Challenge III - Playing with ISO

[ricktas]

Please read the Learning Centre: Experimenting with ISO

You may need to read your camera user manual regarding ISO settings and how to change them.

Go out and take two photos, by setting your camera to Aperture mode (as per the first challenge), and selecting a suitable aperture of your choice. Once selected, do not change your aperture.

Take your first photo at ISO 100
Take your second photo at ISO 1600 (or the closest to 1600 your camera will allow)

Present both photos here and tell us what the differences are. Also consider what your camera did differently to get a correct exposure, between the two photos.

[Nanny]

I will go out tomorrow and do my homework Sir

[Nanny]

Have I done this right. I hop so

Ok here are my findings between ISO 100 and 1600

I had the camera in AV mode the Aperture I chose was 16 ISO was 100 I found the shutter speed was slower than in 1600 it was 1/90 and the lens zoomed in and out just a little there is a slight blurr to this photo.
In the second photo ISO 1600 Aperture 16 not changed the shutter speed was much faster
1/1500 the photo is alot sharper the background blur was ok to me.

Here are the camers settings I used

(ISO 100)
File Name IMG_1082.JPG
Camera Model Canon EOS 1000D
Shooting Date/Time 30/01/2009 9:36:57 AM
Shooting Mode Aperture-Priority AE
Tv( Shutter Speed ) 1/90
Av( Aperture Value ) 16.0
Metering Mode Evaluative Metering
Exposure Compensation 0
ISO Speed 100
Lens EF75-300mm f/4-5.6
Focal Length 300.0 mm
Image Size 3888x2592
Image Quality Fine
Flash Off
White Balance Mode Auto
AF Mode One-Shot AF
Picture Style Standard
Sharpness 3
Contrast 0
Saturation 0
Color tone 0
Color Space sRGB
Long exposure noise reduction 1:Auto
High ISO speed noise reduction 0:Off
File Size 2772 KB
Drive Mode Single shooting

(ISO 1600)

File Name IMG_1081.JPG
Camera Model Canon EOS 1000D
Shooting Date/Time 30/01/2009 9:36:31 AM
Shooting Mode Aperture-Priority AE
Tv( Shutter Speed ) 1/1500
Av( Aperture Value ) 16.0
Metering Mode Evaluative Metering
Exposure Compensation 0
ISO Speed 1600
Lens EF75-300mm f/4-5.6
Focal Length 300.0 mm
Image Size 3888x2592
Image Quality Fine
Flash Off
White Balance Mode Auto
AF Mode One-Shot AF
Picture Style Standard
Sharpness 3
Contrast 0
Saturation 0
Color tone 0
Color Space sRGB
Long exposure noise reduction 1:Auto
High ISO speed noise reduction 0:Off
File Size 4445 KB
Drive Mode Single shooting

[ricktas]

Good work Deb, Now look at the two photos, right above the highest point of your rock. Notice how in the second shot (ISO1600) the background looks not just blurry, but grainy as well. That is noise. You will often hear members talk about noise in high ISO shots. Its a grainy look to the image.

Noise occurs more and more as you increase your ISO. You will find a point where you increase ISO so much, that the noise overpowers the photo, it is good to experiment and find out where that point is with your camera. Remember it, cause in future if you need to use high ISO, you will know at what point to stop increasing the ISO, due to photo quality degredation.

Deb, you also realised how the shutter speed changed as you increased ISO. ISO increases basically make your sensor more sensitive to light, so a shorter shutter speed is required to get a correct exposure. This can be really handy if you are in a low light situation and want to freeze action. Increase your ISO and you can increase your shutter speed.

Looking forward to more members contributing to this thread.

[NikonNellie]

Ok I just did my homework. I promise I am not looking at your answer Rick as I type and have tried to observe the differences by looking at my settings and photos.

Photo 1: F/5, SS -1/30sec at ISO 100
Photo 2: F/5, SS - 1/400sec at ISO 1600

From this exercise I have observed that by setting the ISO to a higher number it reduces the time the shutter stays opened letting in less light, which compensates for the amount of light that the larger ISO number is allowing.

From the photos I have noticed that the photo taken with the larger ISO is more grainy (Noise). I can't really tell whether the exposure is affected because as I was taking the photos the sun was changing but I would have thought not if the shutter speed is being compensated for the larger ISO.

I hope I have explained myself well enough.

[ricktas]

Good work Nellie. read my post now to find out why your shutter speed increased, and where high ISO can be valuable to you.

[NikonNellie]

Thanks Rick - I'll add those tips to my collection. I am trying to put together a word document for my own use with a compilation of the tips I have been learning giving me a quick reference guide for certain situations. e.g Fireworks etc.

[Nanny]

Good work Deb, Now look at the two photos, right above the highest point of your rock. Notice how in the second shot (ISO1600) the background looks not just blurry, but grainy as well. That is noise. You will often hear members talk about noise in high ISO shots. Its a grainy look to the image.

Noise occurs more and more as you increase your ISO. You will find a point where you increase ISO so much, that the noise overpowers the photo, it is good to experiment and find out where that point is with your camera. Remember it, cause in future if you need to use high ISO, you will know at what point to stop increasing the ISO, due to photo quality degredation.

Deb, you also realised how the shutter speed changed as you increased ISO. ISO increases basically make your sensor more sensitive to light, so a shorter shutter speed is required to get a correct exposure. This can be really handy if you are in a low light situation and want to freeze action. Increase your ISO and you can increase your shutter speed.

Looking forward to more members contributing to this thread.

Thanks Rick I see now what you mean these should have been the ones I put up hey,
the 1600 the second one is quit noisy.

[chelle]

i have not read the other replies yet.... i wanted to post mine without reading other's discoveries.....although having read the Learning Centre i knew what to expect.

I took mine indoors under ****ty light so i look forward to taking another photo tomorrow of a decent subject. But this did the job!

The lower ISO was blurry and pointless. The higher ISO, while still blurry, is much better. I would still need a tripod if trying to photograph in such poor light.

The camera (A300) chose a shutter speed of 1sec at ISO 100 and chose 1/25th at 3200. I think 1/25th sounds fast enough to me for me to not get all that much blur....??? But i have deleted all the other daylight indoor shots so i can't check what else i have taken at that speed for a comparison.

The noise is really noticable on the second phoro (higher ISO) particularly on the label of the left wine bottle. It's probably even worse than the blur but i know that there is software to fix it (although i have never done it).

[bigdazzler]

youre all pretty much on the right track .. good work

Increasing your ISO is pretty simple in concept , it has positives and one major negative.

On the plus side by bumping your ISO up you effectively make your sensor more sensitive to the available light and subsequently will enable faster shutter speeds. This is very beneficial in low light situations when you want to handhold your camera or when photographing fast moving subjects and you want to freeze the action.

The major negative is obviously the noise. With increased sensitivity to light, digital noise is just a fact of life. Its handy to know at what ISO your camera starts to show very obvious levels of noise, usually its somewhere beyond 400 on the entry level cameras.

Dont worry too much about noise though as there is plenty of software out there to remove it such as Noise Ninja and Neat Image.

If it comes down to you capturing a little bit of noise in your picture or having motion blur from camera shake or because your shutter speed was too slow to freeze your moving subject , bump the ISO right up and get your shot !! You can deal with the noise later.

[Jcas]

The difference here is also very noticable, i deliberately tried to choose a background that would show it. i chose F16 .

[ricktas]

well done everyone. So now you have learnt that increasing the ISO, makes your sensor more sensitive to light, and therefore you can use a faster shutter speed than you would normally. This can be great for sports on overcast days, and getting the shot of that wren flitting around the local park.

Now consider what you learnt with your aperture challenge. Not the depth of field issue, but the other thing that happened when you shot with the lens wide open (f2.8/f4.5 - depending on the lens) compared to shooting at f16/f22.

If it was quite dark and you had gone to ISO 1600, but the photos are still a bit blurry of the fast moving wren flitting around the Park, what could you do to make the camera chose a faster shutter speed, when you can only change ISO and Aperture yourself, so you get a correct exposure.

[chelle]

increase the ISO like you said and also increase the amount of light coming in, which is a bigger opening which is a small f number. Which would also give you a smaller focused area (a narrower DOF).
So 1600 ISO and 3.5 aperture (for my Sony)

[ricktas]

increase the ISO like you said and also increase the amount of light coming in, which is a bigger opening which is a small f number. Which would also give you a smaller focused area (a narrower DOF).
So 1600 ISO and 3.5 aperture (for my Sony)

Thanks Chelle, great answer. Glad it is all starting to make sense. Will be good to see all the newbies using this area of the site, putting into practice their new skills and posting some photos for critique.

[Jcas]

increase the ISO like you said and also increase the amount of light coming in, which is a bigger opening which is a small f number. Which would also give you a smaller focused area (a narrower DOF).
So 1600 ISO and 3.5 aperture (for my Sony)

Thanks for putting it like that chelle, this is a bit like a jigsaw, finally it's all coming together ..

[chelle]

i actually wanted to go outside and see if, in practice, there was a good middle ground (for example an ISO of 800 and an aperture of 8). And to see how hard it was to capture something that was moving when using a narrower DOF.... but the kids would not go to bed soon enough and now it's too dark! D'oh!.

[clm738]

Hi Rick,
I have finally done my ISO homework.
ISO 100 @ 2.8
speed 1/500
file size 4.5mb
no noise @ 100% magnivication
fly on leaf

ISO 1600 @ 2.8
speed 1/8000
file size 5.5
lighter in colour
noise @ 100% magnification
no fly

conclusion: If I have camera shake I can up the ISO to around 1600 without visible noise to get a steady photo.
Can't insert photo but I will figure that out.

[Kym]

NTPers... You will see a lot of noise at higher ISOs in bad light.

Here's something to try if you feel up to it, you will need a tripod!

Take two night photos of your house from outside on the street
(you will need manual mode, and need to experiment a little at to exact Aperture and Shutter Speed depending on ambient light, full moon etc)

a) start with f/16, 16 seconds, Lowest ISO (100 or 200)
b) then f/16, 1 or 2 seconds at ISO 1600

I bet the noise will be really really obvious !!!

Why?
Simply... low light means low voltage on the sensor so when amplified (ISO 1600) the 'signal to noise' ratio sux (technical term )
Read the 2nd post of this thread (again) http://www.ausphotography.net.au/for...ad.php?t=24049

[Cathi]

Ok, this is my first attempt at putting photos up on here, so I hope I've done it right! I totally see the difference between ISO 100 to ISO 1600.. I had my camera set on F/5.6 and not only is there a definite presence of noise in the 1600 shot, it is also alot brighter. I also wanted to note that they were taken at different distances because the bees weren't liking me being so close to their food hehe

Here's the info (not sure how much to put):
Photo 1
ISO 100
Shutter Speed - 1/800
F-Stop - f/5.6
Focal Length - 54mm

Photo 2
ISO 1600
Shutter Speed - 1/4000
F-Stop - f/5.6
Focal Length - 54mm

[Kym]

Ok, this is my first attempt at putting photos up on here, so I hope I've done it right! I totally see the difference between ISO 100 to ISO 1600.. I had my camera set on F/5.6 and not only is there a definite presence of noise in the 1600 shot, it is also alot brighter. I also wanted to note that they were taken at different distances because the bees weren't liking me being so close to their food hehe

The reason the 2nd one is brighter is the ISO is 16 times more but the shutter speed is only 4000/800 = 5 times more.
So these two photos have been taken with a different exposure!

So lets change the first one to 1/250 and f/11 ISO 100 and the second one to 1/4000 and f/11 ISO 1600 they would be much closer.

Does that make sense?
It is a very important concept - getting the exposure triangle right!
Refer 2nd post in this thread: http://www.ausphotography.net.au/for...ad.php?t=24050