ISO VS Gain

[Randy Johnson]

please excuse my million questions on my new camera but what is the relationship between ISO and gain? It looks like I can go to 3200 ISO and have plenty of light but what is that doing to the image? is it like 36 db gain?

[Erik Wittbusch]

Base ISO is 200und = 0db

Add 6db = double ISO value:
6db = 400ISO
12db = 800ISO
18db = 1600ISO
24db = 3200ISO

I try to avoid values higher than 1600ISO/18db.
But the amount of digital grain also depends on your picture profile.
The higher the shadows are lifted, the more grain you'll see.

[Randy Johnson]

So either I add gain or ISO it really doesnt matter? ISO is equal to gain for the most part?

[Erik Wittbusch]

It's equal.

Just different readings.

Choose ISO if your familiar with and let the db readings alone...

[Randy Johnson]

Wow so it would seem that even with a fast lens this camera really sucks light. I am shooting in a very well flousencent bulb lit room and if I have it on 160 iso I dont have near enough light even if I get a faster lens it wouldnt be enough. On "The bright side:)" I shot last night at 1600 iso (I think) and looked at the footage and I couldnt really see much grain. So maybe there will be a lot of gained up shooting in my future.

[Chris Harding]

Base ISO is actually 160 on this camera not 200 so 6db will be 320ISO and 12db 640ISO etc etc.

I limit my cam at 21db for weddings which is around 3200 but the gain at 24db is still OK to use. Randy? try an F2.8 lens or faster in low light. BIG difference ... My Tokina 11-16 wide zoom at constant F2.8 is magic!!!

Chris

[Randy Johnson]

Where can I get it? B&H doesnt seem to have it. Do I need a adapter?

[Randy Johnson]

What about this?
http://www.bhphotovideo.com/c/product/91680-USA/Canon_2569A004_70_200mm_f_2_8L_USM_Autofocus.html

[Chris Quevedo]

Originally Posted by Randy Johnson

Where can I get it? B&H doesnt seem to have it. Do I need a adapter?

where can u find what? did you tried amazon?

[Chris Harding]

I'm using Novoflex adapters on both cameras (eBay Germany) They are expensive but shucks they are really like the original part and well worth the extra!!

I have Nikon D90's too so mine are for all my Nikon lenses.

Chris

[Chris Quevedo]

Originally Posted by Randy Johnson

What about this?
Canon EF 70-200mm f/2.8L USM Telephoto Zoom Lens2569A004 B&H

oh i see we're talkin about faster lenses. try the sigma 18-35mm f1.8, that will definitely be fast. just needs an adapter ;-)

[Noa Put]

Originally Posted by Chris Harding

the gain at 24db is still OK to use.

That would be 5000 iso I think, no? But have to say it looks bad in terms of noise at that iso, if you are desperate to get a shot then I"d say yes and use neatvideo, but otherwise better stay clear from it.

[Noa Put]

Originally Posted by Randy Johnson

So either I add gain or ISO it really doesnt matter? ISO is equal to gain for the most part?

It doesn't matter, also not what value in iso equals a gain value, you can use whatever you like and judge your footage afterwards to see what the max iso or gain is you can use before it turns ugly.

[Chris Harding]

Hi Noa

Yes, I agree..that's why I limit gain to 21db tops!! (or 3200 ISO) 24db is noisy even if you are using a light fill so both my cams limit at 21db so the dark areas are noise free ... 24 db (5000 ISO) will give you an image if you are desperate but yes, it will need cleaning up considerably. What a lot of people don't realise it that in auto iris, the camera looks at the complete image area so if you have a small subject close up and a huge dark background then it will lift gain or iso EVEN if you are using a fill light on the subject. On my Panny's Randy, I actually used to clamp gain right down to 12db and use a fill light so the big sensor on the 50 does a lot better!

Chris

[Serggio Lamas]

my camera iso starting from 160 after reset now starting from 200 to 6400 why?


solved...starting from 160 with no profile