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Why does it need so much light?

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Norman Willis
Why does it need so much light?
on Jul 26, 2010 at 3:25:45 am

I bought a Canon 5DM2 to make better videos in studio. Lenses are the EF 16-35mm II F2.8L USM, and the EF 24-105mm F4L USM.

The 5DM2 wants something like 4 times as much light as my Canon HF S10's (AVCHD) in order to bring the ISO down to 400 or so. I had thought that it would need less light, since the 16-35 has such a big lens (82mm vs 58mm for the HF S10's).

I had to quadruple my lighting. I went from shooting with six each 45W fluorescent bulbs with the HF S10's, to twenty-four each 45W fluorescent bulbs, for the 5DM2. Is that normal? Or is something wrong with my camera?

Thanks.

Norman Willis
http://www.nazareneisrael.org


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Uli Plank
Re: Why does it need so much light?
on Jul 26, 2010 at 5:48:17 am

Nothing wrong there. You can use much higher ISO before getting noise. You are sure that you are exposing at 1/48th shutter speed?

Director of the Institute of Media Research (IMF) at Braunschweig University of Arts


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Norman Willis
Re: Why does it need so much light?
on Jul 26, 2010 at 10:18:25 am


>> You are sure that you are exposing at 1/48th shutter speed?


1/60th. I usually shoot 29.97, since I don't require a film look, and You-Tube/Vimeo is a secondary format.

>>You can use much higher ISO before getting noise.

Hm. Perhaps there is something I don't understand. I thought the lower the ISO, the higher the quality?

What ISO is ideal for top-quality DVD/BluRay?


Norman Willis
http://www.nazareneisrael.org


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Norman Pogson
Re: Why does it need so much light?
on Jul 26, 2010 at 12:32:51 pm

On a 5D2 you can easily go to 800 iso. I shoot with a 7D and yesterday was doing a home interior shoot with a model, using overcast window light and 10 x 45 watt daylight fluorescent lights diffused. I was getting f2 at 1/60th on 100 iso, as it got darker, I went up in stages to 200 iso.

I'm shooting stock footage so I do not want any visible noise. On the 7D multiples of iso 160 seem to have less noise.

My Canon 7D Blog


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Norman Willis
Re: Why does it need so much light?
on Jul 26, 2010 at 5:17:48 pm

I guess what I'm saying is that I had twelve each 45W light fluorescents blaring at a bookcase maybe twelve feet away, with talent 7 feet from lens, and that was maybe ISO 1000 to get a good picture.

With my HF S10's I would have had to shut over half of those lightbulbs off, or else I would have been wayyyy overexposed.

Norman Willis
http://www.nazareneisrael.org


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Phil Balsdon
Re: Why does it need so much light?
on Jul 26, 2010 at 1:49:04 pm

Sounds wrong to me. The 5D should need way less light than smaller sensor on the HFS10.

Cinematographer, Steadicam Operator, Final Cut Pro Post Production.
http://www.steadi-onfilms.com.au/


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Norman Willis
Re: Why does it need so much light?
on Jul 26, 2010 at 5:08:13 pm

>>Sounds wrong to me. The 5D should need way less light than smaller sensor on the HFS10.

Yeah, me also. I think I need to contact Canon.

Thanks.


Norman Willis
http://www.nazareneisrael.org


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Michael Sacci
Re: Why does it need so much light?
on Jul 26, 2010 at 5:42:27 pm

What was the f/stop of the lenses set to?

Also most of those small camcords have auto gain and can go as high as +18dB. So you have to shoot them side by side and compare the quality.

ISO for DVD/BluRay is the wrong thinking. Especially for DVD you do want the video to be as low noise as possible but proper exposure is still the most import, you have to learn the balance of the camera. Meaning properly exposed footage with iso 800 will look better than underexposed footage at 400.


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Norman Willis
Re: Why does it need so much light?
on Jul 26, 2010 at 5:54:47 pm

>>Also most of those small camcords have auto gain and can go as high as +18dB. So you have to shoot them side by side and compare the quality.

Is auto-gain like 'auto-iso'?

So I have to make sure the auto-gain (auto ISO?) is shut off, and then compare the light needs of the two?

So maybe I was using four bulbs, but could have used a lot more?



Norman Willis
http://www.nazareneisrael.org


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Ed Cilley
Re: Why does it need so much light?
on Jul 26, 2010 at 6:04:16 pm

[Norman Willis] "Is auto-gain like 'auto-iso'?"

Yes. And you don't want to use auto-iso.

We have shot with the 5DmII in office environment, using 1 Diva light (4 tubes) and had great results with similar lenses that you mentioned.

Ed

Avid and FCP Preditor
_________________________________________________
Anything worth doing at all, is worth doing well.
- Philip Dormer Stanhope, Earl of Chesterfield


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Norman Willis
Re: Why does it need so much light?
on Jul 26, 2010 at 6:19:53 pm

How many watts is each tube in your Diva light?

Norman Willis
http://www.nazareneisrael.org


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Norman Willis
Re: Why does it need so much light?
on Jul 26, 2010 at 6:29:40 pm

Hi Ed.

Let me ask this better.

You had one Diva light with four bulbs. How many watts of light is that? And far was your light source from the subject/talent? What ISO? What F-stop?

I am looking to recreate the settings here, and see if my camera gives a similar, or if something is off and I need to recalibrate.

Thanks.

Norman Willis
http://www.nazareneisrael.org


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Norman Willis
Re: Why does it need so much light?
on Jul 27, 2010 at 4:43:55 pm

Ed,

>>We have shot with the 5DmII in office environment, using 1 Diva light (4 tubes) and had great results with similar lenses that you mentioned.

What shutter speed, F/stop and ISO, maybe? (I won't hold you to it)

Thanks.

Norman Willis
http://www.nazareneisrael.org


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Norman Willis
Re: Why does it need so much light?
on Jul 26, 2010 at 6:35:06 pm

>>What was the f/stop of the lenses set to?

F/stop was 5.6, to get both the talent (7 feet to lens) and bookcase (12 feet to lens) in focus.

So perhaps a combination of no auto-gain (like on the prosumer cam), plus f/5.6 means I need lots more light with this rig?

Norman Willis
http://www.nazareneisrael.org


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Norman Willis
Re: Why does it need so much light?
on Jul 27, 2010 at 5:44:52 pm

I called Canon. Basically it is the auto-gain on the small camcorders, plus the fact that I had it choked down to f5.6.

Because the depth of field on the small camcorders is very long, it can shoot at F1.8, and it does not hesitate to boost the ISO. But in order to get both the talent and backdrop in focus I had to choke the 5DM2 down to f5.6, which cut the light by 7/8ths. That plus my earlier choice of ISO 800 and it created the need for a lot of light.

So I will redesign the studio to allow for a shallower depth of field and use ISO 800. Thanks all for your help.

Norman Willis
http://www.nazareneisrael.org


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Ed Cilley
Re: Why does it need so much light?
on Jul 26, 2010 at 5:43:49 pm

Norman,

How are you viewing the images? Is this on the camera LCD, external monitor, clips viewed on a computer?

I have found that the LCD may need adjustment on the 5DMII camera.

Ed

Avid and FCP Preditor
_________________________________________________
Anything worth doing at all, is worth doing well.
- Philip Dormer Stanhope, Earl of Chesterfield


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Norman Willis
Re: Why does it need so much light?
on Jul 26, 2010 at 6:01:38 pm

Good question.

The 5DM2 needs more light on all three (lcd screen, external monitor and clips viewed on the computer).

I think I need to check out what Michael was saying about the possibility that the HF S10 is applying a lot of auto-gain (automatically boosting the ISO).

Norman Willis
http://www.nazareneisrael.org


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Norman Pogson
Re: Why does it need so much light?
on Jul 26, 2010 at 8:15:02 pm

If you knew someone else with a 5D2 or even rent one to do a side by side comparison might point to a defective camera. I'm sure you know this but everything on the 5D2 should be manual settings for video.

My Canon 7D Blog


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Norman Willis
Re: Why does it need so much light?
on Jul 26, 2010 at 10:55:01 pm

Canon reports that I cannot shut off the auto-gain on the prosumer HF S10's, so I really cannot compare it to my 5DM2 :(

I don't know anyone else in this area who has a DSLR (it's rural).

Twelve feet from the lens is a black duvetyn ('commando cloth') backdrop. Directly in front of that is a bookcase. Five feet in front of that (seven feet from lens) is the talent. 16-35mm F2.8L USM lens set to F5.6, 1/60th, ISO 400: is it reasonable that I need twenty four each 45W fluorescent light bulbs (simulating 150W each) for a total of 1080W of fluorescent light, simulating 3600W of incandescent light (24 x 2800 lumens = 67,200 lumens)?

Is that reasonable? Or do I need to follow up? Thanks.

Norman Willis
http://www.nazareneisrael.org


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Norman Willis
Re: Why does it need so much light?
on Jul 26, 2010 at 11:34:35 pm

From Canon:

"The 82mm measurement that you provided has nothing to do with the light gathering abilities of the lens. It has everything to do with filter diameter, which is to say that it has nothing to do with the amount if light the lens is sensitive to.

The EF 16-35mm lens has a front aperture of f/2.8 versus the lens on the VIXIA HF S10 which has a maximum aperture of about f/1.8 and a lower sensitivity, 0.3 LX in the Night illumination mode. So the HF S10 has better light gathering ability in this area.

Once again, using lights with a higher wattage output will solve this issue. You can also consider increasing the ISO range on the EOS 5D Mark II."

So what is the maximum ISO I really want to use?

Norman Willis
http://www.nazareneisrael.org


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Ed Cilley
Re: Why does it need so much light?
on Jul 27, 2010 at 6:30:59 pm

Norman,

Sorry I didn't reply earlier with details. Canon's response sounds reasonable - along with the fact that you are getting auto-gain without asking for it in the HF S10. We tried not to shoot anything higher than ISO 800 and had good results. I know a couple shots used a higher setting, but I can't remember details exactly.

It now makes sense to me that you are having a difficult time getting similar results based on the fact that you had to stop down to f/5.6 on the 5D in order to achieve the depth of field you are looking for. That explains everything.

If you have time, it wouldn't hurt to do some ISO tests for yourself. Make sure to include some black areas, since that is where most noise will appear. Then take the clips into your editor and do a split screen between high and low ISO. This is one (very unscientific) way to determine what you are comfortable with.

Ed

Avid and FCP Preditor
_________________________________________________
Anything worth doing at all, is worth doing well.
- Philip Dormer Stanhope, Earl of Chesterfield


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Michael Sacci
Re: Why does it need so much light?
on Jul 27, 2010 at 12:47:13 am

that is not reasonable.


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