shutter speed? at DVinfo.net

George Goltz · January 29th, 2003, 09:10 AM

will be shooting a fashion show with the XL1S standard lens, last year shoot same fashion show at 1/60, lighting was not the best want to trie to shoot at 1/30 , anyone used this setting with people walking, strobe effect? any imput will be appreciated.

Don Palomaki · January 29th, 2003, 04:42 PM

At 1/30 there will be some strobe effect with movement, especially faster movement. Give it a try with some friends as models and see if the effect works for you or if yo uneed some more light.

Andre De Clercq · January 30th, 2003, 02:51 PM

In addition to the potential strobe effects, you will lose 50% vertical resolution.

Rob Lohman · January 31st, 2003, 07:24 AM

50% vertical resolution loss? How will this happen?

Andre De Clercq · January 31st, 2003, 07:58 AM

Because only one field is being used in those "lower than system" refresh modes (1/50, 1/60)

Adrian Douglas · January 31st, 2003, 08:22 AM

As far as I'm concerned the possible 50% resolution loss is totally academic. The slow shutters speeds are visual effects and the loss isn't noticable when viewed on a television. I suppose this is due to the bluring induced by movement.

Rob Lohman · January 31st, 2003, 08:29 AM

Andre, do you also know why they use only one field? It doesn't
make a lot of sense at the moment here. I'll see if I can do some
resolution tests this weekend....

Jeff Donald · January 31st, 2003, 08:29 AM

I haven't researched this topic, so i'll throw this question in here. I've heard (read?) that some cameras use interpolation for the second field, rather than repeating the same field twice. While this would still lower the resolution, it would be less than the 50% loss caused by repeating fields.

Robert Knecht Schmidt · January 31st, 2003, 08:54 AM

Interpolation is not an increase in resolution.

Bill Ravens · January 31st, 2003, 09:10 AM

Basically, 1/30 is the same as frame movie mode. There's not enough time to multiplex two image captures into two fields per frame at this shutter speed(30 fps > 1/30 sec per frame+ processor overhead). So one field is captured, and replicated into the second field.

Rob Lohman · January 31st, 2003, 09:58 AM

And what if you are in frame mode and have such a low shutter
speed, what then?

Bill Ravens · January 31st, 2003, 10:30 AM

same same

Andre De Clercq · January 31st, 2003, 11:13 AM

Frame mode and low shutter speed settings are two different things. Real frame mode in camera's captures the two fields during the same timeslot (which could be in contrast to the long shutter settings very short,like1/1000..) and dumps the data into a full frame buffer memory. This memory is being read out in interlaced mode. The end result is two fields (interlaced)belonging to the same "shot". Pseudo frame modes, because they don't have the full frame budder memory, try to imitate frame mode by R/B and G combinations or by line repetition or interpolation on a single field, resulting in somewhat better vertical resolution and/or artifact reduction. Slow shutter modes integrate the light during a longer time (like 1/30 or longer) and output (repeat) one field during the time the next image is being integrated on the CCD. Slow shutter images allways show motion blurr(long integration time on the CCD) and can have refreshes going down to 3 times.sec. Frame mode however can have very short shutter times if needed.

Adrian Douglas · February 1st, 2003, 10:47 AM

You can't access the slow shutter speeds in frame mode so it shouldn't be a problem

Rob Lohman · February 2nd, 2003, 10:52 AM

Either my mind is completely wrong here or something else is.
If I have my Canon XL1s in frame mode I can do 1/25 and even
a bit lower (I have the PAL model)....

January 29th, 2003, 09:10 AM	#1
George Goltz Regular Crew Join Date: Dec 2001 Location: new jersey usa Posts: 38	shutter speed? will be shooting a fashion show with the XL1S standard lens, last year shoot same fashion show at 1/60, lighting was not the best want to trie to shoot at 1/30 , anyone used this setting with people walking, strobe effect? any imput will be appreciated. __________________ george goltz

January 31st, 2003, 07:24 AM	#4
Rob Lohman RED Code Chef Join Date: Oct 2001 Location: Holland Posts: 12,514	50% vertical resolution loss? How will this happen? __________________ Rob Lohman, visuar@iname.com DV Info Wrangler & RED Code Chef Join the DV Challenge \| Lady X Search DVinfo.net for quick answers \| Buy from the best: DVinfo.net sponsors

January 31st, 2003, 08:22 AM	#6
Adrian Douglas Trustee Join Date: Oct 2001 Location: Chigasaki, Japan. Posts: 1,660	As far as I'm concerned the possible 50% resolution loss is totally academic. The slow shutters speeds are visual effects and the loss isn't noticable when viewed on a television. I suppose this is due to the bluring induced by movement. __________________ Adrian DVInfo.net Search for quick answers Where to buy? From the best in the business...DVInfo.net sponsors

January 31st, 2003, 08:29 AM	#7
Rob Lohman RED Code Chef Join Date: Oct 2001 Location: Holland Posts: 12,514	Andre, do you also know why they use only one field? It doesn't make a lot of sense at the moment here. I'll see if I can do some resolution tests this weekend.... __________________ Rob Lohman, visuar@iname.com DV Info Wrangler & RED Code Chef Join the DV Challenge \| Lady X Search DVinfo.net for quick answers \| Buy from the best: DVinfo.net sponsors

January 31st, 2003, 08:29 AM	#8
Jeff Donald Warden Join Date: Mar 2002 Location: Clearwater, FL Posts: 8,287	I haven't researched this topic, so i'll throw this question in here. I've heard (read?) that some cameras use interpolation for the second field, rather than repeating the same field twice. While this would still lower the resolution, it would be less than the 50% loss caused by repeating fields. __________________ Jeff Donald Carpe Diem Search DVinfo.net for quick answers \| Where to Buy? From the best in the business: DVinfo.net sponsors

January 29th, 2003, 04:42 PM	#2
Don Palomaki Wrangler Join Date: Sep 2001 Location: Northern VA Posts: 4,487	At 1/30 there will be some strobe effect with movement, especially faster movement. Give it a try with some friends as models and see if the effect works for you or if yo uneed some more light.

January 30th, 2003, 02:51 PM	#3
Andre De Clercq Major Player Join Date: Sep 2002 Location: Belgium Posts: 804	In addition to the potential strobe effects, you will lose 50% vertical resolution.

January 31st, 2003, 07:58 AM	#5
Andre De Clercq Major Player Join Date: Sep 2002 Location: Belgium Posts: 804	Because only one field is being used in those "lower than system" refresh modes (1/50, 1/60)

January 31st, 2003, 08:54 AM	#9
Robert Knecht Schmidt Wrangler Join Date: Feb 2002 Location: Cleveland, Ohio Posts: 1,933	Interpolation is not an increase in resolution. __________________ All the best, Robert K S Search DVinfo.net for quick answers \| The best in the business: DVinfo.net sponsors

January 31st, 2003, 09:10 AM	#10
Bill Ravens Join Date: Nov 2001 Location: santa fe, nm Posts: 3,264 Images: 10	Basically, 1/30 is the same as frame movie mode. There's not enough time to multiplex two image captures into two fields per frame at this shutter speed(30 fps > 1/30 sec per frame+ processor overhead). So one field is captured, and replicated into the second field.

January 31st, 2003, 09:58 AM	#11
Rob Lohman RED Code Chef Join Date: Oct 2001 Location: Holland Posts: 12,514	And what if you are in frame mode and have such a low shutter speed, what then? __________________ Rob Lohman, visuar@iname.com DV Info Wrangler & RED Code Chef Join the DV Challenge \| Lady X Search DVinfo.net for quick answers \| Buy from the best: DVinfo.net sponsors

January 31st, 2003, 10:30 AM	#12
Bill Ravens Join Date: Nov 2001 Location: santa fe, nm Posts: 3,264 Images: 10	same same

January 31st, 2003, 11:13 AM	#13
Andre De Clercq Major Player Join Date: Sep 2002 Location: Belgium Posts: 804	Frame mode and low shutter speed settings are two different things. Real frame mode in camera's captures the two fields during the same timeslot (which could be in contrast to the long shutter settings very short,like1/1000..) and dumps the data into a full frame buffer memory. This memory is being read out in interlaced mode. The end result is two fields (interlaced)belonging to the same "shot". Pseudo frame modes, because they don't have the full frame budder memory, try to imitate frame mode by R/B and G combinations or by line repetition or interpolation on a single field, resulting in somewhat better vertical resolution and/or artifact reduction. Slow shutter modes integrate the light during a longer time (like 1/30 or longer) and output (repeat) one field during the time the next image is being integrated on the CCD. Slow shutter images allways show motion blurr(long integration time on the CCD) and can have refreshes going down to 3 times.sec. Frame mode however can have very short shutter times if needed.

February 1st, 2003, 10:47 AM	#14
Adrian Douglas Trustee Join Date: Oct 2001 Location: Chigasaki, Japan. Posts: 1,660	You can't access the slow shutter speeds in frame mode so it shouldn't be a problem __________________ Adrian DVInfo.net Search for quick answers Where to buy? From the best in the business...DVInfo.net sponsors

February 2nd, 2003, 10:52 AM	#15
Rob Lohman RED Code Chef Join Date: Oct 2001 Location: Holland Posts: 12,514	Either my mind is completely wrong here or something else is. If I have my Canon XL1s in frame mode I can do 1/25 and even a bit lower (I have the PAL model).... __________________ Rob Lohman, visuar@iname.com DV Info Wrangler & RED Code Chef Join the DV Challenge \| Lady X Search DVinfo.net for quick answers \| Buy from the best: DVinfo.net sponsors

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