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Old March 26th, 2010, 11:52 AM   #1
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how to compare ISO to GAIN (dB)?

Hello there!

I own 2 cameras...
One is Sony Z-1 HDV camcorder and the other DSLR Canon 5D Mk II, which, as every bird already knows, shoots quite interesting quality of video...

Now, something's been bothering me, espeically when lightning scenes...

If I need to let more LIGHT into my camcorder, except SHUTTER and APERTURE/IRIS (which both of my cameras have) - the 3rd value is DIFFERENT...

Canon lets me do it with changing ISO value (from 64 up to 6400)
AND
Sony lets me do it with building up my GAIN with form 0 - 18 dB....

Can you COMPARE these two values - are they representing the same thing in the first place, and what GAIN on my Sony Z-1 would equal ISO 100 on my Canon 5D...

I hope there is an answer to my question.. I tired Google it up, but all I got is some Dynamic Range info and very hard to understand charts :(

Hope you guys will be wise and enlighten me!!!

Cheers!
V.
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Old March 26th, 2010, 05:08 PM   #2
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Vanja,
I have never seen a direct comparison but I think of it as something like this:
For the sony there is a range of 0-18, 0 being no gain added. Let's say you could increase the gain +8 and still get a good image, over that it get's increasingly worse. (I don't own one so I'm just using this as an example.)
On the Canon, using ISO 64 as the starting number and ISO 6400 max maybe 1600 is where you notice the dropoff, thus equating to the +8 gain on the Sony. (again these are therorectical numbers, your mileage will vary by lens, condition etc)
There may be a range of numbers, such as ISO 64 to 200 on the Canon = +0 gain on the Sony. 200-400 = +1 gain, 400-600+=+2 etc.
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Old March 26th, 2010, 05:15 PM   #3
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How many forums have you posted this in???
It's the general rule only to POST IN A SINGLE FORUM otherwise the replies get out of hand.
It's very simple 6db gain = 1 stop, doubling ISO = 1 stop.
Steve
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Old March 28th, 2010, 04:50 PM   #4
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That makes sence!

Thnx guys!

And, Phillipe - I am truly sorry for posting it in 3 different forums - but I simply didn't know which one to choose...

I am not gonna do that again!

(although, I must say you are only person that red all 3 of them - the rest brought in handful of helpful threads!!! I know, I am not trying to justify what I did - I just found my self with a topic that I didn't know in which direction to aim - cause it was kind of Off Topic...
Wont happen again!
Thank you very much, again!
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