Challenge III - Playing with ISO

[arthurking83]

....

indeed, I will be using higher ISOs on handheld shots when there is little light available to allow for faster shutter and avoid motion blur and camera shake (now I want an 2.8 IS lens )

there's everything to be gained by bumping up ISO for lower light shots to get the shot right.

Draco(and anyone else interested)
don't just bump up the ISO, use the AutoISO feature on your camera. Modern cameras all have this feature, some to a limited extent than others, but it's a very handy feature to have and use in the right conditions!
Reason it's handy, is that it frees you to simply concentrate on fewer aspects of getting a good shot.. so if you're constantly thinking about .. oooooh! what ISO do I need, am I exposing correctly..etc.
So while the camera is taking care of exposure for you...and you got an auto camera to do just that! .... you concentrate on getting a good composition, and or DOF, or whatever other element you feel is important.

So in Auto ISO, you may want to set ISO maximum to ISOxxxx(maximum of your camera), or an arbitrary limit you feel is best.
On my D300 I set maximum ISO to 3200, as I feel I can get good images(noise wise) at that point, and if I needed ISO6400.. I'll just go out and get a D700 instead!
Set your minimum shutter speed. This is where the ISO starts to vary. so if you need a certain exposure, and the camera's base ISO can't expose correctly(as you've set it!) then the camera will vary ISO upwards to maintain that shutter speed. 1/60s may be the default, as that seems to be the general all round accepted shutter speed for steady handheld shots.
But remember that speed is arbitrary too. If you;re using a 200mm lens, 1/60 may be totally inadequate, and if you are using a 17mm lens, then maybe you can push the minimum shutter speed down to 1/15s, or 1/20s.. and therefore allow a lower ISO.
The point is, that you want to give yourselves the best chance to get a good shot!
So sometimes using manual mode or shutter priority may be best in low light if you think that Auto ISO is going to help.

lastly: I've noticed that if you over expose by up to about 1stop.. that is set exposure compensation upwards(slower shutter) by about +0.3Ev, you can eliminate noise more effectively.
Even though you may need to use a slightly higher ISO level, that extra ISO may actually look less noisy than using less, in the final output as noise is generally more noticeable in the shadows(and as Draco found out in the bokeh or blur)
bokeh/blur noise is never an issue. As it's blurred anyhow.. use a very heavy noise reduction routine on it, you're not gong to lose any detail!
Don't ever worry about noise in blur.. you can totally eliminate noise in processing always.. but the disadvantage of doing that means loss of image sharpness/quality.
So worry about noise only in the detail sections of the image.
I recommend to those that are interested in the benefits of using ISO as an exposure control variable, to test out a few steps of over exposure in the image to see the difference in noise levels.
You may have to lower the brightness level in PP, and maybe use raw file type exclusively, to regain back any loss of highlight detail.
I never shoot in JPG mode, so I can't comment on how much latitude you have in over exposed those image types.

Something else I've noticed too. I did test out using jpg file type in camera, as I once read that the jpg file conversion in lot of cameras is very quite good. You may notice less noise in a jpg image straight out of the camera, than you will in the raw file.
Of course each camera will vary in that aspect too, but I've noticed with the old D70s(now a 5 or more year old camera) where the jpgs at high ISO look ok, as long as exposure was good to begin with. D300 does a little better, with lower noise.
I've never shot in jpg mode, and one day I'll learn to set the camera up to shoot in raw +jpg mode.
I don't have a dedicated noise reduction program, but Andrew(I@M) has shown me just exactly how powerful a program like Neat Image can be on high ISO shots. The ability to retain sharpness and detail while removing the ugly grey spottiness, is like magic!

Hmmmm... D700 or Neat Imaged D300 images?...... I think I'll just get me that D700 instead

[Newbie79]

Hi all,

I have been reading the Learning Centre: Experimenting with ISO Thread and need a few things clarified please.

I understand that Aperture and shutter speed are related. As a guide I believe if you half the shutter speed you need to double the aperture to get the same amount of light in (exposure).

I understand that all of the values below represent the same exposure:

Shutter Speed f/stop
1/4 second f/45
1/8 f/32
1/15 f/22
1/30 f/16
1/60 f/11
1/125 f/8
1/250 f/5.6
1/500 f/4
1/1000 f/2.8
1/2000 f/2
1/4000 f/1.4


What I don't understand is the following line that i read in the experimenting with aperture thread.


ISO is sensor sensitivity in a linear scale so halving or doubling ISO sensitivity therefore = one f/stop.

I understand that increasing ISO increases the sensitivity to light. What i don't understand is how this effects shutter speed and aperture. As an example if I had an ISO of 200 and shutter of 1/4000 and aperture of f/1.4 and then increased ISO to 400 what would happen to the shutter speed and aperture

Any help would be appreciated.

Thanks Matt

[kiwi]

Matt, nothing happens to them automatically. But to achieve the same exposure if you double ISO you neeed to either halve your shutter speed or your apperture

[Newbie79]

Okay,

Would I correct in saying then that if I had an ISO of 200 and shutter of 1/4000 and aperture of f/1.4 and then increased ISO to 400 , then to keep the same exposure I could either

1. change shutter speed to 1/2000 and keep aperture at f 1.4; or

2. change aperture to f2 and keep shutter speed at 1/4000

[ricktas]

That is exactly how it works. You have discovered already that shutter speed and aperture are inter-related, now you are learning the third component of the puzzle. It is often referred to as the exposure triangle, because exposure is reliant on three things - Shutter Speed - Aperture - ISO.

They are the three camera settings you have available to you, to 'create' your photos.

[barrythelizard]

I am working my way through the tutorials here, so thought I would add my discoveries to this thread.

1. ISO is 100 - av mode, f/4.5, shutter speed is 1/2.5 sec
2. ISO is 1600 - av mode, f/4.5, shutter speed is 1/40 sec

Shutter speed is quicker the higher the ISO plus the higher ISO image has noise. I tried every ISO setting on the camera and the cat did not move the entire time, however if the cat had been restless then I'd have more luck with the higher ISO because the shutter speed is quicker.

Next I have to get the cat to move so I can do the shutter speed challenge.

1.


2.


Thanks