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NEX iso step:

Rawfa

Active member
Hi,

I just got my NEX5 and even though I have yet to take to the streets for a real test I've spent a couple of hours playing with it and getting to know it. I have to say I'm glad to find out it's interface is not horrendous as most people were saying (actually the new firmware makes it pretty easy to use it).
I was just wondering if there is a way to increase the steps between ISO values. Right now it's 200, 400, 800, 1600, etc. Is there a way to make it like 200, 300, 400, 500, 600, well you get the idea. I really don't like having to go from 800 straight to 1600 or from 1600 straight to 3200.

cheers

Rafa
 
U

uhligfd

Guest
Well, these NEX ISO values go up by a factor of two; so the exposure time will decrease to half or the aperture will close one stop when going from 800 to 1600 ISO.

A fractional stop makes very little difference since ordinarily no one can tell an off-exposure of 1 stop. And going from 800 to 1600 in 100 ISO steps - as you suggest - would give us control down to 1/8 of a stop variation: quite ridiculous penny pinching in my mind.
 

monza

Active member
The incremental divisions between full ISO stops can help fine tune noise levels, I think that is what Rafa is getting at.
 
M

meilicke

Guest
I have not been able to set it manually. I do see the camera is able to do this when set on auto iso. It sure would be nice to have the option.
 
M

meilicke

Guest
Can't you use EV adjustment to effectively do the same thing?

Cheers,
How would that work?

EV would change just the shutter speed, affecting exposure, where changing ISO (and still using A, or P) would change both the ISO and shutter speed (or aperture if using S), keeping exposure constant.
 

douglasf13

New member
The good thing is that your camera only has one ISO, and everything else is a result of a boost from an analogue or digital amp (or combination of both.) Camera makers were just kind enough to represent this gain as ISOs, so that it made sense to film shooters. Depending on the quality of the camera's amps and the RAW converter that you use, you may be better off exposing only at certain ISOs and boosting in your RAW converter after that. Of course, that won't work if you're a jpeg shooter.
 

simonclivehughes

Active member
How would that work?

EV would change just the shutter speed, affecting exposure, where changing ISO (and still using A, or P) would change both the ISO and shutter speed (or aperture if using S), keeping exposure constant.
But you're still affecting exposure by the same f-stop equivalent. A doubling in ISO is a 1 f-stop difference. Any exposure is a combo of those 3 things: shutter, aperture and ISO. They are therefore interchangeable.

Cheers,
 
M

meilicke

Guest
But you're still affecting exposure by the same f-stop equivalent. A doubling in ISO is a 1 f-stop difference. Any exposure is a combo of those 3 things: shutter, aperture and ISO. They are therefore interchangeable.

Cheers,
I do agree with this. But I think to use EV comp. in place of changing ISO is only valid if the file has the room to pull the details when adjusting back in post. So within 1 EV or so, and an image without *too* much contrast, and you could probably be fine, which I think was the intent of your original post?
 

simonclivehughes

Active member
I do agree with this. But I think to use EV comp. in place of changing ISO is only valid if the file has the room to pull the details when adjusting back in post. So within 1 EV or so, and an image without *too* much contrast, and you could probably be fine, which I think was the intent of your original post?
Exactly... using +/-EV you can effectively fine tune the ISO in 1/3 EV steps, which gives you an even finer increment than the OP asked for.

Ciao,
 

douglasf13

New member
But you're still affecting exposure by the same f-stop equivalent. A doubling in ISO is a 1 f-stop difference. Any exposure is a combo of those 3 things: shutter, aperture and ISO. They are therefore interchangeable.

Cheers,
Exposure is actually only the amount of light hitting the sensor. ie, Shutter and aperture. ISO is the amount of gain that is added to the sensor after the fact (or none at all at base ISO,) and is not a part of exposure itself.
 

Rawfa

Active member
Man, this thread has grown my first post! A simple yes or no would sufice :)
thanks everybody
 

simonclivehughes

Active member
Exposure is actually only the amount of light hitting the sensor. ie, Shutter and aperture. ISO is the amount of gain that is added to the sensor after the fact (or none at all at base ISO,) and is not a part of exposure itself.
Yes, and if you alter the ISO for a given aperture/shutter setting, you alter the exposure. The fact that either aperture or shutter speed now needs to be changed to compensate shows this very clearly.

For what Rafa's wanting to do, (within +/-1 EV) what I suggest will do the trick. A 1/3 EV adjustment is equivalent to a 1/3 stop ISO shift.

Cheers,
 

Rawfa

Active member
I´m going to give this a try, Simon. I canno recall right now but I´m not sure the EV adjustment is available in manual mode, though.
 

douglasf13

New member
Yes, and if you alter the ISO for a given aperture/shutter setting, you alter the exposure. The fact that either aperture or shutter speed now needs to be changed to compensate shows this very clearly.

For what Rafa's wanting to do, (within +/-1 EV) what I suggest will do the trick. A 1/3 EV adjustment is equivalent to a 1/3 stop ISO shift.

Cheers,
We're getting technical here, but that is a common misunderstanding with digital photography. You never determine exposure by adjusting ISO in digital. You determine exposure by setting shutter speed and aperture. ISO is independent of exposure, and it simply changes gain amplification.

Changing ISO with a film camera actually affects the sensitivity of the film itself. However, with digital, changing ISO simply changes the amount of amplification to the exposure after the fact, and it doesn't actually change the sensitivity of the sensor itself. Digital sensors only have one sensitivity, and changing ISO is more akin to pushing or pulling your exposure, like with film. With digital, some decide to change their ISO settings in order to push/pull their exposures while shooting, and others shoot their digital camera at only one ISO and allow their RAW converters to push/pull the exposure at a later time. Neither method is always superior, and deciding which one works for you is dependent on the camera's amp quality and your raw converter's quality.**

When camera companies began with digital, they decided to show camera amplification in terms of ISO, in order for there to be a smooth transition in understanding from film to digital among users, but I think it is good to recognize the difference, if you're into the tech side of photography. As raw converters get better and better, we may someday see cameras with only one ISO.

**obviously, with a live view camera, like the NEX-5, it makes more sense to change ISO in camera, because you're dependent on an LCD screen for viewing, and you'll probably need the gain applied immediately. ie. changing ISO.
 
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C

curious80

Guest
With digital, some decide to change their ISO settings in order to push/pull their exposures while shooting, and others shoot their digital camera at only one ISO and allow their RAW converters to push/pull the exposure at a later time. Neither method is always superior, and deciding which one works for you is dependent on the camera's amp quality and your raw converter's quality.**
I don't think this is correct. The gain provided in hardware should pretty much always be better than doing it later in the RAW conversion (unless you are in one of the "extended" ISO modes which are done using software any way).

The most important reason is that the amplification in hardware is done before quantization, whereas raw converter works on quantized data which is goign to give inferior results.
 

douglasf13

New member
I don't think this is correct. The gain provided in hardware should pretty much always be better than doing it later in the RAW conversion (unless you are in one of the "extended" ISO modes which are done using software any way).
It depends on the camera, the ISO used, and the raw converter being used. For example, with the A900 and RPP, there really isn't a need to shoot over ~ISO 400-800.
 
M

meilicke

Guest
I don't think this is correct. The gain provided in hardware should pretty much always be better than doing it later in the RAW conversion (unless you are in one of the "extended" ISO modes which are done using software any way).

The most important reason is that the amplification in hardware is done before quantization, whereas raw converter works on quantized data which is goign to give inferior results.
I agree with you here, but I think the benefits of using EV is to get just that little more (or less), between available ISO stops.
 
U

uhligfd

Guest
Well, how then do you shoot lightning bugs at night with digital?

With ISO 400 they are too dim to show up on a dark night in the fields. With ISO 6400 they do. Can the raw converter simply pull the light trails out of the digital file?

Just wondering about the in camera gain versus in computer gain ...
 
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