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Questions regarding TX1

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Questions regarding TX1
« on: 29 / April / 2008, 14:01:45 »
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Hi everybody!
Scince this is my first post in this forum, in brief, a few words about myself. I'm a indie film maker also interested in technology and creative digital cutting edge tools. Scince I'm an indie filmmaker I should ad: for little money. Together with a small team I build world's first indie digital cinema camera, called "DRAKE". Check out this page, if you like to learn more:

Drachenfeder - Drake digital HD film camera

We build this camera from scratch, using a 2/3" cmos sensor, there's a windows system running inside and it has exchangable lenses. Check out the sample clips. I wanted it to make "film" not "video" and it does it. This was more than 4 years ago and we still shoot films with it.
 
For a new project I was thinking of a more compact camera and took a closer look at the 1/2.5" sensors.  This is an intersting format because this is about the size of Super 8 film. Now, having a lot of experience with camera building and film making I know that image sensors can produce much more beauty than their (asian) creators originally intended. But the key to success is the optical system and this is where all those tiny new cameras are weak. Now I made already some test builds, using cams from Aiptek and other manufacturers and succesfully build them inside selected super8 cameras. Not only do they allow the usage of very high quality zoom lenses (very fast, with true wide angle and superior resolution) but also optical fiewfinders, variable mechanical shutters and much more. And you can get top notch cameras for a few bucks on ebay.
Now, the big problem is that those cheap digital cameras have lot's of automatic controlls and it's almost impossible to buypass them. So I did another web search, bought finally a digic III / TX1 and landed after a little more search - here.
Now my instinct tells me that the digic III + what you folks have acomplished will be the key to a successfull "cheap" high qaulity indie HD-film-cam.

So far for the "introduction". Now my first question(s) - and the aspect I'm currently most interested in: Did somebody found a method to tweak the "FPS" value? It's of srategic importance. If it could be reduced to 24fps (normal film speed) then a slower shutter speed could be used -> much more light and film like motion blur - a critical aspect of "film look". Also it would mean less data to handle = lower compression. It should be possible to reduce the compression level and to get more quality for the storage space. Second question: Is it possible to turn off the shutter enirely (like for long time exposure), that would be important to eliminate synch problems with the mechanical shutter.

So far... I got many more questions but those are the 2 critical ones for the beginning. I hope those movie making aspects are not off topic here, but I'm really excited by your port and got the impression that you are the right gang to discuss with!

Questions regarding TX1
« Reply #1 on: 30 / April / 2008, 06:06:21 »
We build this camera from scratch, using a 2/3" cmos sensor

Very, very interesting !

Was it OmniVision or Micron or others ?
Which chip ?

> it has exchangable lenses.

C-mount ?


I am interested in making a stereo camera, how did you work-out how to put all the software and hardware together ?
Does the sensor already contain all the software routines for white-balance, snapshot mode, windowing, etc. ?
Do you talk to the sensor over an I2C link ?

>  Now I made already some test builds, using cams from Aiptek

Which one ?
I have disassembled a couple of DV5700's.

> Not only do they allow the usage of very high quality zoom lenses

Yes, but with sensor-based cameras the 'chief-ray' has to hit the sensor quite near to 90 degrees.

> variable mechanical shutters

Still cameras normally require a mechanical shutter that closes quickly AFTER the exposure while charge is being transferred.
These are not easy to make.
Presumably, hybrid cameras (like the Aiptek) do not require this mechanical shutter ?

Quote
> Did somebody found a method to tweak the "FPS" value?
> Is it possible to turn off the shutter enirely (ur port and got the impression that you are the right gang to discuss with!


The only person who knows about such details of the firmware (and the cameras electronics) is EWAVR.

If he does not notice this message, repost it in a new thread .



David
« Last Edit: 30 / April / 2008, 06:16:14 by Microfunguy »

Questions regarding TX1
« Reply #2 on: 30 / April / 2008, 07:20:34 »
We build this camera from scratch, using a 2/3" cmos sensor

Yes, but with sensor-based cameras the 'chief-ray' has to hit the sensor quite near to 90 degrees.

> variable mechanical shutters

Still cameras normally require a mechanical shutter that closes quickly AFTER the exposure while charge is being transferred.
These are not easy to make.
Presumably, hybrid cameras (like the Aiptek) do not require this mechanical shutter ?



We are using an IBIS5 sensor from Fillfactory. Check this link for a datasheet

http://www.tattile.com/new.site/download/details_tapix_cameras/mcm_1300_30_ibis5_datasheet_v1.01.pdf

And yes, it's c-mount. We are using very fast lenses, most with f <1.4 some <f1.0 like the fujinon 50mm f:0.7 (!)

Shutter ->I am refering to a film-gate-shutter. It's different to the still camera shutter -> a rotating disc with an opening angle. More opening angle means more light, means more motion blur. All Super 8 cameras are already equiped with this. Some have adjustable shutters. The lenses that go with the Super8 cams are designed to deliver high resolution and wide angle for this tiny window - that is close to the 1/2.5" sensor size. The better Super 8 cams are of very high mehanical quality (all metall gears, no plastic). So one doesn't have to worry much about the precission when replacing the film plane with the sensor. I disasambled about 10 cams so far and all have enough screw points to attach sensor boards with little effort. Also, the better optics have back focus adjustment. So, all in all, it seems to be a promissing aproach. Shutter is very important. Especially scince those small sensors are mostly equiped with a rolling shutter. At a lower shutter speed you see a "rolling" effect while panning. That's why the manufacturers set higher shutter speeds by default. But this means less light for the sensor and also a more artificial (video like) movement. And we are not talking of a bit of light. With the right lenses and shutter you can get 3 - 5 times more light to the sensor. When people complain about the poor lowlight capabilities of their cams, it's not because the sensors are not sensitive enough, it's because the cheap lenses and high rolling shutter speeds eat up the available light. So, getting controll over the shutter is very important. Only if this is possible the digicIII based cams can be turned into "film machines"...

And I will try to get in contact with EWAVR. Read this name a few times already.

Questions regarding TX1
« Reply #3 on: 30 / April / 2008, 08:02:12 »
It is a long way from a basic sensor to a completed system.

I assume you used the evaluation kit ?

Even so, it must require a lot of development work.


David

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Questions regarding TX1
« Reply #4 on: 30 / April / 2008, 08:19:53 »
maybe it is better to split the topics, shall i move the threads starting from wildcuts' first one to a new topic? this thread here was/is about the _porting_ of chdk to the tx1, not the actual possibilities of the cam. interesting discussion nonetheless :)

Questions regarding TX1
« Reply #5 on: 30 / April / 2008, 08:38:52 »
shall i move the threads starting from wildcuts' first one to a new topic?


I agree.

In fact,  you could also move a few before that to new topic 'TX1  AllBest Build'.


David

Re: Questions regarding TX1
« Reply #6 on: 08 / May / 2008, 08:55:12 »
Obviously there's more interest in photo related functions here, but I'll keep posting my film making issues, so the search engine delivers happy results if more people like me show up.

Now, basicaly the Allbest build runs on the TX1 but it seems the override settings have no effect when shooting video. Also the compression settings don't show visible results in my tests, so I think it would be smartest to start a video build especially for the TX-1

I start with a wishlist from the film maker point of view. Those functions only make sense when they are easy to access. Hitting 5 buttons, starting a script, toggle thru menues to change a shutter value is far to difficult. So the following functions need to be easy in acess (toggle / set)

1) frame rate (24 / 25 / 30 fps)
2) shutter speed (1/30 sec to 1/1000 sec or whatever may be the upper readout limit relative to the framerate)
3) mjpeg compression level (in %)
4) gain control (known as "ISO setting". Finding the right values for 0db, 1.5db, 3.db, 6db. OSD display of value)
5) Aperture (manual by default, to be set with function key up/down, OSD display of value)
6) focus (manual by default, to be set with function key up/down)

Once those software functions are in place the next step would be:
A) building a remote control, asigning butons to each function
B) moving the boards to a new case with an exchangable lens system, mechanical rotating shutter and better power suply
C) finding a method to cluster more SDcard space or using the USB port to attach hard drives

I'll try to track down who is developing what element that could be used for a TX1-film build and to sort informations for non-developers.





Re: Questions regarding TX1
« Reply #7 on: 08 / May / 2008, 11:21:25 »
Interesting thread wildcuts.

Two days ago i asked similar question here TX1 video - possible to change shutter speed?
I already tried running override settings in video mode but they are not working at all.

It seems that You have an acces to change video compression level(quality/bitrate based) in video options(v101b).

I would be really amazing to have all those functions in our little TX1.

Re: Questions regarding TX1
« Reply #8 on: 08 / May / 2008, 11:34:15 »
Welcome then! 2 is not already a movement but at least I don't feel lonley any more ;)
Yeah, read the "shutter" replies and I disagree with the "physical impossible" statements.
I didn't have time (will next week) to disasamble a TX1 but what I've read so far states that is has a mechanical and a electronical shutter. I think the mechanical shutter is only of use in the photo mode the electronical shutter is most likely a rolling shutter. This would mean that below a certain shutter speed (1/100 sec or so) there would be horizintal movement distortions. So people unsing the unit "as it is" would have to stick with that. Faster shutter speeds should be easy. But my aim, as I stated is to build this cam into a Super8 camera case and to use the Super8 rotating shutter instead. I checked the "ida labels" file and there are some promissing informations, but somebody has to look at it, who already has development experience. I was told EWAVR would be the person to talk to, tried to catch him but had no luck so far. Anyway, it's a start :)

Re: Questions regarding TX1
« Reply #9 on: 15 / June / 2008, 04:35:42 »
hi am new here and would be purchasing the Tx1 soon. Made some search and just found out that these hacks exists. (very cool).

About the 24fps and shutter speed control i think it would be a very very very good addition to the Tx1. Owh by the way am wondering how does the Tx1 video looks like with no compression ? im very curious. Can it match the canon hv20 or does it produce sharper image quality ? Apart from that im also wondering does the Tx1 shoots in 4:2:2 ? higher or lower ?. Addition to gain control in video shooting mode is also an A++.
 

Sorry for the many questions.

 

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