D750 ISO Performance

ahsan26

New member
I have got D750 3 days before and loving it by all means as upgraded from D7000 but the only thing which is bothering me is its ISO performance as NEF files show noise even at ISO 3200 and even more if its increased and I have read everywhere that this camera is best in ISO performance and you hardly see any noise even at ISO 6400...So what I am missing here ?
 

J-see

Senior Member
I have got D750 3 days before and loving it by all means as upgraded from D7000 but the only thing which is bothering me is its ISO performance as NEF files show noise even at ISO 3200 and even more if its increased and I have read everywhere that this camera is best in ISO performance and you hardly see any noise even at ISO 6400...So what I am missing here ?

It's not because ISO performance is good, the D750 won't show noise in its shots.

It depends on a lot of factors but the main problem is not ISO but low light. The moment you shoot in low light, you will have more noise in your signal and that gets amplified by ISO. The cam can try to do a clean conversion or amplification but much of it is unavoidable since there's no way to distinguish between a clean signal and a noisy one.
 

ahsan26

New member
So are u suggesting that its normal that D750 is producing or showing that noise and now I have to clean that by using the software ? then why are all people around saying that their images are clean at ISO 3200,6400 and even at ISO 12,800 ?
 

J-see

Senior Member
So are u suggesting that its normal that D750 is producing or showing that noise and now I have to clean that by using the software ? then why are all people around saying that their images are clean at ISO 3200,6400 and even at ISO 12,800 ?

Of course, it is impossible to create a cam that will not have noise during low light situations. It's not the cam, it's the nature of photons.

Let me explain what happens.

What we call noise is nothing but an inaccurate signal. The sensor captures photons and releases electrons in turn. But because photon behavior is not constant and fluctuates, it does receive a variation of the signal it theoretically should receive. There is always noise present in any signal we capture and that amount of noise is the square root of the signal captured. If a sensor pixel captures 100 photons there is 10 noise. If it captures 10.000 photons, there is 100 noise. While the second has more noise, it has a signal to noise ratio of 100 to one while the first with less noise in total only has a signal to noise ratio of 10 to 1 which implies that result will be much noisier in our shot.

There's nothing the cam can do about that part; it's physics and unavoidable.

We can get around it by trying to collect as much light as possible during a shot but that is only possible by opening the aperture or increasing the duration of the shutter. ISO does not affect it since it only amplifies the existing signal and thus also the existing noise.

All of this does not even include any in-cam noise which can be added for several reasons.

Thus, during low light you'll always have noise and the only method in removing it, is by doing that in post.

If people say they have a clean signal, they shoot during perfect situations and either clean the rest in post or simply don't check the shot at 100% level. I never shot any high ISO with the D750 that doesn't have some noise.

Good noise performance only implies that it doesn't fall apart as fast as previous models. The D750 does very well but that's all you can expect.
 
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ahsan26

New member
hmmmmm Thankyou for explaining in detail and the thing which i understand if we we better expose the pictutre even at high iso we will be in a better position to capture less noise in the image ....So whats the safe bet for D750 in ISO ? how far we can go with this camera body ?
 

J-see

Senior Member
hmmmmm Thankyou for explaining in detail and the thing which i understand if we we better expose the pictutre even at high iso we will be in a better position to capture less noise in the image ....So whats the safe bet for D750 in ISO ? how far we can go with this camera body ?

I have shot 6400 ISO and got very decent shots but not if I crop it too much. The best is always try to overexpose without it clipping highlights. When you do that and afterwards in post lower the exposure again, you make much noise disappear in the shadows. Higher than 6400 I consider emergency ISO.

To add: always try to increase the captured light by opening aperture or increasing shutter time. Only when you're at a limit there, use ISO since that does not improve the signal like the two others do.
 
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ahsan26

New member
It seem I get to know with your help what i was doing wrong over all these years as I always shoot underexpose with the impression that i can be in a better position in post by increasing the exposure and thats the reason i am noticing more noise in my images...Will defiantly try and over expose a bit and see the difference...Thanks alot for taking your time out and helping :)
 

J-see

Senior Member
It seem I get to know with your help what i was doing wrong over all these years as I always shoot underexpose with the impression that i can be in a better position in post by increasing the exposure and thats the reason i am noticing more noise in my images...Will defiantly try and over expose a bit and see the difference...Thanks alot for taking your time out and helping :)

The technique is called "Exposing to the right" or ETTR.

Here's the wiki on it and you can find more online if you google it.

Exposing to the right - Wikipedia, the free encyclopedia
 

ahsan26

New member
Very nice article and thanks for sharing it never heard abt this thing before and its seems basic info to me..Just one last thing in reference to this in order to get the right exposure what will you do if u have open the aperture to max as f2.8 and lower the shutter to 60-80 (as hand holding the camera) and using external flash with TTL on would u still increase the ISO to get the right exposure ?
 

J-see

Senior Member
Very nice article and thanks for sharing it never heard abt this thing before and its seems basic info to me..Just one last thing in reference to this in order to get the right exposure what will you do if u have open the aperture to max as f2.8 and lower the shutter to 60-80 (as hand holding the camera) and using external flash with TTL on would u still increase the ISO to get the right exposure ?


It's not an easy question to answer especially not for me since I never use flash and shoot at 100 ISO only regardless the situation but am probably the only D750 owner here shooting like that.

The moment you can not open up wider or go lower in shutter, ISO is the only option to increase the exposure of the shot. We often need a certain aperture or shutter speed to be able to take a shot.

But when we increase ISO, we only increase the exposure of the finished shot, we don't increase the exposure the sensor receives. ISO is the easy method to get the right exposure but there are other possibilities which are not that easy to explain and based upon the technical aspects of the D750 and what can be done during post-processing.

But generally, if your cam indicates the shot is underexposed even after you set the maximum aperture and shutter you need for that shot, it is best to increase ISO.
 
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Woodyg3

Senior Member
Contributor
Compare the noise at ISO 3200 between your D7000 and the D750 in a shot with the same subject and exposure. I'm sure you will see a big difference. :)
 

Horoscope Fish

Senior Member
Very nice article and thanks for sharing it never heard abt this thing before and its seems basic info to me..Just one last thing in reference to this in order to get the right exposure what will you do if u have open the aperture to max as f2.8 and lower the shutter to 60-80 (as hand holding the camera) and using external flash with TTL on would u still increase the ISO to get the right exposure ?
Photography is a juggling act between aperture, shutter speed and ISO. All the time, every time. You simply have to learn to work within those parameters. In a situation where you're shooting with a hot-shoe mounted flash, and using TTL, my go-to adjustments would be ISO and/or the flash compensation button to get the exposure I wanted out of the shot. I find digital "noise" the easiest thing to correct for in post processing, so it's the thing I worry about the least. I concern myself far more with shutter speed and aperture because those factors really determine the mood of the shot; ISO matters far less so, if at all, from an aesthetic standpoint.

Lastly, digital noise will *always* be more prevalent in the shadows than it will be in the highlights. It's not an ISO/noise thing, per se really, so much as an ISO/noise thing when shooting in low light where noise will appear the strongest. As someone pointed out above, try shooting the same LOW LIGHT shot with your D7000 and your D750, both at the same ISO, say 6400 or 12800, and I'm sure you'll a significant difference between how well the two cameras deal with noise.
....
 

J-see

Senior Member
Press the ISO button at the back and use the back scroll wheel at the same time.

Or set auto-ISO which can also be used in manual. Then you can even control that ISO to a degree by using the EV button.

What you also can do is simply up the exposure in post. The first 300 ISO (roughly) the D750 has close to zero increase in the shadows, if you shoot 14bit, which implies about all ISO does is identical to increasing exposure in post. But at a heavier price.
 
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J-see

Senior Member
Just a reminder that ISO is not just about noise. It permanently affects everything in regards to quality.

Everyone shoots as they like but it doesn't hurt to understand that the optimal performance of the D750 is at its native ISO of 100.

The moment we start upping the ISO, we start lowering that optimal performance.

If you look at tonal range as an example. At ISO 100 it can display about 9.6 bits which translates into around 800 distinguishable gray levels your RAW can display. At 1600 ISO that is 7.8 bits which is around 230 levels while at 6400 ISO you're left with 6.8 bits which is only about 110-120.

digitalimagesfigure5.jpg

The same happens to your colors and evidently your dynamic range.

In the end it is up to us to decide what compromise is best for any specific shot but regardless which we decide for, none comes without a cost.
 
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undercoverbrother

Senior Member
I am getting extremely dark images when I set the ISO myself to 100-800 for example. However I see shots at these ranges which are bright and amazing. I will post a picture of said issue later tonight if I get a time and figure out the best route to post images on Nikonites haha.

EDIT:

I have noticed improvements in pictures when the shutter speed is tweaked however @ ISO 100 my shutter is set at 1/3 whereas before it would have been 1/125 or higher.
 
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J-see

Senior Member
I'm not really sure what the problem is.

Each stop of ISO doubles the exposure which in an auto-mode will result in the cam either closing the lens down or increasing the shutter speed to keep the same exposure. If you yourself increase ISO (in manual), shots normally get lighter.
 

undercoverbrother

Senior Member
I'm not really sure what the problem is.

Each stop of ISO doubles the exposure which in an auto-mode will result in the cam either closing the lens down or increasing the shutter speed to keep the same exposure. If you yourself increase ISO (in manual), shots normally get lighter.

I have been shooting in manual lately at 1/60 shutter and 100 ISO the images are too dark, at 1/3 it is fine and with other shutter speeds and higher ISO the images are also fine.
 

J-see

Senior Member
I have been shooting in manual lately at 1/60 shutter and 100 ISO the images are too dark, at 1/3 it is fine and with other shutter speeds and higher ISO the images are also fine.

ISO is part of your exposure triangle so you need to set A, S and ISO in a correct combination when shooting. If the shot is too dark, you can up ISO, open the lens or lower the shutter.

To add: to make things a bit easier, there's an exposure indicator you see in the viewfinder or on the top LCD. If it is filled to the left, the shot is underexposed, if it starts filling to the right, it is overexposing. It'll differ depending metering.
 
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