Nicholas A Micros Posted April 14, 2011 Share Posted April 14, 2011 I'm struggling converting 550 foot candles to a f/stop at 200 iso and 180 shutter. Can anyone help me out? Or 6000 lumens to ... Thanks Link to comment Share on other sites More sharing options...
Tom Jensen Posted April 14, 2011 Share Posted April 14, 2011 I'm struggling converting 550 foot candles to a f/stop at 200 iso and 180 shutter. Can anyone help me out? Or 6000 lumens to ... Thanks Make it easy on yourself and just use stops. You need 100 footcandles at 100 asa to get a 2.8. So at 200 asa you only need 50 footcandles to get a 2.8. 100 to get a 4, 200 to get a 5.6, 400 to get an 8 and 800 to get an 11. So, I'm guessing its 5.6 and 1/3 at 550 with 200 asa. I think I did that right. Someone feel free to correct me if I/m wrong. Link to comment Share on other sites More sharing options...
Nicholas A Micros Posted April 17, 2011 Author Share Posted April 17, 2011 Thanks tom. Your reply is very helpful. Thats all the info I needed Link to comment Share on other sites More sharing options...
Gregory Andracke Posted April 22, 2015 Share Posted April 22, 2015 Thanks tom. Your reply is very helpful. Thats all the info I needed Make it easy on yourself and just use stops. You need 100 footcandles at 100 asa to get a 2.8. So at 200 asa you only need 50 footcandles to get a 2.8. 100 to get a 4, 200 to get a 5.6, 400 to get an 8 and 800 to get an 11. So, I'm guessing its 5.6 and 1/3 at 550 with 200 asa. I think I did that right. Someone feel free to correct me if I/m wrong. My calculation on an old Spectra Pro was more like f/8 1/3 --- I know this is an old post, but I was looking for some other stuff on FC and ISO and stumbled across this one! Link to comment Share on other sites More sharing options...
Premium Member David Mullen ASC Posted April 22, 2015 Premium Member Share Posted April 22, 2015 100 fc = f/2.8 at 100 ASA so... 100 fc = f/4 at 200 ASA 200 fc = f/5.6 at 200 ASA 400 fc = f/8 at 200 ASA 800 fc = f/11 at 200 ASA So Tom was right until he somehow thought that 550 fc was less than 400 fc, not more (or he forgot he had already converted to 200 ASA) and went down to f/5.6 instead of up to f/8... 550 fc should be a bit over f/8 1/3. Link to comment Share on other sites More sharing options...
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