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Messages - jamesd256

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26
Tragic Lantern / Re: 50D and 40D Raw video
« on: November 08, 2013, 12:19:44 PM »

I've been using the Tragic Lantern build from 11 October by Andy600.  First results were good.  I was getting continuous recording at 1920x1080 in crop, with the data rate reported at around 70-80MB/s

For some reason now, it drops out after a second or two at that resolution.  Any suggestions what to try.  I could try formatting the card, but the thing is, if I have to format the card every time it gets a third full, it's not much use.

Could anyone summarise the difference in the level of support for raw on the 50d between TL and the nightlies.  I'm also getting the pink screen on half shutter bug, which I found a report saying was resolved, but it only mentioned the 5d3.

Also I've been reading about auto ETTR with support for automatic dual-iso being available.  Is there a build that has that and gives good results for raw on the 50D?

Thanks 1% for your reply.  I hadn't noticed the FPS override had been reset to off, so it was trying to do 30fps.

However it's actually got worse now.  As soon as I enable raw video, the stability takes a nosedive.  FPS override starts reporting about 1-2 FPS , the camera becomes unstable and crashes within a minute, needing a battery yank.

I have tried re-formatting, but the problem won't go away.  Latest attempt at turning on raw module produced a crash with a crashlog:

ASSERT: 0
at Stub.c:29, task LVC_AE
lv:1 mode:3


Magic Lantern version : Andy600.Build.2013Oct11.50D109
Mercurial changeset   : dd08a07137b8+ (unified) tip
Built on 2013-10-11 15:48:27 UTC by magiclantern@magiclantern-VirtualBox.
Free Memory  : 200K + 3708K



EDIT:  Having tried resetting camera and ML settings, and still having the issue, I simply switched FPS over-ride to a different value (25) then back to 23.96, and the issue went away.  Recording 1080p again.

27
Tragic Lantern / Re: 50D and 40D Raw video
« on: November 08, 2013, 01:50:50 AM »
I've been using the Tragic Lantern build from 11 October by Andy600.  First results were good.  I was getting continuous recording at 1920x1080 in crop, with the data rate reported at around 70-80MB/s

For some reason now, it drops out after a second or two at that resolution.  Any suggestions what to try.  I could try formatting the card, but the thing is, if I have to format the card every time it gets a third full, it's not much use.

Could anyone summarise the difference in the level of support for raw on the 50d between TL and the nightlies.  I'm also getting the pink screen on half shutter bug, which I found a report saying was resolved, but it only mentioned the 5d3.

Also I've been reading about auto ETTR with support for automatic dual-iso being available.  Is there a build that has that and gives good results for raw on the 50D?

28
http://en.wikipedia.org/wiki/Angle_of_view#Measuring_a_camera.27s_field_of_view

FOV =  2 * arctan (frame size/(focal length * 2))
2 * arctan ( 35mm / (16 mm * 2) ) = 95 deg
2 * arctan ( 22mm / (16 mm * 2) ) = 69 deg

There are different types of fisheyes with different equations, here is common one:
Equisolid FOV = 4 * arcsin (frame size/(focal length * 4))

4 * arcsin ( 35mm / (16 mm * 4) ) = 132 deg
4 * arcsin ( 22mm / (16 mm * 4) ) = 80 deg

OK, that's actually useful, thanks.

The 170 deg diagonal sounds like it might confirm the Zenitar has an equisolid mapping function.  I'm used to talking horizontal FOV, so:

I have a 50d, so the cropped raw mode will be using a multiplier of

4752 / 1920  = 2.475

That means my sensor size will be

22.3 / 2.475 = 9mm

So the angle I'd get from the lens is

4 * arcsin ( 9 / (16mm * 4)) = 32 deg

I'm guessing the distortion will be minimal using this centre portion of the lens, and certainly the sharpness will be excellent at f4-f11:

http://www.ephotozine.com/article/nikon-10-5mm-zenitar-16mm-fisheye-lens-comparison-interchangeable-lens-review-14651

I would think that with minimal de-fishing, you could have a reasonably sharp image, free of pixel binning induced moire and aliasing. 

29
16mm * 1.6 = 25.6mm

You are a bit confused: a 16mm lens on a cropped sensor would look like a 25.6mm lens on a FF.

NOT:
a 16mm lens on a cropped frame would look like a 25.6mm on a cropped frame (why would that make sense!?)

I'm not sure how you arrived at your interpretation of my comments, so sorry for not making it clear.  Maybe you thought it was a simple question about the crop factor?  I actually do understand this principle. It was more a question about the FOV of fisheyes in relation to their focal lengths vs the same for rectilinear lenses.

Yes I understand how the 24mm comment is arrived at.  But a 16mm lens on a full frame camera will have a viewing angle of 96 degrees.  The zenitar I read has a viewing angle of 170 degrees on a ff sensor, so simply put, what will be the FOV on a cropped sensor of the zenitar 16mm.




30
While the subject of fisheye lenses is a live one...

I looked at getting a Zenitar 16mm for use on a 50d for video.  I was thinking of using it in cropped mode with some de-fishing action.  I read some suggestions (repeated in a few places) that on a cropped sensor, the 16mm lens becomes a 24mm non-rectiliear. 

This doesn't make sense to me because the full frame FOV of the lens is either 170 or 180 deg depending on what you read, so surely there would be more angle of view than a 24mm lens on the cropped sensor?

The centre sharpness of this lens is supposed to be excellent stopped down to f11, and they go for around £70-80 in the UK used on ebay.


31
Tragic Lantern / Re: 50D and 40D Raw video
« on: October 31, 2013, 02:10:15 PM »
It would be a shame not to have a VAF for the 50D but you're probably right in what you're saying. It would be interesting to see how many people on this forum would actually buy one if it was available for the 50D. Maybe we should do a poll?

I don't see the BMPCC as an alternative for me as it would require an investment in lenses to make best use of the Super16 sized sensor.  I've already got all the lenses I need to shoot on APS-C, so it makes sense to stick with that sensor size. I did think about maybe going for an EF BMCC but even that would require another lens to cover the wide end.

I shall just work around the moire/aliasing as best I can.

I'm guessing the solution in this video loses you resolution?  Looks quite a nice way of tackling scenes where you know you will face moire:


32
Tragic Lantern / Re: 50D and 40D Raw video
« on: October 30, 2013, 11:53:06 PM »
Just chiming in to say thanks to all the developers, deep gratitude for your efforts.  After a long hiatus, back in love with ML.

Just gone out and bought a 50d and a 32GB Komputerby 1000x for a grand total of £255 + £55.  Just recorded my first 1920x1080 video using the latest tragic lantern build, card didn't miss a frame.  Jaw dropping stuff.  Anyone want to buy a 550d?  :)  Tragic lantern looks beautiful by the way, and the new features are stunning.  DIGIC focus peaking is a thing of joy, totally un-expected.

Just a couple of small comments about workflow.  First attempts using the free tools have been succesful.

Going raw2dng -> ufraw-batch -> virtualdub (cineform 10-bit codec from GoPro studio).  I found using the ufraw gui to correct exposure and white balance, and do some noise reduction then going to config, copying the XML and saving to a file to call from ufraw-batch worked well and gave good results.  The noise reduction in Ufraw is very good actually, but slows the workflow down.

Dissapointed to find that Aftershot Pro doesn't pick up the DNG format generated.  Anyone have success with that?  I would love to use this, because the OpenCL acceleration really is very good on my system

Since been trying raw2gpcf.exe.  It's very fast, but only 422 with the free version.   Looks like I'd need to spend $1k to get the raw output on the pro version.  Is that correct?  Looks to me like the 422 version isn't that useful in a raw workflow because you miss the chance to grade in raw.  I don't have ACR, so looking for the best workflow to get the best out of the footage.

Exciting times.

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