Show posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.

Show posts Menu

Messages - Scipione205


I didn't understood how this script works; I would like to understand how to apply a tonal curve so that I can decide wich raw value will correspond to the middle gray. I shoot dual iso 100/3200 and I use an exposure meter and I set aperture and shutter speed for a choosed EI from 100 up to 3200, then when I develop the image I must fight with the curve tool... it's a nightmare because it is only 255x255...
I would like to meter the raw values of middle gray for every EI from 100 to 3200, and then write a script that applies a tonal curve to retrieve the proper EI.

Share Your Photos / Re: Thread photos dual iso
October 05, 2015, 07:35:16 PM
Canon EOS 600D - Yashica 50mm f/2

Dual ISO 100/3200 - EI 3200*

I don't do the "ettr" because: for the exposure I don't use preview, histograms, zebras, etc. but only my exposure meter ( a Sekonik L-398A ) because I'm learning cinematography and I also shoot 16mm color and bw negative. The exposure index is the film/sensor sensitivity or speed.

I was thinking about collect as much infos as we could regarding the use of Octave for generating test patterns and process RAW files (also combining dual iso images in one single 16 bit linear or stuff like that).

I didn't used Octave for years since I had to studying Linear Algebra, so I'ma sking for help.

Regarding Blender, the node compositor wich supports Python scripts and OSL is very interesting for this kind of stuff; I already opened a discussion on blenderartists about that.

Any help regarding Octave? (getting started, examples, tutorials, etc.)


**EDIT June, 28th 2015**

I had a little chat with Alex, and he he gave me those two links:

for understand how to compile Octave for 16bpc processing.

The following link:

Contains test images, and also the octave sources.

For better understanding color spaces, color management, etc. , thanks to TJS from BlenderArtists:

Quote from: dmilligan on December 05, 2014, 01:00:45 PM
Why wouldn't you do: last line reset = shutter open, first line readout = shutter closed? You would just need to use a shutter speed in camera that's as close to the frame rate as possible (as soon as you readout a line you turn it back on).

If you think about it, it makes no difference if you can do a global reset or not, as long as you turn each line back on right after reading it out, all of the lines will be back on by the time you open your external shutter (it makes no difference if they come on early).
The silent picture mode that a1ex is talking about is a "photo" mode. It does not use LV (you use it "from" LV so that the shutter/mirror mechanism is open, but during this time, LV itself is actually disabled). In LV, only rolling shutter is possible (for now).

Maybe I understood what you mean...
Quote from: a1ex on December 04, 2014, 02:20:45 PM
This only happens in photo mode. In LiveView, it uses rolling shutter for both start and end.

I don't know how to switch between the two modes yet.

I downloaded the original video and examinated it frame by frame; I don't think he just synchronized the LCD Shutter with the Sensor's readout (First Line reset = Ex. Shutter Opened, Last line readout = EX Shutter closed), because in this case the effect would be like when you are filming in video mode, in a complete dark room, an a flash flashes.

The only way to overcome the Rolling Shutter readout without using Global Shutter Circuits (on all the scentific literature I studied, the Global Shutter is always connected in a loss of DR performance), is to perform a Global Reset on all the lines, keep opened the external shutter for the exposure time selected, and then read the lines in the classic rolling way after the external shutter is closed.

I don't know how he did this, I'm still struggling to contact him, today I will try to do a series of phone calls to find him.


I was thinking that since in silent picture mode you saw that blur effect (I assumed that it is a Global Reset readout, but without the camera's mirror shutter operating, so you see that effect) maybe it would be possible to do that when shooting RAW?

I don't remember how the RAW Video trick works; I recall that we just grab the data from the buffer or VRAM, but maybe in LiveView mode it is still impossible because since the Mirror Shutter is locked in the open positions, the camera does perform Rolling SHutter Readout to allow you see in the LCD.

I will find him today and ask, that's a promise.

he's Italian, like me, today I will try to call him
not only how did he synced the LCD shuttr, but also did he performed a Global Reset?
Ok how to implement that on EOSs ? I am very disappointed by the RS on the cameras we have acces to here (600D, 6D, 5D MkII/MkIII, BMCC 2.5K ) because I can't let the steadycam operator to do slap pans, we can't record muzzle flashes and I can't implement 'broken' flickering neons in the scene.

from an old post of a1ex :

QuoteThere seems to be a global shutter for starting the exposure, but a rolling one for stopping it. It's visible on the motion blur shape from the full-res silent pictures, which matches the graphs from the other thread.

It's called 'Global Reset' and is available on scientific CMOS sensors. I was wondering if it was possible to do it, and sending a signal outside the camera for each RESET (and also the time of the shutter selected in Exposure Override), while shooting movies (either in H264, either in RAW).

WIth an external shutter it would be possible to caputre action scenes (fast moving cars, trains, chasing, rapid camera movements), flashes and gunshots' muzzle flashes, etc. I feel the camera with the rolling shutter an extreme stop to my creativity.

The ARRI Alexa Studio M works in this way: it has a regular rotary disc shutter (so it has got a conventional loupe, also).

In another thread I asked if it was possible to synch the camera's shutter with an external one, and you guys told me it was possible using the led. However I thought it was useless, because the sensor need to be reset on all lines as soon as the shutter will open (and the it doesn't matter how much time is needed to scan all the lines in rolling mode, but at least before the next global reset.).

Hope it would be possible.
geez, I didn't know I where using a fork... I remember that in the past I was looking for much control over H264 compression... however I never saw the mRAW function till some days ago (after this shooting), and my brother selected it accidentally (and consider that he uses full auto...)

I think that for this time I will try to take some dark frames with the lens cap, and try using ufraw and the mRAW DNG pictures..

However it is MY FAUGHT because every time prior to pull the trigger, I must check everything, as I do when I am in charge as a DP during filmmaking. I thought 'yeah, taking pictures of girls in studio is much easier!' - NOPE.
what is not present? and why?

I'm sorry I can't be nice as usal (in the real life I joke everyone everytiomes) but this time I just screwed up a professional chance.

However as soon as I have time, I will take some DNG pictures with the same lens and exposure settings (at least I can read the EXIF data from corrupted CR2s) with the lens cap on it, and then I will try the Dark Frame feature of UFRAW

I hate digital... all hail film! (but clients doesn't want to spend...)
when opening with UFRAW, if I try to open CR2 files the error messages sais :

Corrupt data near 0x341ab0

(the hex code changes for every file)

some CR2 files stills open after the error warning, showing something like a black picture with a roe on the right with a strange comrpessed pinky picture (or something like that).

Meanwhile, the DNG files (approx 3.8 MBs each) works, about 85% of them (some files appears a s a strange distorted pinky picture, like TV's noise).

However all the DNG files I opened seems to have a strange pattern of pixels overlayed, the same for every picture taken; pink or green points (not just pixels) and very much noise.

In the past I never saw nothing like that with standard RAW images (CR2s ), maybe when ML stores an mRAW picture in DNG it doesn't apply the Fixed Pattern Noise to it?

I checked some DNG and CR2 files with EMACS; i don't know the file specifications, but it appears to me that there are information in it; and the data seems to use a recurrent structure.


yesterday I did a hooting for two of my syster's friends. I have Canon 600D with ML on it.

CANON 600D - Firmware Ver. 1.0.2-ml-vTL20.201

Pic Quality: MRAW+LargeFine (othe rpeople handled my camera befor emy shooting and I didn't checked for that).

When I downloaded pictures from the CF card to PC, I discovered that there are 11 jpg files (all of those are ok, except 2 wich has got corrupted lines with magenta pixels), 111 CR2 files wich can't be opened either in UFRAW, either in PS CameraRaw (UFRaw and CameraRaw both latest verison), and also 169 DNG files (???).
Those DNG files can't be opened, except for the first two, wich appears to be the first two pictures I shot.

WTF ??

I need help because my reputation is in extreme danger...
Ciao walter,
potrei complicarmi meno la vita usando il jack del microfono (low level I/O, attivando/disattivando l'alimentazione - sta nelle API di scripting). Vi farò sapere xD

I hink it would be an easier and better solution to use the mic jack (low level I/O, using scripting APIs). I will tell you in the future...

thank you. I will see. However flashing a LED is ussless xD
thank you. what's the vsync hook? however I need to tell the sync to an arduino (I saw the low-level I/O APIs for scripting). Can you address me better?

Hi, I want to do some experiments with my 600D; even tough I think that it can be helpful for a series of applications (such as cine strobo lights), I would like to know if there's a practical way to send an electronic signal to an external electronic device (in my case, just an Arduino) to tell when the electronic shutter starts to scan the sensors lines, and when it finishes.
At least when the electronic shutters opens.

I thought that the flashmount or the mic jack (using Low-Level I/O scripting) can work? However I need the fastest synchro possible.

Thank you very much.
and if 2 frames at a time is too much for the CPU, if we store a single S2 jpeg per frame for the highlights (from EV 9 to 14, using 6 stops available from th 8 of 32bit JPEG) while saving an H264 (EV 1 to 8, using a linear picture style) with GOP 1? Then a program on the PC will reconstruct a 14bit per channel sequence. Sound disabled, of course.

I'm just trying to push the envelope by squeezing our brain.

1% what do you think?
I'm trying to better understand how the cameras works. The H264 encoding is done by a dedicated DSP, and the JPEG compression ?
this night I was thinking about how to borrow a 5D MkIII to shoot my action short film, or what best profile+workflow to use for H264 recording if RAW wasn't possible.

Then I got an idea, about recording lossy 14 stops of dynamic range on my 600D (Rebel T3i).

I was thinking about a sort of motion JPEG, but instead of RGB JPEGs, RGBE JPEGS (Red, Green, Blue and Exponent) or something like that (or even for every frame, a normal JPEG and a grayscale JPEG for exponent). This allows hig dynamic range, so it would be possible to store the 14 bit data from sensor without clipping higligts and shadows (maintaing 14 stops instead of 8).

Then I thought that JPEG2000 supports 48 bit depth (16 bits per channel).

Also another solution would be to store 2 pictures (24 bit) per frame (one spanning form 1 EV to 8 EV, the second from 9 EV to 14 EV).

So that we will record a sort of lossy RAW. I was thinking about 600D wich is limited by the SD slot bottleneck to 20 MB/s; at this speed, assuming 23.976 fps, the maximum frame size would be approx 800 KB, and for 2-pictures-per-frame it would be max 400 Kb for piture.

The S2 size (JPEG, 1920x1280, fine compression) is approx 1.3 MB as of T3i's manual, and about 3-500 KB as of my tests. It's too high, maybe cropping 1920x800 can work.

It's just an idea, I don't know if it would be possible (I don't know how the camera works, I'm starting right now to understand that).

What does the developers think?

I think that if we can enable the T3i to shoot 14 stops dr lossy video footage, we will push the envelope on serious cinema filmmaking on cheap machines... this will push the manufactures to develop even better digital cinema movie cameras at even low prices.

Thank you very much. Now it's perfectly clear. Maybe is because of the 1880 buffer and upscaling (then in-camera H264) that MkII has badder moiré than MkIII?

@guentergunter @bnvm

Thank you very much, you people are wonderful.
The resolution You mention is not an option. However a 1920x084 can be set in ZOOM mode - 5X.
The closest at 1X is 1880x786 - which also is normal to use.

What to use is up to You. I think that the scaled picture is just as good + the benefit of using the lens at normal 1x ratio.

Both are giving me continius - with Transcend 1000x 16GB card - first is 62Mb/s the second is lower.

Yeah I think I got it: it's impossible to record raw 1920xsomething, the maximum in 1x is 1880x786 wich I can upscale to 1920x800 ; or I can record in crop mode 5x at 1920x804 (then I have to crop 4 pixels).

The 5x is ok only If I can borrow super narrow and super fast lenses (I want cine-depth of field and there are a lot of action scenes with narrow lenses), and that's quite impossible.

I'm not sure if upscaling will work well... we have already the moiré... but the RAW dynamic range is awesome... :'(

Anybody can tell me where I will find why 1920xsomething is not an option? I know that it's a software limitation but I'ms truggling in finding something in the forum.

Thanks you're awesome
what do you mean? I thought that since 1880x940 is supported for continuous shooting (which is 1'767'200 pixels), maybe 1920x800 would be (wich is 1'536'000 pixels, so about 231'200 pixels less).

That's only a simple tought, assuming that the MkII can handle the calculations (1920x800 isn't 'simpler' than 1880x940, due to bayern pattern etc.), and thinking only about the CF slot writing speed.

I'm not sure about the capabilities of MKII... I will shoot a short film this month, and I really want to shoot RAW but nobody in my city (who I know, in Brindisi Italy) has got the MKIII; I can find only MKII.

Is it possible to shoot continuous 1920 x 800 @23.976 fps ? I read on the main topic about 1880x840 at 24 fps so I thought that [email protected] will be possible.

Anyone tried ?