Hi guys. i was looking at my footage compared to the elphel cameras Andrey has set up.

camera4.elphel.com

and such

and i am noticing a big differece in resolution and im pretty sure its the lens im using. it dont think it was the best quality made c-mount lens. it doesnt even have a brand name written on it.

so i ordered 2 new lenses. One is a 12mm prime c-mount lens with f1.4 and the other is a computar f1.3 5-50mm cs mount zoom lens. The computar brand new costs 135. so i think that might do the trick. as for the other c-mount (the f1.4 one i bought) eh, i dont know if it will be good either, but the Computar i am hoping will get er' done.

both lenses are one their way, so when i recieve them. i will test with them.
PS, i have already tested with a 35mm adapter, and the results are good. great DOF. but i need to have a better lens because the quality of the glass really matters in this case. also, the ground glass i used for the test was just a clear plastic diffused on one side. it was a stationary peice so you can see all the stracthes and such. When i get all the new lenses and a new ground glass. I will post tests with that rigged up. And after that, its off to build an optical viefinder for the 35mm adapter. more on that later.

On Obin's 4:4:4 thread he had the same problem. They eventually tracked down the best c mount lens, but found lens from good film cameras very good (what format would that be, 8MM?). Have a read there, it should be within the first 1-10% of the thread.

have a look
 

a silly question
on the axis page
there is nothing to be found about their CPU's
maybe I'm stupid, seems so

I did a test today , so that when i get the new lenses, i will be able to compare the focus ablilities >The chart was hung in the shade out of direct sunlight.

http://i11.photobucket.com/albums/a1...colortest1.jpg

please note the colors on that chart are not your standard R G B. the blue is a deeper blue and the Green is a deeper green also. That is how they are on the paper.
when i get a chance, ill print out colorcorrect r g b and shoot that.

here is the same thing with the exposure set longer.

http://i11.photobucket.com/albums/a1.../colotest2.jpg

Forrest -- a while back I started a thread called "Call for C-mount lens info" here in Alt Imaging, there might be some info there for you...
John.

Lenses
 

Dear Wayne
16mm lenses are there with a real very good quality
adapter C-mount Pl are there also.

I used on an Aaton S16 Nikon lenses,
the wide angel was the best for money
we could get.

C-mount is industrie, for watching chicken farms or so quite ok LOL

I think that was another of Obin's thread.

Ronald, 16MM lens, but aren't these sensors are far smaller than 16mm?

Be prepared, I have found something interesting, and if I get it home, I may post on it in future.

I found nothing but trouble trying to run camera4.elphel.com . I get one photo with box and one web page that says loading.

I'm impressed with the color and ease of use of this camera, and I know it can create sharp images using a nicer lens since i am using the same sensor. what kind of IR filter is being used? is it all built in? because ive had some problems getting good color out of my camera. Otherwise what im really interested in is the quality of the mjpeg compression, what is the least compression it can apply? all the way up to the ~7MBps that 100BT can handle? that was a little unclear. Another really important thing is how is the framerate control? accurate? you really need an accurate and consistent framerate for sound sync. Also does it give you control over vertical blanking to keep rolling shutter artifacts under control?


BTW this is the same sensor obin was using and decided to scrap due to rolling shutter or something. Also, these sensors arent that much smaller than 16mm, its 1/2" and 16mm i think is somewhere between 2/3 and 1". Although when running at 1600x896 only about a 1/3" area is being used.

Also Forrest, I noticed you mentioned rolling shutter artifacts at your high resolutions. rolling shutter is definitely a big problem with this sensor, ive even run it at 720x540 with 1200+ vertical blank and been able to notice significant rolling shutter artifacts in fast horizontal pans. Makes me kind of worry this sensor will never be appropriate for filmmaking. Now a 96MHz sensor sounds more like it, but if its 5mp its likely to have to be run at at a <2mp windowed resolution only using like 1/4" in sensor area if we want the minimal rolling shutter artifact and framerate we want...

I agree with everything you said Noah, thats also nice to know i can get sharper picture with the better lens attached.

at 1600x896, you see more of the sensor, therefore rolling shutter is more evident. but that resolution isnt needed, plus it isnt too stable. 1440 by 800 is much more stable, and even 1280 by 720. I will do tests with all these when i get the new lens. I havent seen frames drop except in 1600 by 896 mode. I dont know if there is control over vertical blanknig. i dont know how that works. Thank you for your help.

Wayne, there might be problems connecting to these cameras - interface is all open and visitors sometimes leave it with some weird settings - I need to make some simple script to periodically reset it to some known state.

What browser did you use when you've seen only "loading"? Interface is designed now only for Mozilla Firefox, but I've heard that with Opera it also works.

It is dielectric filter (t=0.3mm) and it is glued in. We can machine a version of the front-end piece (a little shorter to compensate for the optical length difference) - it should be rather easy to replace.

any standard JPEG up to 100% quality - virtually lossless (all quantization coefficients equal to 1.0), but in most cases it will not work because of the limit in the network bandwidth. Maximum what we've got with the ETRAX100LX is about 70 mbps - that will increase with the new processor.

Yes, it is possible. When you set up fps limit, it adds vertical blanking to match the frame period. Frame rate is not very precisely set - up to integer number of lines, but we now have a project where we need much better - so it will be done. Currently I added precise timestamping of the frames (to one microsecond), but we still need to make some software interface to it.

This I strongly beliebe can be solved with the software post-processing, especially if distortion is related to the camera pan, not the object moving. It can use similar algorithms as used when the frames are interpolated when changing from 24 to 30fps (or opposite). Each line is exposed at exactly known time, so it is possible to interpolate between the two frames.

Opera, I didn't even know anything about controls, just saw a picture in the pop-up, and some sort of bordered region in that.

Rollign Shutter
 

Obin adjusted more then frame rate to reduce rolling shutter. He shot double frame rate and had to adjust the other parameters of the frame timing to reduce the rolling shutter further (big tip). I doubt the Elphel is set up for any of this normally (like overclocking the sensor, compressing every second frame, and dropping the others to get the 180 degree reduced rolling shutter). It is all mentioned in the first part of Obin's thread, I asked some questions to clarify it, and is worth reading to find out what to change.


Thanks

Wayne.

Yes I recall that, but when it all comes down to it, isnt it all just keeping the frequency as high as possible while capturing a certain number of pixels? I mean in terms of reducing rolling shutter, isnt capturing a 1000x500 frame with 500 vertical blanking essentially the same as capturing twice as many 1000x500 frames and throwing every other one out? either way, the frame time for the active sensor area is the same, right?

Andrey, so you are saying that the camera does at least use vertical blanking (and only vertical blanking) to control frame rate? That is a good thing at least in terms of rolling shutter, although maybe not as useful for accurate framerates.

Also, could you tell me why it is that if the camera runs at 48mhz, the max framerates listed for 1600x896 etc correspond with a pixel rate more like ~35MHz? I have had this same issue in my camera running the same sensor, is the camera clock not reliable? Or is it some bottleneck?

QUOTE=Noah Yuan-Vogel]Yes I recall that, but when it all comes down to it, isnt it all just keeping the frequency as high as possible while capturing a certain number of pixels? I mean in terms of reducing rolling shutter, isnt capturing a 1000x500 frame with 500 vertical blanking essentially the same as capturing twice as many 1000x500 frames and throwing every other one out? either way, the frame time for the active sensor area is the same, right?[/QUOTE]

Approximately - yes (there is a fixed minimal blanking of 4 lines or so fro MT9T001 sensor). And current FPGA (or software) does not support throwing each other frame (not so difficult to implement).

Driver uses the vertical blanking, not the horizontal - exactly because of the rolling shutter issues, but it is still possible to use the horizontal blanking by specifying "virtual frame" width and height directly (available in cgi interface, but not in the javascript code - easy to add). As for precise frame rate - we will implement it by skipping/adjusting pixel clock during vertical blanking. That will be done on ythe FPGA level and precision will be limited only by the thermal drift of the quartz master clock. For timestamping we already have a real time clock (it counts microseconds - 20 bits and seconds - 32 bits) and is digitally adjusted with the step of +/-0.125ppm.

Sensors need extra horizontal blanking - you may find formulae in the Micron datasheet - PDF on their web site. And horizontal is much bigger than vertical (only 4 lines but some 200-300 pixels)

16mm lenses
 

Dear Wayne that's quite true
but as you are at the center there is the least distorsion.

One of my silly stupid ideas,
Why not use a mechanical shutter somebodie did it with a Dvcam once.
There are no rolling shutter artifacts, Kreins (??) I guess does it this way.

a viewfinder from a Bolex would be fine as you see what the picture will be.

otherwise is on the board any RGB out to have a small CRT connect ??

I can not post so much sick with my teeths

No there is none - there is no "videosignal" (and no RGB - Bayer data is directly converted to YCbCr 4:2:0 - this happens in the macroblock order in front of the compressor, not in the scan-line sequence) inside the camera so making such an output will require something similar to computer videocard.

But there is a solution - just use a separate hand-held computer with WiFi and use it as an external monitor (with reduced resolution/frame rate). I.e. Nokia 770

I have thought about the external 180 degree mirror shutter. So you can also have a viewfinder image, but then i wouldnt think it would be easy to sync the movement of the shutter with the 24 fps to make sure it happens exactly how it should. And for the syncing part, i wouldnt know at all how to do that. I could easily build a 180 degree spinning shutter though.

I have seen electric shutter out there, if anybody is worried about noise power consumption or reliability.


Maybe B&H is where I saw it.


With new cameras, like the Silicon Imagine Altasens one coming out, it is easy to get distracted about the possibilities. But, even if they could reduce the price of it to less than $5K, which size would you prefer to be using, as the Elphel could be combined with a small Origami tablet unit (or PDA or linux micro-controller board) looking like an Sharp view-cam)?:

http://photos1.blogger.com/blogger/3...0/DSC_3238.jpg

The smaller JVCHD10 one is closer to the size volume that an Elphel unit can be made into ;)


Thanks

Wayne.

shutter
 

electric shutter have been used for decades,
no problem with reliability.
Noise either.
I only do mean,
if the immage comes out with no artifacts,
you dont have to hassle in post, each step in post will alter the image a bit. It takes time, a lot of and will be boring to do the dammed work
on each rush again, again and again.
I do know what I speek from.
Was working with Inferno, Maya, Quantel way to long,
stopped just before going totally mad.
Mad anyway Madhatter you can name me.

Wayne it was a long time ago we, you and me we found ephel at linuxdevices.com, do you remeber ??? Linux bahhh nobody was
talking friendly about it....

Yes.

(10 character post limit, don't they believe in short posts around here ;))

Question to Andrey Filippov
It is possible record compressed RAW (similar to CineformRAW) from smos direct-to-hdd with small modification of existing architecture of Elphel333 ?
I mean solution like mentioned by Rai Orz:
http://dvinfo.net/conf/showpost.php?...postcount=2071
http://dvinfo.net/conf/showpost.php?...2&postcount=68

That's the Kineta way doing it

No - that will be a major redesign - our cameras do not have a disk interface.

Thank you, Andrey for clarification. How much cost work to make a such solution camera:
Compressed RAW from CMOS direct-to-disk and streaming proxy (low 1/2 or 1/4 resolution) through GIGe ?

I think it would be out of the way for Andrey right now. he makes High resolution Network cameras mainly for security purposes. This thread is for tests done with his current design to make it possible for filmmaking. His design right now really really good quality. I should be getting my lenses in these few days. and ill show you what i mean.

Forrest (and others)

I got my camera a few days ago. I'm not able to do tests this week because I'm out of the country, but I'll follow this thread and post my results when I'm back.

heres a test with the new f1.3 computar varifocal lens:
http://i11.photobucket.com/albums/a1...etti/rexx5.jpg

sorry for the horrible lighting, i had the blown out areas because that paper is glossy and i was getting light reflected from through the windows from outside. and my back is basiaclly a wall of french doors, (glass doors) so they all are windows.

Pardon my ignorance, but can this camera acquire motion video at more than 8 bits deep ?
Other than that, what are we gaining over a normal HD video camera , other than something to tinker with ?
It's good to see people trying out new devices! keep it up!
-Les

have a look please
 

bonjour

as I did tell you,
have a mechanical shutter,
use a classical viewfinder

I lost this link
voila
here it goes
www.arri.de/entry/416.htm

nothing is dead, it is brand new

a really good one, who knows??

direct to disc
a huge choice of lenses
and so on

Ronald, would you have any idea as to know how sync a 180 degree shutter to the Elphel's stream? It would be very cool in theroy, but i dont think id be able to build something that would cover the light at the right time inervals.

and after that was built, the viewfinder would go next.

Thank you for that link, i think i figured out what else i need to make the viefinder i was going to make. that pechan prism looks very handy.

an old one
 

http://home.teleport.com/~gdi/25pscha.htm
came up decades ago
http://www.dvinfo.net/conf/showthrea...25808&page=140

a question
 

So
maybe an idiot one
but how to get sync out of this board??

The 3mp micron chip that the elphel uses is capable of running snapshots in global reset mode which means all the lines are exposed at the same time, but this requires a mechanical shutter to cut it off at the end (i assume exposure time becomes longer for the lower lines because they just keep exposing until readout gets to them or something). also the chip has the ability to recieve an external trigger that begins a frame. I assume that if you run in global reset mode with a mechanical shutter, you lose the ability to have much longer than 180degree shuttters, but rolling shutter artifacts would be totally removed. The question is whether or not elphel has support for these functions and if you can find a way to hook up a crystal to the camera and the shutter. WIthout this, i dont think a mechanical shutter would do much since the actual exposure period of the first and last rows, in many configurations, hardly even overlap at all, so youd just end up reducing the exposure of probably the first and last rows, basically darkening the tops and bottom of the frame.

Andrey,

Just curious, I downloaded the open source stuff and was picking through you FPGA code.

Since I'm not to familiar with Verilog (I'm coding in VHDL) I was wondering if you have any documentation to go with the compressor. Is all the compression done in the FPGA, I only took a quick look and its hard to tell from unfamiliar code, or do you have to do entropy encoding in the processor or something.

I'm pretty sure that their would be translation tools out there, from one to the other, if that would help you.