While moving into my new place I unearthed a video camera that I bought 10 years ago or so. It's a Sony DCR-TRV250 and after charging the battery it still works! Yeah Sony! There are two really neat things about this camera (well three actually). The first thing is it has a great 20X optical zoom and a 700X digital zoom. The second thing is it has 'Night Vision' that lets you see stuff in low light conditions. The last thing that I didn't realize was neat until today was the I.Link as Sony calls it, in reality it's a IEEE 1394 Fire Wire interface. I didn't realize how cool the fire wire thing was until I tried to get the videos I made off the camera and onto my computer. More about that later. Anyway the first thing I thought of doing once I got this thing working was to use it to make some Schlieren videos.
If you have read my other posts and seen the videos that I was making with my FujiFilm FinePix camera (a great camera by the way) I was always having trouble getting zoomed in enough on my parabolic mirror to get a good image. That problem went away with the Sony camera and it's insane zoom system.
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| Sony DCR-TRV250 In My Schlieren Setup |
The videos that I ended up making with this camera were more just to see if I could do it and not really all that experimental. After all everyone makes a video of a candle burning using Schlieren. One thing that I did decide to try that I hadn't done before was instead of using a razor edge or 'Schlieren Stop' was to try a Circular Polarizer instead. Above is a picture of what I ended up doing and below is a more detailed explanation.
I put the Sony camera on the linear slide that I was using to position my FujiFilm camera. You can see a picture of that HERE. The purpose of the slide is to allow the camera to be moved closer and farther from the mirror without it moving side to side and loosing the image frame. With everything zoomed in at the mirror 10 feet away it's easy to bump the camera and have it move off the shot.
Once I had it on the slide I put a Circular Polarizer in front of the lens. My thinking here is that the light if not refracted would make it to the camera OK and if refracted the light would be blocked. I'm not sure yet if thats what was happening but it worked. I'll play around with that a little later. The pin point light source was again the same LED that I was using before with the foil tape over it. Lastly I put a piece of red colored film over the LED to attenuate the light a bit. Without that the Sony was way overexposed. There is a exposure adjustment in the camera and I'll try adjusting that next time.
I did end up making a video or two with this setup and you can watch it below. As I mentioned there is nothing too special about the video, it's just me playing with a candle and trying some baking soda and vinegar experiments in a fish tank. The typical afternoon in the garage for me.
In a couple of places in the video I was using the 'Night Vision' setting and a couple of others I was shooting normal. The differences were interesting and I would like to play around with that some more.
The next challenge after making the video was getting it off of the camera and onto my computer. There are 4 video outputs from this camera, USB, FireWire, S Video and Composite. The first thing that I tried to do was use the USB video which required downloading a driver from Sony and installing it in Windows XP compatibility mode on my Vista laptop. I had to set the video camera settings to enable the USB and the video came right off and into a program called VLC Media Player. I chose USB because I have the cables even though the quality isn't all that great.
VLC Media Player is a free open source program that lets you play and convert video files as well as a bunch of other stuff. All I could do was get it to download and play the videos. I screwed around for 2 hours watching How To videos and reading the instructions and help files and never could get it to convert from it's native format to MPEG (or anything else). The native format seems to only be viewable by VLC and pretty much useless so I gave up on that nonsense. If anyone knows how to convert videos with the latest version of VLC please let me know with an email ottobelden@yahoo.com or by leaving a comment. I would really appreciate it!
After becoming thoroughly frustrated with the USB I tried the FireWire and it worked great. I plugged the Sony into my computer, Windows found the driver and with Movie Maker Live I could control the camera from windows and get the video. Worked great!
The last thing that I did in the video was to put some baking soda and a candle in a fish tank in front of the mirror. I wanted to see if I could see the carbon dioxide when the baking soda was mixed with vinegar and the candle go out. I can see it in the video but it's not all that clear after the YouTube conversion.
All in all I think this was a success. The Sony camera works much better that the FujiFilm for Schlieren photography and this has given me some more ideas to try.
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| Baking Soda and Vinegar Experiment |
http://www.any-video-converter.com/products/for_video_free/
ReplyDeleteThis is a good video convertor , use the free version of the software and it will do it's job good. Sorry if my English is bad, and that you very much in the name of humankind for sharing you're experiments :D ... Have a great day...
Andrei,
ReplyDeleteThanks for the compliment. I'll have a look at the converter you linked to.
- Otto
sir,
ReplyDeleteI would like to know how to make a multicolor filter for Schlieren photography
Anju,
ReplyDeleteThanks for the question. How many colors are you interested in? One way is to use a photograph for a slide projector:
http://4.bp.blogspot.com/_MmHvaTCHnvo/Sd9pVsTMdrI/AAAAAAAAE-s/yW3FznfrKLU/s1600-h/35mm-Slide-film-processing.gif
I have had a lot of luck using colored plastic film and placing them very carefully over the lens of the camera.
Are you building a Schlieren system?
Hi
ReplyDeleteWe are trying to set up a Schlieren system to detect striation faults in small sections of glass. So far have light source with a condensing lens, adjustable slit, two matched lenses and on to a knife edge. We can just about make out the striations projected against a white screen, we need to get the best image possible to be able to see the faults which are very slight and are hoping that a video camera that could be viewed via computer monitor will help. Not sure though what type of camera and set up would be best, would it need a special lens or non at all and would a filter of some kind be needed in front of the lens...........any help would be appreciated.
Thanks
Pete
Pete,
ReplyDeleteThanks for checking out my blog. Do the striation faults create some refraction in the light? I have had better luck getting more contrast using a colored filter instead of the knife edge. I place the filter right where the knife edge would be and slowly move it into the field of view. You don;t want the filter to be covering the entire view just as you don't want the knife edge to cover the entire field. The best thing is a colored filter that has many colors and blends them. Have a look at the "rainbow" slide on this link:
http://www.ian.org/Schlieren/HowTo.html
I got one of those kids "View Master" toys with the circular cardboard disc. Google "View Master" to see what I mean. I cut one of the pictures out and used it as a filter. The refraction causes a lot of different colors. You might try that.
As far as the camera I just use a Sony video camera and I zoom in until I can see the mirror that I use filling the screen. I didn't have to remove the lenses or use a special lens.
I'm happy to help if I can, just let me know! I'd be interested in hearing more about your setup.
Cheers,
Otto
Hi Otto
DeleteYes they do create some refraction but the sample needs to be to be rotated to get the best image, thanks for the coloured filter knife edge suggestion i have tried a plane polarising filter in place of the knife edge which seems to help some as does a section of of old floppy disc !!!, will investigate the multicoloured slide filter. The set up is lenses only with a halogen light source condensed to an adjustable slit 250mm from a matched doublet lens, the sample glass which is approx 30mm x 20mm x 1mm thick is placed after this lens with a 250mm gap to the matched lens then on to the knife edge focused at 250mm again. After the knife edge i am using a 80mm ordinary magnifying glass which seems to help to loose the double image at the edge of the sample image projection,which at the moment is just displayed on a white background. Will be looking at some cameras shortly hoping that this will define the striations with more contrast. Would i be able to place the camera immediately after the knife edge and get (after it is stopped down) a useable image via computer do you think? By the way your projects are amazing i don't how you fit so many hours in to the day.
thanks
Pete
Pete,
DeleteThanks, I don't have a lot of time to sleep these days! I have been working two jobs recently and then... you get the idea.
You have a nice setup from what you describe!! :-)
When you say that you have tried a polarizing filter at the knife edge is the filter being used as an 'edge' as well? In other words have you moved the filter in to partially block the view?
Try removing the filters and/or knife edges completely and get all the optics set up so you have a very clear image of the sample glass using either a camera or a projection on white sheet. Make sure that the camera (or sheet) is after the focal point of your lens setup. I use a piece of paper in the dark to find the focal point, the pin point of light.
Place the razor or better the colored filter at that point and move it slowly in and out the field of view to get the best image.
Another thing to try is put one linear polarizer at the light source and another at the knife edge and rotate one or the other to enhance the Schlieren effect. I have had good results doing this with some specific density differentials of gasses.
Getting all of this right takes a lot of time and patience. Once you get it right the next time is easier and from then on easier still. For each application you have to experiment a bit until you get it to work.
I hope this helps, please let me know if you have any more questions. I plan on getting back to some Schlieren experiments once my work schedule settles down. I want to out my homemade wind tunnel and plasma actuators to some use!
- Otto
Otto
DeleteNow have a better image using the polariser as a knife edge on a white sheet which just needs enhancing with a detailed camera image. Will try some of your very helpful suggestions, with further experimenting, perseverance needed as you know. Really appreciate your advice hope the workload reduces soon.
Pete
Pete,
ReplyDeleteI hope that some of the info that I gave you helps. As always if you have any questions please let me know and I'll get back to you as soon as I can!
- Otto
Hi Otto
DeleteIf i use a microscope objective atatched to a video camera, one with a very short focal length of say less than 25mm would i be able to get an image. As at the moment it is too bright to make out anything when using an ordinary camera focused on a point where the image can be seen ok against a white sheet
thanks
Pete
Pete,
DeleteYou can try using the microscope lens. I did something similar (on my blog) with a binocular. I also read that you can't or it's hard to get an image using a camera with a zoom because of where the focal point is, inside the lens assembly. I tried it anyway and didn't seem to have any problems. I'll try to get some time this weekend to publish something on my blog about how I set everything up.
- Otto