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MrWhite
Joined: 09 May 2017
Posts: 105
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 Posted: Thu Apr 12, 2018 8:39 pm Post subject: Old Pathe news reel. |
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I think you will find this interesting if you haven't seen to before. There's a bit of everything in there, Cars, planes, boats, bit of land speed record info. Be ineresed to know what teh car is with wheels that turn opposite directions and how on earth thaht system worked? Here it is anyway; https://youtu.be/LpgMCeU9nos
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peter scott
Joined: 18 Dec 2007
Posts: 7118
Location: Edinburgh
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| Posted: Thu Apr 12, 2018 11:43 pm Post subject: |
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Suppose that cine film takes a photo every 24th of a second and it is filming a car whose wheels complete exactly one revolution in a 24th of a second (i.e. the wheels are turning at 24 revs/sec which is 1440 rpm) then the wheels on the film would be shown at the same position in every frame and would appear to be stationary.
Now consider if the car slows down slightly and its wheels are now turning at 23 rev/sec. The successive frames on the film will now capture the wheels in a position earlier in its revolution by one 24th of a turn every second and so the wheels will appear to be rotating backwards at sixty 24ths of a rev per minute, which is 2.5 rpm (backwards).
Peter
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lowdrag
Joined: 10 Apr 2009
Posts: 1585
Location: Le Mans
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| Posted: Fri Apr 13, 2018 5:49 am Post subject: |
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| I am glad I grew up after the war before life got complicated, but I so wish that I could have been there to see those pioneers. These films are so evocative. Thank you for posting. |
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Penman
Joined: 23 Nov 2007
Posts: 4755
Location: Swindon, Wilts.
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| Posted: Fri Apr 13, 2018 6:25 am Post subject: |
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Peter
I don't think Mr5White is on about the strobe effect you get on many films, he means the car with the front wheels which can turn right and left at the same time.
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peter scott
Joined: 18 Dec 2007
Posts: 7118
Location: Edinburgh
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| Posted: Fri Apr 13, 2018 9:37 am Post subject: |
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Oops! I should have watched the film. Sorry.
Peter 
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1939 SS Jaguar 2 1/2 litre saloon |
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MikeEdwards
Joined: 25 May 2011
Posts: 2467
Location: South Cheshire
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| Posted: Fri Apr 13, 2018 10:26 am Post subject: |
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| peter scott wrote: | ... stuff about why wheels appear to go backwards on old TV ...
Peter |
That always used to intrigue me when I'd see a car on the TV and the wheels would appear to turn backwards, until I found that out. Just like now, when I hear people asking why "the cars on Top Gear always seem to have flickering lights" and brace myself to try to explain the difference in LED oscillation rate, high-frame-rate cameras and conversion to broadcast-rate video.
I know, I know, "the long winter evenings" etc. etc. |
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MrWhite
Joined: 09 May 2017
Posts: 105
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| Posted: Fri Apr 13, 2018 10:30 am Post subject: |
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Thank you Peter for the wonderful, detailed explanation, just a slightly different question but probably my fault for not explaining adequately what I was on about.......what, you didn't actually watch the film 
Sorry, couldn't resist  |
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Penman
Joined: 23 Nov 2007
Posts: 4755
Location: Swindon, Wilts.
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| Posted: Fri Apr 13, 2018 11:18 am Post subject: |
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Hi
Expensive record turntables have a strobe facility to enable fine tuning of the record speed.
https://www.youtube.com/watch?v=Rzvqe-OcNvs
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Bristols should always come in pairs.
Any 2 from:-
Straight 6
V8 V10 |
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peter scott
Joined: 18 Dec 2007
Posts: 7118
Location: Edinburgh
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| Posted: Fri Apr 13, 2018 7:29 pm Post subject: |
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| MrWhite wrote: | .what, you didn't actually watch the film
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I have watched it now 
Thanks for your understanding response.
Peter
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1939 SS Jaguar 2 1/2 litre saloon |
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Ellis
Joined: 07 Mar 2011
Posts: 1382
Location: Betws y Coed, North Wales
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| Posted: Fri Apr 13, 2018 7:42 pm Post subject: |
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Fascinating.
Thank you for posting.
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1964 Jaguar Mark 2 3.4 litre
1962 Land Rover Series 2a 88"
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