little red light" discussion that ChrisR mentions is down toward the end of the 2nd page.

--Rik

pontop · Post by **pontop** » Wed Apr 22, 2015 2:34 pm

Thanks Rik for the information. It figures that I have this brilliant idea - and you have already done it several years ago

There is a red LED on the 6D that comes on during the exposure. I guess that could be used to trigger the flash if it turns out the timing varies a lot. My rig is controlled by a LEGO mindstorms unit, and that does come with a light sensor.....

I was playing with this some more just now and found that the camera does not return to live view after taking the picture - I have to half press the shutter again! That makes this a little more difficult. I means that I have to give one signal that is followed by a delayed flash and then a signal without a flash following it.

ChrisR · Post by **ChrisR** » Wed Apr 22, 2015 2:58 pm

I did a little experimenting with a phototransistor held to my T3i/600D's red light.
I formed a pad of "low melt plastic" into a flat pad, wrapped it around the camera in a way that it clips on, then drilled a hole for the sensor. It could be made quite neat.