Challenge III - Playing with ISO [Archive] - AusPhotography:: Australia's Premier Photography Forum::

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ricktas

29-01-2009, 8:47pm

Please read the Learning Centre: Experimenting with ISO (http://www.ausphotography.net.au/forum/showthread.php?t=24049)

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

29-01-2009, 9:03pm

I will go out tomorrow and do my homework Sir

Nanny

30-01-2009, 4:24pm

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

30-01-2009, 5:54pm

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

30-01-2009, 7:03pm

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

30-01-2009, 7:09pm

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

30-01-2009, 7:23pm

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

30-01-2009, 7:52pm

chelle

30-01-2009, 8:41pm

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

30-01-2009, 10:04pm

youre all pretty much on the right track .. good work :th3:

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

31-01-2009, 10:04am

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

ricktas

31-01-2009, 12:46pm

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

31-01-2009, 6:36pm

ricktas

31-01-2009, 6:56pm

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

31-01-2009, 7:05pm

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

31-01-2009, 7:22pm

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

03-02-2009, 11:28am

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

03-02-2009, 11:44am

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/forum/showthread.php?t=24049

Cathi

04-02-2009, 1:42pm

Kym

04-02-2009, 1:52pm

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/forum/showthread.php?t=24050

Cathi

04-02-2009, 1:56pm

That does make sense! I'm slowly getting the grasp of all these numbers hehe.. so should I go take another set with the settings you posted and see how it turns out? What priority should I set my camera to?

Cathi

04-02-2009, 2:11pm

Ok, so I just headed out and used the settings you mentioned in manual (M).. I definitely see the maths working now! I hope its ok to post another set of photos...

Photo 1
ISO 100
Shutter Speed - 1/250
F-Stop - f/11

Photo 2
ISO 1600
Shutter Speed - 1/4000
F-Stop - f/11

Awesome! Thank you for helping me learn something new today :D

MrJorge

04-02-2009, 3:06pm

Good job Cathi. Looks like you've done exactly what Kym was suggesting and by the sounds of it learnt something in the process. Well done :)

bigdazzler

04-02-2009, 3:08pm

and youll notice your exposure is now identical .. good job :th3:

Kym

04-02-2009, 3:52pm

Yes! Well done!

Now.... the noise in #2 is hardly noticeable!
Why? High ISO noise is more noticeable in low light situations; and these photos have good light.
This is to do with the electronics and the signal to noise ratio being bad in low light situations.

See: previous post http://www.ausphotography.net.au/forum/showthread.php?p=236961#post236961

chelle

04-02-2009, 6:51pm

Kym

04-02-2009, 10:08pm

ergh.. i'm tired and my brain is moosh but i want to understand the exposure triangle.... so despite having read it before i will attempt to read it again. Oh, i just stared at the numbers for long enough to realise what the maths of it is. Thank god that was not too hard!
I have not taken a photo for 36hours. It's probably still light enough outside..... nah, i'll finish this glass of wine instead...

In the learning guide I said it takes 2 - 4 months. http://www.ausphotography.net.au/forum/showthread.php?t=24290
Not without reason! You could do everything in the learning guide in a few days BUT you would not absorb the understanding!

Don't rush - its just takes time for this stuff to be 2nd nature and not some theoretical maths.
The odd glass of Shiraz (or whatever) does not hurt the process either!

Nic076

31-03-2009, 10:19am

Tried my shots in side.

First is:
ISO 100
Set Ap to f/5.2
Shutter was 1/1.6

Second is:
ISO 1600
Ap the same - f/5.2
Shutter was 1/20

As I was holding the camera, rather than tripod the first shot has a bit of shake due to the slowness of the shutter - causing a really soft image.

It was much faster the second time for a slightly sharper image. A bit hard to see the noise as the area was relatively good for lighting. I might try your suggestion Kym later tonight to see evidence of noise a bit easier.

ricktas

31-03-2009, 11:00am

Nic... Look at the background on the right side of your shot, where the shadow area is, you can see the noise there quite pronounced in the second shot compared to the first. As has been said, noise first becomes apparent in shadow areas, before the rest of the photo.

Good work.

Nic076

31-03-2009, 12:17pm

Thanks Rick - Have to admit I was looking more at the sauce and the left side of the pic. But now I do see it.

jaqson

02-04-2009, 6:37am

Hi All,
I took the op after work yesterday to grab my daughter and head down to the regatta grounds to take a few shots using different ISO settings. On my camera I have the choice between 100,200,400,500,1600. (So I did um all)

The first shot is 100ISO looking over the Tamer River, cloudy day.

http://i161.photobucket.com/albums/t224/edmondclan/The%20Tasmanian%20Clan/100ISO.jpg
Olympus E410
f8
1/100
100 ISO

http://i161.photobucket.com/albums/t224/edmondclan/The%20Tasmanian%20Clan/1600ISO.jpg
Olympus E410
f8
1/1250
1600 ISO

When physically taking the pictures I noticed that I had to increase the shutter speed on average around 3 stops (probably not correct terminology) per increase if ISO value.

Therefore the higher ISO I was using the more sensitive to light my image sensor became, needing a faster shutter speed to get the correct (or in my case near enough) exposure.

At first I didn't see the noise in this picture, however when I attempted to zoom in, I could visually see the grainy texture. Once I could pic up on it I noticed the noise in the hills at the back and the foreground around my daughter.

saratoga

02-04-2009, 10:11am

Thought I would have a go at this since I have never really played around much with ISO(usually tried to keep it on 100), but I'm now starting to realise it's a very important adjustment, perhaps just as important as aperture and shutter speed.

These photos of a hibiscus were taken with a tripod and a Nikon D200. The camera was set to Aperture priority with f10. The camera set the shutter speed as I changed the ISO settings.

The D200 is now a few years old and I believe the newer Nikons handle noise at higher ISO levels much better.

These are screen grabs of straight out of the camera jpegs with no adjustments to the image in photshop.

http://i239.photobucket.com/albums/ff85/pseudechis/100.jpg

http://i239.photobucket.com/albums/ff85/pseudechis/1600.jpg

These close ups are viewed at 100%..the same size as if the print was printed full size.

http://i239.photobucket.com/albums/ff85/pseudechis/2up.jpg

These four show the intermediate stages at 200%....I also took shots at ISO 400 and ISO 800 so that you can see the gradual degradation of the image.

http://i239.photobucket.com/albums/ff85/pseudechis/4up.jpg

I suppose it's all a fine balancing act of deciding the image quality you want, the end size you may print it at (in good quality) and either capturing, missing or blurring the shot.

As an aside, if you are looking at several versions of the same image like I have done, it's very handy in Photoshop to use the Window>Arrange>Tile horizontally feature and also the Window>Arrange>Match Zoom and Location feature.

sketty

11-05-2009, 8:33pm

These are about 15% of the full picture, I think that would make it a 600% crop?

ISO 100 0.8 f/5.6
http://farm4.static.flickr.com/3596/3521141329_c4c3c1e2ac_b.jpg

ISO 1600 1/20 f/5.6
http://farm4.static.flickr.com/3629/3521951946_1a295ee0eb_b.jpg

Ok, we've made the sensor more sensitive to light (by 4 stops) in order to reduce the shutter speed from 0.8 to 1/20 (4 stops), at the cost of introducing more noise. The noise can be removed in PP (haven't tried this yet so don't know how effective it is at this level).

Mostly you want to keep the camera at it's ideal/base ISO to minimise noise but you may need to bump up the iso when you need to get a certain aperture/shutter combination - probably especially important for those of us without 'fast' lenses who have less range to play with!

Would be important to know what the acceptable limit of your camera's ISO is before you get too much noise and how much you can remove in PP. Also depends on the size you plan on looking at/printing the image - the noise in the ISO1600 shot wasn't readily apparent in the original shot, only once you zoom in.

ricktas

11-05-2009, 8:45pm

Another good evaluation Skelly. You can post process noise out (neat image and noise ninja being two good bits of software that do it well). Generally though noise removal results in some smoothing of the photo, and sharpening is often needed in conjunction with noise removal.

A good scenario for higher ISO is sports shooting on dull days, or under lights, letting you get the shutter speed needed to freeze the action.

AmPhot

25-05-2009, 7:49pm

Just had a quick play in the loungeroom for this challenge, my very sleepy dog was the subject. Here's the results :

ISO 100, F22 18 sec :
http://img.photobucket.com/albums/v227/crouchy/CH03-ISO01.jpg

ISO 1600, F22, 1.1 sec :
http://img.photobucket.com/albums/v227/crouchy/CH03-ISO02.jpg

So in poor lighting, cranking up the ISO gives you a faster shutter speed but at the expense of having more noise in the background. But if you don't have a tripod handy or steady base to rest your camera it may be an option worth considering to gain some low light shots. As Rick mentioned, you can recover the image with some noise reduction in a graphics editing program.

ricktas

25-05-2009, 8:06pm

Someone looks very comfortable there amphot! Glad you have worked out where high ISO will be beneficial. Certainly helps for sport/action shots in dull light.

Humps n Bumps

27-05-2009, 10:27am

These were my results. Now I don't know if it's old eyes or not, but I can't seem to find the noise difference, more so just the exposure difference. (excuse me if I'm wording this all wrong). Should I try a different subject matter or background to see the difference?

Outside full sun

ISO 100
F16
SS 1/80

ISO 1600
F16
SS 1/1250

Inside no flash (I used the table as my tripod :) )

ISO 100
F4.5
SS 2

ISO 1600
F 4.5
SS 1/13

Humps n Bumps

27-05-2009, 10:31am

Oh, I forgot to add. I can see a the noise in the other photos (some after they were pointed out).

Lucky23

18-06-2009, 3:54am

I just had a go too.

Aperture=f/6.3
ISO=100
Shutter Speed=2.5sec
http://i696.photobucket.com/albums/vv323/Lucky2386/Foruploading0008.jpg

Aperture=f/6.3
ISO=1600
Shutter Speed=1/6sec
http://i696.photobucket.com/albums/vv323/Lucky2386/Foruploading0007.jpg

The noise in the second photo is quite obvious in comparison to the first one.

Through this challenge i learnt that a decrease in ISO number results in a decrease in shutter speed, to allow more light to hit the sensor. Through this principle i'm assuming a higher ISO is used for hand held shot in low light, as it would have a faster shutter speed. Good for me, since i don't have a tripod yet, although it would be at a cost of image quality :rolleyes:.

Hope that made sense. Well it does in my head :th3:.

draco

07-07-2009, 9:51pm

ok.. i thought i might give this a go and here are the results..

first, with ISO100, 1/4 sec

http://farm3.static.flickr.com/2656/3697133219_3f6eb67841_o.jpg

then, with ISO3200, 1/100 sec (grainy and noise very noticeable)

http://farm3.static.flickr.com/2459/3697945462_d02b974dbe_o.jpg

initially, what i wanted was to have the two shots to have the same settings except the ISO so I put it on manual and dialled in the aperture and shutter speed.. fine with the first photo.. but when I adjusted the ISO, the camera "cried foul" and gave me a warning that the photo would be over-exposed and this is due to the very high ISO ("light sensitivity") so I had to change the shutter to 1/100..

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 :D )

arthurking83

07-07-2009, 11:06pm

....

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 :D )

:th3:

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! :D.... 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! :p
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 :D

Newbie79

21-12-2009, 8:54pm

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

21-12-2009, 8:57pm

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

21-12-2009, 9:19pm

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

22-12-2009, 4:51am

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

01-06-2010, 10:46pm

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.
http://barrythelizard.jalbum.net/Clair%27s%20Pics/slides/iso100.jpg

2.
http://barrythelizard.jalbum.net/Clair%27s%20Pics/slides/iso1600.jpg

Thanks :)