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Photo Forum / Digital Photography / DSLR Cameras / June 2006Taking Photos of TV Images
I have a D50 w/18-55mm lens and have attempted to take photos of images appearing on my TV with only moderate success and was wondering if anyone has a recommended technique. Bill > I have a D50 w/18-55mm lens and have attempted to take photos of images > appearing on my TV with only moderate success and was wondering if anyone has a > recommended technique. HD only: Use freeze frame, and take your time. I forget the settings, maybe something like 1/40th @ 2.8... .but that's now a WAG. Doubt NTSC will ever produce good results, but I'd go with frozen frame on tv there, too.  Signaturejohn mcwilliams Max thought the night-time burglary at the California surfing museum would be a safe caper, but that was before he spotted the security cop riding a bull mastiff, blond hair blowing in the wind, and noticed the blue-and-white sign wired to the cyclone fence, "Guard dude on doggy."8:11:36 AM > I have a D50 w/18-55mm lens and have attempted to take photos of images > appearing on my TV with only moderate success and was wondering if anyone has a > recommended technique. Bill- Television sets in the U.S. display alternate scan lines, 1/60 second per scan. It takes 1/30 second for a full picture to be displayed. Therefore you need to set your exposure time to something slower than 1/30 second. Use of a tripod is probably a good idea. I don't know how the European system works, but it probably has a similar time required for the picture to be displayed. Similarly, HDTV must have some kind of speed limit. Fortunately with digital cameras, it doesn't cost much to experiment. Fred > In article <cjcd921pgi9shpkh11gur5l81161n6787t@4ax.com>, Bill > Helbron [quoted text clipped - 19 lines] > with > digital cameras, it doesn't cost much to experiment. Yes. If there is motion in the TV picture, it will be displayed in a blur, so it's a good idea to choose a static picture when possible. Our eye and brain facilities do an amazing job of making TV and movie images appear to be sharp and smooth. Stop the transitions (freeze a frame) and yo see what material they work with. SignatureFrank ess > Television sets in the U.S. display alternate scan lines, 1/60 second > per > scan. It takes 1/30 second for a full picture to be displayed. > Therefore > you need to set your exposure time to something slower than 1/30 > second. But not too much slower, unless the image isn't moving. --------------- Marc Sabatella marc@outsideshore.com Music, art, & educational materials Featuring "A Jazz Improvisation Primer" http://www.outsideshore.com/ >> I have a D50 w/18-55mm lens and have attempted to take photos of images >> appearing on my TV with only moderate success and was wondering if [quoted text clipped - 7 lines] >you need to set your exposure time to something slower than 1/30 second. >Use of a tripod is probably a good idea. Newer digital systems come in both flavors. Interlaced and progressive like a computer monitor. I have an HD set with better than 1300 horizontal resolution and 720p vertical. The "p" stands for Progressive so the scan is one line at a time instead of every other line. OTOH being digital there really isn't a scan like the old CRTs. >I don't know how the European system works, but it probably has a similar >time required for the picture to be displayed. I believe their system is based on the 50 cycles per second electrical frequency, but they use a system that is different and incompatible with NTSC. I do believe they may use a progressive scan at 50 cps, but please note all the weasel words in that statement. But, back to the original question, as Fred has said: slow shutter speed (1/30 second or slightly slower) with a tripod. >Similarly, HDTV must have some kind of speed limit. Fortunately with >digital cameras, it doesn't cost much to experiment. HD is like shooting a computer monitor. But when it comes to over the air stations you *usually* find an analog version, and then 2 or 3 digital versions which may even have different programming. You will find digital with standard definition (SD) along with 460?i, 720P, and 1080i. I've not seen any 1080p yet although there are sets coming out with that capability. Now with HD I can get to see the actors and actresses have complexions as bad as the rest of us. Warts, wrinkles, pimples (for the younger ones) and age spots for the older ones ... <:-)) OTOH I have to admit National Geographic and some other shows are great in wide screen and HD. Roger Halstead (K8RI & ARRL life member) (N833R, S# CD-2 Worlds oldest Debonair) www.rogerhalstead.com >Fred My thanks to you all! I did NOT use a tripod, but was about 18" from the screen surface. It would appear that I get the best results with the exposure set at 1/25 (mode "S"). I tried 1/30, 1/25, and 1/20. As mentioned earlier, these are good enough for my immediate purposes, but will continue to experiment. There was also some minor reflection from the glass noticable and some chromatic distortions (like moire patterns) on one side in the 1/20 exposure. Bill >I have a D50 w/18-55mm lens and have attempted to take photos of images >appearing on my TV with only moderate success and was wondering if anyone has a >recommended technique. > >Bill > My thanks to you all! I did NOT use a tripod, but was about 18" from the > screen [quoted text clipped - 15 lines] >> >>Bill The best way to capture a TV image is with a video card with TV input. A camera to do the same is just a cludge. SignatureRegards, Matt Clara www.mattclara.com > The best way to capture a TV image is with a video card with TV input. A > camera to do the same is just a cludge. If all you want is the TV image itself ... sometimes the image is a room that contains a TV, or more likely today, a computer display. ... and it's kludge with a 'K' ... awkward like a kludge. According to no_name <no_name@no.where.invalid>: > > The best way to capture a TV image is with a video card with TV input. A > > camera to do the same is just a cludge. [quoted text clipped - 3 lines] > > ... and it's kludge with a 'K' ... awkward like a kludge. Actually, there is some debate as to whether the 'd' belongs in there as well. It apparently came in from a mis-spelling in a magazine article in the UK. Before that, it was spelled "Kluge". Enjoy, DoN. SignatureEmail: <dnichols@d-and-d.com> | Voice (all times): (703) 938-4564 (too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html --- Black Holes are where God is dividing by zero --- On 6/20/06 7:12 PM, the clairvoyantDoN. Nichols posted the following: > According to no_name <no_name@no.where.invalid>: >> [quoted text clipped - 9 lines] > there as well. It apparently came in from a mis-spelling in a magazine > article in the UK. Before that, it was spelled "Kluge". That in turn came out of an Olympic event, where the Committee wanted to name a thousand metre luge event, but they could never put it together right, but the letters got merged. Signaturejohn mcwilliams According to John McWilliams <jpmcw@comcast.net>: > On 6/20/06 7:12 PM, the clairvoyantDoN. Nichols posted the following: > > According to no_name <no_name@no.where.invalid>: [quoted text clipped - 14 lines] > name a thousand metre luge event, but they could never put it together > right, but the letters got merged. Sounds like a good story, but what I have heard are several origins, of which I remember two. 1) The term "kluge" is "clever" in German. 2) There was a machine -- part of a printing shop -- I think the paper folder which had the brand name "Kluge", and while it worked from all descriptions, it was indeed a prototype to the current interpretation of "kluge". There used to be long debates about the origin of the term and the proper spelling in alt.folklore.computers. There may still be, for all that I know. Enjoy, DoN. SignatureEmail: <dnichols@d-and-d.com> | Voice (all times): (703) 938-4564 (too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html --- Black Holes are where God is dividing by zero --- > My thanks to you all! I did NOT use a tripod, but was about 18" from > the screen > surface. It would appear that I get the best results with the exposure > set at > 1/25 (mode "S"). I tried 1/30, 1/25, and 1/20. At those shutter speeds - which are indeed about idea, you really should be considering a tripod. Also, you should be conisdering shooting from further away - with a longer lens if necessary. Shooting that close will only exaggerate the distortions inherent in what you are trying to do. Consider that even if you have a flat screen TV, the edges of the TV are considerably further form the camera than the center is when the camera is that close. The fact that most TV screens curve away from you as you go to the edges only exacerbates this problem. If the camera is several feet away, then those differences is minimized. But the longer the focal length, the more you'll need a tripod, all else being equal. --------------- Marc Sabatella marc@outsideshore.com Music, art, & educational materials Featuring "A Jazz Improvisation Primer" http://www.outsideshore.com/ > My thanks to you all! I did NOT use a tripod, but was about 18" from the screen > surface. It would appear that I get the best results with the exposure set at > 1/25 (mode "S"). I tried 1/30, 1/25, and 1/20. As mentioned earlier, these are > good enough for my immediate purposes, but will continue to experiment. There > was also some minor reflection from the glass noticable and some chromatic > distortions (like moire patterns) on one side in the 1/20 exposure. Bill- If you have a polarizing filter, see if it will help eliminate the reflections. Exposure time will be increased, but may be worth the trouble. Fred On 6/19/06 2:54 PM, the clairvoyantBill Helbron posted the following: > My thanks to you all! I did NOT use a tripod, but was about 18" from the screen > surface. It would appear that I get the best results with the exposure set at > 1/25 (mode "S"). I tried 1/30, 1/25, and 1/20. As mentioned earlier, these are > good enough for my immediate purposes, but will continue to experiment. There > was also some minor reflection from the glass noticable and some chromatic > distortions (like moire patterns) on one side in the 1/20 exposure. Is your TV HD? Does it have freeze frame? Signaturejohn mcwilliams None of our TV's are HD, but one here (Channel 7) does broadcast in HD. One TV does have freeze frame capability but, unfortunately, the channel which has the images I'm most interested in getting does not get good reception. Several respondents have suggested using a tripod and I've tried it both ways, but my results are about the same! 1/25 seems to work best, but I'll try the freeze frame approach! I wish my freeze frame would give you the option of full screen instead of just two smaller windows! I don't know if newer models will do this. Bill >On 6/19/06 2:54 PM, the clairvoyantBill Helbron posted the following: >> My thanks to you all! I did NOT use a tripod, but was about 18" from the screen [quoted text clipped - 5 lines] >> >Is your TV HD? Does it have freeze frame? On 6/22/06 7:13 AM, Bill Helbron posted the following: > None of our TV's are HD, but one here (Channel 7) does broadcast in HD. One TV > does have freeze frame capability but, unfortunately, the channel which has the [quoted text clipped - 5 lines] > screen instead of just two smaller windows! I don't know if newer models will do > this. My Sony HD TV allows full frame HD to be frozen, or I can do split screen. I don't know that freeze frame will help or hinder with NTSC, but you've received a lot of advice how to do it without freezing. Signaturejohn mcwilliams if you are in Australia, you can buy masthead amplifiers that will return your TV to excellent reception > None of our TV's are HD, but one here (Channel 7) does broadcast in HD. > One TV [quoted text clipped - 28 lines] >>> >>Is your TV HD? Does it have freeze frame? > if you are in Australia, you can buy masthead amplifiers that will return > your TV to excellent reception They won't make signal where there ain't no signal, they won't fix multipath, in areas where the problem is excessive rather than insufficient signal they make things worse, etc. Not a panacea. >> None of our TV's are HD, but one here (Channel 7) does broadcast in HD. >> One TV [quoted text clipped - 28 lines] >>>> >>>Is your TV HD? Does it have freeze frame? Signature--John to email, dial "usenet" and validate (was jclarke at eye bee em dot net) >I have a D50 w/18-55mm lens and have attempted to take photos of images > appearing on my TV with only moderate success and was wondering if anyone > has a > recommended technique. > > Bill The frame rate for NTSC is 1/30 second, so you're going to need a shutter speed slower than that. The reason being, at exactly 1/30 second you'll capture part of a frame and parts of the adjacent frames, unless you're lucky enough for the shutter to open right at a vertical blanking interval. As for moire, it's probably unavoidable unless you have lots of megapixels, because you're putting dots on top of dots. Some will line up and some won't. >I have a D50 w/18-55mm lens and have attempted to take photos of images >appearing on my TV with only moderate success and was wondering if anyone has a >recommended technique. It's easy if you know how. The simplest method is to use a tripod & a 1/2 second exposure. SignatureW . | ,. w , "Some people are alive only because \|/ \|/ it is illegal to kill them." Perna condita delenda est ---^----^--------------------------------------------------------------- > I have a D50 w/18-55mm lens and have attempted to take photos of > images appearing on my TV with only moderate success and was > wondering if anyone has a recommended technique. > > Bill Tripod, and about 1/15th to 1/30th second. Much faster and you're likely to only get a partial picture due to interlacing. SignatureImages (Plus Snaps & Grabs) by Mark² at: www.pbase.com/markuson why not record the image on a DVD recorder then pause it? I have found LCD panels to be the best for shotting images of TV, but always on freeze or pause Steve >> I have a D50 w/18-55mm lens and have attempted to take photos of >> images appearing on my TV with only moderate success and was [quoted text clipped - 5 lines] > Much faster and you're likely to only get a partial picture due to > interlacing. >I have a D50 w/18-55mm lens and have attempted to take photos of images >appearing on my TV with only moderate success and was wondering if anyone has a >recommended technique. The TV has a refresh rate of 30 images per second. Thus you need to have a shutter speed *slower* than that. On the other hand, if the scene is changing rapidly, and your shutter speed too low, you will get blurring and streaking. I'd try 1/20 or 1/15 and see what happens. Put the camera on a tripod if need be and remember that the TV is providing its own light. ---- Paul J. Gans |
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