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-   -   Same ISO, more light..? (http://www.dvinfo.net/forum/canon-eos-full-frame-hd/311592-same-iso-more-light.html)

Alessandro Merletti de Palo August 23rd, 2009 04:59 AM

Same ISO, more light..?
 
Hi everyone. I'm feeling a little bit stupid to ask it but:

why if I'm in manual, I have a dark subjet, I put 3200 ISO and it's still dark, while in Automatic/CA/P/TV etc. it still has 3200 ISO but pressing the af button it tells me the shutter's below 30 [impossibile with manual] so it gets more light?? Where's the trick? The exposure's the same in the various modes.. Sometimes I get very slow shutter values, but it doesn't even blend the frames! What is the camera really doing, and why the af button gives me those values?

Thank you,
A.

Don Miller August 23rd, 2009 11:36 AM

Which firmware version are you using?

Noah Yuan-Vogel August 24th, 2009 04:31 PM

its actually going into higher iso modes. you can tell because the image gets noisier as the shutter number goes down when iso is already at 3200. i also find isos over 3200 give an ugly green cast and very poor color rendition. i wouldnt go over iso3200.

Jon Fairhurst August 24th, 2009 05:01 PM

It sounds like you need a faster lens. Choose only 50, 160, 320, 640, and 1250 ISO, if you can, and make sure that HTP is off.

Wayne Avanson August 25th, 2009 04:57 AM

Sorry Jon,

what's HTP?

Avey

Ramesh Singh August 25th, 2009 11:44 AM

Keeping Shutter speed 1/60, WB in Shade, in dark rooms I have to ISO to something like 6400, is that really bad? I am using 70-200 f2.8.

If I try to keep it below 3200, picture becomes totally dark.

Daniel Browning August 25th, 2009 11:57 AM

Quote:

Originally Posted by Ramesh Singh (Post 1268140)
Keeping Shutter speed 1/60, WB in Shade, in dark rooms I have to ISO to something like 6400, is that really bad?

First you have to define "bad".

Is it bad compared to an HV20 in the same conditions? No, because the HV20 would come out looking even worse.

Is it bad compared to adding artificial lighting and shooting at ISO 100? Maybe. Only you can decide if you have the time/money/grip/etc. to setup lights for the shot.

Is it bad compared to using an f/1.2 lens and ISO 1250? Maybe. Only you can decide if you have the money, focus accuracy, and DOF to switch to f/1.2.

Is it bad compared to not getting the shot at all? Maybe. Only you can decide if ISO 6400 is so noisy that you will never use it (and is therefore a waste of time). For SD-DVD and a high key shot with good color balance, I think 6400 is just fine. In Tungsten, I wouldn't use anything above 1600.

Mike Hannon August 25th, 2009 04:17 PM

You mention the various modes that you are trying.

However, the camera should be in M mode for shooting video, with Live View set to Movie Display.

Otherwise what you see on the LCD and the readings that are given will not be accurate for video.

Jon Fairhurst August 25th, 2009 04:33 PM

Noise is lowest at 50 (extended), 160, 320, 640, and 1250 ISO. Above 1250, things get worse fast.

I try to shoot everything at the above ISOs with HTP disabled. Above 1250, try 1/30 shutter and 2500 ISO. Above that, get a faster lens and/or more light...

Daniel Browning August 25th, 2009 04:38 PM

Quote:

Originally Posted by Jon Fairhurst (Post 1269037)
Noise is lowest at 50 (extended)

We should warn people that ISO 50 is different: it has one stop less highlight headroom than all other ISO settings.

(What "ISO 50" actually does, behind the scenes, is just a one stop digital pull of ISO 100, so it clips highlights by one stop.)


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