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Different histograms with Canon 7D

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#1 Alex1990
I'm new to the forum (not a new reader but fresh member) so an excited HEY to everyone!
I'm using LRTimelapse for quite a satisfied while now. Today I took a step forward and started my first tests of timelapsing via TL-MR3040 and DSLRDashboard.
So first: Huge thanks to the great installing guide written by Gunther and the fantastic video tutorial by saw0. With this combination I just managed to set up everything on the first try! Smile
I'm using my Samsung Galaxy S III mini to connect to a Canon EOS 7D.

Questions showed up when I started a test shooting...
On my first try I ran into one of these dreaded Error messages where the camera freezes. Lucky me, I just removed the battery and after some seconds I could restart the 7D normally. Maybe that was because I'm using Magic Lantern and the applications just didn't work together too well. Might be a warning to all the Magic Lantern users! Has anyone already experience with that? However, next tests were done without ML.

Two big issues for me:
1. With my 7D the check on "Display JPG for next capture" won't remove after showing me the first JPG. Instead it results in constantly refreshing previews on my smartphone for maybe 10 pictures. After that I don't get any more JPG previews at all. No matter if I check "Display JPG for next capture" on or off. No more JPGs. Some other times I couldn't even get one JPG.
So I thought: Well, that's not too bad. It's all work in progress and stuff. At least I can navigate to the camera's folder system with DDB and view the pitures manually to get a histogram. But there I found issue #2...

2. DDB gives me a different histogram than the camera does! All pictures that I transfer to my smartphone and view within DDB show a clearly darker appearance. It's also visible in the histograms. Where does that come from? I mean in the end the pictures are taken like my camera shows them. If I can't rely on the picture's histogram from DDB then the whole construction is useless.
I give you two screenshots. One is from DDB with histograms and the other one is a picture from my Canon 7D display with histograms. Both should show the same values for the same picture.
       

Did anyone come along the same problem? Is there a solution?
Hopefully I could explain everything understandable.

Best, Alex
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#2 saw0
Quote:With this combination I just managed to set up everything on the first try!

Great to hear that Smile

Quote:Maybe that was because I'm using Magic Lantern and the applications just didn't work together too well. Might be a warning to all the Magic Lantern users! Has anyone already experience with that? However, next tests were done without ML.

I have no problems, even with the latest ML Alpha Versions. I am on 550D / 650D however. But technically I doubt that ML would cause issues with DDB.

Quote:I mean in the end the pictures are taken like my camera shows them.

You are shooting in RAW, so what is shown is always kind of an approximation or interpretation.

Quote:2. DDB gives me a different histogram than the camera does! All pictures that I transfer to my smartphone and view within DDB show a clearly darker appearance. It's also visible in the histograms.

I think you could do the following: Check if the DDB histogram changes when you change your picture style. Be sure to have the exact same scene.

Why?

I could imagine that DDB is pulling the embedded jpeg in the CR2, whereas the camera uses the histo information from the CR2 itself. If it gets darker, that may be due to the Picture style.
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#3 Alex1990
Thanks saw0 for your fast answer!
Gives me a slightly more courage that you're convinced of ML + DDB Smile

I tested on a bit and maybe found an explanation to this.
Because the "Display JPG for next capture" causes troubles I only shoot RAW. When I then navigate manually to the camera's folder and download one of the RAW pictures this leads to clearly darker previews on my mobile. But if I shoot RAW+JPEG and download the JPG file the preview on my mobile is nealry 100% the same as shown on the camera (judged by histogram).
So maybe the difference comes from some kind of conversion from RAW to "viewable on mobile". Would make sense to me.
Unfortunately I can't do hours of timelapsing with RAW+JPEG simply because my card would fill up to fast.

And I still can't figure out why the normal process with "Display JPG for next capture" does so much fail me. I just tried it again 10 minutes ago. Always same procedure:
1. I do all settings
2. Start the intervalometer
3. Check on "Display JPG for next capture"
4. Get the first preview
5. The box doesn't uncheck. I get a lot more previews for a short time.
6. Either I don't get any more previews but can still change settings
7. or sometimes the whole app shuts down.

What am I doing wrong?
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#4 hubaiz
(2014-01-06, 03:47)Alex1990 Wrote: Thanks saw0 for your fast answer!
Gives me a slightly more courage that you're convinced of ML + DDB Smile

I tested on a bit and maybe found an explanation to this.
Because the "Display JPG for next capture" causes troubles I only shoot RAW. When I then navigate manually to the camera's folder and download one of the RAW pictures this leads to clearly darker previews on my mobile. But if I shoot RAW+JPEG and download the JPG file the preview on my mobile is nealry 100% the same as shown on the camera (judged by histogram).
So maybe the difference comes from some kind of conversion from RAW to "viewable on mobile". Would make sense to me.
Unfortunately I can't do hours of timelapsing with RAW+JPEG simply because my card would fill up to fast.

And I still can't figure out why the normal process with "Display JPG for next capture" does so much fail me. I just tried it again 10 minutes ago. Always same procedure:
1. I do all settings
2. Start the intervalometer
3. Check on "Display JPG for next capture"
4. Get the first preview
5. The box doesn't uncheck. I get a lot more previews for a short time.
6. Either I don't get any more previews but can still change settings
7. or sometimes the whole app shuts down.

What am I doing wrong?

Hi

I also have ML on my Canon 650D and works without any problem.

The problem with the RAW+JPG on Canon is that on 650D there is only one settings for it and it crates 'Large Fine' JPG files that take to much time for download. Now I find a way for the Canon image format property so the next test version should have it (this should also solve the Err 70) and probably speed up the LRTimalapse 'display last JPG' for the more advanced Canon cameras that have more RAW+JPG image format modes.

The problem with the histogram probably comes from the RAW processing. In DD I'm using LibRaw for RAW processing that uses dcraw. Because Android devices are not so powerful the 'half size' option is ussed for processing (the full size would take 30-60 sec depending on size).
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#5 Alex1990
(2014-01-06, 09:12)hubaiz Wrote: Now I find a way for the Canon image format property so the next test version should have it (this should also solve the Err 70) and probably speed up the LRTimalapse 'display last JPG' for the more advanced Canon cameras that have more RAW+JPG image format modes.

This sounds awesome. You're totally right there are so many possible combinations of RAW, mRAW, sRAW, LargeJPG, MediumJPG, ...

Your reply about the JPG transfer filesize gave me an idea:
I chose RAW+SmallJPG on my camera and didn't change a thing with DDB. After starting the intervalometer I navigated to the camera's folder via DDB and used the filter to see only JPGs. I then could manually take one of them and it was transferred to my mobile really quick. I checked the histogram, did a 1EV change with LRT mode and came back to the camera's JPG folder to check the new pictures. Never had to do a check on "Display JPG for next capture". Best thing about it: I can delete all the JPG files after a while to get back card space.
The method is a bit much of clicking and rushing through the app but it worked out fine.

Nevertheless your solution sounded much more convincing! So I'm looking forward to the next update! Wink
If there is anything where I can help you with maybe providing data from my 7D or something just let me know.

...also check out: