1/30th; 1/60th; Low Light Performance at DVinfo.net

Miguel Lombana · June 24th, 2004, 11:44 AM

I think I alraedy know the answer to this but wanted to hear it from a couple of the guru's.

When shooting fully manual and in a low light environment and I can't get the exposure close to center at f1.6 and 6 to 12db of gain and I drop to 1/30th at 1.6 and 6db of gain, am I sacrificing anything?

I've only been at this a few months and feel that I've gotten pretty good at what I do but am always looking for a helping hand.

With a recent shoot (not for profit, educational only) I opted to shoot a portion at 1/30th and 6db (12db in a very rare cases) to get the exposure meter at center or just below.

The footage looks very good, I really can't complain so I guess I'm just asking, is it ok to be at this shutter speed on these occasions.

Final question, there are places at the same event that 1/30th was overkill so I stepped it back up to 1/60th, is intermixing this footage an issue, naked eyes say no, but from a project perspective is there anything that I should be worried about.

Thanks in advance gang, I figure that when I finally go and start charging for these events I should actually be ready, armed with all the lessons learned here.

Miguel

Boyd Ostroff · June 24th, 2004, 12:01 PM

I haven't tried this on the GL2, but have shot some stuff at 1/30 sec on my Sony cameras. The problem with 1/30 sec shutter speed is that the same data must be written to each of the interlaced video fields. This effectively cuts your vertical resolution in half. If you look at something with fine detail on a good monitor you should be able to see this.

Some people like using 1/30 to get sort of a "film motion". The individual frames will show more blurring in moving objects as compared to 1/60 sec since the shutter stays open longer.

These differences may not be all that noticeable on a regular TV however. You'll need to decide whether it suits your needs. I tried shooting one of our darker operas at 1/30 sec shutter speed on my PDX-10 and although it helped with exposure I wasn't happy with the image quality. I found the resolution loss very noticeable.

If you want to make your 1/60 footage match the 1/30 footage you could just deinterlace it I suppose.

Your mileage may vary...

Federico Dib · June 24th, 2004, 12:29 PM

In case of need (low light), I´d rather go down to 1/25 (I use pal) than to hit the gain over 6db.

The loss of quality here is not very noticeable (for me), and I like better the blurring and motion effects at this speed, than the noise grains that gain gives.

Of course the only times I´ve had to do this is when shooting rock concerts, so the effect added to the motion with that shutter speed actually looks pretty cool.
I´ve been paid for these concerts footage, and the client is happy because I´ve been hired a few times already.

Dave Croft · June 24th, 2004, 07:15 PM

But surely if you use frame mode with a lower shutter speed, of 1/25 pal or 1/30 ntsc, then you won't lose as much resolution as when using interlaced and low shutter speed.

Instead of losing half your resolution because of the low shutter speed combined with 60i, won't you just lose the 25% from using frame mode, and the have motion blur. Is this not correct?

I thought that because the frame created in frame mode lasts 1/25 or 1/30 and so does the shutter speed, then you won't lose all that resolution.

Miguel Lombana · June 24th, 2004, 08:09 PM

<<<-- Originally posted by Dave Croft : But surely if you use frame mode with a lower shutter speed, of 1/25 pal or 1/30 ntsc, then you won't lose as much resolution as when using interlaced and low shutter speed.

Instead of losing half your resolution because of the low shutter speed combined with 60i, won't you just lose the 25% from using frame mode, and the have motion blur. Is this not correct?

I thought that because the frame created in frame mode lasts 1/25 or 1/30 and so does the shutter speed, then you won't lose all that resolution. -->>>

I should have mentioned that I use frame exclusively, but this is exactly the type of stuff that I'm curious about. For my perspective the view does look great but is it right.

June 24th, 2004, 11:44 AM	#1
Miguel Lombana Major Player Join Date: Mar 2004 Location: Litchfield Park, AZ (W/of Phoenix) Posts: 502	1/30th; 1/60th; Low Light Performance I think I alraedy know the answer to this but wanted to hear it from a couple of the guru's. When shooting fully manual and in a low light environment and I can't get the exposure close to center at f1.6 and 6 to 12db of gain and I drop to 1/30th at 1.6 and 6db of gain, am I sacrificing anything? I've only been at this a few months and feel that I've gotten pretty good at what I do but am always looking for a helping hand. With a recent shoot (not for profit, educational only) I opted to shoot a portion at 1/30th and 6db (12db in a very rare cases) to get the exposure meter at center or just below. The footage looks very good, I really can't complain so I guess I'm just asking, is it ok to be at this shutter speed on these occasions. Final question, there are places at the same event that 1/30th was overkill so I stepped it back up to 1/60th, is intermixing this footage an issue, naked eyes say no, but from a project perspective is there anything that I should be worried about. Thanks in advance gang, I figure that when I finally go and start charging for these events I should actually be ready, armed with all the lessons learned here. Miguel __________________ Miguel Lombana http://www.miguellombana.com & http://www.phoenixhamradio.com

June 24th, 2004, 12:29 PM	#3
Federico Dib Major Player Join Date: Jul 2003 Location: Barcelona Posts: 312	In case of need (low light), I´d rather go down to 1/25 (I use pal) than to hit the gain over 6db. The loss of quality here is not very noticeable (for me), and I like better the blurring and motion effects at this speed, than the noise grains that gain gives. Of course the only times I´ve had to do this is when shooting rock concerts, so the effect added to the motion with that shutter speed actually looks pretty cool. I´ve been paid for these concerts footage, and the client is happy because I´ve been hired a few times already. __________________ Messenger Boy : The Thessalonian you're fighting, he's the biggest man I've ever seen. I wouldn't want to fight him. Achilles : That is why no one will remember your name.

June 24th, 2004, 08:09 PM	#5
Miguel Lombana Major Player Join Date: Mar 2004 Location: Litchfield Park, AZ (W/of Phoenix) Posts: 502	<<<-- Originally posted by Dave Croft : But surely if you use frame mode with a lower shutter speed, of 1/25 pal or 1/30 ntsc, then you won't lose as much resolution as when using interlaced and low shutter speed. Instead of losing half your resolution because of the low shutter speed combined with 60i, won't you just lose the 25% from using frame mode, and the have motion blur. Is this not correct? I thought that because the frame created in frame mode lasts 1/25 or 1/30 and so does the shutter speed, then you won't lose all that resolution. -->>> I should have mentioned that I use frame exclusively, but this is exactly the type of stuff that I'm curious about. For my perspective the view does look great but is it right. __________________ Miguel Lombana http://www.miguellombana.com & http://www.phoenixhamradio.com

June 24th, 2004, 12:01 PM	#2
Boyd Ostroff Wrangler Join Date: Dec 2002 Location: Mays Landing, NJ Posts: 11,787	I haven't tried this on the GL2, but have shot some stuff at 1/30 sec on my Sony cameras. The problem with 1/30 sec shutter speed is that the same data must be written to each of the interlaced video fields. This effectively cuts your vertical resolution in half. If you look at something with fine detail on a good monitor you should be able to see this. Some people like using 1/30 to get sort of a "film motion". The individual frames will show more blurring in moving objects as compared to 1/60 sec since the shutter stays open longer. These differences may not be all that noticeable on a regular TV however. You'll need to decide whether it suits your needs. I tried shooting one of our darker operas at 1/30 sec shutter speed on my PDX-10 and although it helped with exposure I wasn't happy with the image quality. I found the resolution loss very noticeable. If you want to make your 1/60 footage match the 1/30 footage you could just deinterlace it I suppose. Your mileage may vary...

June 24th, 2004, 07:15 PM	#4
Dave Croft Regular Crew Join Date: Apr 2004 Location: Yorks UK Posts: 89	But surely if you use frame mode with a lower shutter speed, of 1/25 pal or 1/30 ntsc, then you won't lose as much resolution as when using interlaced and low shutter speed. Instead of losing half your resolution because of the low shutter speed combined with 60i, won't you just lose the 25% from using frame mode, and the have motion blur. Is this not correct? I thought that because the frame created in frame mode lasts 1/25 or 1/30 and so does the shutter speed, then you won't lose all that resolution.