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-   -   HC9 auto gain feature (https://www.dvinfo.net/forum/sony-hvr-a1-hdr-hc-series/144131-hc9-auto-gain-feature.html)

Nelson Alexandre February 19th, 2009 06:42 AM

HC9 auto gain feature
 
Hi all,

Does anyone knows a way to get rid of the HC9 auto gain, or at least limit it to a low value?

All thoughts on this matter will be much appreciated.

Thanks

Nelson Alexandre February 20th, 2009 08:57 PM

No One? :(

Toby Giessen February 21st, 2009 08:24 AM

It's something I would really like to know, too.

Adam Gold February 21st, 2009 11:25 AM

You can't control it directly, but you can assign the scroll wheel to exposure and make sure you are always four to six notches to the left of the maximum (18dB). Each notch is 3dB in most exposure modes, so six to the right is 0dB gain. Up to six, even nine dB is not really noticeable.

Nelson Alexandre February 21st, 2009 02:48 PM

Quote:

Originally Posted by Adam Gold (Post 1015811)
You can't control it directly, but you can assign the scroll wheel to exposure and make sure you are always four to six notches to the left of the maximum (18dB). Each notch is 3dB in most exposure modes, so six to the right is 0dB gain. Up to six, even nine dB is not really noticeable.

So what you're saying is that the exposure manual control controls aperture and gain after dialing the iris to all open?

I don't know if I expressed correctly. Imagine f/1.8 as maximum aperture. In low light you open the iris to max to a point (say, just for the purpose that it's the exposure bar middle point), and if you continue to dial the exposure it will kick up the gain bacause it doesn't have any more iris to open?

Thanks

J. Stephen McDonald February 21st, 2009 04:13 PM

In Photo Mode, the Auto-gain Goes Off
 
And sometimes, the only way to get a still photo in very dim light, is to shoot it in video mode, so the auto-gain will bring up the level.

Adam Gold February 22nd, 2009 10:40 AM

Quote:

Originally Posted by Nelson Alexandre (Post 1015904)
So what you're saying is that the exposure manual control controls aperture and gain after dialing the iris to all open?

I don't know if I expressed correctly. Imagine f/1.8 as maximum aperture. In low light you open the iris to max to a point (say, just for the purpose that it's the exposure bar middle point), and if you continue to dial the exposure it will kick up the gain bacause it doesn't have any more iris to open?

Thanks

Exactly. It actually will control shutter speed as well, but it takes a lot to move it off of 1/60th.

So you can control gain by just avoiding the last six steps on the bar.

Nelson Alexandre February 22nd, 2009 01:30 PM

Quote:

Originally Posted by Adam Gold (Post 1016298)
Exactly. It actually will control shutter speed as well, but it takes a lot to move it off of 1/60th.

So you can control gain by just avoiding the last six steps on the bar.

What you are saying is great news for me Adam.

I’ve been thinking the pros and cons about buying a HC9 camera. Everybody states that HV30 has a superior image but I really need a LANC port.

On the other hand the low light performance that many reviews had with the HC9 is keeping me back. But if you say I just can control auto gain that way I think I can take the noise down on low light situations.
I'm willing to sacrifice info and recording really black where's no sufficient light than capture info with noise in it!

J. Stephen McDonald February 22nd, 2009 07:16 PM

Quote:

Originally Posted by Nelson Alexandre (Post 1016396)
What you are saying is great news for me Adam.

I’ve been thinking the pros and cons about buying a HC9 camera. Everybody states that HV30 has a superior image but I really need a LANC port.

On the other hand the low light performance that many reviews had with the HC9 is keeping me back. But if you say I just can control auto gain that way I think I can take the noise down on low light situations.
I'm willing to sacrifice info and recording really black where's no sufficient light than capture info with noise in it!

Nelson, the HC9 and other models in this series, are not really as limited in low light, as many people keep saying. I have a VX2100, which is the king of low light video and when I use my HC9, I don't feel too much of a handicap. Much of my wildlife video is shot near dusk and sometimes after that. Here's a link to a video I shot last August with my HC9, called "Evening Beavers". I began shooting it 5 minutes before sunset and finished 15 minutes later. It was set entirely on auto. Evening Beavers on Vimeo

The HC9 has a roller control that can be designated for any one of several functions, including manual exposure and shutter speed. I have learned that with fast-moving subjects, it's best to manually set it at 60 fps (in your case, 50 fps), to keep the motion sufficiently blurred and to avoid strobing of wings or legs. This will also keep the gain from rising so much in lower light levels, due to the auto system having increased the shutter speed. You can see many other videos on my Vimeo album that I shot near sunset, sometimes in heavily-shaded swamps. If you register for a free subscription with Vimeo, you can download my videos, to see them at a much higher bit-rate and better quality, than directly viewing them on their website. The Vimeo playback is so heavily compressed, there is often jerkiness in the motion.

I'm very pleased by the faultless function of my HC9 and there's a lot to be said for the dependability and longterm durability of videotape. I have evaporated-metal Hi-8 tapes, of the same type formulation used by DV and HDV, that are 20 years old and still playing back without any loss of quality (something that shows up quickly in analog recording, if the tape is degraded). It doesn't appear that Sony is going to make any more small HDV camcorders of this type, so the HC9 is the last one that will be available. I'm glad it uses interlaced scanning. When you combine a CMOS with progressive scan, there can be a serious problem with rolling shutter, which has an especially bad effect on videos of moving subjects.

For a high-performance telextender for the HC9, that doesn't vignette above 30% in the zoom range, you might try the Sony VCL-DH1758. It's a 1.7X telex, that is designed for high-resolution still cameras, but is ideal for small camcorders. I mount it with a 37mm to 58mm step-up ring, that I bought from B & H, one of the few places that carry such a step-ring, that adapts over a size range that wide. Its extra barrel size, is a main reason that it vignettes only in the bottom 30% of the zoom, while 37mm telextenders may cause vignetting at any point below 70% or 80% of the range. It can be bought for only about $100. (U.S.) and is a big bargain at that price.

For a photo of my HC9 on a shoulder-mount and a description of the accessories I have bought or made for it, go to this thread:
http://www.dvinfo.net/conf/hdv2-sony...cessories.html

Alastair Traill February 23rd, 2009 04:21 AM

Quote:

Originally Posted by Adam Gold (Post 1015811)
You can't control it directly, but you can assign the scroll wheel to exposure and make sure you are always four to six notches to the left of the maximum (18dB). Each notch is 3dB in most exposure modes, so six to the right is 0dB gain. Up to six, even nine dB is not really noticeable.

I have been considering purchasing an HC9 so that I can use the Nightshot mode with some more powerful IR lighting than the built-in camera light. However I have been put off because I am led to believe that in Nightshot the camera automatically selects the widest aperture and the highest gain. Does the above technique work with Nightshot?

Nelson Alexandre February 23rd, 2009 05:24 AM

Hi Stephen,

Many thanks for all your info. It really helps to make a decision.

I've been watching your videos. Cool stuff and impressive performance in low light as you had mentioned! I was under the impression that it performed much worse on those situations.

About telex and so, I'm planing to use it with my 35mm adapter. I mostly do documentary work and it's a pain doing a all day work with a XH-A1 fully loaded with 35mm adapter and bits on the shoulder. The HC9 takes about 2Kg from my shoulder and the whole rig becomes the same weight as the Canon XH-A1 alone!

I'm going to buy it definitely. Thanks once again.

J. Stephen McDonald February 23rd, 2009 06:13 AM

Quote:

Originally Posted by Nelson Alexandre (Post 1016754)
Hi Stephen,

Many thanks for all your info. It really helps to make a decision.

I've been watching your videos. Cool stuff and impressive performance in low light as you had mentioned! I was under the impression that it performed much worse on those situations.

About telex and so, I'm planing to use it with my 35mm adapter. I mostly do documentary work and it's a pain doing a all day work with a XH-A1 fully loaded with 35mm adapter and bits on the shoulder. The HC9 takes about 2Kg from my shoulder and the whole rig becomes the same weight as the Canon XH-A1 alone!

I'm going to buy it definitely. Thanks once again.


Thanks, Nelson, for your remarks. I'm glad you found my descriptions of the HC9 useful in making a decision. I'll be interested in seeing how that 35mm adaptor works out on this little camera. I used to pack around a full-sized Beta camcorder, on a counter-weighted shoulder-mount, that had a total weight of 10.5 Kg., so I understand how the HC9 will be an advantage for you. I once shot a speech by a presidential candidate, that lasted two hours with the big rig and it took me a couple of days to recover. I expected it to last just half an hour, but you know how politicians are.

Adam Gold February 23rd, 2009 03:24 PM

Quote:

Originally Posted by Alastair Traill (Post 1016745)
Does the above technique work with Nightshot?

I don't think it's possible.

Graham Hickling February 23rd, 2009 08:48 PM

Adam is correct - manual exposure is disabled when the camera is in nightshot mode. (Apparently people were using the mode in daylight to see through other folks' light clothing - ahem!).

I believe there is a company that offered to engineer the Sony nightshot mode for use in wildlife film-making - essentially adding a switch that moves the IR filter away from the sensor. There is a thread about that here: HDR-HC9 Conversion for Infrared use - The Digital Video Information Network

Edit: D'oh! That was your thread, Alastair. Sorry....

Nelson Alexandre February 23rd, 2009 08:59 PM

Quote:

Originally Posted by J. Stephen McDonald (Post 1016770)
I'll be interested in seeing how that 35mm adaptor works out on this little camera. (...) I expected it to last just half an hour, but you know how politicians are.

I'll be posting footage as soon I'll buy the camera which I'm planning to do this week. I'm also expecting to receive my SgBlade this week so I'll be eager to try it out. (...) and yes, I know how politicians are! I live in Portugal... So there's plenty of them around here! Unfortunately :)


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