Caution to new users at DVinfo.net

Mark Donnell · July 29th, 2006, 10:25 PM

I used a GL-2 for about three years before getting a DVX-100A. Much of the indoor video I shot turned out to be of lower quality than it could have been because I used the shutter priority (TV) mode without closely paying attention. This camera, once it opens up the aperture as far as it can, will automatically add increasing gain to adjust the exposure. As a result, a significant amount of my video was unintentionally shot with 9 to 18 db gain, resulting in a grainy picture which could have been avoided. I strongly recommend that when shooting indoors or under low-light situations, you consider using the manual setting mode and watch closely that unwanted gain is not added by the camera.

Tom Hardwick · July 30th, 2006, 12:43 AM

I don't get this Mark. If you were shooting in lighting conditions that required maximum aperture plus 18dB of electronic gain, then switching to manual mode wouldn't have helped at all.

OK, you could've used 1/6th sec shutter speed, but in reality you'd have simply needed to add more light. Using TV mode or manual mode amounts to the same thing when the light gets low - added gain and grain.

tom.

Mark Donnell · July 31st, 2006, 02:18 PM

Actually, Tom, I was generally using a faster shutter than I would have if I had realized that the gain was set so high. It was indeed my error, but as a new user I had considerably less understanding of how this camera worked. If you are going to use auto modes indoors, I think you need to aware that the gain may be much higher than you would normally choose. You could avoid this problem by using the shutter priority mode at 1/60 second, but I frequently had it set around 1/120 or 1/180, not realizing that the gain was shifted up to compensate.

Tom Hardwick · August 1st, 2006, 12:33 AM

Ah, now it becomes clear. This is one reason I like the way Sony apply gain up on the VX2100. In shutter priority mode and low light the camera will open up to the maximum aperture available at that particular focal length, then it'll add the bare minimum of gain to give the correct exposure.

As you zoom to full tele more and more gain will be applied to compensate for the lense's loss of speed. The PD170, the FX1 and Z1 all operate like the DVX100 does - that is you have to decide on a gain setting and the iris will work within these parameters. This always adds more gain than necessary - a sadness in my view, as max aperture gives better quality than a stop down and +6dB of gain up.

tom.

Graham Bernard · August 1st, 2006, 12:52 AM

Quote:

Originally Posted by Tom Hardwick

Ah, now it becomes clear.

Yes Tom, this was a real "GOTCHA!" for me too. "How dare this camera ADD gain when I haven't told it too?!??

Quote:

Originally Posted by Tom Hardwick

This is one reason I like the way Sony apply gain up on the VX2100. In shutter priority mode and low light the camera will open up to the maximum aperture available at that particular focal length, then it'll add the bare minimum of gain to give the correct exposure.

This always adds more gain than necessary - a sadness in my view, as max aperture gives better quality than a stop down and +6dB of gain up.

. .and yes, this was ALSO something a SONY friend couldn't appreciate/understand and that was when I started out, neither did I! "Who IS adding this bleedin' graininess? I've got this on full manual?"

Moral of story?: Mixing "experiences" and "believing" that there is conformity is the way of madness.

Tom Hardwick · August 1st, 2006, 01:19 AM

Remember Graham that there's no such thing as correct exposure. The camera's meter is only a guide, and experience (that most expensive and valuable piece of your video kit) is what you need to call upon at such times. You're adding to it every day.

tom.

Graham Bernard · August 1st, 2006, 03:57 PM

Quote:

Originally Posted by Tom Hardwick

Remember Graham that there's no such thing as correct exposure.

True . . True . .

July 29th, 2006, 10:25 PM	#1
Mark Donnell Major Player Join Date: Nov 2005 Location: Silver City, NM Posts: 385	Caution to new users I used a GL-2 for about three years before getting a DVX-100A. Much of the indoor video I shot turned out to be of lower quality than it could have been because I used the shutter priority (TV) mode without closely paying attention. This camera, once it opens up the aperture as far as it can, will automatically add increasing gain to adjust the exposure. As a result, a significant amount of my video was unintentionally shot with 9 to 18 db gain, resulting in a grainy picture which could have been avoided. I strongly recommend that when shooting indoors or under low-light situations, you consider using the manual setting mode and watch closely that unwanted gain is not added by the camera.

July 30th, 2006, 12:43 AM	#2
Tom Hardwick Inner Circle Join Date: Mar 2003 Location: Billericay, England UK Posts: 4,711	I don't get this Mark. If you were shooting in lighting conditions that required maximum aperture plus 18dB of electronic gain, then switching to manual mode wouldn't have helped at all. OK, you could've used 1/6th sec shutter speed, but in reality you'd have simply needed to add more light. Using TV mode or manual mode amounts to the same thing when the light gets low - added gain and grain. tom.

July 31st, 2006, 02:18 PM	#3
Mark Donnell Major Player Join Date: Nov 2005 Location: Silver City, NM Posts: 385	Actually, Tom, I was generally using a faster shutter than I would have if I had realized that the gain was set so high. It was indeed my error, but as a new user I had considerably less understanding of how this camera worked. If you are going to use auto modes indoors, I think you need to aware that the gain may be much higher than you would normally choose. You could avoid this problem by using the shutter priority mode at 1/60 second, but I frequently had it set around 1/120 or 1/180, not realizing that the gain was shifted up to compensate.

August 1st, 2006, 12:33 AM	#4
Tom Hardwick Inner Circle Join Date: Mar 2003 Location: Billericay, England UK Posts: 4,711	Ah, now it becomes clear. This is one reason I like the way Sony apply gain up on the VX2100. In shutter priority mode and low light the camera will open up to the maximum aperture available at that particular focal length, then it'll add the bare minimum of gain to give the correct exposure. As you zoom to full tele more and more gain will be applied to compensate for the lense's loss of speed. The PD170, the FX1 and Z1 all operate like the DVX100 does - that is you have to decide on a gain setting and the iris will work within these parameters. This always adds more gain than necessary - a sadness in my view, as max aperture gives better quality than a stop down and +6dB of gain up. tom.

August 1st, 2006, 01:19 AM	#6
Tom Hardwick Inner Circle Join Date: Mar 2003 Location: Billericay, England UK Posts: 4,711	Remember Graham that there's no such thing as correct exposure. The camera's meter is only a guide, and experience (that most expensive and valuable piece of your video kit) is what you need to call upon at such times. You're adding to it every day. tom.